Extract
Mutations of homeobox genes may be responsible for congenital
osseous anomalies of the cervical spine.
Mutations of homeobox genes may be responsible for congenital
osseous anomalies of the cervical spine.
Congenital osseous anomalies of the cervical spine may herald
congenital malformations of other organ systems, such as those of
the kidney and heart.
Most congenital anomalies of the cervical spine are innocuous
and may go undetected throughout life.
Translational instability of adjacent vertebral bodies in a congenitally
stenotic cervical spinal canal has serious implications.
No existing prognostic classification system can predict which
patients with a congenital osseous anomaly of the cervical spine
are at risk for future neurologic injury.
Congenital osseous anomalies of the upper and lower cervical
spine are rare, yet their detection and treatment are important,
as these deformities often set the stage for cervical spine instability
and potential neurologic injury. Many of these conditions are associated
with various syndromes and are, in part, developmental conditions.
The presence of a congenital osseous anomaly in any part of the
cervical spine often heralds congenital malformations in other organ
systems. This factor is of paramount importance to the treating
physician, whose main attention may be directed toward the patient’s
neck. However, the vast majority of congenital anomalies pose no
problems for the patient and thus go undetected. The current review
focuses on the description, radiographic examination, physical findings, and
treatment of these anomalies.
Homeobox, or Hox, genes are a family of genes that regulate,
among other things, the differentiation processes of the axial and
appendicular skeletons1,2. These
genes regulate the embryonic differentiation and segmentation of
the craniocaudal axis by activation and repression of DNA sequences
that encode the transcription factors and proteins affecting the
order and direction of development of the axial skeleton3. Mutations of the homeobox genes
may be responsible for congenital anomalies of the cervical spine4.
Clarke and colleagues have written extensively about familial
Klippel-Feil syndrome and have noted that this condition is usually
marked by fusion of the second and third cervical vertebrae and
is consistently associated with congenital anomalies of other systems5-8. They have also identified evidence
of a familial Klippel-Feil-syndrome gene locus on the long arm of
chromosome 8. Bavinck and Weaver believed that disruption of the
blood supply of the vertebral vessels and their branches during
development might be responsible for the vertebral defects9. None of these observations have
been confirmed or refuted by other researchers. Teratologic events, such
as the maternal consumption of ethanol during pregnancy, have also
been suggested to cause vertebral anomalies in the cervical spine10,11.
An anteroposterior radiograph; an open-mouth odontoid radiograph;
and lateral neutral, flexion, and extension radiographs are essential
in the initial evaluation of these conditions12.
The three lateral views provide the most information. The fusion
of two levels is best determined with use of flexion and extension
radiographs, which will demonstrate a change in the distance between
the spinous processes if the vertebrae are unfused. Translational
instability is seen most easily by comparing the lateral flexion
and extension radiographs, whereas spinal stenosis is best evaluated
by measuring the sagittal diameter of the spinal canal on the lateral
neutral radiograph. Standing posteroanterior and lateral radiographs
of the thoracolumbosacral spine should be made to check for any
other congenital spinal deformity.
In Klippel-Feil syndrome, the vertebrae are often widened and
flattened. The vertebrae may assume a so-called wasp-waist appearance,
with the anterior and posterior cortices concave toward the center
of the vertebral body, which has been considered to be pathognomonic
for congenital fusion13. The neural
foramina should be inspected for osteophytes, which may be present
in older individuals with degenerative changes. These osteophytes may
cause nerve-root compression and radicular symptoms. Disc spaces
may be absent or narrowed. Magnetic resonance imaging has shown
that protrusion of disc material into the spinal canal may occur at
levels that appear to be fused on radiographs14.
In general, fusion of the posterior elements is associated with
fusion of the vertebral bodies. However, in young children, careful
attention should be paid to the laminae and the posterior elements,
as these areas may ossify before the intervertebral spaces do15.
