Levodopa-resistant parkinsonism developing after ventriculoperitoneal shunting for obstructive hydrocephalus and improving after endoscopic third ventriculostomy, with specific consideration of brainstem morphology: illustrative case.

Background: Parkinsonism has been reported in patients with obstructive hydrocephalus (OH) following ventriculoperitoneal shunting (VPS). While levodopa works well, some cases are drug resistant. A few case series have reported that endoscopic third ventriculostomy (ETV) is beneficial, though its mechanism remains unclear. The use of a pathophysiology-reflected marker can aid in the diagnosis and treatment strategy. The authors report a case of parkinsonism due to OH after VPS that improved after ETV in a patient taking levodopa, which was subsequently discontinued.

Observations: A 52-year-old man who had undergone VPS for OH caused by aqueductal stenosis with a tectal tumor presented with severe consciousness disturbance due to acute hydrocephalus and levodopa-refractory parkinsonism after multiple episodes of shunt malfunction. Magnetic resonance imaging showed an elevation of the floor of the third ventricle. ETV was performed to stabilize the pressure imbalance across the stenosis, and his parkinsonism symptoms improved after long-term rehabilitation, resulting in levodopa discontinuation. His pontomesencephalic angle, the angle between the anterior surface of the midbrain and upper surface of the pons in the midline of the sagittal plane, was significantly decreased.

Lessons: The focus in such cases should be on the essence of the pathophysiology for improving the symptoms rather than on easy-to-understand indicators such as ventricle size. https://thejns.org/doi/10.3171/CASE2429.