Accurate Posterior Fossa Decompression Technique for Chiari Malformation Type I and a Syringomyelia With Navigation: A Technical Note.

Background: Posterior fossa decompression (PFD) has been widely accepted for the surgical treatment for Chiari malformation type I (CM1). However, inadequate decompression causes surgical mortality and complications such as cerebrospinal fluid leakage, meningitis, or progression of syrinx and symptoms. The authors report a novel technique of PFD under navigation.

Methods: Five female patients with CM1 who developed severe symptoms and underwent surgical treatment were evaluated (mean age 14.0 years; mean follow-up 1.3 years). Surgical outcomes, surgical time, intraoperative blood loss, and operative complications were assessed.

Results: Four patients with CM1 who developed severe symptoms and underwent surgery were evaluated (mean age 14 years; mean follow-up 1.2 years). All patients were treated with PFD, C1 (and partial C2) laminoplasty to decompress the spinal cord under navigation guidance. Suboccipital craniectomy with 3 cm in diameter around the foramen magnum was performed. The postoperative radiograms and computed tomographic images showed adequate bony resection for CM1. Average surgical time was 114 minutes and average blood loss was 82 mL. There were no postoperative complications. After surgery, the numbness and muscle weakness of the patients were improved. The final follow-up magnetic resonance imaging displayed a good decompression of cerebral tonsile, and cervical syringomyelia was decreased.

Conclusions: PFD under navigation guidance can reduce inappropriate decompression and may decrease a revision surgery. During decompression surgery, cerebrospinal fluid leakage can be prevented using an ultrasonic bone cutter and navigation.