Klippel-Feil Syndrome 

In 1912, Maurice Klippel and Andre Feil independently provided the first descriptions of Klippel-Feil syndrome. They described patients who had a short, webbed neck; decreased range of motion (ROM) in the cervical spine; and a low hairline. Feil subsequently classified the syndrome into 3 categories:

• 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

Since their original description, other classification systems have been advocated to describe the anomalies, predict the potential problems, and guide treatment decisions.

In a series of articles, Samartzis and colleagues suggested their classification system.^{[1, 2]} In this classification system, type I patients have a single-level fusion; type II patients have multiple, noncontiguous fused segments; and type III patients have multiple, contiguous fused segments. Using their system, the investigators reviewed a series of patients to clarify prognosis (see Clinical). See images below.

Gray et al^[3] described 462 patients with Klippel-Feil syndrome who had low hairline, short neck, and decreased range of motion (ROM). They thought 2 factors affected the prognosis and increased the risk from trauma. The first was that the level of fusion did not greatly affect the incidence of neurologic symptoms. The most frequent level they identified was a defect of the occiput to C1, C2, and C3. These produced the most symptoms. Lesions below C3 and 4 were slightly less likely to cause symptoms. Twenty-seven percent of symptoms occurred in the first decade.

Nagib et al^[4] described 3 types and related the incidence of neurologic symptoms to each. Type I is 2 sets of block vertebrae with open intervening spaces that can sublux gradually or with acute trauma. Type II involves craniocervical anomalies with occipitalization of the axis and basilar invagination. This causes increased mobility at the craniocervical level and can lead to foramen magnum encroachment. It can be associated with Arnold-Chiari malformation and syringomyelia. Type III is fusion of one or more levels with associated spinal stenosis.^[5]

Patients with Klippel-Feil syndrome usually present with the disease during childhood, but may present later in life. The challenge to the clinician is to recognize the associated anomalies that can occur with Klippel-Feil syndrome and to perform the appropriate workup for diagnosis.

Frequency

The true incidence of Klippel-Feil syndrome is unknown. No one has ever studied a cross-section of healthy people to determine the true incidence.

The incidence of Klippel-Feil syndrome has been investigated in 2 studies, using 2 different means. Gjorup and Gjorup reviewed all of the radiographic cervical spine films from a single hospital in Copenhagen.^[6] From these films, they determined an incidence of 0.2 cases per 1000 people. Brown and colleagues reviewed 1400 skeletons from the Terry collection, which at that time was located at the Washington University School of Medicine.^[7] They found an incidence of 0.71%.

The etiology of Klippel-Feil syndrome and its associated conditions is unknown. The syndrome can present with a variety of other clinical syndromes, including fetal alcohol syndrome, Goldenhar syndrome, and anomalies of the extremities.^{[8, 9, 10]} Gunderson suggested that it is a genetic condition, while Gray found a low incidence of inheritance.^{[11, 12]} Others have considered Klippel-Feil syndrome to be some type of global fetal insult, which could explain the other associated conditions. Some have considered it to be caused by vascular disruption.^{[13, 14]}

Clinical presentation is varied because of the different associated syndromes and anomalies that can occur in patients with Klippel-Feil syndrome. A complete history and careful physical examination may reveal some associated anomalies. From an orthopedic standpoint, most of the workup involves imaging (see Workup, Imaging Studies).

Klippel-Feil syndrome is detected throughout life, often as an incidental finding. Patients with upper cervical spine involvement tend to present at an earlier age than those whose involvement is lower in the cervical spine. Most patients present with a short neck and a decreased cervical ROM, with a low hairline occurring in 40-50% of patients. Decreased ROM is the most frequent clinical finding. Rotational loss usually is more pronounced than is the loss of flexion and extension.