Cineradiography is a fluoroscopic method that is used to dynamically
evaluate the status of the cervical spine through its range of motion16,17. This method is an important
tool for the evaluation of the upper cervical spine but is less
useful for the evaluation of the middle and lower cervical spine.
We believe that the study should be performed under the supervision
of the physician who will be using the data. Tomograms are helpful
for identifying hemivertebrae and for determining whether vertebral
levels are fused; however, they are not routinely ordered. Computed
tomography may be performed to better define osseous anatomy. Head-wag
autotomography has been used to evaluate the upper cervical spine
in infants with torticollis to rule out congenital anomalies that
are difficult to see on standard radiographs18.
The advent of magnetic resonance imaging has greatly enhanced
our ability to evaluate the soft-tissue anatomy in patients with
congenital anomalies of the cervical spine. Intraspinal lesions
such as syringomyelia, meningioma, and lipoma are clearly identified
(Fig. 1).
Evaluation of the intervertebral discs with use of magnetic resonance
imaging can show disc desiccation, herniation, and protrusion. One
of us (J.T.G.) and colleagues, in a study of twenty-two patients
with Klippel-Feil syndrome who were evaluated at an average age
of thirty-five years (range, twenty-six to fifty-seven years), noted degenerative
changes of the discs in all patients as demonstrated by a low-intensity
signal on T2-weighted images14.
Nineteen patients (86%) had abnormal findings on the magnetic
resonance imaging scans, including disc protrusion, osteophytes,
and narrowing at the craniovertebral junction, that were not apparent
on standard radiographs. Four patients had a cervical syringomyelia.
No congenital spinal stenosis or instability was documented (Figs. 2-A, 2-B, and 2-C). In contrast,
Ritterbusch et al., in a study of twenty patients with Klippel-Feil
syndrome, reported stenosis of £9 mm in five patients (25%)
and subluxation of >5 mm in five patients (25%)
as demonstrated by magnetic resonance imaging19.
Three patients had a total of four cervical cord abnormalities,
including hydromyelia (one patient), Arnold-Chiari type-I malformation
(one patient), and diplomyelia (two patients). Ulmer et al. reported
on twenty-four patients who were evaluated with magnetic resonance
imaging and computed tomography studies20.
Ten patients (42%) had cervical spondylosis (most commonly
in the lower cervical spine) or disc herniation, five had cervical
cord dysraphism or diastematomyelia, and two had an Arnold-Chiari type-I
malformation. Kinematic magnetic resonance imaging has potential
for the dynamic evaluation of the stability of the upper cervical
spine in flexion and extension21.
Occipitoatlantal Fusion
Occipitoatlantal fusion, also known as occipitalization of the
atlas, is, as its name implies, partial or total fusion of the atlas
to the occiput22. Anomalies at
the occipitocervical junction are commonly seen in patients with
achondroplasia, diastrophic dwarfism, spondyloepiphyseal dysplasia,
Larsen syndrome, and Morquio syndrome. Occipitalization of the atlas
is also seen in conjunction with fusion of the second and third
cervical vertebrae, and this pattern may predispose the atlantoaxial
joint to abnormal stress, premature degeneration, and potential
instability. In its isolated form, occipitalization of the atlas
causes no problems and is inconsequential in nature. In their classic
report of 1953, McRae and Barnum described twenty-five patients
with this condition and found that the anterior aspect of the complex was
fused more commonly than the posterior elements were23,24. The posterior elements of the
atlas may be hypoplastic and anomalous, causing compression posteriorly25. Eighteen (72%) of the
twenty-five patients in the report by McRae and Barnum reported
neurologic problems, such as weakness, numbness, or pain in the
upper extremities or dull headaches. Sixteen of these eighteen patients
had long-tract signs indicative of pyramidal compression. Wackenheim reported
that instability at this level may be caused by a deficiency of
the transverse atlantal ligament26.
Respiratory and autonomic dysfunction also have been reported in
patients with this condition27.
