title: Craniocervical junction fusions in patients with hindbrain herniation and syringohydromyelia.
abstract: OBJECTIVE
  Patients with hindbrain herniation or the so-called Chiari malformation Type I (CM-I) and/or syringohydromyelia are treated with dorsal decompression alone; however, a small percentage of patients with other associated abnormalities require concomitant dorsal craniocervical junction (CCJ) fusion. The authors surveyed the indications for CCJ fusions in this population.
  
  
  METHODS
  A retrospective review of University of Iowa medical records and radiographs obtained between 1996 and 2005 was performed. Inclusion criteria encompassed patients with diagnoses of CM-I and/or syringohydromyelia requiring dorsal CCJ fusions, and others with CCJ abnormalities who had CM-I and/or syringohydromyelia.
  
  
  RESULTS
  Two hundred thirty-four patients were identified, all of whom were symptomatic at presentation. Their ages ranged from 2.5 to 86 years; 33% of the patients were < 16 years of age. Patients were categorized as follows, with some being assigned to > 1 category: Group I, congenital or acquired CCJ abnormalities with reducible bone compression (25% of patients); Group II, previous anterior CCJ/upper brainstem decompression (44%); Group III, occipitocervical complex instability with CM-I and/or syringohydromyelia but without CCJ bone abnormalities requiring adjunctive posterior fossa decompression (26%); and Group IV, musculoligamentous instability, either from pathological states or from muscle dehiscence from repeated posterior fossa procedures (14%). Instrumentation was used in 96% of patients, with all 96% receiving semirigid fixation with titanium loop and sublaminar cables; all fusion constructs incorporated autologous bone. At last follow-up evaluation, fusion was radiographically complete in 97%, and symptom improvement was seen in 92%.
  
  
  CONCLUSIONS
  Dorsal CCJ fusions are required in patients with CM-I and/or syringohydromyelia who have concomitant CCJ abnormalities (Groups I and II). A definite group (CM-I and/or syringohydromyelia) without bone abnormality exists (Groups III and IV). This may be due to muscle weakness secondary to a high syrinx.
authors.affiliation: Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA.
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Fenoy
authors.forename: Arnold H
authors.initials: AH
authors.lastname: Menezes
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Fenoy
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001139:Arnold-Chiari Malformation / Q000150:complications / Q000601:surgery*; D002574:Cervical Vertebrae / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D019299:Decompression, Surgical; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009777:Occipital Bone / Q000601:surgery; D012189:Retrospective Studies; D012249:Rhombencephalon; D013123:Spinal Fusion / Q000379:methods; D013595:Syringomyelia / Q000150:complications / Q000601:surgery*