[Third cranial nerve palsy due to intracranial hypotension syndrome].

INTRODUCTION: Intracranial hypotension syndrome (IHS) is clinically defined by orthostatic headache due to cerebrospinal fluid (CSF) hypovolemia. It is frequently associated with lower cranial nerve (CN) paresis, especially the 6th one. However, neuropathy of the 3rd CN is rare. CASE REPORT: A 43 year old man presented with orthostatic headache and vertical diplopia of gradual onset. Clinical examination detected incomplete, pupil sparing left third CN palsy. Magnetic resonance imaging (MRI) of the brain and spine demonstrated typical abnormalities that confirmed the clinical suspicion of IHS. Lumbar puncture showed an opening pressure of 5 cm of water. CSF disclosed mild protein elevation (0.63 g/l) and lymphocytic pleocytosis (13 cells/ml). A history of spinal trauma three months prior to the onset of the symptoms and lumbar fractures identified in a spine computed tomography scan suggested the likely origin of the CSF leak. The symptoms responded to conservative measures in three months and a cranial MRI performed ten months later was normal. DISCUSSION: Third CN palsy is an extremely unusual manifestation of IHS and contributes to the expansion of its clinical spectrum.