Surgical outcome of Chiari I malformations--an experience sharing and literature review.

The Chiari malformations are a group of central nervous system defects that involve the posterior cranial fossa. The clinical complaints range from headache, sensory changes, vertigo, ataxia, and imbalance to hearing loss. In patients with Chiari malformation, only those with type I malformation were born grossly normal, the neurological dysfunction developing gradually as they grew up, which spurred our interest. From August 1990 to September 1998, seven patients received surgical intervention at Kaohsiung Medical College Hospital under the impression of Chiari malformations. There were 4 males and 3 females, with age ranging from 7 years to 41 years. All these patients were diagnosed via magnetic resonance imaging and surgical findings revealed a hypoplasic vermis. Among them, 4(57%) were cranial nerve plasy, 2(29%) nystagmus, 6(100%) syringomyelia, 7(100%) scoliosis and one (14%) with hydrocephalus. Cerebellar ataxia and upper limbs weakness was noted in 5(71%) patients. Our surgical interventions included suboccipital craniectomy and dural opening(7/7), C1 posterior arch decompression (7/7), C4,5 laminectomy (1/7), and syringostomy(4/7). There was one mortality in a 41 y/o male with progressively lower cranial nerve(V, VII, IX) impairment as well as poor lung compliance. Other patients improved in their symptoms after follow-up periods of 6 months to 6 years. Our study shows that 1) surgical decompression was indicated in all patients with brain stem and lower cranial nerve dysfunction as well as central cord syndrome caused by syringomyelia; 2) a better result was achieved in those patients who received adequate nervous system decompression; and 3) much attention should be payed to cases with lower cranial nerves XI, X, XII impairment, because complications such as choking and aspiration pneumonia can happen.