SYNOSTOSIS OF CERVICAL SPINE (KLIPPEL-FEIL
SYNDROME)
Klippel-Feil syndrome refers to the congenital fusion of two or more cervical vertebrae. In some patients, the entire cervical spine is involved. The fusion is a result of failure of segmentation of the cervical somites during the third to eighth weeks of embryonic development. Although the etiology is not yet determined, the developmental defect is not limited to the cervical spine. Unilateral or bilateral elevation of the scapula occurs in 25% to 30% of patients. Other, less apparent defects in the genitourinary, nervous, and cardiopulmonary systems and hearing loss often occur in patients with Klippel-Feil syndrome.
Clinical Manifestations. The classic clinical
signs of the syndrome low posterior hairline, short neck, and limitation of
neck motion are not consistent findings; fewer than one half of
patients exhibit all three signs. Although the most common finding is
limitation of neck motion, many patients with marked cervical involvement
maintain a deceptively good range of motion.
Whereas anomalies of the atlantoaxial joint (C1-2) may be symptomatic,
fusion of lower cervical vertebrae causes no symptoms. Rather, the problems
commonly associated with Klippel-Feil syndrome originate at the open segments
adjacent to the area of synostosis, which may become compensatorily
hypermobile. As a result of trauma or increased demands placed on these joints,
hypermobility can lead to frank instability or degenerative osteoarthritis.
Symptoms may be due to mechanical irritation at open articulations, nerve root
irritation, or spinal cord compression. The development of symptoms is most
likely with fusion of more than four vertebrae; occipitalization of the atlas
plus a C2-3 fusion, leading to excessive demands on the atlantoaxial
articulation; and an open articulation between two zones of vertebral fusion.
Potentially serious conditions that are associated with Klippel-Feil
syndrome include scoliosis or kyphosis (60% of patients); urinary tract
abnormalities (33%); congenital heart disease (14%); and deafness (30%).
Because the urinary tract problems are often asymptomatic in children but if
present require treatment or monitoring, ultrasonography or evaluation by MRI
should be performed routinely.
Radiographic Findings. Radiographic
examination can be problematic because fixed bony deformities frequently
prevent proper positioning of the patient for standard views and overlapping
shadows from the mandible, occiput, and foramen magnum may obscure the upper
vertebrae. Standard laminagraphic views of the neck on flexion and extension
are therefore helpful, and CT with reconstruction views are helpful in
delineating the bony anatomy. MRI is a powerful tool in assessing spinal cord
morphology and nerve root impingement. Ossification of the vertebral body is
not complete until adolescence, and in children the unossified physes may give
the false impression of a normal disc space. Therefore, a suspected fusion in a
child should be confirmed with lateral flexion-extension radiographs.
The bony cervical defects may extend to the upper thoracic area,
particularly in patients with severe involvement. However, narrowing of the
vertebral canal, due to degenerative changes or developmental hypermobility,
does not usually occur until adulthood.
Treatment. Children with minimal involvement usually
lead a normal, active life with minor or no restrictions or symptoms. Symptoms
referable to the cervical spine may occur in adulthood as a result of osteoarthritis
or instability of the hypermobile articulations. Although conservative
treatment is sufficient in most patients, a few require judicious surgical
stabilization. Scoliosis must be monitored carefully and treated if necessary.
However, the relatively good prognosis of the cervical condition is
overshadowed by the hidden or unrecognized associated anomalies. Early
recognition and treatment of these problems may spare the patient
further deformity or serious illness.
