Cervical myelopathy at the C4-5 level is a potential risk for motor dominant C5 paralysis. Although it is merely a speculation, when C5 radiculopathy occurs after laminoplasty, C5 paralysis becomes clinically apparent because the deltoid muscle gets predominantly innervated by C5 root due to intramedullary spinal cord damage on the C6 segment in C4-5 myelopathy before surgery. It may represent the high signal intensity area on T2-weighted MRI at the C4-5 level.

The residual function of motor and sensory nerve roots involved with cervical schwannoma differed between individuals and could be detected using intraoperative electrophysiologic assessment.

Ten patients with cervical spinal schwannomas were operated using a new posterior approach, termed cervical hemilaminoplasty. A thread wire saw (T-saw) was used to cut the lamina at the center of the spinous process and at the unilateral pars interarticularis on the affected side. The unilateral lamina, the inferior articular process, and half of the spinous process were resected as a single mass. After tumor excision, the resected lamina was restored to the original site and fixed. Fusion technique was not required. The mean number of resected and restored lamina was 1.5. No instability of the cervical spine was detected using flexion/extension x-ray photography. Although worsening of radicular motor function was observed in 2 cases, the weakness was not permanent and both cases showed full recovery. Postoperative magnetic resonance imaging was performed in 7 of the 10 cases and showed no recurrences. Cervical hemilaminoplasty is a useful posterior approach method for spinal tumors and especially dumbbell-type tumors. This method provides wide exposure of the foramen and of the inside of the canal. Furthermore, it allows reconstruction of the posterior element of the spinal canal and results in good stability.

Previous studies have presented evidence which indicates that the regeneration of axons in the spinal cord occurs following spinal cord transection in young rats. However, in a transection-regeneration model, the completeness of the transection is often a matter of dispute. We established a method for shortening the rat spine and spinal cord to provide a spinal cord injury (SCI) model in which there was no doubt about whether the axonal transection was complete. In the future, this model may be applied to the chronic period of complete paralysis following SCI. Adult, female Wistar rats (220–250g) were used in the study. The spinal cord was exposed and a 4-mm-long segment of the spinal cord was removed at Th8. Subsequently, the Th7/8 and Th8/9 discs were cut between the stumps of the spinal cord to remove the Th8 vertebra. The stitches which had been passed through the 7th and 9th ribs bilaterally were tied gradually to bring together the stumps of the spinal cord. Almost all the rats survived until the end of the experiment. Uncoordinated movements of the hind limbs in locomotion were observed at 4 weeks after surgery. However coordinated movements of the hind limbs in locomotion were not observed until the end of the experiment. After 12 weeks, an intracardiac perfusion was performed to remove the thoracic spine and the spinal cord. There were no signs of infection. The bone fusion of the Th7 and Th9 vertebrae was observed to be complete in all specimens and the alignment of the thoracic spine was maintained. The spinal canal was also correctly reconstituted. The stumps of the spinal cord were connected. Light microscopy of the cord showed that scar tissue intervened at the connection site. Cavitation inhibiting the axonal regeneration was also observed. This model was also made on the assumption that glial scar tissue inhibits axonal regeneration in chronic SCI. Axonal regeneration was not observed across the transected spinal cord in this model. Attempts should be made to minimize the damage to the spinal cord and the surgery time for successful axonal regeneration to occur. The model developed in this study may be useful in the study of axonal regeneration in SCI.

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