Content area
Full text
Correspondence to Dr Faisal Alotaibi; [email protected]
Description
A 52-year-old woman presented with a headache and ataxic gait. MRI of the cranial and cervical spine showed Chiari malformation type 1, for which she underwent suboccipital decompression and duroplasty without arachnoid opening (figure 1). Four weeks after surgery, she presented with a severe headache and vomiting. MRI of the brain and spine showed a large subdural hygroma involving the supratentorial and infratentorial spaces and spine (figures 1 and 2). Urgent bilateral burr holes and subdural drain placement were performed, and she was treated with diuretics and dexamethasone. Her symptoms improved for 1 week and then recurred. MRI of the brain and spine revealed a reaccumulating subdural hygroma without hydrocephalus. Re-exploration of the Chiari decompression and wide fenestration of the arachnoid membrane resulted in the resolution of the subdural hygroma and patient symptoms. At the last follow-up, 4 years after treatment, the patient remained asymptomatic and no subdural hygroma was found with MRI (figure 2).
Subdural hygroma development after Chiari type I decompression is rare, with only a limited number of reported paediatric and adult cases in the literature.1–4 Different mechanisms have been proposed as likely causes, such as a one-way valve mechanism at the foramen magnum arachnoid membrane, a reduction of cerebrospinal fluid (CSF) absorption, overdrainage of CSF flow through the Magendie foramen and increased intracranial blood vessels’ permeability. Here, we describe a single mechanism by which a small puncture in the arachnoid membrane at the foramen magnum results in a slit valve mechanism...