Endoscopic Management of Arnold-Chiari Malformation Type I with or without Syringomyelia.

INTRODUCTION:  Several different surgical techniques have been used in the treatment of patients with symptomatic Arnold-Chiari malformation type 1 (ACM-1) with or without syrinx. Endoscope-assisted decompression of the posterior fossa has been found to be safe and effective. We report our initial experience of endoscopic management of ACM-I.

MATERIAL AND METHODS:  This was a prospective study of 15 symptomatic patients. Pre- and postoperative clinical status and computed tomography and magnetic resonance imaging findings were recorded. Suboccipital bone of ∼ 3 cm distance from the foramen of magnum and posterior arch of atlas was removed. Partial splitting of the dura mater with preservation of the inner portion and the arachnoid membrane was performed. Any change in axial and sagittal length of the syrinx, tonsillar ascension, shape of the tonsil tip, appearance of cerebrospinal fluid posterior to the tonsil, and formation of the cisterna magna were recorded. Patients with atlantoaxial instability, tethered cord, associated myelomeningocele, hydrocephalus, or elevated intracranial pressure were excluded.

RESULTS:  Age of patients ranged from 26 to 48 years. There were nine female patients. There were six patients with ACM-I without and nine with ACM-I with syrinx. Average pre- and postoperative Karnofsky performance score was 78 and 93, respectively. Average operative time was 130 minutes (110-190 minutes), and blood loss was 30 mL (20-180 mL). Follow-up ranged from 9 to 21 months.

CONCLUSION:  Although the study is limited by the small number of patients with a short follow-up, endoscopic decompression in selected patients of ACM-I with or without syrinx with dural splitting was a safe and effective alternative to microsurgical treatment.