Posterior impingement by the foramen magnum, a fibrous dural
band, or the posterior elements of the atlas can lead to such symptoms
as altered sensation to deep touch, vibration, and proprioception (posterior
column signs). Cerebellar herniation may lead to nystagmus, ataxia,
and imbalance in coordination. Compression of the vertebral arteries
can lead to vertigo, seizures, changes in mental status, and syncope.
The onset of neurologic problems may occur late in these patients,
with progression being slow. Clinically, these children may present with
a shortened neck and the other stigmata commonly associated with
the Klippel-Feil syndrome.
McRae emphasized the importance of the space available for the
cord in patients with neurologic problems23.
This space is measured on the lateral radiograph from the posterior
arch of the odontoid process to the anterior aspect of the posterior
arch of the atlas. McRae initially noted that the space available
for the cord in his patients with neurologic problems was <19
mm. Today, it is accepted that a sagittal diameter of £13
mm may be associated with neurologic symptoms or signs. Routine
radiographs of the cervical spine may be difficult to interpret because
of patient positioning and the presence of overlapping shadows on
the images. It has been suggested that the x-ray beam should be
directed 90° perpendicular to the skull, and not the cervical spine,
when lateral radiographs of the craniovertebral junction are made.
This is because the ring of the atlas usually stays with the occiput
during motion. We believe that tomograms and computed tomography
scans provide the best visualization of the osseous anatomy, whereas
magnetic resonance imaging is best used for the evaluation of soft
tissues.
Cervical collars and traction may initially help patients who
have signs or symptoms, which usually are related to instability
at the atlantoaxial junction. Traction can be used in an attempt
to reduce any subluxation prior to a posterior fusion and may predict
the success of surgery22,25. In
the presence of posterior signs and symptoms, decompression of the
posterior elements should be considered. Posterior fusion of the
occiput-atlas complex to the axis is then done to provide stability.
Care should be taken when internal fixation is used in the presence
of anomalous anatomy.
Basilar Impression and Invagination
Basilar impression implies that the floor of the skull is indented
or has been violated by the upper cervical spine, usually the odontoid,
which may sit within the foramen magnum28.
There are two types of basilar impression: primary impression, which
is congenital and more common, and secondary impression, which is
developmental. Primary impression can be associated with occipitoatlantal
fusion, hypoplasia of the atlas, a bifid posterior arch of the atlas,
odontoid anomalies, and achondroplasia. Secondary basilar impression
in seen in association with conditions such as rickets, osteogenesis
imperfecta, Paget disease, neurofibromatosis, skeletal dysplasias,
and rheumatoid arthritis.
Children with primary basilar impression present with a short
neck, often with a limited or painful range of motion. Facial asymmetry
and torticollis may be present. Neurologic signs and symptoms are
often evident but may not present until the second or third decade
of life. Some signs or symptoms may be precipitated by trivial trauma,
such as a fall or sports injury. The signs and symptoms are usually
related to compression of the neural elements and the medulla oblongata
at the level of the foramen magnum29.
Patients may have weakness and paresthesias of the limbs and sexual
dysfunction. They also may have neck pain, headaches in the distribution
of the greater occipital nerve, cranial-nerve involvement, ataxia,
vertigo, or nystagmus, depending on the site of impingement. The
impinged structures can include the vertebral arteries, posterior
columns, pyramidal tracts, cerebellar tonsils, and aqueduct of Sylvius.
Basilar impression can be evaluated on a lateral radiograph with
use of Chamberlain’s, McRae’s, or McGregor’s
line30. Chamberlain’s
line is drawn from the posterior lip of the foramen magnum (the
opisthion) to the dorsal margin of the hard palate. McGregor’s
line is drawn from the upper surface of the posterior edge of the
hard palate to the most caudad point of the occipital curve of the
skull. This line is best for screening purposes, as the landmarks
are clearly seen on the lateral radiograph at all ages. McRae’s line
defines the opening of the foramen magnum and is important because
most patients in whom the odontoid is above this line will probably
be symptomatic. The value of using these three measurements is unclear,
as variations in gender, patient positioning, and the presence of
congenital anomalies of the skull and face may skew the results.
