<s> [INST] <<SYS>> You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information. <</SYS>> What is Apraxia and explain in detail? [/INST] Apraxia is a motor disorder caused by damage to the brain (specifically the posterior parietal cortex or corpus callosum), which causes difficulty with motor planning to perform tasks or movements. The nature of the damage determines the disorders severity, and the absence of sensory loss or paralysis helps to explain the level of difficulty. Children may be born with apraxia; its cause is unknown, and symptoms are usually noticed in the early stages of development. Apraxia occurring later in life, known as acquired apraxia, is typically caused by traumatic brain injury, stroke, dementia, Alzheimers disease, brain tumor, or other neurodegenerative disorders. The multiple types of apraxia are categorized by the specific ability and/or body part affected.
The term "apraxia" comes from the Greek ἀ- a- ("without") and πρᾶξις praxis ("action").

Types
The several types of apraxia include:

Apraxia of speech (AOS) is having difficulty planning and coordinating the movements necessary for speech (e.g. potato=totapo, topato). AOS can independently occur without issues in areas such as verbal comprehension, reading comprehension, writing, articulation, or prosody.
Buccofacial or orofacial apraxia, the most common type of apraxia, is the inability to carry out facial movements on demand. For example, an inability to lick ones lips, wink, or whistle when requested to do so. This suggests an inability to carry out volitional movements of the tongue, cheeks, lips, pharynx, or larynx on command.
Constructional apraxia is the inability to draw, construct, or copy simple configurations, such as intersecting shapes. These patients have difficulty copying a simple diagram or drawing basic shapes.
Gait apraxia is the loss of ability to have normal function of the lower limbs such as walking. This is not due to loss of motor or sensory functions.
Ideational/conceptual apraxia is having an inability to conceptualize a task and impaired ability to complete multistep actions. This form of apraxia consists of an inability to select and carry out an appropriate motor program.  For example, the patient may complete actions in incorrect orders, such as buttering bread before putting it in the toaster, or putting on shoes before putting on socks. Also, a loss occurs in the ability to voluntarily perform a learned task when given the necessary objects or tools. For instance, if given a screwdriver, these patients may try to write with it as if it were a pen, or try to comb their hair with a toothbrush.
Ideomotor apraxia is having deficits in the ability to plan or complete motor actions that rely on semantic memory.  These patients are able to explain how to perform an action, but unable to "imagine" or act out a movement such as "pretend to brush your teeth" or "pucker as though you bit into a sour lemon." When the ability to perform an action automatically when cued remains intact, though, this is known as automatic-voluntary dissociation. For example, they may not be able to pick up a phone when asked to do so, but can perform the action without thinking when the phone rings.
Limb-kinetic apraxia is having the inability to perform precise, voluntary movements of extremities. For example, a person affected by limb apraxia may have difficulty waving hello, tying shoes, or typing on a computer. This type is common in patients who have experienced a stroke, some type of brain trauma, or have Alzheimers disease.
Oculomotor apraxia is having difficulty moving the eye on command, especially with saccade movements that direct the gaze to targets. This is one of the three major components of Balints syndrome.

Causes
Apraxia is most often due to a lesion located in the dominant (usually left) hemisphere of the brain, typically in the frontal and parietal lobes. Lesions may be due to stroke, acquired brain injuries, or neurodegenerative diseases such as Alzheimers disease or other dementias, Parkinsons disease, or Huntingtons disease. Also, apraxia possibly may be caused by lesions in other areas of the brain.Ideomotor apraxia is typically due to a decrease in blood flow to the dominant hemisphere of the brain and particularly the parietal and premotor areas. It is frequently seen in patients with corticobasal degeneration.Ideational apraxia has been observed in patients with lesions in the dominant hemisphere near areas associated with aphasia, but more research is needed on ideational apraxia due to brain lesions. The localization of lesions in areas of the frontal and temporal lobes would provide explanation for the difficulty in motor planning seen in ideational apraxia, as well as its difficulty to distinguish it from certain aphasias.Constructional apraxia is often caused by lesions of the inferior nondominant parietal lobe, and can be caused by brain injury, illness, tumor, or other condition that can result in a brain lesion.

Diagnosis
Although qualitative and quantitative studies exist, little consensus exists on the proper method to assess for apraxia. The criticisms of past methods include failure to meet standard psychometric properties and research-specific designs that translate poorly to nonresearch use.The Test to Measure Upper Limb Apraxia (TULIA) is one method of determining upper limb apraxia through the qualitative and quantitative assessment of gesture production. In contrast to previous publications on apraxic assessment, the reliability and validity of TULIA was thoroughly investigated. The TULIA consists of subtests for the imitation and pantomime of nonsymbolic ("put your index finger on top of your nose"), intransitive ("wave goodbye"), and transitive ("show me how to use a hammer") gestures. Discrimination (differentiating between well- and poorly performed tasks) and recognition (indicating which object corresponds to a pantomimed gesture) tasks are also often tested for a full apraxia evaluation.However, a strong correlation may not be seen between formal test results and actual performance in everyday functioning or activities of daily living (ADLs). A comprehensive assessment of apraxia should include formal testing, standardized measurements of ADLs, observation of daily routines, self-report questionnaires, and targeted interviews with the patients and their relatives.As stated above, apraxia should not be confused with aphasia (the inability to understand language); however, they frequently occur together. Apraxia is so often accompanied by aphasia that many believe that if a person displays AOS, then the patient also having some level of aphasia should be assumed.

Treatment
Treatment for individuals with apraxia includes speech therapy, occupational therapy, and physical therapy. Currently, no medications are indicated for the treatment of apraxia, only therapy treatments. Generally, treatments for apraxia have received little attention for several reasons, including the tendency for the condition to resolve spontaneously in acute cases. Additionally, the very nature of the automatic-voluntary dissociation of motor abilities that defines apraxia means that patients may still be able to automatically perform activities if cued to do so in daily life. Nevertheless,  patients experiencing apraxia have less functional independence in their daily lives, and that evidence for the treatment of apraxia is scarce. However, a literature review of apraxia treatment to date reveals that although the field is in its early stages of treatment design, certain aspects can be included to treat apraxia.One method is through rehabilitative treatment, which has been found to positively impact apraxia, as well as ADLs. In this review, rehabilitative treatment consisted of 12 different contextual cues, which were used to teach patients how to produce the same gesture under different contextual situations. Additional studies have also recommended varying forms of gesture therapy, whereby the patient is instructed to make gestures (either using objects or symbolically meaningful and nonmeaningful gestures) with progressively less cuing from the therapist. Patients with apraxia may need to use a form of alternative and augmentative communication depending on the severity of the disorder. In addition to using gestures as mentioned, patients can also use communication boards or more sophisticated electronic devices if needed.No single type of therapy or approach has been proven as the best way to treat a patient with apraxia, since each patients case varies </s>


<s> [INST] <<SYS>> You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information. <</SYS>> What is 4 and explain in detail? [/INST] 4 (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5. It is the smallest semiprime and composite number, and is considered unlucky in many East Asian cultures.

