Saturday, October 4, 2008

Bitemporal hemianopia


When I was in UK, I attended a PACES course. There were 3 patients whom I was asked to examine the visual fields and the findings were bitemporal hemianopia. They also had a scar as shown above. In fact, they had craniopharyngioma which has been operated via a transfrontal approach. You don't always get a clear scar like this in the exam. So, sometimes you have to look in between the hairs for the scar.

Where is the lesion ? Optic chiasm

If you are asked to examine the eyes,
1) Inspection for scars (transfrontal and transphenoidal)
2) Examine the visual acuity with a Snellen chart
3) Test the visual fields (you will find bitemporal hemianopia)
4) Check light reflex and look for RAPD(relative afferent pupillary light reflex or Marcus Gunn pupil), accomadation reflex
5) Check eye movements
6) Do a fundoscopy ( look for optic atrophy, particularly if there is RAPD)
7) Look for a medic alert bracelet
8) Look for other features of endocrinopathy eg acromegaly, Cushing's syndrome which should also have been picked up during inspection
The other causes of a chiasmal lesion include pituitary adenoma, meningioma, aneurysm, glioma