Klippel-Feil syndrome (KFS) is a congenital disorder of cervical vertebral segmentation that arises from defective somitogenesis during weeks 3–8 of embryogenesis. Because the early embryologic disturbance affects multiple structures sharing developmental origins, KFS is associated with multiple extra-cervical anomalies, including conductive or sensorineural hearing loss in approximately 30% of patients. The pattern marked A — bilateral conductive loss with air-bone gap — is characteristic of middle ear or ossicular pathology. In KFS, conductive hearing loss typically results from ossicular chain malformations or fixation, or external/middle ear structural anomalies arising from the same embryologic disruption that causes cervical vertebral fusion. This finding aligns directly with the embryologic basis of KFS affecting multiple tissues during the critical developmental window (Cummings Otolaryngology 7e, Ch 198).
Cummings Otolaryngology 7e, Ch 198
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