Shinichi Hida

The effects of the degenerative changes in the functional spinal unit on the kinematics of the cervical spine.

Study Design. The sagittal kinematics of the cervical spine was evaluated using kinematic magnetic resonance imaging (kMRI). Objective. To investigate the effect of degenerative changes in the functional spinal unit on cervical kinematics by using kMRI. Summary of Background Data. Few studies have, thus far, by using MR images, described the contribution of degenerative changes in the functional spinal unit to cervical kinematics; however, the exact cervical kinematics remains uncertain. Methods. A total of 289 consecutive symptomatic patients underwent dynamic cervical MRI in flexion, neutral, and extension postures. All digital measurements and calculations of the variations in segmental angular motion were automatically performed by an MR analyzer using true MR images with 77 predetermined points marked on each image. Each segment was assessed based on the extent of intervertebral disc degeneration (Grades 1–3) and cervical cord compression (groups A–C) observed on T2-weighted MR images. Results. The segmental mobility of the segments with severe cord compression and moderate disc degeneration tended to be lower than that of the segments with severe cord compression and severe disc degeneration, and a significant difference was observed in the segmental mobility of the C5–C6 segment. Moreover, in all segments with moderate disc degeneration, the segmental mobility was significantly reduced in the presence of severe cord compression, as compared with no compression. However, in segments with severe disc degeneration, no significant differences were observed between the segmental mobility of the cord compression groups. Conclusion. Our results suggest that cervical cord compression may cause deterioration of cervical cord function and kinematic changes in the cervical spine. We hypothesize that the spinal cord may potentially protect its functions from dynamic mechanical cord compression by restricting segmental motion, and these mechanisms may be closely related to the intervertebral discs.

Measurement of the Local Pressure of the Intervertebral Foramen and the Electrophysiologic Values of the Spinal Nerve Roots in the Vertebral Foramen

Study Design. The intraoperative findings of the local pressure of the intervertebral foramen and the electrophysiologic values of the spinal nerve roots were evaluated. Objective. To investigate the neurophysiologic changes of the spinal nerve roots in the vertebral foramen. Summary of Background Data. As far as we know, few reports have so far described the neurophysiologic changes of the spinal nerve roots in the vertebral foramen. Methods. The local pressure of the intervertebral foramen was continuously measured while the lumbar spine posture was changed in 66 vertebral foramens. In addition, 20 L5 nerve roots were electrophysiologically evaluated using the compound muscle action potentials (CMAPs) from tibialis anterior (TA) muscle after L5 nerve root stimulation. Results. The local pressure of the intervertebral foramen was significantly increased during lumbar spine extension (P < 0.001); moreover, the latency and amplitude of the CMAPs both significantly deteriorated in line with the increasing local pressure. Conclusions. Our findings suggested that a double compression of the nerve root exists in lumbar spinal stenosis with lumbar spine extension, which includes the spinal canal and the vertebral foramen.

Peripheral nerve lengthening by controlled isolated distraction: a new animal model.

We have developed a simple and effective animal model to study the distraction neurogenesis utilizing the sciatic nervelengthening technique in rats. The model allows macroscopic, physiological, and histological evaluation of the distraction site. Fourteen adult Harlan Sprague Dawley rats (300–350 g) were used in this study. A 10 mm segment of the right sciatic nerve of each animal in the nerve‐lengthening group was resected. Gradual nerve lengthening was performed by advancing the proximal nerve stump at a rate of 1 mm/day. The proximal stump neuroma was then resected and a direct nerve anastomosis was performed. On the left side a standard autogenous nerve‐grafting procedure was performed with a 10 mm segment of sciatic nerve used as an in situ nerve graft. Three months after the second surgery, the sciatic nerves were exposed and investigated by gross observation and EMG followed by histological processing and tissue analysis. Neomicrovascularization was observed surrounding the sciatic nerve anastomosis in all five specimens of the nerve‐lengthening group as compared to the more white‐colored scar tissue that was observed in the nerve‐grafting group. The EMG results were similar for both groups. Histological studies of the lengthened nerves showed axon morphology equivalent to the grafted nerves. This study demonstrated a clear evidence of the successful nerve regeneration within a segmental nerve gap by nerve lengthening.

Neurogenic intermittent claudication in lumbar spinal canal stenosis: the clinical relationship between the local pressure of the intervertebral foramen and the clinical findings in lumbar spinal canal stenosis.

Study Design The clinical relationship between the local pressure of the intervertebral foramen and the clinical findings in lumbar spinal canal stenosis were evaluated. Objective To investigate the pathogenesis of neurogenic intermittent claudication in lumbar spinal canal stenosis. Summary of Background Data The genesis of neurogenic intermittent claudication is generally considered to result from nerve root ischemia; however, the exact pathogenesis of neurogenic intermittent claudication remains uncertain. Methods From a total of 20 lumbar spinal canal stenosis patients, 29 L5/S1 vertebral foramens were studied. All patients showed neurogenic intermittent claudication, and also showed neurologic abnormalities in L5 area. Intraoperatively, the local pressure of the intervertebral foramen was continuously measured using a micro-tip catheter transducer whereas the lumbar spine postures were changed under passive movement, and the relationships between the local pressure and the preoperative clinical findings in lumbar spinal canal stenosis were analyzed. Results The local pressure of the intervertebral foramen significantly increased during lumbar spine extension (P<0.001). The patients who demonstrated large changes in the local pressure between flexion and extension showed a significantly poor walking ability (P=0.003). Moreover, the patients who had 2-level lumbar spinal canal stenosis showed significantly smaller changes in the local pressure between flexion and extension than 1-level lumbar spinal canal stenosis patients (P=0.01). Conclusions The present study suggests that the genesis of neurogenic intermittent claudication in lumbar spinal canal stenosis may be greatly affected by the variation of the dynamic mechanical stress on the spinal nerve roots of the lumbar spine, rather than the static mechanical stress on the spinal nerve roots with each posture. Moreover, 2-level lumbar spinal canal stenosis patients demonstrated radicular symptoms with relatively less external stress on their spinal nerve roots in the vertebral foramen than that observed in 1-level lumbar spinal canal stenosis patients.

A Combined Thoracoscopic and Posterior-Spinal Approach for "Dumbbell" Neurofibroma Minimizes the Anatomical Destruction of the Vertebrae: Report of a Case

Abstract A dumbbell-shaped neurogenic tumor was resected using a combined approach employing a thoracoscopic procedure and limited laminectomy. The part of the tumor at the thoracic cavity was first amputated at the orifice of the foramen and then removed. Part of the spinal canal and intervertebral foramen was then removed by means of limited laminectomy without facetectomy. As a result, surgery was performed with a minimum of surgical stress and the patient did not require vertebral instrumentation.

Three Dimensional Imaging of the Spine with Helical Volume CT

Helical volume computed tomography (CT) involves continuous patient translation during x-ray source rotation and scan data acquisition. As a result, high-quality three-dimensional images can be produced from the continuous volume data sets in a relatively short period of time. Helical CT scanning and three-dimensional surface reconstruction of the spinal lesions were performed. In fracture and dislocation of the spine, three-dimensional CT provides excellent images of posterior aspects of the lesion and demonstrates sharp sagittal images of vertebral fractures compared with magnetic resonance imaging. In degenerative spinal disorders, three-dimensional CT is helpful in evaluating patients with ossification or calcification of ligaments. Three-dimensional images with helical volume scanning may be useful for the diagnosis of spinal disorders.