Upright MRI was more than twice as sensitive as standard MRI, likely because gravity affects cerebellar position.Cases of congenital Chiari malformation may be explained by evolutionary and genetic factors. Typically, an infants brain weighs around 400g at birth and triples to 1100-1400g by age 11. At the same time the cranium triples in volume from 500 cm3 to 1500 cm3 to accommodate the growing brain. During human evolution, the skull underwent numerous changes to accommodate the growing brain. The evolutionary changes included increased size and shape of the skull, decreased basal angle and basicranial length. These modifications resulted in significant reduction of the size of the posterior fossa in modern humans. In normal adults, the posterior fossa comprises 27% of the total intracranial space, while in adults with Chiari Type I, it is only 21%. H. neanderthalensis had platycephalic (flattened) skulls. Some cases of Chiari are associated with platybasia (flattening of the skull base). History
The history of Chiari malformation is described below and categorized by the year:

1883: Cleland was the first to describe Chiari II or Arnold–Chiari malformation on his report of a child with spina bifida, hydrocephalus, and anatomical alterations of the cerebellum and brainstem. 1891: Hans Chiari, a Viennese pathologist, described the case of a 17-year-old female with elongation of the tonsils into cone shaped projections which accompany the medulla and are crammed into the spinal canal.
Ant venom is any of, or a mixture of, irritants and toxins inflicted by ants. Most ants spray or inject a venom, the main constituent of which is formic acid only in the case of subfamily Formicinae. Ant stings
Of all extant ant species, about 71% are considered to be stinging species, as some subfamilies have evolutionarily lost the ability to sting. Notable examples include a few species of medical importance, such as Solenopsis (fire ants), Pachycondyla, Myrmecia (bulldog ants), and  Paraponera (bullet ants). In the case of fire ants, the venom consists mainly of alkaloid (>95%) and protein (<1%) components. Stinging ants cause a cutaneous condition that is different from that caused by biting venomous ants. Particularly painful are stings from fire ants, although the bullet ants sting is considered by some to be the most painful insect sting. : 450 First aid for fire ant bites includes external treatments and oral medicines. External treatments: a topical steroid cream (hydrocortisone), or one containing Aloe vera
Oral medicines: antihistamines
Applying zinc oxide or  calamine lotion  .Severe allergic reactions can be caused by ant stings in particular and venomous stings in general, including severe chest pain, nausea, severe sweating, loss of breath, serious swelling, fever, dizziness, and slurred speech; they can be fatal if not treated. See also
Acidopore
Poneratoxin, the neurotoxic component of bullet ant venom
Pulicosis (flea bites)
Skin lesion
Solenopsin, the primary toxin in fire ant venom

References


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