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Skip laminectomy indicated for cervical spondylotic myelopathy
MRI scans indicated that the procedure seems effective for multilevel decompression.
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TOCHIGI, Japan — A
controlled study comparing results of skip laminectomy with open-door
laminoplasty demonstrated that skip laminectomy reduced axial symptoms yet
maintained neck range of motion postoperatively.
A new minimally invasive, multilevel cervical spine procedure, skip laminectomy is indicated for patients with cervical spondylotic myelopathy (CSM) and calcification of the ligamentum flavum without increased congenital narrowing of the cervical canal. It is contraindicated in patients with continuous ossification of the posterior longitudinal ligament, according to co-investigator Tateru Shiraishi, MD, in the department of orthopaedic surgery at Saiseikai Utsonomiya Hospital, here.
The procedure limits vertical incisions to posterior anatomical structures, so that at levels where anterior spinal cord compression is less significant, surgeons can perform an interlaminar decompression instead of a laminectomy.
“Skip laminectomy is a less invasive procedure and is effective in preventing postoperative morbidities such as axial symptoms, the restriction of neck motion and the loss of lordotic curvature,” said Shiraishi, who presented results with the new technique during the 4th Annual Meeting of the Spine Society of Europe.
Prevents postoperative problems
--- If spinal stenosis remains after decompression is done as part of the skip laminectomy, a flexible 0.15-mm
ribbon rasp is used to undercut the lamina at a preserved level.
COURTESY OF TATERU SHIRAISHI
To date, more than 100 patients with CSM have been treated with skip laminectomies. With the technique, instead of treating every level requiring decompression, every other level is treated. For example, for a C4 to C6 skip laminectomy, just the C4 and C6 laminae are exposed and removed. The spinous processes at only those two levels are split in half and their attached muscles preserved.
“The decompression of the upper two levels, C3-C4 and C4-C5, is performed by removing the C4 lamina and the cephalad half of the C5 lamina and the ligamentum flavum,” Shiraishi said. Decompression at the lower two levels is done similarly, with removal of the cephalad half of the C7 lamina.
“The four-level decompression is accomplished by preserving the posterior extensor mechanism of C3, C5 and C7,” he said. If spinal stenosis persists at one of the preserved levels, its lamina is undercut using a 0.15-mm-diameter, flexible ribbon rasp that is smooth on one side and rough on the other.
Before closing, any split fragments are sutured together. By the morning of the first postoperative day, patients can usually sit or walk, Shiraishi said.
Controlled study conducted
--- This intraoperative photo taken at the end of decompression shows how the dura was exposed by removing the cephalad
half of the C5 lamina and ligamentum flavum. Numbers 4 and 5 indicate the C4
and C5 spinous processes.
COURTESY OF TATERU SHIRAISHI
For the controlled study, 47 patients with CSM were treated with skip laminectomies and 51 patients underwent open-door laminoplasties. Follow-up for all patients was more than two years. Investigators compared results of five outcome measures: Japanese Orthopaedic Association (JOA) scores, axial symptoms, cervical curvature index, range of motion on flexion/extension radiographs, and cross sections of the deep extensor muscle from axial MRI scans of the four treated levels. The researchers used a special formula to calculate the rate of muscle atrophy.
The recovery rate for JOA scores was 60.3% for the skip laminectomy patients, compared to 61.3% in the other group. C5 paresis developed in three patients (5.7%) after open-door laminoplasty but in no patients after skip laminectomy. “In the skip laminectomy group, none of the patients complained of deterioration or new development of axial symptoms. The range of neck motion was not reduced after the operation,” he said.
One skip laminectomy patient had loss of cervical lordosis, but muscle atrophy was approximately one-fifth that seen in the laminoplasty patients. “MRI demonstrated that the multilevel decompression was successfully maintained by skip laminectomy for longer than three years,” Shiraishi said.
An operating microscope was used to avoid such complications as dural tears. Cervical spine surgeons with basic skills can perform the procedure safely, he said.
For your information:
- Shiraishi T, Yato Y, Fukuda K, et al. Skip laminectomy — minimally invasive multilevel decompression of the cervical spine. #16. Presented at the 4th Annual Meeting of the Spine Society of Europe. Sept. 11-14, 2002. Nantes, France.