Discussion: Klippel-Feil Syndrome is a rare disorder characterized by the congenital fusion of cervical vertebrae. It is caused by a failure in the normal segmentation of the cervical vertebrae during the early weeks of fetal development. The most common signs of the disorder are short neck, low hairline at the back of the head, and restricted mobility of the upper spine especially lateral bending.
Initially classified by Feil in 1912 in the following way:
- Type I - a massive fusion of the cervical spine
- Type II - the fusion of 1 or 2 vertebrae
- Type III - the presence of thoracic and lumbar spine anomalies in association with type I or type II Klippel-Feil syndrome
In 2006, Samartzis and colleagues suggested a new classification system.
- Type I - a single-level fusion
- Type II - multiple, noncontiguous fused segments
- Type III - multiple, contiguous fused segments
Failure of normal segmentation of cervical somites at 3-8 weeks gestation results in fused cervical segments. A familial Klippel-Feil-syndrome gene locus has been located on the long arm of chromosome 8.
Klippel-Feil syndrome is often associated with other congenital anomalies including:
- Congential scolosis (60%) and other vertebral anomalies including hemivertebrae and block vertebrae
- Sprengel’s deformity (33%) which is failure of the scapula to decend resulting in attachment to the cervical spine by omovertebral bone or fibrous band
- Renal anomalies (33%) including double collecting system, renal ectopia, bilateral tubular ectasia, hydronephrosis, absence of kidney, and horsehoe kidney.
- Congenital heart disease mainly septal defects
- Craniocervical junction abnormalities including Arnold-Chiari malformation
- Congenital cervical stenosis
- Syndactyly and hypoplastic thumb
- Hearing loss
- Synkinesis (mirror motions).
75% of cases occur in C1-C3 with fusion of C2-3 being most common. 50% of cases involve less than three vertebrae.
After initial diagnosis, addition imaging may be required depending on the patient’s clinical presentation:
- Flexion-extension c-spine views to evaluate for instability
- Plain radiographs of entire spine to detect other spinal anomalies
- MRI for those with neurologic deficits possibly including flexion-extension MRI to evaluate for cord compression
- Renal ultrasound and IVP
- Audiometric and otologic evaluation
