Bilaterally pinpoint pupil, hyperpyrexia and loss of consciousness is suggestive of: March 2005

Ans. C: Pontine hemorrhage Pupillary size (normal 3-4 mm in diameter) and reactivity is dependent on sympathetic parasympathetic innervation. Brain stem reflexes, such as the pupillary reaction to light, offer clues to the location of the lesion responsible for the coma. Bilateral dilated pupils - Are greater than 7 mm in diameter and do not react to light stimulation. Are seen in: - Transtentorial herniation of both medial temporal lobes - Anticholinergic or Sympathomimetic drug intoxication Bilateral pinpoint pupils - Have 1-1,5 mm in diameter and are seen in: - Morphine poisoning - Pontine hemorrhage - neurosyphilis - Organophosphates poisoning - Miotic eyes drops Asymmetric pupils (anisocoria) - With a difference of 1 mm or less in diameter and a normal constriction response to light is a normal finding in 20% of the population. If the dilated pupil do not react to light or do it slowly, it usually indicates a rapidly expanding lesion on the ipsilateral side as in subdural or middle meningeal hemorrhage or brian tumor, that is compressing the midbrain or oculomotor nerve directly or by mass effect. Fixed midsized pupils - Are about 5 mm in diameter, do not react to light and are the result of midbrain lesion.