We have found that computed tomography scans with reconstruction
and magnetic resonance images (Fig. 1) provide more clinically useful
information.
If the symptoms are the result of an aberrant odontoid that cannot
be reduced, resection of the odontoid may be indicated. If the symptoms
are due to posterior compression, a suboccipital decompression with
decompressive laminectomies of the atlas and axis with posterior
fusion may be required22,29. Menezes
recommended using gradual traction with increasing weight over several
days in an attempt to achieve reductionpreoperatively31. Following reduction and posterior
stabilization, the patients were immobilized in a halo device for six
months. Theoretically, the use of internal fixation may reduce the
need for or length of postoperative immobilization.
Occipital Vertebrae and Condylar Hypoplasia
Accessory vertebrae or their remnants may be present at the craniovertebral
junction, especially at the lateral masses. Condylar hypoplasia
or dysplasia, another finding often seen on radiographs, may cause
instability, but its clinical importance is not known because of
its rarity32,33. Iniencephaly
is characterized by a short, immobile, lordotic neck; hyperextension
deformity of the head; an occipital defect; and cervical spina bifida34,35. This condition was once thought
to be incompatible with life because of the spinal cord problems
at the craniovertebral junction, but many patients now survive into
adulthood.
Occipitoatlantal Instability
Instability at the occipitoatlantal joint has been described
after trauma to the cervical spine and in association with Down
syndrome, familial cervical dysplasia, and hyperlaxity syndromes36. Gilles et al., in a cadaveric model,
postulated that anomalies at the occipitoatlantal junction may even be
responsible for infantile sleep apnea and sudden infant death syndrome37. Symptoms of nontraumatic occipitoatlantal
instability can include neck pain, headache, torticollis, and weakness
as well as vertebrobasilar symptoms such as nausea, vomiting, and
vertigo. As treatment with immobilization has produced unsatisfactory results,
Georgopoulos et al. and Wiesel and Rothman recommended arthrodesis
of the occiput to the atlas for all patients with nontraumatic occipitoatlantal
instability32,38.
Aplasia or Hypoplasia of the Atlas
Hypoplasia of the atlas is a rare condition that usually presents
early in life as a torticollis. This torticollis, however, is distinguished
by initial flexibility at the craniovertebral junction followed by
increased rigidity, no sternocleidomastoid muscle tightness, and
aplasia of the muscles in the nuchal cavity on the affected side.
Dubousset described three forms of the anomaly39.
Type I is characterized by an isolated hemi-atlas; type II, by partial
or complete aplasia of one hemi-atlas with congenital fusions in
the cervical spine; and type III, by partial or complete occipitoatlantal fusion
and symmetrical or asymmetrical hemi-atlas aplasia with or without
anomalies of the odontoid or other cervical vertebrae. The anomaly
may be missed on routine radiographs, and traction on the head may
facilitate its discovery. In Dubousset’s series, the anomaly
in one patient was detected on a routine dental radiograph. Computed
tomography and magnetic resonance imaging provide the most useful
information. Angiography of the vertebral vessels should be performed
prior to any operation, as anomalies are common on the side of the
hemi-atlas.
Familial Cervical Dysplasia
Familial cervical dysplasia is an autosomal dominant condition
that was recently described by Saltzman et al.40.
The entity consists of various anomalies of the atlas and axis,
most commonly hypoplasia of the posterior arch of the atlas. Occipitoatlantal
instability is more common than atlantoaxial instability. Posterior
fusion of the craniovertebral junction may be required for the treatment
of pain, torticollis, neurologic symptoms, instability, or pending
instability.
Anomalies of the Axis
Congenital anomalies of the axis most often involve the odontoid
and present as a spectrum from hypoplasia to aplasia, all of which
can cause atlantoaxial instability41-44.
