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Craniocervical junction fusions in patients with hindbrain herniation and syringohydromyelia
Albert J Fenoy1, Arnold H Menezes, Kathleen A Fenoy
1Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA.
Insights
Dorsal craniocervical junction fusion is necessary for patients with Chiari malformation Type I and/or syringomyelia who have associated abnormalities. This procedure is effective, with high fusion and symptom improvement rates.
Area of Science:
- Neurosurgery
- Orthopedic Surgery
- Pediatric Neurosurgery
Background:
- Chiari malformation Type I (CM-I) and syringomyelia are often treated with dorsal decompression alone.
- However, some patients require additional dorsal craniocervical junction (CCJ) fusion due to associated abnormalities.
Observation:
- A retrospective review identified 234 symptomatic patients (ages 2.5-86 years) with CM-I and/or syringomyelia requiring CCJ fusion.
- Patients presented with congenital/acquired CCJ abnormalities, prior anterior decompression, occipitocervical instability, or musculoligamentous instability.
- Instrumentation (96%) and autologous bone were used, with semirigid fixation in all cases.
Findings:
- Radiographic fusion was achieved in 97% of patients, and 92% experienced symptom improvement.
- Dorsal CCJ fusions are indicated for CM-I/syringomyelia with concomitant CCJ abnormalities (bone abnormalities or prior surgery).
- Instability without bone abnormalities may be linked to muscle weakness from high syrinx.
Implications:
- Dorsal CCJ fusion is a valuable adjunct for select CM-I/syringomyelia patients with complex CCJ issues.
- Identifying specific indications for CCJ fusion improves surgical decision-making in this population.
- Further research may elucidate the role of muscle weakness in instability requiring fusion.
Object:
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.
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