In mathematics
Four is the smallest composite number, its proper divisors being 1 and 2. Four is the sum and product of two with itself:

        2

    {\displaystyle 2}
   +

        2

    {\displaystyle 2}
   =

        4

    {\displaystyle 4}
   =

        2

    {\displaystyle 2}
   x

        2

    {\displaystyle 2}
  , the only number

        b

    {\displaystyle b}
   such that

        a

    {\displaystyle a}
   +

        a

    {\displaystyle a}
   =

        b

    {\displaystyle b}
   =

        a

    {\displaystyle a}
   x

        a

    {\displaystyle a}
  , which also makes four the smallest squared prime number

          p

            2

    {\displaystyle p^{2}}
  . In Knuths up-arrow notation, 2 ↑↑ 2 = 2 ↑↑↑ 2 = 4, and so forth, for any number of up arrows. By consequence, four is the only square one more than a prime number, specifically three. The sum of the first four prime numbers two + three + five + seven is the only sum of four consecutive prime numbers that yields an odd prime number, seventeen, which is the fourth super-prime. Four lies between the first proper pair of twin primes, three and five, which are the first two Fermat primes, like seventeen, which is the third. On the other hand, the square of four 42, equivalently the fourth power of two 24, is sixteen; the only number that has

          a

            b

    {\displaystyle a^{b}}
   =

          b

            a

    {\displaystyle b^{a}}
   as a form of factorization. Holistically, there are four elementary arithmetic operations in mathematics: addition (+), subtraction (−), multiplication (×), and division (÷); and four basic number systems, the real numbers

          R

    {\displaystyle \mathbb {R} }
  , rational numbers

          Q

    {\displaystyle \mathbb {Q} }
  , integers

          Z

    {\displaystyle \mathbb {Z} }
  , and natural numbers

          N

    {\displaystyle \mathbb {N} }
  .
Each natural number divisible by 4 is a difference of squares of two natural numbers, i.e.

        4
        x

    {\displaystyle 4x}
   =

          y

            2

    {\displaystyle y^{2}}
   −

          z

            2

    {\displaystyle z^{2}}
  . A number is a multiple of 4 if its last two digits are a multiple of 4. For example, 1092 is a multiple of 4 because 92 = 4 × 23.
Lagranges four-square theorem states that every positive integer can be written as the sum of at most four square numbers. Three are not always sufficient; 7 for instance cannot be written as the sum of three squares.There are four all-Harshad numbers: 1, 2, 4, and 6. 12, which is divisible by four thrice over, is a Harshad number in all bases except octal.
A four-sided plane figure is a quadrilateral or quadrangle, sometimes also called a tetragon. It can be further classified as a rectangle or oblong, kite, rhombus, and square.
Four is the highest degree general polynomial equation for which there is a solution in radicals.The four-color theorem states that a planar graph (or, equivalently, a flat map of two-dimensional regions such as countries) can be colored using four colors, so that adjacent vertices (or regions) are always different colors. Three colors are not, in general, sufficient to guarantee this. The largest planar complete graph has four vertices.A solid figure with four faces as well as four vertices is a tetrahedron, which is the smallest possible number of faces and vertices a polyhedron can have. The regular tetrahedron, also called a 3-simplex, is the simplest Platonic solid. It has four regular triangles as faces that are themselves at dual positions with the vertices of another tetrahedron. Tetrahedra can be inscribed inside all other four Platonic solids, and tessellate space alongside the regular octahedron in the alternated cubic honeycomb.
Four-dimensional space is the highest-dimensional space featuring more than three regular convex figures:

Two-dimensional: infinitely many regular polygons.
Three-dimensional: five regular polyhedra; the five Platonic solids which are the tetrahedron, cube, octahedron, dodecahedron, and icosahedron.
Four-dimensional: six regular polychora; the 5-cell, 8-cell or tesseract, 16-cell, 24-cell, 120-cell, and 600-cell. The 24-cell, made of regular octahedra, has no analogue in any other dimension; it is self-dual, with its 24-cell honeycomb dual to the 16-cell honeycomb.
Five-dimensional and every higher dimension: three regular convex

        n

    {\displaystyle n}
  -polytopes, all within the infinite family of regular

        n

    {\displaystyle n}
  -simplexes,

        n

    {\displaystyle n}
  -hypercubes, and

        n

    {\displaystyle n}
  -orthoplexes.The fourth dimension is also the highest dimension where regular self-intersecting figures exist:

Two-dimensional: infinitaly many regular star polygons.
Three-dimensional: four regular star polyhedra, the regular Kepler-Poinsot star polyhedra.
Four-dimensional: ten regular star polychora, the Schläfli–Hess star polychora. They contain cells of Kepler-Poinsot polyhedra alongside regular tetrahedra, icosahedra and dodecahedra.
Five-dimensional and every higher dimension: zero regular star-polytopes; uniform star polytopes in dimensions

        n

    {\displaystyle n}
   >

        4

    {\displaystyle 4}
   are the most symmetric, which mainly originate from stellations of regular

        n

    {\displaystyle n}
  -polytopes.Altogether, sixteen (or 16 = 42) regular convex and star polychora are generated from symmetries of four (4) Coxeter Weyl groups and point groups in the fourth dimension: the

            A

            4

    {\displaystyle \mathrm {A} _{4}}
   simplex,

            B

            4

    {\displaystyle \mathrm {B} _{4}}
   hypercube,

            F

            4

    {\displaystyle \mathrm {F} _{4}}
   icositetrachoric, and

            H

            4

    {\displaystyle \mathrm {H} _{4}}
   hexacosichoric groups; with the

            D

            4

    {\displaystyle \mathrm {D} _{4}}
   demihypercube group generating two alternative constructions.
There are also sixty-four (or 64 = 43) four-dimensional Bravais lattices, and sixty-four uniform polychora in the fourth dimension based on the same

            A

            4

    {\displaystyle \mathrm {A} _{4}}
  ,

            B

            4

    {\displaystyle \mathrm {B} _{4}}
  ,

            F

            4

    {\displaystyle \mathrm {F} _{4}}
   and

            H

            4

    {\displaystyle \mathrm {H} _{4}}
   Coxeter groups, and extending to prismatic groups of uniform polyhedra, including one special non-Wythoffian form, the grand antiprism. There are also two infinite families of duoprisms and antiprismatic prisms in the fourth dimension.
Four-dimensional differential manifolds have some unique properties. There is only one differential structure on

