Spinal cord syrinx expansion following acquired Chiari malformation decompression: Case report

Objective: Chiari malformation development after lumboperitoneal (LP) shunting for pseudotumor cerebri is a recognized phenomenon. Treatment options for an acquired Chiari malformation include observation, LP shunt revision or ligation, ventriculoperitoneal (VP) shunt placement, and suboccipital decompression. The authors describe a case of suboccipital decompression of an acquired Chiari malformation that resulted in the development of a spinal cord syrinx. Clinical presentation: A 24-year-old woman presented with headaches, photophobia, and blurred vision. No ventricular enlargement was seen on a computed tomographic scan of the brain. The patient was diagnosed with pseudotumor cerebri based on the clinical presentation and a lumbar puncture with a high opening pressure. She underwent an LP shunt. At the time of her 10-month follow-up evaluation, she was noted to have a symptomatic acquired Chiari malformation without a spinal cord syrinx. Intervention: The patient underwent a suboccipital decompression to treat her Chiari malformation. Postoperatively, she developed an enlarging, symptomatic spinal cord syrinx. The patient underwent LP shunt ligation and VP shunt placement and had subsequent resolution of her spinal cord syrinx. Conclusion: An enlarging spinal cord syrinx can occur following the suboccipital decompression of an acquired Chiari malformation in pseudotumor cerebri patients. Careful consideration to VP shunting should be given prior to posterior fossa decompression in such cases in an attempt to avoid syrinx development.