title: Clinical features and pathomechanisms of syringomyelia associated with spinal arachnoiditis.
abstract: BACKGROUND
  Syringomyelia is a common intramedullary lesion associated with spinal arachnoiditis and obstruction of the foramen magnum such as in Chiari's malformation. Disturbance of cerebrospinal fluid flow around the spinal cord has an important role in the development of syringomyelia due to spinal arachnoiditis; however, the exact mechanisms have not been clarified. The purpose of this retrospective study is to understand the clinical features and pathomechanisms of syringomyelia secondary to spinal arachnoiditis and to provide the current choice of surgical treatment in this difficult clinical entity.
  
  
  METHODS
  Clinical and radiological findings in 15 patients with syringomyelia associated with spinal arachnoiditis who underwent surgical treatment in our institutes between 1982 and 2000 were reviewed. All patients presented with paraparesis or tetraparesis on admission.
  
  
  RESULTS
  Magnetic resonance imaging (MRI) or computed tomography-myelography revealed that the syrinx predominantly existed at the thoracic levels. Five patients showed complete block of the thoracic subarachnoid space by conventional myelography. T2-weighted MRI showed diffuse intramedullary hyperintensity at the level of arachnoiditis. As the first surgical treatment, 10 patients underwent syringo-peritoneal shunt placement. Three patients were treated with a syringo-subarachnoid shunt, and 2 patients were treated with a ventriculoperitoneal shunt. Eight patients required further shunting operations for syringomyelia 2 months to 12 years after the first surgery. Neurologic improvement was obtained in 9 patients (60%) with decreased size of the syrinx. One patient remained stable; 5 patients showed gradual deterioration.
  
  
  CONCLUSIONS
  The syrinx originated from the thoracic levels where severe adhesion of the subarachnoid space was present. The mechanisms of syrinx formation may be based on the increased interstitial fluid in the spinal cord. Shunting procedures were effective in some population of the patients. Decompression procedures of the spinal subarachnoid space may be an alternative primary surgical treatment except for patients with longitudinally extensive arachnoiditis.
authors.affiliation: Department of Neurosurgery, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan. koyai@sapmed.ac.jp
authors.forename: Izumi
authors.initials: I
authors.lastname: Koyanagi
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Iwasaki
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Hida
authors.forename: Kiyohiro
authors.initials: K
authors.lastname: Houkin
mesh_terms: D000328:Adult; D001100:Arachnoiditis / Q000150:complications*; D002557:Cerebrospinal Fluid Shunts; D019299:Decompression, Surgical; D018450:Disease Progression; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009192:Myelography; D012189:Retrospective Studies; D013118:Spinal Cord Diseases / Q000150:complications* / Q000601:surgery; D013346:Subarachnoid Space / Q000473:pathology; D013595:Syringomyelia / Q000209:etiology* / Q000503:physiopathology* / Q000601:surgery; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome