Isolated relative afferent pupillary defect secondary to contralateral midbrain compression.
BACKGROUND
Relative afferent pupillary defects are typically related to ipsilateral lesions within the anterior visual pathways.


OBJECTIVE
To describe a patient who had a workup for headache and was found to have an isolated left relative afferent pupillary defect without any other neurological findings.


METHODS
We review the neuroanatomy of the pupillary light reflex pathway and emphasize the nasotemporal bias of decussating fiber projections, which accounts for the relative afferent pupillary defect contralateral to the described lesion. Result Magnetic resonance imaging of the brain revealed a pineal tumor compressing the right rostral midbrain.


CONCLUSIONS
While rare, a relative afferent pupillary defect can occasionally occur secondary to lesions in the postchiasmal pathways. In these circumstances, the pupillary defect will be observed to be contralateral to the side of the lesion.
Chen
Cheun Ju
CJ
Departments of Neurology and Ophthalmology, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75235, USA.
Scheufele
Mia
M
Sheth
Maushmi
M
Torabi
Amir
A
Hogan
Nick
N
Frohman
Elliot M
EM
D000328:Adult; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008636:Mesencephalon / Q000473:pathology*; D009408:Nerve Compression Syndromes / Q000150:complications*; D010871:Pinealoma / Q000150:complications* / Q000000981:diagnostic imaging; D011681:Pupil Disorders / Q000209:etiology*; D011859:Radiography; D014795:Visual Pathways / Q000033:anatomy & histology