For Craniocervical Junction, A Novel Surgical Approach
Date: March 1, 2008
A rare and serious condition affecting the skull and upper cervical region occurs when the dens, the cone-shaped odontoid process on the second cervical vertebra, telescopes into the skull, compressing the front of the brainstem and the cervical spinal cord.
Known as basilar invagination, the condition can be the result of congenital abnormalities or acquired over time in people with rheumatoid arthritis, for example. Symptoms include weakness in the arms and legs, numbness, gait impairment and any number of problems related to the lower cranial nerves. Untreated, people become wheelchair-bound and eventually die
To treat basilar invagination, surgeons resect the odontoid through a transoral-transpharyngeal approach. The technique has its drawbacks, though, for sometimes the jaw must be split in order to reach the back of the throat, and complications can result if there is a CSF leak. “That is serious enough in itself,” says Ziya Gokaslan, director of the Spine Center at Johns Hopkins, “but when the cerebrospinal fluid leaks into the mouth, bacteria from the mouth can get into the CSF and cause postoperative meningitis, which is very difficult to treat.”
Now, to circumvent these impediments, Jean-Paul Wolinsky, clinical director of the spine program, has developed a surgical approach through the neck. The novel approach was inspired by the standard technique for placement of odontoid screws for odontoid fractures. If the dens can be repaired transcervically, Wolinsky wondered, why then can it not be removed in this fashion?
At first, Gokaslan was skeptical. “When you are putting in a single screw, you can look through a very small channel and go there,” he reminded Wolinsky. “But if you need to drill out the bone near the brainstem, if the dens is not in its normal location but actually sitting inside the skull, now that is a much more complicated situation.”
But Wolinsky persisted. For the working channel, he modified a tubular retractor system he originally developed for placement of odontoid screws. For visualization down the retractor, he adapted an endoscopic system similar to those used in GI surgery. While operating, Wolinsky and Gokaslan work through the retractor with long, specially developed instruments - high-speed drills and irrigation devices to remove the dust. Frameless stereotactic navigation helps them know exactly where they are at all times.
So far, Wolinsky and Gokaslan have performed the endoscopic transcervical odontoidectomy on about a dozen patients and published their results (Journal of Neurosurgery: Spine, February 2007). They have found the technique to be safe and effective for resection of the odontoid and for brainstem and spinal cord decompression, a useful addition to treatments for disorders involving the craniocervical junction.
To refer a patient: 410-502-6103