Klippel-Feil syndrome: Should additional examination be conducted?

Klippel-Feil syndrome (KF) is a rare disease defined as single or multi-level cervical vertebra fusion. KF could be accompanied by other spinal anomalies or isolated, and in which case necessity of whole spine screening is not clearly known. KF is investigated in terms of prevalence, gender distribution, fusion types, and frequency of accompanying anomalies according to types of KF.

Approval from our hospital's ethics committee was received for this single-center, retrospective study. Considering the exclusion criteria among the 40,901 cervical spine MRIs, 40,450 patients were included in the study. It was re-evaluated for KF, fusion level, classification, cervical scoliosis, and other musculoskeletal and spinal anomalies.

125 (0.309%) of 40,450 patients is diagnosed with KF, which is more common in women (P < 0.001). Single fused segment 106 (84.8%), multilevel fused segments 8 (6.4%), contiguous fused segments 11 (8.8%) are observed. Upper level KF is detected in 13 (10.4%) patients. The frequency of additional anomaly is significantly higher in upper level KF compared to other level fusions (P < 0.001, Chi-square t). The cervical scoliosis is diagnosed 34 (27%). In KF patients with scoliosis, the frequency of additional anomalies was significantly higher (P < 0.001, Chi-square t).

Klippel-Feil prevalence is 0.309%, it is frequently observed in women, and at C2-C3 level. Additional anomalies are especially associated with 'contiguous fused segments' and 'upper level' types. Klippel-Feil with scoliosis is an indicator of increased risk for associated anomalies, and examination of the whole spine is recommended.