Background - Cleland first described the anomaly later referred to as the Arnold-Chiari malformation, in 1883.78 Chiari and Arnold in 1891 and 1894 respectively,79,80 reported their descriptions and students of Arnold later used a single eponymic term to describe the various abnormalities.81 More recently, Peach82,83,84 and Carme| 85,86,87 have reviewed these early reports and others,88,89,90 and clearly delineate the anatomical features of the Chiari malformations. In both the Chiari I and Chiari II anomalies, the cerebellar tonsils are displaced downwards below the foramen magnum to variable levels of the upper cervical cord. The Chiari II anomaly, better known as the Arnold-Chiari malformation, usually includes caudal dislocation of the medulla, inferior vermis and/or the fourth ventricle and may involve dorsal kinking of the cervicomedullary junction. The upper cervical nerve roots course rostrally. In both Chiari I and II malformations, hydrocephalus and syringomyelia may be present. Aim - To study the outcome of surgical treatment in patients with Chiari type I malformation with and without syringomyelia Methods and Material - We conducted a retrospective review of the medical records of patients having Chiari type I malformation with and without syringomyelia who were treated in our hospital, Shri Sai baba hospital, shirdi, between January 2011 and December 2017. Their age, sex, initial presentation, extent of syrinx, duration of follow up, syringosubarachnoid done or not, complication, second surgery done or not and outcome were reviewed. This is a retrospectively analyzed consecutive series of 66 patients (mean patient age 15 years, range 1–53 years). The uniform posterior craniovertebral decompression consisted of a small suboccipital craniectomy, a C-1 laminectomy, microsurgical reduction of the cerebellar tonsils, and dural closure with a synthetic dural graft to increase the cerebrospinal fluid space at the craniocervical junction. The presence of a large syrinx, with significant thinning of the spinal cord tissue and obliteration of the spinal subarachnoid space, particularly when combined with syrinx-related symptoms, was an indication for the placement of a syringosubarachnoid shunt. Results - In 32 patients Chiari I malformation alone was present, and 34 in patients it was present in combination with syringomyelia. Clinical findings included pain, neurological deficits, and spinal deformity. The presence of syringomyelia was significantly associated with the presence of scoliosis (odds ratio 74.4 [95% confidence interval 8.894–622.4]). All patients underwent a posterior craniovertebral decompression procedure. In 22 of the 34 patients with syringomyelia a syringosubarachnoid shunt was also placed. The mean follow-up period was 24 months (range 3–95 months). Excellent outcome was achieved in 54 patients (82%) and good outcome in 12 (18%). In no patient were symptoms unchanged or worse at follow-up examination, including four patients who initially required a second operation for persistent syringomyelia. Pain was more likely to resolve than sensory and motor deficits after decompressive surgery. Radiological examination revealed normalization of tonsillar position in all patients. The syrinx had disappeared in 15 cases, was decreased in size in 17, and remained unchanged in two. Conclusion - Posterior craniovertebral decompression and selective placement of a syringosubarachnoid shunt in patients with Chiari I malformation and syringomyelia is an effective and safe treatment. Primary placement of a shunt in the presence of a sufficiently large syrinx appears to be beneficial. The question of if and when to place a shunt, however, requires further, preferably prospective, investigation.