Other patients present with torticollis or facial asymmetry. In very young children, it is important to differentiate congenital muscular torticollis form Klippel-Feil syndrome. It is often difficult to obtain good plain radiographs of young children with torticollis, especially of the craniocervical junction. Neurologic problems may develop in 20% of patients. Gray found that 27% developed symptoms in the first decade.^[3]

Rouvreau found that 5 of 19 patients with Klippel-Feil syndrome had neurologic involvement; of these 5 patients, 2 had neurologic problems resulting from hypermobility at 1 level.^[15] Occipitocervical abnormalities were the most common cause of neurologic problems, as seen in the images below. Some patients present with pain.^[16]

Nagib et al^[4] reviewed 21 cases of Klippel-Feil syndrome over a 25-year period to identify high-risk patients and describe the treatment required. Eight had been admitted for complications of the genitourinary system or cardiovascular or otologic anomalies. Ten were male and 11 were female. Twelve patients had no neurologic deficit. Of these 12, 11 had a single block vertebra with no other cervical or craniocervical anomalies. Nine patients presented with neurologic deficits that occurred spontaneously or after minor trauma. These had the most varied and complicated radiographic findings.

Using the classification system described above, there were 4 type I patients with an unstable fusion pattern, 3 type II patients with craniocervical abnormalities, and 2 type III patients with fusion anomalies and spinal stenosis. Nine patients (43%) required decompression and stabilization in the second or third decade of life. They concluded that types I and II are commonly combined with hypermobility of the craniocervical junction. Foramen magnum encroachment may be associated with tight dural bands or upward migration of the odontoid. In type III patients, they found that the level of stenosis could be above or below the abnormal area.

Hensinger and colleagues, in a review of 50 patients with Klippel-Feil syndrome, found that 30 (60%) of them had associated scoliosis.^{[17, 18]} In some patients with Klippel-Feil syndrome, the scoliosis is congenital, as seen in the first image below, owing to the involvement of other parts of the thoracic or lumbar spine. Other patients develop scoliosis in the thoracic spine, to compensate for cervical or cervicothoracic scoliosis. In addition to fusion anomalies in the cervical spine, cervical spinal stenosis can occur. While uncommon, this condition can increase the risk of neurologic involvement.

Anomalies of the craniocervical junction can cause instability at lower segments. Traumatic tetraplegia has been reported following minor trauma.^[19] A Sprengel anomaly occurs in 20-30% of patients, as seen in the first image above.^[20] The ROM of the shoulders must be checked, and the patient should be examined for an omovertebral bone, an osteocartilaginous connection that tethers the scapula to the spine, as seen in the second image above. An omovertebral bone ossifies with age, further limiting the ROM. A computed tomography (CT) scan best demonstrates the presence of an omovertebral bone; however, this feature can also be detected through palpation or radiographs. Other upper extremity anomalies occur less frequently. A thorough examination of the ROM and function of the upper extremity must be performed.

Renal anomalies are common in individuals with Klippel-Feil syndrome, and they can be quite serious. Out of 41 patients in Hensinger's series who underwent an intravenous pyelogram, 16 were found to have renal anomalies. Minor renal anomalies—including a double collecting system, renal ectopia, and bilateral tubular ectasia—were detected in 6 of these individuals. Major renal anomalies—including hydronephrosis, absence of a kidney, as seen in the image below, and a horseshoe kidney —were detected in 10 patients. (For patients with Klippel-Feil syndrome, ultrasound [US] scanning now serves as the initial test to determine whether both of an individual's kidneys are functioning.^[21] )

Cardiovascular anomalies, mainly septal defects, were found in 7 patients in Hensinger's series, with 4 of these individuals requiring corrective surgery. Synkinesia, or mirror movement, as seen in the image below, occurred in 9 of the 50 patients. Hearing was impaired in 15 of 41 patients tested. Early audiometric and otologic evaluation are indicated in all children when the diagnosis of Klippel-Feil syndrome is established.^[22]

Torticollis and facial asymmetry occur in 21-50% of patients with Klippel-Feil syndrome. These persons may also have a muscular torticollis.^[23] Craniofacial anomalies can occur as well.^[24]

Less-common anomalies associated with Klippel-Feil syndrome include congenital limb deficiencies, craniosynostosis, ear abnormalities, iniencephaly, and craniofacial abnormalities.^{[25, 26, 27, 28, 29, 30]} Note the image below.

