Klippel-feil syndrome

Philippe Jeanty, MD, PhD Sandra R Silva, MD

Updated 2006-01-18 by Juliana Leite, MD

Original text 1999-05-08 Philippe Jeanty, MD, PhD & Sandra R Silva, MD

Synonyms: Segmentation syndrome 1

Definition: Klippel-Feil syndrome first was described by Klippel and Feil in 1975. It is a congenital anomaly characterized by a classid triad including short neck, low posterior hairline, and limited range of motion of the due to fusion of cervical vertebrae. It now is known that fewer than 50% of patients with congenital defects of the cervical spine have all three signs of this classic triad. Patients with Klippel-Feil syndrome were assigned to one of three types:

  • Type I comprises fusion of many cervical and upper thoracic vertebrae into bony blocks.

  • Type II has fusion at only one or two vertebrae and may associate hemivertebrae and fusion of the occipito-atlantoic joint.

  • Type III has both cervical fusion and lower thoracic or lumbar fusion.

Incidence: It has been estimated that it occurs in approximately 1:40,000–42,000 births, which may be an underestimate because some mild forms may be under reported. A slight female predominance of approximately 3:2 has been reported.

Etiopathology: Anomalies of segmentation of the somites in the 4th to 8th week.

Diagnosis: The short neck may be associated with opisthotonos (retroflexion of the head), and the disorganization of the cervical vertebrae is potentially recognizable. It is sometimes associated with ocular malformations, cleft lip and/or palate and occasional oligodontia in both the primary and permanent dentition, craniofacial asymmetry, maxillary constriction and velopharyngeal insufficiency, persistent trigeminal artery, congenital heart defects and renal (renal agenesis) and genital anomalies. It has been reported also an interesting case of an intramedullary mass associated to this syndrome due, perhaps, to a mal development of the cervical spine.


Figure 1: The opisthotonotic position should not be maintained for long periods of time. If after stimulation the position is kept up, the diagnosis should be suspected.


Figure 2: A child with Klippel-Feil syndrome. Note the opisthotonotic position, low set ears, and micrognathia.

Genetic anomalies: Dominant inheritance with reduced penetrance and variable expression of a defective gene on the long arm of chromosome 8 at locus 22.2. Possible role of PAX1 in the pathogenesis of KFS is object of studies. It has been shown that a PAX1 mutant mouse is characterized by vertebral segmentation defects, reminiscent of the human disorder Klippel-Feil syndrome.

Differential diagnosis: Iniencephaly presents with similar opisthotonos but appears more severe (cervical spina bifida); dyssegmental dysplasia presents with similar vertebral findings but adds short limbs and cephaloceles. It is unclear whether Klippel-Feil syndrome is a discrete entity, or if it is one point on a spectrum of congenital spinal deformities. Only by identifying the link between the genetic etiology and the phenotypic pathological anatomy of the syndrome we'll be able to rationalize the heterogeneity of it.

Prognosis: The complications result from the vertebral fusion and include cord compression syndrome, cervical instability, and motility impairment.

Management: Termination of pregnancy can be offered before viability. Standard prenatal care is not altered when continuation of the pregnancy is chosen. Confirmation of diagnosis after birth is important for genetic counseling.


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2: Erol M, Caksen H, Tan O, Atik B, Unal O, Odabas D. Report of a girl with Klippel-feil syndrome and Poland anomaly. Genet Couns. 2004; 15(4):469-72.

3: Dickerman RD, Colle KO, Mittler MA.Intramedullary inflammatory mass dorsal to the Klippel-Feil deformity: error in development or response to an abnormal motion segment? Spinal Cord. 2004 Dec; 42(12):720-2.

4: Tracy MR, Dormans JP, Kusumi K. Klippel-Feil syndrome: clinical features and current understanding of etiology. Clin Orthop Relat Res. 2004 Jul ;( 424):183-90.

5: Paksoy Y, SEker M, Kalkan E. Klippel-Feil syndrome associated with persistent trigeminal artery. Spine. 2004 Apr 23; 29(9):E193-6.

6: McGaughran JM, Oates A, Donnai D, Read AP, Tassabehji M.Mutations in PAX1 may be associated with Klippel-Feil syndrome.Eur J Hum Genet. 2003 Jun; 11(6):468-74.

7. Klippel M, Feil A. The classic: A case of absence of cervical vertebrae with the thoracic cage rising to the base of the cranium (cervical thoracic cage). Clin Orthop. 1975;109:3–88. Tracy MR, Kusumi K. Klippel-Feil Syndrome: Clinical features and current understanding of etiology. Pediatrics 2004;(424):183-190

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