            R

            n

    {\displaystyle \mathbb {R} ^{n}}
   except when

        n

    {\displaystyle n}
   =

        4

    {\displaystyle 4}
  , in which case there are uncountably many.
The smallest non-cyclic group has four elements; it is the Klein four-group. An alternating groups are not simple for values

        n

    {\displaystyle n}
   ≤

        4

    {\displaystyle 4}
  .
Further extensions of the real numbers under Hurwitzs theorem states that there are four normed division algebras: the real numbers

          R

    {\displaystyle \mathbb {R} }
  , the complex numbers

          C

    {\displaystyle \mathbb {C} }
  , the quaternions

          H

    {\displaystyle \mathbb {H} }
  , and the octonions

          O

    {\displaystyle \mathbb {O} }
  . Under Cayley–Dickson constructions, the sedenions

          S

    {\displaystyle \mathbb {S} }
   constitute a further fourth extension over

          R

    {\displaystyle \mathbb {R} }
  . The real numbers are ordered, commutative and associative algebras, as well as alternative algebras with power-associativity. The complex numbers

          C

    {\displaystyle \mathbb {C} }
   share all four multiplicative algebraic properties of the reals

          R

    {\displaystyle \mathbb {R} }
  , without being ordered. The quaternions loose a further commutative algebraic property, while holding associative, alternative, and power-associative properties. The octonions are alternative and power-associative, while the sedenions are only power-associative. The sedenions and all further extensions of these four normed division algebras are solely power-associative with non-trivial zero divisors, which makes them non-division algebras.

          R

    {\displaystyle \mathbb {R} }
   has a vector space of dimension 1, while

          C

    {\displaystyle \mathbb {C} }
  ,

          H

    {\displaystyle \mathbb {H} }
  ,

          O

    {\displaystyle \mathbb {O} }
   and

          S

    {\displaystyle \mathbb {S} }
   work in algebraic number fields of dimensions 2, 4, 8, and 16, respectively.

List of basic calculations
Evolution of the Hindu-Arabic digit
Brahmic numerals represented 1, 2, and 3 with as many lines. 4 was simplified by joining its four lines into a cross that looks like the modern plus sign. The Shunga would add a horizontal line on top of the digit, and the Kshatrapa and Pallava evolved the digit to a point where the speed of writing was a secondary concern. The Arabs 4 still had the early concept of the cross, but for the sake of efficiency, was made in one stroke by connecting the "western" end to the "northern" end; the "eastern" end was finished off with a curve. The Europeans dropped the finishing curve and gradually made the digit less cursive, ending up with a digit very close to the original Brahmin cross.While the shape of the character for the digit 4 has an ascender in most modern typefaces, in typefaces with text figures the glyph usually has a descender, as, for example, in .

On the seven-segment displays of pocket calculators and digital watches, as well as certain optical character recognition fonts, 4 is seen with an open top.Television stations that operate on channel 4 have occasionally made use of another variation of the "open 4", with the open portion being on the side, rather than the top. This version resembles the Canadian Aboriginal syllabics letter ᔦ. The magnetic ink character recognition "CMC-7" font also uses this variety of "4".

In religion
Buddhism
Four Noble Truths – Dukkha, Samudaya, Nirodha, Magga
Four sights – observations which affected Prince Siddhartha deeply and made him realize the sufferings of all beings, and compelled him to begin his spiritual journey—an old man, a sick man, a dead man, and an ascetic
Four Great Elements – earth, water, fire, and wind
Four Heavenly Kings
Four Foundations of Mindfulness – contemplation of the body, contemplation of feelings, contemplation of mind, contemplation of mental objects
Four Right Exertions
Four Bases of Power
Four jhānas
Four arūpajhānas
Four Divine Abidings – loving-kindness, compassion, sympathetic joy, and equanimity
Four stages of enlightenment – stream-enterer, once-returner, non-returner, and arahant
Four main pilgrimage sites – Lumbini, Bodh Gaya, Sarnath, and Kusinara

Judeo-Christian symbolism
The Tetragrammaton is the four-letter name of God.
Ezekiel has a vision of four living creatures: a man, a lion, an ox, and an eagle.
The four Matriarchs (foremothers) of Judaism are Sarah, Rebekah, Leah, and Rachel.
The Four Species (lulav, hadass, aravah and etrog) are taken as one of the mitzvot on the Jewish holiday of Sukkot. (Judaism)
The Four Cups of Wine to drink on the Jewish holiday of Passover. (Judaism)
The Four Questions to be asked on the Jewish holiday of Passover. (Judaism)
The Four Sons to be dealt with on the Jewish holiday of Passover. (Judaism)
The Four Expressions of Redemption to be said on the Jewish holiday of Passover. (Judaism)
The four Gospels: Matthew, Mark, Luke, and John. (Christianity)
The Four Horsemen of the Apocalypse ride in the Book of Revelation. (Christianity)
The four holy cities of Judaism: Jerusalem, Hebron, Safed, and Tiberius

Hinduism
There are four Vedas: Rigveda, Samaveda, Yajurveda and Atharvaveda.
In Puruṣārtha, there are four aims of human life: Dharma, Artha, Kāma, Moksha.
The four stages of life Brahmacharya (student life), Grihastha (household life), Vanaprastha (retired life) and Sannyasa (renunciation).
The four primary castes or strata of society: Brahmana (priest/teacher), Kshatriya (warrior/politician), Vaishya (landowner/entrepreneur) and Shudra (servant/manual laborer).
The swastika symbol is traditionally used in Hindu religions as a sign of good luck and signifies good from all four directions.
The god Brahma has four faces.
There are four yugas: Satya, Dvapara, Treta and Kali