Odontoid aplasia is characterized by the absence of the basilar
portion of the odontoid, a structure that usually dips into and
contributes to the body of the axis. The basilar portion of the
odontoid sits caudad to the level of the superior articular facets
of the axis. Collectively, anomalies of the odontoid present with
the same signs and symptoms and are treated similarly. The true
prevalence of this condition is unknown, as many cases are noted
by chance. Anomalies of the odontoid frequently are seen in association
with Down syndrome and Morquio syndrome as well as many other skeletal dysplasias.
The clinical features of odontoid anomalies can include neck
pain, transitory paresis following trauma, and myelopathy. Many
odontoid anomalies are discovered following a seemingly mild injury. Mechanical
symptoms such as neck pain, headache, or torticollis may result
from irritation and instability of the structures or cord compression
at the atlantoaxial junction with resultant myelopathy. Few patients
present with vertebrobasilar symptoms. Routine radiographs should
be made, with consideration given to tomography and cineradiography.
Dynamic computed tomography and magnetic resonance imaging scans
are the imaging modalities of choice45.
The natural history of congenital anomalies of the odontoid is
usually one of progressive atlantoaxial instability and myelopathy.
Nonoperative modalities such as traction or immobilization may provide temporary
relief initially, but operative intervention is suggested for all
patients with neurologic symptoms25,31,41-43.
The role of prophylactic arthrodesis has not been established for
the asymptomatic patient with instability. However, many authors
have recommended fusion in the presence of radiographic signs of instability,
especially in active patients46-48.
Reduction of the atlantoaxial junction with traction or positioning
should be attempted prior to arthrodesis. This should be done several
weeks prior to surgery to determine if there is an amelioration
of neurologic symptoms. If reduction is accomplished with a halo,
the device may be left in place during the operation and used for
immobilization in the postoperative period. Open reduction is associated
with a high rate of complications and is not recommended. Irreducible
dislocations may require a posterior decompressive laminectomy. Recently,
good results have been reported in association with the use of internal
fixation to augment these procedures46-48.
Os Odontoideum
Os odontoideum is an anomaly of the odontoid process that was
once thought to be congenital. In recent years, a traumatic etiology
has been popularized by several authors49-53.
When the ossicle lies in the normal location of the odontoid process,
it is termed an orthotopic odontoideum; when rostrally displaced,
it is termed a dystopic os odontoideum. This separate ossicle travels
with the atlas through flexion and extension and can be a cause
of atlantoaxial instability. The signs and symptoms of this condition
are the same as those described for other anomalies of the odontoid,
and treatment with a posterior fusion of the first and second cervical
vertebrae may be required.
Klippel-Feil Syndrome
The prevalence of Klippel-Feil syndrome is unknown, as the majority
of individuals who have this condition are asymptomatic and may
not have any other associated anomalies54.
In a study of the skeletal specimens from 1400 cervical spines,
Brown et al. noted that only ten of seventy-five fused segments
that were found caudad to the second cervical vertebra were congenital
in nature, for an overall prevalence of 0.71%55. Congenital fusion was noted in
only 0.60% of the 1158 specimens with available radiographs
and most commonly was associated with so-called wasp-waist vertebrae.
Congenital fusion can occur at any level in the cervical spine.
Approximately 75% of cases occur in the region of the first
three cervical vertebrae, and approximately 50% of cases involve
three or fewer vertebrae. Fusion of the second and third cervical
vertebrae occurs most often, followed by fusion of the fifth and
sixth cervical vertebrae. Fusion at these sites may be inherited
in an autosomal dominant or autosomal recessive fashion, respectively56.
Lower cervical spine fusions occur in association with many syndromes
and conditions. Tredwell et al. reported that nineteen (50%)
of thirty-eight patients with fetal alcohol syndrome had congenital fusions
on radiographs of the neck10.
