CHIARI-I MALFORMATION - CLASSIFICATION AND MANAGEMENT

CONSIDERABLE DEBATE EXISTS about which surgical options are best for t he management of the Chiari malformation. We present a classification system for the Chiari I malformation that improves the prediction of o utcome and guides the selection of surgical treatment. Twenty-seven ad ult patients with Chiari malformations were grouped on the basis of th e presence of signs and symptoms of brain stem compression, syringomye lia, or both. To objectively assess changes in clinical status postope ratively, a scale was developed to quantify the signs and symptoms, wh ich were statistically analyzed by the paired t test. Five patients we re asymptomatic and underwent no treatment. Ten patients had symptoms of brain stem compression without associated syringomyelia and underwe nt brain stem decompression, including anterior decompression in one p atient with basilar invagination; all 10 patients had significant impr ovement at 4-year mean follow-up visits (P < 0.0001), In 12 patients w ith syringomyelia 5 were symptomatic from syringomyelia only, 6 were s ymptomatic from both brain stem compression and syringomyelia, and 1 w as symptomatic from brain stem compression only. The median length of symptoms before presentation was longer for patients with syringomyeli a than for patients without (2 yr versus 9 mo; P < 0.025); the mean fo llow-up was 4 years. Surgical procedures included posterior brain stem decompression in 12 patients, plugging of the obex in 7, and placemen t of syringosubarachnoid shunts in 7, a syringopleural shunt in 1, and fourth ventricular stents in 2. In the 12 patients with syringomyelia , symptoms from brain stem compression dramatically improved with surg ical decompression (P < 0.025), whereas symptoms from syringomyelia le ss dramatically improved or stabilized. The slight improvement or stab ilization of syrinx symptoms represents a successful result, given the documented progressive nature of syringomyelia in this group. We conc lude that surgical treatment for the Chiari I malformation can stabili ze or slightly improve the symptoms attributed to syringomyelia and dr amatically relieve the symptoms of brain stem compression. Furthermore , early diagnosis and treatment are critical in obtaining the best out come for the patient.