Islam
Eid al-Adha lasts for four days, from the 10th to the 14th of Dhul Hijja.
The four holy cities of Islam: Mecca, Medina, Jerusalem and Damascus.
The four tombs in the Green Dome: Muhammad, Abu Bakr, Umar ibn Khattab and Isa ibn Maryam (Jesus).
There are four Rashidun or Rightly Guided Caliphs: Abu Bakr, Umar ibn al-Khattab, Uthman ibn Affan and Ali ibn Abi Talib.
The Four Arch Angels in Islam are: Jibraeel (Gabriel), Mikaeel (Michael), Izraeel (Azrael), and Israfil (Raphael)
There are four months in which war is not permitted: Muharram, Rajab, Dhu al-Qidah and Dhu al-Hijjah.
There are four Sunni schools of fiqh: Hanafi, Shafi`i, Maliki and Hanbali.
There are four major Sunni Imams: Abū Ḥanīfa, Muhammad ibn Idris ash-Shafi`i, Malik ibn Anas and Ahmad ibn Hanbal.
There are four books in Islam: Taurait, Zaboor, Injeel, Quran.
Waiting for four months is ordained for those who take an oath for abstention from their wives.
The waiting period of the woman whose husband dies is four months and ten days.
When Abraham said: "My Lord, show me how You give life to the dead," Allah said: "Why! Do you have no faith?" Abraham replied: "Yes, but in order that my heart be at rest." He said: "Then take four birds, and tame them to yourself, then put a part of them on every hill, and summon them; they will come to you flying. [Al-Baqara 2:260]
The respite of four months was granted to give time to the mushriks in Surah At-Tawba so that they should consider their position carefully and decide whether to make preparation for war or to emigrate from the country or to accept Islam.
Those who accuse honorable women (of unchastity) but do not produce four witnesses, flog them with eighty lashes, and do not admit their testimony ever after. They are indeed transgressors. [An-Noor 24:4]

Taoism
Four Symbols of I Ching

Other
In a more general sense, numerous mythological and cosmogonical systems consider Four corners of the world as essentially corresponding to the four points of the compass.
Four is the sacred number of the Zia, an indigenous tribe located in the U.S. state of New Mexico.
The Chinese, the Koreans, and the Japanese are superstitious about the number four because it is a homonym for "death" in their languages.
In Slavic mythology, the god Svetovid has four heads.

In politics
Four Freedoms: four fundamental freedoms that Franklin D. Roosevelt declared ought to be enjoyed by everyone in the world: Freedom of Speech, Freedom of Religion, Freedom from Want, Freedom from Fear.
Gang of Four: Popular name for four Chinese Communist Party leaders who rose to prominence during Chinas Cultural Revolution, but were ousted in 1976 following the death of Chairman Mao Zedong. Among the four was Maos widow, Jiang Qing. Since then, many other political factions headed by four people have been called "Gangs of Four".

In computing
Four bits (half a byte) are sometimes called a nibble.

In science
A tetramer is an oligomer formed out of four sub-units.

In astronomy
Four terrestrial (or rocky) planets in the Solar System: Mercury, Venus, Earth, and Mars.
Four giant gas/ice planets in the Solar System: Jupiter, Saturn, Uranus, and Neptune.
Four of Jupiters moons (the Galilean moons) are readily visible from Earth with a hobby telescope.
Messier object M4, a magnitude 7.5 globular cluster in the constellation Scorpius.
The Roman numeral IV stands for subgiant in the Yerkes spectral classification scheme.

In biology
Four is the number of nucleobase types in DNA and RNA – adenine, guanine, cytosine, thymine (uracil in RNA).
Many chordates have four feet, legs or leglike appendages (tetrapods).
The mammalian heart consists of four chambers.
Many mammals (Carnivora, Ungulata) use four fingers for movement.
All insects with wings except flies and some others have four wings.
Insects of the superorder Endopterygota, also known as Holometabola, such as butterflies, ants, bees, beetles, fleas, flies, moths, and wasps, undergo holometabolism—complete metamorphism in four stages—from (1) embryo (ovum, egg), to (2) larva (such as grub, caterpillar), then (3) pupa (such as the chrysalis), and finally (4) the imago.
In the common ABO blood group system, there are four blood types (A, B, O, AB).
Humans have four canines and four wisdom teeth.
The cows stomach is divided in four digestive compartments: reticulum, rumen, omasum and abomasum.

In chemistry
Valency of carbon (that is basis of life on the Earth) is four. Also because of its tetrahedral crystal bond structure, diamond (one of the natural allotropes of carbon) is the hardest known naturally occurring material. It is also the valence of silicon, whose compounds form the majority of the mass of the Earths crust.
The atomic number of beryllium
There are four basic states of matter: solid, liquid, gas, and plasma.

In physics
Special relativity and general relativity treat nature as four-dimensional: 3D regular space and one-dimensional time are treated together and called spacetime. Also, any event E has a light cone composed of four zones of possible communication and cause and effect (outside the light cone is strictly incommunicado).
There are four fundamental forces (electromagnetism, gravitation, the weak nuclear force, and the strong nuclear force).
In statistical mechanics, the four functions inequality is an inequality for four functions on a finite distributive lattice.

