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A gaseous collection in the intervertebral space, or the vacuum phenomenon, was observed on computed tomograms in as many as 30% of the patients with cervical disk disease. The condition most frequently occurred at the level of C5-6. The gas tended to accumulate more often at the marginal region of the intervertebral disks, the level at which marked degeneration was seen; thus, it may be related to cracks within not only the nucleus pulposus, but also in the annulus fibrosus.

The authors reported the changes of spinal-cord-evoked potential following impact injury by the weight dropping technique (Allen's method). The correlation between the change in amplitude of the spinal-cord-evoked potential after injury, and the prognosis for motor recovery of the legs was discussed. The spinal cord of adult dogs was traumatized by the weight dropping technique (Allen's method) at the level of Th10. The trauma consisted of a 300 gm-cm impact injury, a 400 gm-cm impact injury, and a 500 gm-cm impact injury. The spinal-cord-evoked potential following direct stimulation of the spinal cord was recorded from the epidural space for 5 hours. The recording electrode was located cephalad to the site of the impact injury. The stimulating electrode was located at the caudal site of the injured area. The motor function of the dogs was observed by clinical scale for rating hind limb motor function (modified Tarlov score) for one month after the trauma. The recovery of the spinal cord evoked potential following impact injury by the weight dropping technique could be estimated one hour after trauma in the 300 gm-cm injury, 30 minutes after trauma in the 400 gm-cm injury and immediately only after trauma in the 500 gm-cm injury. A greater reduction of amplitude of I potential was noted with the higher energy injury (p less than 0.05). There was no parallel correlation between the change in amplitude of the spinal cord evoked potential after injury and the prognosis for motor recovery of legs. However, the changes in amplitude corresponded moderately well to the prognosis of motor function.

The authors describe a case of flexion myelopathy due to specific morphological changes of the cervical cord, termed a "tight dural canal mechanism." The patient was an 18-year-old man with progressive weakness and muscle atrophy of the left arm. Neuroradiological examination revealed that the lower cervical cord was compressed during flexion of the cervical spine, but that there was no disc disease or cervical vertebral instability. The cord compression was attributed to a pinching mechanism by the posterior border of the vertebral body and the posterior component of the dura on flexion.

The clinical features of 31 cases of syringomyelic syndrome, confirmed by metrizamide CT myelography (CTM) or magnetic resonance imaging (MRI), were analysed. Bilateral suspended sensory disturbance, previously regarded as a characteristic feature, was encountered in only 2 cases (6.5%). Thirteen patients (41.9%) showed no motor deficits of the upper limbs and 7 patients (22.6%) did not have weakness or atrophy in any of the four extremities. Cervical segmental signs were absent in 7 cases (22.6%) and in 2 (6.5%) signs were only present in the lower limbs. Scoliosis and foot deformity, such as pes cavus or equinovarus, were seen in 17 (54.8%) and 5 cases (16.1%) respectively. These skeletal abnormalities were initial symptoms in some childhood cases. In syringomyelic syndrome, clinical features are variable with many atypical clinical manifestations, apart from the previously recognized characteristic clinical features.