Classification of Congenitally Fused Cervical Patterns in Klippel-Feil Patients: Epidemiology and Role in the Development of Cervical Spine-Related Symptoms

Methods: A radiographic and clinical review of KFS patients. Radiographically, Type I patients exhibited a single congenitally fused cervical segment. Type II patients demonstrated multiple non-contiguous, congenitally fused segments, and Type III patients had multiple contiguous, congenitally fused cervical segments. Clinical records were reviewed for patient history, demographics, and the presence of cervical symptoms (axial, radiculopathy, and myelopathy). Radiculopathy and myelopathy were considered clinically significant symptoms.

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 of onset of cervical spine-related symptoms was 11.9 years. Clinically, 64.3% were asymptomatic. Radiographically, 25%, 50%, and 25% were Type I, Type II, and Type III, respectively. On final clinical follow-up, two patients were myelopathic (Types II & III) and two were radiculopathic (Types II & III). Axial symptoms were predominantly associated with Type I patients. Myelopathic patients developed initial cervical spine-related symptoms earlier (mean age, 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, whereas Type III patients were mainly males. Surgery entailed 10.7% of patients (2 Type II, 1 Type III).

Conclusions: 35.7% of patients were symptomatic, the majority of which were axial and associated with Type I patients. Radicular and myelopathic symptoms occurred in Types II & III patients. Type I patients had an earlier onset of axial symptoms. Myelopathic patients were diagnosed later in adolescence, but presented with initial cervical symptoms at an earlier age. Fusion patterns may be associated with sex-type.