In logic and philosophy
The symbolic meanings of the number four are linked to those of the cross and the square. "Almost from prehistoric times, the number four was employed to signify what was solid, what could be touched and felt. Its relationship to the cross (four points) made it an outstanding symbol of wholeness and universality, a symbol which drew all to itself". Where lines of latitude and longitude intersect, they divide the earth into four proportions. Throughout the world kings and chieftains have been called "lord of the four suns" or "lord of the four quarters of the earth", which is understood to refer to the extent of their powers both territorially and in terms of total control of their subjects doings.
The Square of Opposition, in both its Aristotelian version and its Boolean version, consists of four forms: A ("All S is R"), I ("Some S is R"), E ("No S is R"), and O ("Some S is not R").
In regard to whether two given propositions can have the same truth value, there are four separate logical possibilities: the propositions are subalterns (possibly both are true, and possibly both are false); subcontraries (both may be true, but not that both are false); contraries (both may be false, but not that both are true); or contradictories (it is not possible that both are true, and it is not possible that both are false).
Aristotle held that there are basically four causes in nature: the material, the formal, the efficient, and the final.
The Stoics held with four basic categories, all viewed as bodies (substantial and insubstantial): (1) substance in the sense of substrate, primary formless matter; (2) quality, matters organization to differentiate and individualize something, and coming down to a physical ingredient such as pneuma, breath; (3) somehow holding (or disposed), as in a posture, state, shape, size, action, and (4) somehow holding (or disposed) toward something, as in relative location, familial relation, and so forth.
Immanuel Kant expounded a table of judgments involving four three-way alternatives, in regard to (1) Quantity, (2) Quality, (3) Relation, (4) Modality, and, based thereupon, a table of four categories, named by the terms just listed, and each with three subcategories.
Arthur Schopenhauers doctoral thesis was On the Fourfold Root of the Principle of Sufficient Reason.
Franz Brentano held that any major philosophical period has four phases: (1) Creative and rapidly progressing with scientific interest and results; then declining through the remaining phases, (2) practical, (3) increasingly skeptical, and (4) literary, mystical, and scientifically worthless—until philosophy is renewed through a new periods first phase. (See Brentanos essay "The Four Phases of Philosophy and Its Current State" 1895, tr. by Mezei and Smith 1998.)
C. S. Peirce, usually a trichotomist, discussed four methods for overcoming troublesome uncertainties and achieving secure beliefs: (1) the method of tenacity (policy of sticking to initial belief), (2) the method of authority, (3) the method of congruity (following a fashionable paradigm), and (4) the fallibilistic, self-correcting method of science (see "The Fixation of Belief", 1877); and four barriers to inquiry, barriers refused by the fallibilist: (1) assertion of absolute certainty; (2) maintaining that something is unknowable; (3) maintaining that something is inexplicable because absolutely basic or ultimate; (4) holding that perfect exactitude is possible, especially such as to quite preclude unusual and anomalous phenomena (see "F.R.L." [First Rule of Logic], 1899).
Paul Weiss built a system involving four modes of being: Actualities (substances in the sense of substantial, spatiotemporally finite beings), Ideality or Possibility (pure normative form), Existence (the dynamic field), and God (unity). (See Weisss Modes of Being, 1958).
Karl Popper outlined a tetradic schema to describe the growth of theories and, via generalization, also the emergence of new behaviors and living organisms: (1) problem, (2) tentative theory, (3) (attempted) error-elimination (especially by way of critical discussion), and (4) new problem(s). (See Poppers Objective Knowledge, 1972, revised 1979.)
John Boyd (military strategist) made his key concept the decision cycle or OODA loop, consisting of four stages: (1) observation (data intake through the senses), (2) orientation (analysis and synthesis of data), (3) decision, and (4) action. Boyd held that his decision cycle has philosophical generality, though for strategists the point remains that, through swift decisions, one can disrupt an opponents decision cycle.
Richard McKeon outlined four classes (each with four subclasses) of modes of philosophical inquiry: (1) Modes of Being (Being); (2) Modes of Thought (That which is); (3) Modes of Fact (Existence); (4) Modes of Simplicity (Experience)—and, corresponding to them, four classes (each with four subclasses) of philosophical semantics: Principles, Methods, Interpretations, and Selections. (See McKeons "Philosophic Semantics and Philosophic Inquiry" in Freedom and History and Other Essays, 1989.)
Jonathan Lowe (E.J. Lowe) argues in The Four-Category Ontology, 2006, for four categories: kinds (substantial universals), attributes (relational universals and property-universals), objects (substantial particulars), and modes (relational particulars and property-particulars, also known as "tropes"). (See Lowes "Recent Advances in Metaphysics," 2001, Eprint)
Four opposed camps of the morality and nature of evil: moral absolutism, amoralism, moral relativism, and moral universalism.

In technology
The resin identification code used in recycling to identify low-density polyethylene.
Most furniture has four legs – tables, chairs, etc.
The four color process (CMYK) is used for printing.
Wide use of rectangles (with four angles and four sides) because they have effective form and capability for close adjacency to each other (houses, rooms, tables, bricks, sheets of paper, screens, film frames).
In the Rich Text Format specification, language code 4 is for the Chinese language. Codes for regional variants of Chinese are congruent to 4 mod 256.
Credit card machines have four-twelve function keys.
On most phones, the 4 key is associated with the letters G, H, and I, but on the BlackBerry Pearl, it is the key for D and F.
On many computer keyboards, the "4" key may also be used to type the dollar sign ($) if the shift key is held down.
It is the number of bits in a nibble, equivalent to half a byte
In internet slang, "4" can replace the word "for" (as "four" and "for" are pronounced similarly). For example, typing "4u" instead of "for you".
In Leetspeak, "4" may be used to replace the letter "A".
The TCP/IP stack consists of four layers.

In transport
Many internal combustion engines are called four-stroke engines because they complete one thermodynamic cycle in four distinct steps: Intake, compression, power, and exhaust.
Most vehicles, including motor vehicles, and particularly cars/automobiles and light commercial vehicles have four road wheels.
"Quattro", meaning four in the Italian language, is used by Audi as a trademark to indicate that all-wheel drive (AWD) technologies are used on Audi-branded cars. The word "Quattro" was initially used by Audi in 1980 in its original 4WD coupé, the Audi Quattro. Audi also has a privately held subsidiary company called quattro GmbH.
List of highways numbered 4

In sports
In the Australian Football League, the top level of Australian rules football, each team is allowed 4 "interchanges" (substitute players), who can be freely substituted at any time, subject to a limit on the total number of substitutions.
In baseball:
There are four bases in the game: first base, second base, third base, and home plate; to score a run, an offensive player must complete, in the sequence shown, a circuit of those four bases.
When a batter receives four pitches that the umpire declares to be "balls" in a single at-bat, a base on balls, informally known as a "walk", is awarded, with the batter sent to first base.
For scoring, number 4 is assigned to the second baseman.
Four is the most runs that can be scored on any single at bat, whereby all three baserunners and the batter score (the most common being via a grand slam).
The fourth batter in the batting lineup is called the cleanup hitter.
In basketball, the number four is used to designate the power forward position, often referred to as "the four spot" or "the four".
In cricket, a four is a specific type of scoring event, whereby the ball crosses the boundary after touching the ground at least one time, scoring four runs. Taking four wickets in four consecutive balls is typically referred to as a double hat trick (two consecutive, overlapping hat tricks).
In American Football teams get four downs to reach the line of gain.
In rowing, a four refers to a boat for four rowers, with or without coxswain. In rowing nomenclature, 4− represents a coxless four and 4+ represents a coxed four.
In rugby league:
A try is worth 4 points.
One of the two starting centres wears the jersey number 4. (An exception to this rule is the Super League, which uses static squad numbering.)
In rugby union:
One of the two starting locks wears the jersey number 4.
In the standard bonus points system, a point is awarded in the league standings to a team that scores at least 4 tries in a match, regardless of the match result.

