Purpose: Variation exists in the surgical methods employed for decompression of Chiari II malformation (CIIM), yet an evaluation of these techniques has not been performed. The purpose of this study was to assess the efficacy of bony decompression (cervical laminectomy alone versus suboccipital craniectomy with laminectomy) with or without dural augmentation for the treatment of symptomatic CIIM.
Methods: Clinical records of children 0-18 years of age who underwent surgical repair of myelomeningocele or CIIM decompression at St. Louis Children's Hospital (SLCH) from 1990-2011 were reviewed. Signs/symptoms prompting decompression, surgical technique, operative parameters, and clinical outcomes were recorded for analysis.
Results: Thirty-three subjects were treated at SLCH for CIIM decompression. Twenty-six subjects underwent bony decompression only (21 cervical laminectomy alone, 5 suboccipital craniectomy + cervical laminectomy) while seven underwent bony decompression with upfront dural augmentation (three cervical laminectomy alone, four suboccipital craniectomy + cervical laminectomy). Median follow up was 5.0 years (range, 3 months-19 years). Symptomatic improvement was noted in 20/33 subjects (60.6%). Sixty-two (61.5%) percent of children who underwent bony decompression had symptomatic improvement, compared with 57.1% of those with upfront dural augmentation (p = 0.37). Estimated blood loss, operative time, and length of perioperative hospital stay appeared lower in the bony decompression group but were not statistically different in this limited cohort.
Conclusions: The results from this series suggest that bony CIIM decompression via tailored cervical laminectomies alone, without suboccipital craniectomy or upfront dural augmentation, is a reasonable initial management approach for decompression of symptomatic CIIM.
Keywords: Brainstem compression; Chiari type II malformation; Decompression; Dural augmentation; Myelomeningocele; Syrinx.