Intraparenchymal cyst formation after invasive intracranial pressure monitoring: a rare complication. Illustrative case.

BACKGROUND

Intraparenchymal cysts are rare complications that are most commonly associated with ventriculoperitoneal shunt or external ventricular drain malfunction.

OBSERVATIONS: The authors describe a rare case of intraparenchymal cyst formation after intraparenchymal intracranial pressure (ICP) monitor placement for traumatic brain injury. The cyst developed after device removal, was demonstrated on CT and MR images, and improved following surgical drainage. Bacterial cultures of both the catheter tip and cyst fluid were negative. The cyst showed near-total resolution after device removal and surgical drainage at the 5-month follow-up.

LESSONS: Tissue reaction and reactive gliosis may contribute to cyst formation around monitoring devices. Clinicians should be aware of this unusual complication, especially after intraparenchymal ICP monitoring. https://thejns.org/doi/10.3171/CASE25491.