In other fields
The phrase "four-letter word" is used to describe many swear words in the English language.
Four is the only number whose name in English has the same number of letters as its value.
Four (四, formal writing: 肆, pinyin sì) is considered an unlucky number in Chinese, Korean, Vietnamese and Japanese cultures mostly in Eastern Asia because it sounds like the word "death" (死, pinyin sǐ). To avoid complaints from people with tetraphobia, many numbered product lines skip the "four": e.g. Nokia cell phones (there was no series beginning with a 4 until the Nokia 4.2), Palm PDAs, etc </s>


<s> [INST] <<SYS>> You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information. <</SYS>> What is Intractability and explain in detail? [/INST]  </s>


<s> [INST] <<SYS>> You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information. <</SYS>> What is Ear pain and explain in detail? [/INST] Ear pain, also known as earache or otalgia, is pain in the ear. Primary ear pain is pain that originates from the ear. Secondary ear pain is a type of referred pain, meaning that the source of the pain differs from the location where the pain is felt.
Most causes of ear pain are non-life-threatening. Primary ear pain is more common than secondary ear pain, and it is often due to infection or injury. The conditions that cause secondary (referred) ear pain are broad and range from temporomandibular joint syndrome to inflammation of the throat.In general, the reason for ear pain can be discovered by taking a thorough history of all symptoms and performing a physical examination, without need for imaging tools like a CT scan. However, further testing may be needed if red flags are present like hearing loss, dizziness, ringing in the ear or unexpected weight loss.Management of ear pain depends on the cause. If there is a bacterial infection, antibiotics are sometimes recommended and over the counter pain medications can help control discomfort. Some causes of ear pain require a procedure or surgery.83 percent of children have at least one episode of a middle ear infection by three years of age.

Signs and symptoms
Ear pain can present in one or both ears. It may or may not be accompanied by other symptoms such as fever, sensation of the world spinning, ear itchiness, or a sense of fullness in the ear. The pain may or may not worsen with chewing. The pain may also be continuous or intermittent.Ear pain due to an infection is the most common in children and can occur in babies. Adults may need further evaluation if they have hearing loss, dizziness or ringing in the ear. Additional red flags include diabetes, a weakened immune system, swelling seen on the outer ear, or swelling along the jaw.

Causes
Ear pain has a variety of causes, the majority of which are not life-threatening. Ear pain can originate from a part of the ear itself, known as primary ear pain, or from an anatomic structure outside the ear that is perceived as pain within the ear, known as secondary ear pain. Secondary ear pain is a type of referred pain, meaning that the source of the pain differs from the location where the pain is felt. Primary ear pain is more common in children, whereas secondary (referred) pain is more common in adults.Primary ear pain is most commonly caused by infection or injury to one of the parts of the ear.

External ear
Many conditions involving the external ear will be visible to the naked eye.  Because the external ear is the most exposed portion of the ear, it is vulnerable to trauma or environmental exposures.  Blunt trauma, such as a blow to the ear, can result in a hematoma, or collection of blood between the cartilage and perichondrium of the ear. This type of injury is particularly common in contact sports such as wrestling and boxing. Environmental injuries include sunburn, frostbite, or contact dermatitis.Less common causes of external ear pain include:
Auricular Cellulitis: a superficial infection of the ear that may be precipitated by trauma, an insect bite, or ear piercing
Perichondritis: infection of the perichondrium, or fascia surrounding the ear cartilage, which can develop as a complication of untreated auricular cellulitis. It is important to identify and treat perichondritis with antibiotics to avoid permanent ear deformities.
Relapsing polychondritis: a systemic inflammatory condition involving cartilage in many parts of the body, but often including the cartilage of both ears. The severity and prognosis of the disease varies widely.

Otitis externa
Otitis externa, also known as "swimmers ear", is a cellulitis of the external ear canal. In North America, 98% of cases are caused by bacteria, and the most common causative organisms are Pseudomonas and Staph aureus. Risk factors include exposure to excessive moisture (e.g. from swimming or a warm climate) and disruption of the protective cerumen barrier, which can result from aggressive ear cleaning or placing objects in the ear.Malignant otitis externa is a rare and potentially life-threatening complication of otitis externa in which the infection spreads from the ear canal into the surrounding skull base, hence becoming an osteomyelitis. It occurs largely in diabetic patients. It is very rare in children, though can be seen in immunocompromised children and adults. Pseudomonas is the most common causative organism. The pain tends to be more severe than in uncomplicated otitis externa, and laboratory studies often reveal elevated inflammatory markers (ESR and/or CRP). The infection may extend to cranial nerves, or rarely to the meninges or brain. Examination of the ear canal may reveal granulation tissue in the inferior canal. It is treated with several weeks of IV and oral antibiotics, usually fluoroquinolones.

Mechanical obstruction
Earwax impaction: results in 12 million medical visits annually in the United States. Cerumen impaction may cause ear pain, but it can also prevent thorough examination of the ear and identification of an alternate source of pain.
Foreign body: commonly include insects or small objects like beads

Less common
Herpes zoster: varicella zoster virus can reactivate in an area that includes the ear. Reactivation can produce pain and visible vesicles within the ear canal and, when combined with facial paralysis due to facial nerve involvement, is called Ramsay Hunt syndrome.
Tumors: the most common ear canal tumor is squamous cell carcinoma. Symptoms can resemble those of otitis externa, and cancer should be considered if the symptoms are not improving on appropriate treatment.

Middle and inner ear
Acute otitis media
Acute otitis media is an infection of the middle ear. More than 80% of children experience at least one episode of otitis media by age 3 years.  Acute otitis media is also most common in these first 3 years of life, though older children may also experience it. The most common causative bacteria are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.  Otitis media often occurs with or following cold symptoms. The diagnosis is made by the combination of symptoms and examination of the tympanic membrane for redness, bulging, and/or a middle ear effusion (collection of fluid within the middle ear).Complications of otitis media include hearing loss, facial nerve paralysis, or extension of infection to surrounding anatomic structures, including:
Mastoiditis: infection of the air cells in the mastoid process, the area of the skull located right behind the ear
Petrositis: infection of the petrous portion of the temporal bone
Labyrinthitis
Meningitis
Subdural abscess
Brain abscess
Cerebral venous sinus thrombosis

Trauma
Barotrauma: results from changes in atmospheric pressure that occur when descending in a plane or deep diving.  As atmospheric pressure increases with descent, the eustachian tube collapses due to pressure within the middle ear being less than the external pressure, which causes pain. In severe cases, middle ear hemorrhage or tympanic membrane rupture can result.
Tympanic membrane rupture: disruption of the eardrum. This can be caused by a blow to the ear, blast injury, barotrauma, or direct penetration of the tympanic membrane by an object entering the ear.

