[Isolated abducens nerve palsy caused by the compression of the basilar artery: a case report].

Several pathological etiologies are responsible for abducens nerve palsy, but a neuro-vascular compression of the basilar artery has rarely been recognized as one of the causes. We performed magnetic resonance imaging of the brainstem of 71-year-old female patient with left abducens nerve palsy using constructive interference in the steady state (CISS) method, which allowed high-resolution T 2-weighted imaging and detection of the artery and nerves as high and low intensity area respectively. MRI with CISS revealed the compression of the abducens nerve by the basilar artery at the root exit zone. During the first examination her systolic blood pressure was over 180 mmHg, so we prescribed hypotensive agents until it to normalized. Her symptom of abducens nerve palsy improved after a few days. It is conceivable that compression of the basilar artery may have caused isolated abducens nerve palsy as disclosed by MRI with CISS.