Obstructive hydrocephalus and progressive psychosis: rare presentations of neurosarcoidosis.

BACKGROUND: Neurosarcoidosis presents with meningitis, cranial nerve involvement, and parenchymal masses. Usually, abnormal MR enhancement and/or structural lesion(s) are present. Communicating hydrocephalus arises from meningeal arachnoid granulation involvement. Reported cases of obstructive hydrocephalus have all involved obstructing ventricular lesions.

CASE DESCRIPTION: A 40-year-old African American man presented with papilledema, diplopia, and headache. Magnetic resonance imaging revealed "aqueductal stenosis" without abnormal enhancement or obstructive lesion. Although symptoms resolved with shunting, he soon developed progressive psychotic symptoms. Serial MR scans remained free of abnormal enhancement or structural mass lesion(s) but revealed long repetition time and proton density signal changes within the medial temporal lobe structures and deep white matter that remained stable over 8 months despite clinical progression. Serial CSF studies were nondiagnostic. Open temporal lobe brain and meningeal biopsy revealed noncaseating granulomas within the parenchyma and meninges consistent with sarcoid. Total-body computed tomography scans ruled out systemic sarcoid. The patient steadily improved on steroid therapy.

CONCLUSION: Neurosarcoid psychiatric symptoms are usually associated with diffuse meningeal enhancement from meningitis. Our case reveals that absence of abnormal enhancement or structural mass lesion on MR and normal CSF ACE levels do not rule out neurosarcoid. Based on a patent cerebral aqueduct and the T2 MR and pathology findings, we postulate that altered brain tissue compliance with impairment of normal pulsatile augmentation of aqueduct CSF flow was the likely cause of obstructive hydrocephalus. This represents a very rare psychiatric presentation and reports a new potential mechanism for the development of hydrocephalus with neurosarcoid.