Klippel-Feil Syndrome¶
Definition¶
Klippel-Feil syndrome (KFS) is a complex congenital condition characterized by failure of segmentation of two or more cervical vertebrae, resulting in congenital fusion. The classic clinical triad is a short neck, low posterior hairline, and limited cervical range of motion, though the complete triad is present in fewer than 50% of patients. Most common fused segments are C2-C3 and C5-C6.
Imaging Findings¶
Radiography/CT¶
- Congenital fusion of two or more cervical vertebral bodies (block vertebra)
- The fused segment shows a wasp-waist narrowing of the anteroposterior vertebral body diameter at the level of the vestigial disc
- The fused disc space may show a vestigial disc remnant or complete bony fusion
- Variable: occipitalization of the atlas, basilar invagination, Sprengel deformity (elevated scapula)
MRI¶
- Evaluates the spinal cord for associated anomalies (syringomyelia, diastematomyelia)
- Evaluates for cord compression at hypermobile segments adjacent to the fused levels
- Chiari I malformation may be associated
Clinical Pearl
The clinical significance of Klippel-Feil syndrome is that the fused cervical segments transfer abnormal stress to the adjacent unfused levels, leading to premature degenerative changes, hypermobility, and potential instability at these levels. Patients may present in adulthood with myelopathy or radiculopathy from degenerative disease at the levels adjacent to the congenital fusion.
Associated Anomalies¶
- Sprengel deformity (congenital elevation of the scapula) — present in 20–30%
- Hearing loss (sensorineural or conductive)
- Renal anomalies (unilateral agenesis, horseshoe kidney)
- Congenital heart disease
- Chiari I malformation
- Syringomyelia
Key Points¶
- Congenital fusion of ≥2 cervical vertebrae from failure of segmentation
- Classic triad: short neck, low hairline, limited ROM (complete triad in <50%)
- Adjacent unfused levels develop premature degeneration and hypermobility
- Associated with Sprengel deformity, renal anomalies, and hearing loss
- MRI evaluates the cord and adjacent level degeneration
References¶
- Menger RP, Rayi A, Notarianni C. Klippel Feil Syndrome. In: StatPearls. Treasure Island (FL): StatPearls Publishing; updated 2024 May 11. Available from: https://www.ncbi.nlm.nih.gov/books/NBK493157/
- Samartzis DD, Herman J, Lubicky JP, Shen FH. Classification of congenitally fused cervical patterns in Klippel-Feil patients: epidemiology and role in the development of cervical spine-related symptoms. Spine (Phila Pa 1976). 2006;31(21):E798-804. PMID: 17023841.
- Tracy MR, Dormans JP, Kusumi K. Klippel-Feil syndrome: clinical features and current understanding of etiology. Clin Orthop Relat Res. 2004;(424):183-90. PMID: 15241163.
- Nouri A, Patel K, Evans H, et al. Demographics, presentation and symptoms of patients with Klippel-Feil syndrome: analysis of a global patient-reported registry. Eur Spine J. 2019;28(10):2257-2265. PMID: 31363914.
- Ulmer JL, Elster AD, Ginsberg LE, Williams DW 3rd. Klippel-Feil syndrome: CT and MR of acquired and congenital abnormalities of cervical spine and cord. J Comput Assist Tomogr. 1993;17(2):215-24. PMID: 8454748.
- Frikha R. Klippel-Feil syndrome: a review of the literature. Clin Dysmorphol. 2020;29(1):35-37. PMID: 31577545.
- Klippel-Feil syndrome. Radiopaedia. Available from: https://radiopaedia.org/articles/klippel-feil-syndrome-3