Patients with Klippel-Feil syndrome present at different ages with varying clinical manifestations. Indications for workup vary individually. For the orthopedic surgeon, the most frequent indications for surgery depend on the amount of deformity, its location, and its progression with time. Other indications include instability of the cervical spine and/or neurologic problems. These indications can occur with craniocervical junction anomalies and when 2 fused segments are separated by a normal segment.

Some patients present early in life with complex cervical and cervicothoracic deformity that is progressive and disfiguring. Some of these patients require cervical spine fusions to prevent progression.

Other patients may develop compensatory or associated congenital scoliosis, which also can be progressive over time and requires fusion to prevent progressive deformity. Over 50% of the patients in Hensinger's study had scoliosis.^[17] Treatment of the scoliosis with bracing or surgery was required in 18 of the 50 patients.

Using their above-described classification system, Samartzis and co-investigators reviewed 28 patients radiographically and clinically.^[2] Mean follow-up was 8.5 years. Mean age at presentation was 7.1 years, with mean age of onset of symptoms in the symptomatic patients being 11.9 years. Sixty-four percent of patients had no symptoms. Two patients developed myelopathic symptoms (type II and type III patients). Two patients developed radiculopathic symptoms (type II and type III patients). Axial symptoms were more common in type I patients. The investigators recommended activity modification in high-risk patients.

The same authors reported on a patient who developed a symptomatic cervical disc herniation.^[1] The patient had occipitalization of C1 and fusion of C2-3 and C4-T1. This left only C3-4 as a hypermobile segment, so the patient was at high risk. The patient was treated successfully with a same-day, combined anteroposterior (AP) procedure.

Theiss et al reviewed 32 patients with congenital scoliosis followed for more than 10 years.^[31] Only 7 (22%) developed cervical or cervical-related symptoms, and only 2 required surgery for their cervical-related symptoms. No fusion pattern was identified that placed the patients at greater risk for developing symptoms

Auerbach et al studied spinal cord dimensions in children with Klippel-Feil syndrome.^[32] They reviewed magnetic resonance imaging studies and clinical records of Klippel-Feil patients and age-matched controls. Torg ratios were measured, and the Torg-Pavlov ratios were found to be identical in the 2 groups. The cross-sectional area of the spinal cord was smaller in Klippel-Feil syndrome patients at each level from C2-C7. These differences were statistically significant, with no differences in the CSF column, suggesting the cord size is smaller in children with Klippel-Feil syndrome, as compared with control subjects. Four of the 12 children with Klippel-Feil syndrome presented with neurologic symptoms that improved after posterior cervical stabilization.

Samartzis et al studied the extent of fusion in the congenital K-F segment to evaluate the presence and extent of specific fusion patterns across the involved cervical segments.^[33] In older patients, complete fusion was more prevalent in regard to C2-C7. In the absence of complete fusion, fusion of the posterior elements was noted more often than fusion of the anterior elements.

In another paper, Samartzis et al reviewed the role of the congenitally fused segments in 29 Klippel-Feil syndrome patients in relation to the space available to the cord (SAC) and associated cervical spine-related symptoms (CSS).^[34] They suggested that an arrest of normal vertebral development may affect appositional bone development. The effect on vertebral body width may delay neurologic compromise resulting from the congenital fusion process and subsequent degenerative manifestations.

Since Klippel-Feil syndrome is associated with a constellation of possible abnormalities, no set of definite contraindications exists. If a surgeon believes that an operation is indicated, it is incumbent upon him/her to make certain that none of the conditions that could cause morbidity or mortality are present. Cervical or occipitocervical instability could increase the risk of neurologic damage during intubation. An underlying heart defect could increase anesthetic risk. An underlying spinal stenosis or spinal cord abnormality could increase the risk of neurologic damage during spinal fusion for correction of deformity. A thorough workup of the patient is imperative prior to surgical intervention.