Occipital-Cervical Spine Surgery in Children

Children with Down syndrome are screened for neck instability before they are allowed to participate in the Special Olympics. More than 15 percent of those with Down syndrome have occipital-cervical junction abnormalities.

Nicholas M. Wetjen, M.D., a pediatric neurosurgeon at Mayo Clinic in Minnesota, would like to see effective screening for occipital-cervical instability in children with other genetic conditions that put them at risk, including Klippel-Feil syndrome and achondroplasia (dwarfism). Before his staff appointment, Dr. Wetjen completed his neurosurgical residency at Mayo and received extensive training in pediatric neurosurgery and in pediatric occipital-cervical spine surgery at the University of Utah with Douglas L. Brockmeyer, M.D., a world-renowned expert in this specialized area.

Extension (left) and flexion (right) lateral radiographs of the neck

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Symptoms and Cause

Congenital instability can be caused by ligament laxity, abnormal bone segmentation, or bone deficiencies and other abnormalities in the occipital-cervical junction. These problems may affect the enclosed nervous system structures. For example:

• Because of impaired bone development at the junction of the skull and spine, the cerebellum may be abnormally low, and the brain stem may be compressed in the upper cervical spine
• Excessive range of motion in the neck can create tissue build-up which then compresses the spinal cord and affects the functions of the lower cranial nerves or the peripheral nerves exiting the upper cervical spine
• There may be a risk of stroke if the vertebral artery is stretched or compressed with excessive range of motion in the neck

Symptoms of occipital-cervical instability include neck pain, respiratory and swallowing difficulties, disorders of eye movement, sensory impairment, and weakness of the upper and lower limbs. The most common symptom is occipital and upper neck pain.

These problems also can occur in otherwise healthy children and adults and in those who have suffered trauma to the area. Cervical instability may be at issue in children with persistent torticollis that is not relieved by a course of physical therapy.

Postoperative lateral cervical spine radiograph

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Surgical Intervention

At Mayo Clinic in Minnesota, imaging studies before surgery include MRI, CT scanning, and x-ray studies. The combination allows views of the degree of motion in flexion and extension (x-ray), the bony anatomy (CT), and the soft tissue (MRI). Occasionally, MRI with contrast is used to map the arterial anatomy, particularly if the neurologic deficits occur in a specific head and neck position.

The goal of surgery is to stabilize the junction, a procedure that usually involves fusing the bony anatomy of the craniovertebral junction using titanium plates and screws and bone grafts from either the hip or the rib. Bone grafts incorporate better and are considered stronger than artificial materials. The combination of hardware and bone grafts usually allows the neck to heal without the need for a halo, except in those with very soft bones.

The youngest patient Dr. Wetjen has operated on was 16 months old, but surgical treatment of patients that young is rare. For the procedure to be effective the bones must be dense enough and large enough to accommodate the instrumentation. Surgery is usually reserved for children at least 3 years old. Children tend to heal well because they have rapid bone growth. Problems may arise in syndromes in which disorders of bone metabolism play a role.

The surgery usually reduces normal head and neck motion by approximately 50 percent. Long-term follow-up data have shown that fusion surgery of this type does not seem to have a detrimental effect on the overall growth of the cervical spine. The bones tend to remodel around the instrumentation.

Which Patients to Treat and When

Only a few medical centers in the world perform the extremely complicated procedure of occipital-cervical spine fusion in children. The goal is to treat the problem before it creates neurologic damage, which may not be reversible. But who should be treated and when?

"A major issue," notes Dr. Wetjen, "is that some children with these abnormalities do not have symptoms, and they may or may not be at risk for neurologic deficits. We need more information on the natural history of these spinal abnormalities to know which patients need intervention and when to intervene." To that end, he and approximately 15 other pediatric neurosurgeons across the country are forming the Pediatric Craniocervical Society (PCS) to build a database of patients with these abnormalities.

By pooling their data, the members of PCS hope to learn more about the long-range outcomes in asymptomatic patients and how long these patients should be followed with imaging studies. They hope to identify which types of abnormalities pose the greatest risk of developing cervical spine instability and neurologic impairment and to establish criteria for typical and atypical head and neck movement. The database will include a description of the surgical procedures in patients with these disorders to better refine operative management.

Finally, PCS members hope to establish screening programs for those with conditions that pose a risk of neurologic injury.