Sixteen of the nineteen patients had fusions involving the second
and third cervical levels, and six had additional fusions at other
levels. In addition, three of eighteen patients had mild renal anomalies
on intravenous pyelograms, and thirty-one of seventy-six patients
had cardiovascular anomalies, a prevalence much higher than that
normally observed in patients with Klippel-Feil syndrome.
Classifications
Feil classified the syndrome into three types on the basis of
the site and extent of the fusion, but no clinically relevant correlations
have been made with use of that system57.
Hensinger popularized a classification system, based on a variation
of the findings reported by McRae, that described three patterns
of potentially unstable fusions25,58.
Type I is characterized by fusion of the second and third cervical
vertebrae with occipitalization of the atlas; type II, by a long
fusion with an abnormal occipitocervical junction; and type III,
by two segments of block fusion with a single open interspace. The
type-III pattern of fusion, with its two long lever arms and one
open disc interspace, has long been associated with a poor prognosis
because of the mechanics of overuse at the one open disc space.
Long-term data from other studies, however, have not shown an increased
prevalence of neurologic problems in patients with this fusion pattern. In
the report by Michie and Clark, thirteen patients with osseous anomalies
of the cervical spine (including eight patients with congenital
fusions) were separated into clinical groups on the basis of the
presenting signs, which included root compression, cord compression,
myelopathy, syringomyelia, vascular disorders, and internal hydrocephalus59. Nagib et al., in a report on twenty-one
patients, divided the nine patients who had neurologic deficits
into three groups on the basis of the most clinically important
anomaly and the probable mechanism of injury60.
Treatment recommendations were then offered for each group. One
of us (J.T.G.) and colleagues14 noted
three patterns of fusion but found no correlation between the fusion
pattern and the presence of signs or symptoms that could be attributed
to the syndrome at the time of long-term follow-up. Pizzutillo et
al. described a functional classification system61,62 and
concluded that patients with hypermobility of the upper cervical
spine are at increased risk for neurologic problems whereas those
with involvement of the lower cervical spine are at increased risk
for early degenerative disease.
Phenotypic Features and Associated Conditions
The original description of the Klippel-Feil syndrome included
not only congenital fusion of the cervical vertebrae but also decreased
range of neck motion and a short neck with a low hairline. This triad
has been reported in approximately half of the patients with the
syndrome, partly because of the subjective nature of what is considered
a short neck or low hairline (Figs. 3-A, 3-B, 3-C, and 3-D)58,63.
The majority of patients, however, appear normal. The most consistent
finding is a limited range of motion of the neck, especially lateral
bending. Flexion and extension, which occur primarily at the occipitocervical
junction, and rotation, which occurs primarily at the atlantoaxial
junction, are usually preserved unless these levels are fused or anomalous.
If fewer than three vertebral levels are fused, loss of motion may
be unnoticeable, as much of this motion may be compensated for at
adjacent, unfused levels. Malformations of other systems have been
reported in association with the spinal anomalies64-67.
Torticollis is often a clinical manifestation of a congenital
osseous cervical spine anomaly, especially a hemivertebra of the
atlas39,68. Tumors of the posterior
fossa, infection, and cervicothoracic scoliosis also may result
in a torticollis. The deformity is characterized by a lateral tilt
of the head with rotation of the face. Often, the deformity is mild
and is unconsciously compensated for by the patient. Facial asymmetry,
which may be permanent, can occur in long-standing untreated cases. All
children who present with torticollis should be evaluated with cervical
spine radiographs to rule out osseous etiologies. Patients with
Klippel-Feil syndrome may have pterygium colli, a condition characterized
by various degrees of webbing of the skin from the sides of the
neck to the shoulders. When pterygium colli is bilateral, it gives
the appearance of a short neck; when unilateral, it can give the
appearance of a torticollis.
