A 42-year-old woman presented with intermittent hemiparesis mimicking
a reversible ischemic neurologic deficit. Magnetic resonance imaging (
MRI) demonstrated a compression of the left side of the midbrain by a
quadrigeminal arachnoid cyst without hydrocephalus. After the cystic w
all was widely excised under operating microscope, the patient made a
good recovery and remained well at a follow-up of 18 months. The absen
ce of hydrocephalus in a symptomatic patient with a quadrigeminal cyst
was exceptional, which might result from the early diagnosis with MRI
. The use of microsurgical technique made it possible to excise the cy
stic wall widely and omit a shunting procedure.