Classification of congenitally fused cervical patterns in Klippel-Feil patients: epidemiology and role in the development of cervical spine-related symptoms.

STUDY
DESIGN: A retrospective cohort and series review.
OBJECTIVES: To determine the role of cervical spine fusion patterns on the development of cervical spine-related symptoms (CSS) in patients with Klippel-Feil syndrome (KFS) and evaluate age- and time-dependent factors that may contribute to fused cervical patterns and the development of the CSS. SUMMARY OF BACKGROUND DATA: Although the "hallmark" of KFS is the presence of congenitally fused cervical vertebrae, the epidemiology and role of specific cervical fused patterns are limited. In addition, the incidence of symptoms and various age- and time-dependent factors that are directly attributed to the congenitally fused cervical segments in KFS patients is unknown.
METHODS: A radiographic and clinical review of 28 KFS patients at a single institution. Radiographically, Type I patients were defined as having a single congenitally fused cervical segment. Type II patients demonstrated multiple noncontiguous, congenitally fused segments, and Type III patients had multiple contiguous, congenitally fused cervical segments. Clinical records were reviewed for patient demographics, presence and type of symptoms, and clinical course.
RESULTS: Twelve males and 16 females were reviewed for clinical follow-up (mean, 8.5 years) and radiographic assessment (mean, 8.0 years). The mean age at presentation was 7.1 years; mean age of onset of CSS was 11.9 years. Clinically, 64% had no complaints referable to their cervical spine. Radiographically, 25%, 50%, and 25% were Type I, Type II, and Type III, respectively. At final clinical follow-up, 2 patients were myelopathic (Type II and Type III) and 2 were radiculopathic (Type II and Type III). Type III patients were largely asymptomatic but were associated with the highest risk in developing radiculopathy or myelopathy than Type I or Type II patients. Axial symptoms were predominantly associated with Type I patients. Myelopathic patients developed initial CSS earlier (meanage, 10.6 years) than patients with predominant axial (mean age, 13.0 years) or radiculopathic symptoms (mean age, 18.6 years) (P > 0.05). Patients with radiculopathy or myelopathy were diagnosed at a mean age of 17.9 years. Type I patients were predominantly females, while males were largely Type III. Surgery entailed 11% of patients, composed of 2 myelopathic patients (Type II and Type III) and 1 radiculopathic patient (Type II).
CONCLUSIONS: In our review, 36% of KFS patients had CSS and the majority had axial symptoms. Axial neck symptoms were highly associated with Type I patients, whereas predominant radicular and myelopathic symptoms occurred in Type II and Type III patients. This classification system has promise for early detection for CSS. Activity modification should be stressed in KFS patients at high risk for neurologic compromise.