The face and head of individuals with congenital cervical spine
problems should be inspected for abnormal facies and ear anomalies69,70. Facial asymmetry may be secondary
to long-standing torticollis. Congenital cervical spine anomalies
have been associated with Apert and Crouzon syndromes69,70. Block vertebrae and hemivertebrae
in the cervical and thoracic areas, as well as facial and ear deformities,
have been reported in patients with oculo-auriculo-vertebral dysplasia
(Goldenhar syndrome)69,70. Cervico-oculo-acoustic
dysplasia (Wildervank syndrome) consists of Klippel-Feil syndrome, abducens
nerve paralysis, retraction of the eyeball, and deafness71.
A history for hearing impairment should be obtained and a basic
auditory test should be performed for all patients being evaluated
for Klippel-Feil syndrome. Hearing loss has been reported to occur
in approximately 30% of patients with this syndrome, and
ear deformities, with and without deafness, can occur in such patients
as well72-76.
Congenital elevation of the scapula, also known as Sprengel deformity,
is found in approximately 25% to 35% of patients
with Klippel-Feil syndrome71.
The clinical appearance is characterized by uneven shoulder heights,
and bilateral Sprengel deformity can give the appearance of a short
neck. This deformity may or may not be seen in association with
an omovertebral bone.
Congenital scoliosis, kyphosis, and lordosis, either individually
or in combination, have been reported to occur in association with
congenital cervical spine fusions in more than half of patients
with Klippel-Feil syndrome77-80.
The exact prevalence is unknown, as many studies have included all
types of deformities and much of the research has been done at tertiary
referral centers that specialize in these problems. Theiss et al., in
a series of 120 patients with Klippel-Feil syndrome, sixty-five
of whom had scoliosis, found that no particular fusion pattern was
a risk factor for neurologic symptoms and that neither the number nor
the level of fused vertebrae was predictive of symptomatology80. Clinically, the deformity most
germane to the topic of the present article is cervicothoracic scoliosis79. A cervicothoracic curve, by definition,
has its apex at the cervicothoracic junction, with a hemivertebra
often found at this level. This deformity may give the appearance
of uneven shoulder heights, rotation of the upper part of the thorax,
and torticollis. Hensinger et al. noted such a high prevalence of
Klippel-Feil syndrome in patients with congenital cervicothoracic
scoliosis that they recommended making radiographs of the cervical spine
for such patients to screen for the syndrome58.
Congenital anomalies of the cardiovascular system have been reported
to occur in 4.2% to 14% of patients with Klippel-Feil
syndrome, especially girls81,82.
A ventricular septal defect is the most common anomaly, but atrial
septal defects, dextrocardia, aortic stenosis, and patent ductus
arteriosus have also been reported81,82.
Auscultation should be done to detect murmurs, and a baseline electrocardiogram
should be considered for all patients with a known fusion in the
cervical spine, especially if an operation is planned.
The prevalence of genitourinary defects in patients with Klippel-Feil
syndrome has ranged from 2% to 64%83-85. The most common anomaly is unilateral
renal agenesis, followed by malrotation of a normally functioning
kidney. All patients with Klippel-Feil syndrome should have an ultrasound
evaluation of the renal system. An intravenous pyelogram need only
be done if abnormalities are found on the sonogram or if the study
is inconclusive84. If the sonographic
study reveals abnormalities in the renal system, the female reproductive
organs should be scanned as well.
Neurologic Assessment
The distinction between the terms signs and symptoms is important
when evaluating clinical conditions. Signs are physical manifestations
of a condition, whereas symptoms are subjective assessments offered
by the patient. There are no specific symptoms that can be attributed
directly to congenital fusions in the lower cervical spine. Generally, symptoms
are localized to the head, neck, and upper extremities and can include
headaches, syncope, weakness, and numbness, all of which may be
nondescript. Radiculopathies usually are the result of nerve-root
irritation or impingement from osteophytes at the hypermobile segments
adjacent to the fused vertebrae. Long-tract signs may develop as
a result of long-standing spinal cord compression. A well-held belief
is that the presence and magnitude of signs and symptoms are related
to the location and extent of the congenital fusion; however, many
clinicians have found little truth to this statement. Neurologic
problems have been observed in patients with an isolated fusion
of only two vertebrae86. Synkinesis
is a phenomenon in which mirror movements are observed, most often
in the upper extremities87,88.
