Medical Surgical Neurosensory Practice Test

Overdrainage lowers the pressure inside the skull. When CSF is drained too quickly from a ventriculoperitoneal shunt, the brain can sag slightly within the skull, which stretches the veins that bridge the brain’s surface. Those bridging veins are prone to tearing under that traction, allowing blood to collect in the subdural space and form a subdural hematoma. This is the classic, direct complication of excessive CSF drainage.

Headache from low CSF pressure can occur, but it’s the subdural bleeding resulting from the brain’s increased descent that’s the characteristic danger of overdrainage. Obstruction points to underdrainage or shunt failure, leading to hydrocephalus symptoms rather than a subdural bleed. Seizures can happen in various brain conditions but are not the defining complication of overdrainage.