Skip laminectomy--a new treatment for cervical spondylotic myelopathy, preserving bilateral muscular attachments to the spinous processes: a preliminary report.
BACKGROUND
Techniques in current use for expansive laminoplasty operations (ELAP) on the cervical spine damage the extensor mechanisms, resulting in restriction of neck motion, loss of lordosis and persistent axial pains.


OBJECTIVE
This article introduces a new surgical technique called skip laminectomy, which reduces morbidity after decompression of the cervical spinal canal.


METHODS
A prospective study is presented of all patients with multilevel cervical spondylotic myelopathy (CSM), treated by this new procedure between December 1998 and March 2000.


METHODS
Since December 1998, 61 patients with CSM have undergone the procedure, of whom 24 (13 men and 11 women) were selected for this study. Follow-up periods ranged from 12 to 25 months, with an average of 18 months. Average age at operation was 69 years (range, 50 to 82 years). Eighteen patients with CSM on whom C3-C7 open-door laminoplasties had been performed by the author before 1998 were selected as controls for study of postoperative atrophy of the deep extensor cervical muscles. There were 11 men and 7 women, average age 67 years (range, 45 to 81).


METHODS
Axial symptoms and Japanese Orthopaedic Association (JOA) scores were recorded. Pre- and postoperative ranges of neck motion were measured on lateral flexion and extension radiographs. Pre- and postoperative cervical curvature indexes were calculated according to Ishihara's method. For quantitative analysis of damage to the posterior cervical muscles, atrophy rates were calculated from cross-sectional areas of the deep extensor muscles on the pre- and postoperative axial magnetic resonance imaging.


METHODS
In skip laminectomy, standard laminectomies are performed at selected levels, combined with partial laminectomies of the cephalad halves of laminae at other selected levels, where the muscular attachments to the spinous processes are left undisturbed. Instead of a standard laminectomy, an interlaminar decompression can be performed at levels where the anterior spinal cord compression is insignificant. It is accomplished by simply removing the cephalad half of the inferior lamina and ligamentum flavum without detaching the semispinalis cervicis and multifidus muscles from the adjacent spinous processes.


RESULTS
Using JOA scores, the average recovery rate was 61.0%. None of the patients complained of persistent axial symptoms. The postoperative range of flexion-extension motion averaged 97% of the preoperative measures. The cervical curvature index was reduced in 1 of the 24 patients. The atrophy rate of the deep extensor muscles after skip laminectomy was 20% of that seen after open-door laminoplasty.


CONCLUSIONS
Skip laminectomy for cervical spinal canal decompression is less invasive than conventional laminectomy and ELAP. It is effective in preventing postoperative problems, such as persistent axial symptoms, restriction of neck motion and loss of cervical lordosis.
Shiraishi
Tateru
T
Department of Orthopaedic Surgery, National Tochigi Hospital, 1-10-37, Nakatomatsuri, Utsunomiya, Tochigi, 320-0057, Japan. tateru_shiraishi@samiya.com
D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000601:surgery*; D019299:Decompression, Surgical / Q000379:methods*; D005260:Female; D006801:Humans; D007796:Laminectomy / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D017887:Ossification of Posterior Longitudinal Ligament / Q000150:complications / Q000473:pathology / Q000601:surgery; D010865:Pilot Projects; D011446:Prospective Studies; D013117:Spinal Cord Compression / Q000209:etiology / Q000473:pathology / Q000601:surgery*; D013128:Spinal Osteophytosis / Q000150:complications / Q000473:pathology / Q000601:surgery*; D013130:Spinal Stenosis / Q000150:complications / Q000473:pathology / Q000601:surgery