Endoscopic third ventriculotomy improves parkinsonism following a ventriculo-peritoneal shunt in a patient with non-communicating hydrocephalus secondary to idiopathic aqueduct stenosis.

We report a 47-year-old woman who manifested ocular motility disorder, bilateral pyramidal signs, and severe parkinsonism after a ventriculo-peritoneal shunt for non communicating hydrocephalus secondary to idiopathic aqueduct stenosis. The ocular motility disorder consisted of severe vertical gaze palsy and convergence retraction nystagmus. Parkinsonism included not only bradykinesia but also resting tremor and cogwheel rigidity. On the other hand, striatal uptake did not decrease in (18)F-dihydroxyphenylalanine positron emission tomography, and anti-Parkinsonian drugs were not effective. 99mTc-ethyl cysteinate dimer bicisate single-photon emission computed tomography and F-18 fluorodeoxyglucose positron emission tomography revealed wide-ranged frontal cerebral cortical dysfunction due to midbrain dysfunction. Moreover, endoscopic third ventriculotomy markedly improved the clinical symptoms as well as the frontal cerebral cortical flow. A neural network formation known as the 'cortico-basal ganglia loop,' which intimately connects the frontal lobe with the basal ganglia, is possibly associated with the Parkinsonism observed in our patient.