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Low-pressure shunt 'malfunction' following lumbar puncture in children with shunted obstructive hydrocephalus
1Division of Pediatric Neurosurgery, Children's Hospital of Buffalo, State University of New York at Buffalo, N.Y., USA. mdias @chob.edu
Insights
A rare low-pressure hydrocephalus can occur after lumbar puncture in children with shunts. Symptoms resolved with bed rest, suggesting cerebrospinal fluid leakage, not shunt malfunction.
Area of Science:
- Neurosurgery
- Pediatric Neurology
- Hydrocephalus Research
Background:
- Most shunt malfunctions for hydrocephalus present with high intracranial pressure and ventricular enlargement.
- A rare 'low-pressure' hydrocephalic state, characterized by ventricular enlargement despite low or negative intracranial pressure, has been described.
Observation:
- This study reports two pediatric cases of obstructive hydrocephalus with a 'low-pressure state' following lumbar puncture.
- Computed tomography scans showed ventricular enlargement, yet the shunts were functioning correctly.
Findings:
- Symptoms resolved, and ventricles returned to baseline with enforced recumbency alone, without shunt revision.
- The 'low-pressure state' is hypothesized to result from cerebrospinal fluid leakage via the lumbar puncture site, decreasing intracranial pressure below shunt valve opening pressures.
Implications:
- Postural headaches were a consistent feature in the observed patients.
- Enforced recumbency or a blood patch may resolve this condition, obviating the need for shunt revision or external ventricular drainage.
- Neurosurgeons should be aware of this potential complication following lumbar puncture in hydrocephalic patients with shunts.
Abstract:
Most shunt malfunctions present with signs and symptoms of high intracranial pressure, and computed tomography scans demonstrate ventricular enlargement. However, several authors have described a rare 'low-pressure' hydrocephalic state in which ventricular enlargement can occur in the face of low, or even negative, intracranial pressures. We report 2 children with obstructive hydrocephalus in whom this 'low-pressure state' followed a lumbar puncture; in both children, the shunts were functioning properly despite increased ventricular size on computed tomography scans, and all symptoms resolved (and the ventricles returned to baseline) following a period of enforced recumbency without shunt revision. We hypothesize that subarachnoid cerebrospinal fluid leakage through the puncture site in the lumbar theca decreases the intracranial pressures globally to a point below the opening pressures of the shunt valves. The ventricular cerebrospinal fluid, unable to be drained through either the subarachnoid space or the shunt, accumulates within the ventricular system under low pressure. One consistent feature in our 2 patients has been the postural nature of the headaches. We recommend enforced recumbency and, if necessary, a blood patch to seal the lumbar leakage. Shunt revision or prolonged external ventricular drainage appears to be unnecessary in these patients. Finally, neurosurgeons should be aware of this potential complication.