Cervical myelopathy is a common cause of neurological disability among the elderly; however, the exact mechanism for the insidious and progressive deterioration remains to be elucidated. To study the pathophysiology, we developed a simple experimental model reproducing the course. In rats, a thin sheet of expanding polymer was implanted microsurgically underneath the C5-C6 laminae. In the control group, the polymer sheet was removed immediately. Changes in motor functions were monitored for 25 weeks after the operation, with voluntary exercise activity measured by odometer attached to revolving cages, and forced running capability measured by duration of exercise on a rotating treadmill. Motor neurons were counted stereologically in continuous sections. In the compression group, the forced running capability deteriorated after a latent period of 17 weeks and progressively thereafter. In the control group, it stayed unchanged throughout 25 weeks. Course of the voluntary exercise was comparable between the groups. Motor neuron density in the compression group decreased significantly in 9 weeks (-20.3%) and 25 weeks (-35.5%), but not in 1 or 3 weeks. This practical model properly reproduces characteristic features of the clinical cervical myelopathy, with progressive motor disturbance after a latency and insidious neuronal loss preceding the symptoms.

Object Laminoplasty has been used to expand the cervical spinal canal, based on the belief that reconstruction of the laminae preserves musculoskeletal function. The true efficacy of laminoplasty for maintaining spinal alignment, stability, and flexibility, however, remains to be proven. The authors have developed a new method, myoarchitectonic spinolaminoplasty (MSLP), which preserves all of the nuchal muscles and reconstitutes all of the musculoskeletal couplings to the posterior elements of the vertebrae. The details of this technique are described, and the efficacy of the technique in conserving muscle volume, alignment, and motion, as well as in preventing postoperative musculoskeletal discomfort, is assessed. Methods The authors' previous midline-splitting laminoplasty procedure, which utilized a hydroxyapatite (HA) implant as a substitute for the spinous process, was improved. Detachment of the muscles is avoided with this new technique by cutting inside the spinous process. The bone–muscle flaps are affixed to the HA spinous process. Radiographs, computed tomography scans, and neurological evaluations obtained at the 1-year follow-up in the groups of consecutive patients assessed immediately prior to and after the modification of the previous technique (the control and the MSLP groups, respectively) were analyzed and compared. Results The HA bone constructs became integrated due to osteoconduction. The cross-sectional area of the semispinalis capitis, semispinalis cervicis, and multifidus muscles remained significantly larger in the MSLP group. Slight attenuation in lordosis was observed in the control group, but was prevented in the MSLP group. Range of motion was somewhat restricted in the MSLP group, but the incidence of neck pain and shoulder strain was significantly reduced. Conclusions The new MSLP method was effective in preserving the volume and functions of the nuchal musculature and helping to minimize postoperative musculoskeletal complaints.

MEP monitoring has a limitation in predicting postoperative weakness in surgery for IMTs. False-positive and false-negative indices were abundant, with sensitivity and specificity of 0.65 and 0.83 in predicting postoperative weakness.

No abstract

✓ A case of a dural arteriovenous fistula (DAVF) that developed at the site of nerve root sleeve damage as a result of lumbar disc extrusion is reported. A 60-year-old man who had undergone lumbar discectomy 3 years previously for severe left-sided sciatica and L5—S1 disc herniation presented with progressive gait disturbance. After the initial surgery, the symptoms resolved. Fourteen months after the operation, however, he started to experience dysesthesias in both legs and progressive gait and urinary disturbances. Physical examination revealed a weakness of the anterior tibialis and the gastrocnemius muscles, as well as decreased contractility of the anal sphincter and marked sacral hypesthesia. Magnetic resonance (MR) imaging revealed swelling and a T2 signal elongation in the conus medullaris; angiography demonstrated arteriovenous dural shunting between the left lateral sacral artery and the left S-1 radicular vein at the site of the previous operation. Surgery was conducted to excise the DAVF on the S-1 nerve root sleeve and an arterialized intradural vein on the root. The procedure resulted in resolution of the symptoms and disappearance of the abnormal angiographically and MR imaging—documented anomalies. This is the first report of a DAVF in which progressive conus myelopathy developed after a lumbar discectomy.