Referred ear pain
A variety of conditions can cause irritation of one of the nerves that provides sensation to the ear.
Conditions causing irritation the trigeminal nerve (cranial nerve V):
Temporomandibular joint syndrome: inflammation or abnormal movements of the joint between the jaw and skull. These disorders are most common in women of childbearing age, and are uncommon in children younger than 10 years old.
Myofascial pain syndrome: pain in the muscles involved in chewing. There may be certain parts of the muscles or tendons (connective tissue connecting the muscles to bones) that are especially painful when pressed
Trigeminal neuralgia: attacks of shooting pain down the face that may be triggered by touching the face or temperature changes
Dental pain from cavities or an abscess
Oral cavity carcinomaConditions causing irritation of the facial nerve (cranial nerve VII) or glossopharyngeal nerve (cranial nerve IX):
Tonsillitis: infection/inflammation of the tonsils
Post-tonsillectomy: pain following surgical removal of the tonsils
Pharyngitis: infection/inflammation of the throat
Sinusitis
Parotitis: inflammation of the parotid gland, the salivary gland right in front of the ear
Carcinoma of the oropharynx (base of tongue, soft palate, pharyngeal wall, tonsils)Conditions causing irritation of the vagus nerve (cranial nerve X):
GERD
Myocardial ischemia (inadequate oxygen supply to the heart muscle)Conditions causing irritation of cervical nerves C2-C3:
Cervical spine trauma, arthritis (joint inflammation), or tumor
Temporal arteritis: an autoimmune disorder leading to inflammation of the temporal artery, a large artery in the head. This condition tends to occur in adults older than 50.

Pathophysiology
Primary ear pain
The ear can be anatomically divided into the external ear, the external auditory canal, the middle ear, and the inner ear. These three are indistinguishable in terms of the pain experienced.

Secondary ear pain
Many different nerves provide sensation to the various parts of the ear, including cranial nerves V (trigeminal), VII (facial), IX (glossopharyngeal), and X (vagus), and the great auricular nerve (cervical nerves C2-C3). These nerves also supply other parts of the body, from the mouth to the chest and abdomen. Irritation of these nerves in another part of the body has the potential to produce pain in the ear. This is called referred pain. Irritation of the trigeminal nerve (cranial nerve V) is the most common cause of referred ear pain.

Diagnostic
While some disorders may require specific imaging or testing, most etiologies of ear pain are diagnosed clinically. Because the differential for ear pain is so broad, there is no consensus on the best diagnostic framework to use. One approach is to differentiate by time course, as primary causes of ear pain are typically more acute in nature, while secondary causes of ear pain are more chronic.
Acute causes may be further distinguished by the presence of fever (indicating an underlying infection) or the absence of fever (suggesting a structural problem, such as such as trauma or other injury to the ear). Etiologies leading to chronic pain may be broken down by the presence or absence of worrisome clinical features, also known as red flags.
One red flag is the presence of one or multiple risk factors including smoking, heavy alcohol use (greater than 3.5 drinks per day), diabetes, coronary artery disease, and older age (greater than 50). These factors increase the risk of having a serious cause of ear pain, like cancer or a serious infection. In particular, second hand smoke may increase risk of acute otitis media in children. In addition, swimming is the most significant risk factor for otitis externae, though other risk factors include high humidity in the ear canal, eczema and/or ear trauma.If red flags are present it may be necessary to do additional workup such as a CT scan or biopsy to rule out a more dangerous diagnosis. Such diagnoses include malignant (or necrotizing) otitis externa, mastoiditis, temporal arteritis, and cancer. It is important to note that while the presence of a red flag does raise suspicion for one of these four disease, it does not guarantee a diagnosis as any one symptom can be seen in a variety of situations. For example, jaw claudication can be seen in temporal arteritis, but also in TMJ dysfunction.If there are no red flags, other sources of referred ear pain become more likely and are reasonable to pursue.

*Indicates a "Cant Miss" diagnosis or a red flag.

Management
Management of ear pain depends on the underlying cause.

Antibiotics
While not all causes of ear pain are treated with antibiotics, those caused by bacterial infections of the ear are usually treated with antibiotics known to cover the common bacterial organisms for that type of infection. Many bacterial ear infections are treated with cleaning of the area, topical or systemic antibiotics, and oral analgesics for comfort. Some types of bacterial ear infections can benefit from warm compresses included in the treatment. Some of the causes of ear pain that are typically treated with either a topical or systemic antibiotic include:

Uncomplicated acute bacterial otitis externa (AOE). For symptoms that are not responsive to treatment within 10 days, a physician should evaluate for necrotizing external otitis.
Acute otitis media (AOM) self-resolves within 24–48 hours in 80% of cases. If it does not self-resolve, AOM thought to be caused by bacteria is treated with systemic antibiotics. If symptoms do not respond to a week of treatment, a physician should evaluate for mastoiditis.
Acute folliculitis.
Auricular cellulitis.
Suppurative otitis media. There is also a risk for tympanic membrane rupture.
Perichondritis. An otorhinolaryngologist should also evaluate it and if a foreign body is present in the cartilage, this foreign body should be removed. If there is cartilage involvement, then more advance care with hospitalization is needed.
Sinusitis can cause secondary ear pain. Treating the underlying sinusitis will treat the ear pain. (See sinusitis.)Some bacterial infections may require a more advanced treatment with evaluation by otorhinolaryngology, IV antibiotics, and hospital admission.

Necrotizing external otitis is potentially fatal and should be evaluated by an otorhinolaryngologist with admission to the hospital and IV antibiotics.(See otitis externa.)
Acute mastoiditis is treated with admission to the hospital, otorhinolaryngology consultation and empiric IV antibiotics. Cases with intracranial involvement are treated with a mastoidectomy with myringotomy.
Chondritis.

Procedures
Some causes of ear pain require procedural management alone, by a health professional, or in addition to antibiotic therapy.

Keratosis obturans is treated with removal of impacted desquamated keratin debris in the ear canal.
Chronic perichondritis and chondritis that continues to be symptomatic despite appropriate antibiotic management may require surgical debridement. Surgical drainage could be required.
Bullous myringitis leads to the development of bullae on the tympanic membrane that can be punctured to give pain relief.
Foreign body in the ear canal can cause pain and be treated with careful removal.
Infected sebaceous cyst is treated with incision and drainage of the cysts, oral antibiotics and otorhinolaryngology assessment.

Other
Given the variety of causes of ear pain, some causes require treatment other than antibiotics and procedures.

Relapsing polychondritis is an autoimmune disease treated with immunomodulating medications (medications that help modulate the immune system).
Temporomandibular joint dysfunction can lead to secondary ear pain and can be initially treated with a soft food diet, NSAIDs, application of a heat pack, massage of local area, and a referral to a dentist.
Myofascial pain syndromes are initially treated with NSAIDs and physical therapy. Local anesthetic injection into the muscle trigger point can be considered in severe cases.
Glossopharyngeal neuralgia is treated with carbamazepine.

