A Case of Hypertensive Encephalopathy with Enlarged Optic Nerve Sheath Measured by Transorbital Sonography

This case report describes our experience in using transorbital sonography to evaluate pathological changes in the central nervous system in hypertensive encephalopathy. A 49-year-old man with nausea, headache, and mild confusion was diagnosed with hypertensive encephalopathy by brain magnetic resonance imaging (MRI), which revealed vasogenic edema in the bilateral thalamus and the brain stem. Lumbar puncture showed no severe intracranial hypertension. Transorbital sonography showed an increase in the optic nerve sheath diameter (ONSD). Repeated examination revealed a return of the ONSD to an almost normal range after a reduction in blood pressure and a resolution of symptoms. An improvement in cerebral vasogenic edema was confirmed by brain MRI. ONSD might be related to the severity of cerebral vasogenic edema. Repeated measurement of ONSD by transorbital sonography may be useful to assess the pathological course and the effect of treatment in hypertensive encephalopathy.