Introduction: Several different surgical techniques have been used in the treatment of patients with symptomatic, persistent, recurrent, or increasing syringomyelia. The pathophysiology is controversial but most authors explains it due to enlarged cervical subarachnoid pressure waves that compress the spinal cord from without, not from within, and propagate syrinx fluid caudally with each heartbeat, which leads to syrinx progression. We propose a minimally invasive alternative by ressecting the foramen magnum dura mater.

Methods: This was a prospective study of 26 symptomatic patients. The majority of patients (21) had Chiari malformation type I associated Syringomyelia. Five patients had persistent syringomyelia after standard decompressive craniectomy with duroplasty. Three patients had idiopathic syringomyelia. Two patients had arachnoiditis at the craniocervical junction. Pre- and postoperative clinical status and MRI findings were recorded. The decompression was performed by 1,5 to 2,5 cm midline incision via a speculum retractor. All patients underwent a limited suboccipital craniectomy and C1 laminectomy. All patients underwent a foramen magnum durectomy. No duroplasty was performed and the dura mater was left open. In all patients, the arachnoid was opened and intradural dissection was carried out.

Results: Age of patients ranged from 26 to 61 years old. All patients experienced radiographic improvement in syringomyelia (decreased size or resolution) during the follow-up period. Most patients (88,4%) experienced postoperative headaches due to CSF hypotension that lasted approximately 2-3 weeks. Twenty four (92,3%) patients experienced symptomatic improvement. The median time to symptom improvement was 2 months after surgery. No patients had CSF fistula or meningitis. Follow-up ranged from 9 to 37 months.

Conclusions: Although the study is limited by the small number of patients with a short follow-up, minimally invasive durectomy of the foramen magnum was a safe and effective alternative to standard treatment for different spectrum of syringomyelia cases.

Patient Care: Minimally Invasive Durectomy of the foramen magnum may be a new alternative for recurrent syringomyelia.

Learning Objectives: 1- Durectomy of the foramen magnum may function by decreasing the cervical subarachnoid pressure 2- CSF fistula was not observed, probably due to the small skin incision

References: 1-Heiss JD, Patronas N, DeVroom HL, Shawker T, Ennis R, Kammerer W, Eidsath A, Talbot T, Morris J, Eskioglu E, Oldfield EH. Elucidating the pathophysiology of syringomyelia. J Neurosurg. 1999 Oct;91(4):553-62. 2- Pakzaban P. Technique for Mini-open Decompression of Chiari Type I Malformation in Adults. Oper Neurosurg (Hagerstown). 2017 Aug 1;13(4):465-470.