Epidemiology
2/3 of people presenting with ear pain were diagnosed with some sort of primary otalgia and 1/3 were diagnosed with some sort secondary otalgia.A common cause of primary otalgia is ear infection called otitis media, meaning an infection behind the eardrum. The peak age for children to get acute otitis media is ages 6–24 months. One review paper wrote that 83% of children had at least one episode of acute otitis media by 3 years of age. Worldwide, there are 709 millions cases of acute otitis media every year. Hearing loss globally due to ear infection is estimated to be 30 people in every 10,000. Around the world there is around 21,000 to 28,000 deaths due to complications from ear infections. These complications include brain abscesses and meningitis.
Otitis externae peaks at age 7–12 years of age and around 10% of people has had it at least once in their lives.Cerumen impaction occurs in 1 out of every 10 children, 1 in every 20 adults and 1 in every 3 elderly citizens.Barotrauma occurs around 1 in every 1000 people.Of people presenting with ear pain, only 3% was diagnosed with eustachian tube dysfunction.

History
Not much was known about ear pain and acute otitis media before the 17th century. It was a common phenomenon with no treatment. That changed when the otoscope was invented in the 1840s by Anton von Troeltsh in Germany.  Another shift came with the invention of antibiotics. Before antibiotics was introduced there use to be a high rate of ear infections spreading to the bone around the ear, but that is now considered a rare complication.

Society and culture
There was previously a strong tradition of treating acute otitis media with amoxicillin. One quote from the 1980s shows this sentiment by saying "any child with an earache has an acute amoxicillin deficiency" </s>


<s> [INST] <<SYS>> You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information. <</SYS>> What is Central retinal vein occlusion and explain in detail? [/INST]  </s>


<s> [INST] <<SYS>> You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information. <</SYS>> What is Denasalization and explain in detail? [/INST]  </s>


<s> [INST] <<SYS>> You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information. <</SYS>> What is Stress and explain in detail? [/INST]  </s>


<s> [INST] <<SYS>> You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information. <</SYS>> What is Acute infectious thyroiditis and explain in detail? [/INST] Acute infectious thyroiditis (AIT) also known as suppurative thyroiditis, microbial inflammatory thyroiditis, pyrogenic thyroiditis and bacterial thyroiditis.The thyroid is normally very resistant to infection. Due to a relatively high amount of iodine in the tissue, as well as high vascularity and lymphatic drainage to the region, it is difficult for pathogens to infect the thyroid tissue. Despite all this, a persistent fistula from the piriform sinus may make the left lobe of the thyroid susceptible to infection and abscess formation.  AIT is most often caused by a bacterial infection but can also be caused by a fungal or parasitic infection, most commonly in an immunocompromised host.

Signs and symptoms
In most cases AIT is characterized by onset of pain, firmness, tenderness, redness or swelling in the anterior aspect of the neck.  Patients will also present with a sudden fever, difficulty swallowing and difficulty controlling the voice. Symptoms may be present from 1 to 180 days, with most symptoms lasting an average of about 18 days. The main issue associated with the diagnosis of AIT is differentiating it from other more commonly seen forms of thyroid conditions. Pain, fever and swelling are often much more severe and continue to get worse in people who have AIT compared to those with other thyroid conditions.

Causes
Despite the thyroid gland being extremely resistant to infection, it is still susceptible to infection by various bacteria.  The cause can be almost any bacterium.  Staphylococcus aureus, Streptococcus pyogenes, Staphylococcus epidermidis, and Streptococcus pneumoniae in descending order are the organisms most commonly isolated from acute thyroiditis cases in children. Other aerobic organisms are Klebsiella sp, Haemophilus influenza, Streptococcus viridans, Eikenella corrodens, Enterobacteriaceae, and salmonella sp.
Occurrences of AIT are most common in patients with prior thyroid disease such as Hashimotos thyroiditis or thyroid cancer.  The most common cause of infection in children is a congenital abnormality such as pyriform sinus fistula.  In most cases, the infection originates in the piriform sinus and spreads to the thyroid via the fistula. In many reported cases of AIT the infection occurs following an upper respiratory tract infection. One study found that of the reported cases of AIT, 66% occurred after an acute illness involving the upper respiratory tract. Although the rates of infection are still very low, cases of AIT have been on the rise in recent years due to the higher occurrence of immune-compromised patients.
Other causes of AIT are commonly due to contamination from an outside source and are included below.

Repeated fine needle aspirates
Perforation of esophagus
Regional infection

Diagnosis
Patients who are suspected of having AIT often undergo tests to detect for elevated levels of white blood cells as well as an ultrasound to reveal unilobular swelling.  Depending on the age and immune status of the patient more invasive procedures may be performed such as fine needle aspiration of the neck mass to facilitate a diagnosis.
In cases where the infection is thought to be associated with a sinus fistula it is often necessary to confirm the presence of the fistula through surgery or laryngoscopic examination.  While invasive procedures can often tell definitively whether or not a fistula is present, new studies are working on the use of computed tomography as a useful method to visualize and detect the presence of a sinus fistula.

Diagnostic tests
Fever, redness, swelling
Pain
Blood tests of thyroid functions including TSH, T4 and T3 are usually normal
Ultrasonographic examination often shows the abscess or swelling in thyroid
Gallium scan will be positive
Barium swallow will show fistula connection to the piriform sinus and left lobe
Elevated white blood cell count
Elevated erythrocyte sedimentation rate
Fine-needle aspiration

Subtypes of thyroiditis
Treatment
Treatment of AIT involves antibiotic treatment. Based on the offending organism found on microscopic examination of the stained fine needle aspirate, the appropriate antibiotic treatment is determined. In the case of a severe infection, systemic antibiotics are necessary.  Empirical broad spectrum antimicrobial treatment provides preliminary coverage for a variety of bacteria, including S. aureus and S. pyogenes.  Antimicrobial options include penicillinase-resistant penicillins (ex: cloxacillin, dicloxacillin) or a combination of a penicillin and a beta-lactamase inhibitor.  However, in patients with a penicillin allergy, clindamycin or a macrolide can be prescribed. The majority of anaerobic organisms involved with AIT are susceptible to penicillin. Certain Gram-negative bacilli (ex: Prevotella, Fusobacteriota, and Porphyromonas) are exhibiting an increased resistance based on the production of beta-lactamase. Patients who have undergone recent penicillin therapy have demonstrated an increase in beta-lactamase-producing (anaerobic and aerobic) bacteria.  Clindamycin, or a combination of metronidazole and a macrolide, or a penicillin combined with a beta-lactamase inhibitor is recommended in these cases. Fungal thyroiditis can be treated with amphotericin B and fluconazole. Early treatment of AIT prevents further complications.  However, if antibiotic treatment does not manage the infection, surgical drainage is required. Symptoms or indications requiring drainage include continued fever, high white blood cell count, and continuing signs of localized inflammation. The draining procedure is also based on clinical examination or ultrasound/CT scan results that indicate an abscess or gas formation </s>