The etiology is unknown, but a central nervous system anomaly is
suspected. The condition is more common in younger children and
tends to improve with age. We recommend that individuals who exhibit
synkinesis should be referred to an occupational therapist as early
as possible for rehabilitation.
Stenosis and Instability in the Middle and
Lower Cervical Spine
Various criteria have been established to evaluate spinal canal
stenosis and vertebral instability. These measurements are notoriously
difficult to make because of the presence of congenitally dysplastic vertebrae89. The sagittal diameter of the canal
is measured on the lateral radiograph from the midpoint of the posterior
aspect of the vertebral body to the nearest point on the line representing
the junction of the laminae and spinous process. Normal values vary according
to the age of the patient, vertebral level, and beam-to-target distance89,90. The ratio of Pavlov et al.,
which is useful for the evaluation of spinal stenosis, is measured
as the distance from the midpoint of the posterior aspect of the
vertebral body to the nearest point on the corresponding spinolaminar
line divided by the anteroposterior width of the vertebral body91. A ratio of <0.8 is considered
abnormal. Again, this measurement is difficult to make in the presence
of a wasp-waist vertebral body. Anterior or posterior translation
of one vertebral body relative to another of >5 mm may
signify instability, especially if it is associated with neurologic
findings. Flexion and extension of the cervical spine may exacerbate
this relationship between the vertebrae, as can be seen on cineradiography
or flexion and extension radiographs (Figs. 4-A and 4-B). Magnetic resonance imaging should
then be done to evaluate for cord impingement by vertebral bodies
or disc material (4-C).
Spinal stenosis and instability of the cervical spine in individuals
with Klippel-Feil syndrome are topics of debate. First, it must
be determined whether the stenosis is congenital and part of the
syndrome or is secondary to degenerative changes. Therefore, the
spinal levels in question must be defined. Some authors have believed
that primary spinal stenosis is uncommon in this patient population,
and some have even found the canal to be enlarged14,92-94.
Ritterbusch et al. noted that stenosis occurred both in the regions
of congenital fusion and at the level of hypermobile segments as
seen on magnetic resonance imaging19.
Ritterbusch et al. also found radiographic evidence of vertebral
subluxation of >5 mm in five of twenty patients. These
findings were not supported in the study of adults by one of us
(J.T.G.) and colleagues14.
Trauma to an individual with a congenital cervical spine anomaly
can be catastrophic, as demonstrated in many reports95-107. In most of those reports, the
patient had either congenital anomalies of the upper cervical spine
or translational instability of the vertebral bodies in a stenotic
cervical canal. Torg et al. noted an association between neuropraxia
of the cervical spinal cord in football players with congenital
fusion and a decreased anteroposterior diameter of the osseous canal108. Those authors recommended that
players with stenosis and a congenital anomaly should be treated and
counseled on an individual basis, as there are no guidelines and
no classification system to provide clinically prognostic information
for such patients.
Treatment
Most of these patients remain asymptomatic throughout life, with
occasional mild complaints such as headaches or vague nonradicular
weakness and numbness14,102. In
the series of one of us (J.T.G.) and colleagues14,
none of the twenty-two patients had had an operation for instability
or neurologic problems by an average age of thirty-five years (range,
twenty-six to fifty-seven years), although one patient had had a posterior
spinal fusion as a child for the treatment of cervicothoracic scoliosis.
Few authors have discussed the operative treatment and outcome of
congenital conditions involving the lower cervical spine109,110. Care must be taken when operative
procedures are performed and when internal fixation is used because
of the presence of dysplastic vertebrae. Patients should be treated
on an individual basis until the role of prophylactic stabilization
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