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.

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.

The transverse placement laminoplasty using titanium miniplates for the reconstruction of the laminae in thoracic and lumbar lesion.

Laminoplasty for thoracic and lumbar spine surgery enables surgeons to preserve the posterior arch of the spine while preventing invasion of hematoma and scar tissue, postoperative instability, subluxation, and kyphotic deformities. The authors have developed a new surgical technique: namely, transverse placement laminoplasty (TPL) using titanium miniplates. Eight patients and 18 laminae underwent TPL using a titanium mini-plate. The preoperative diagnoses were six intradural tumors, one ossification of a yellow ligament and one spontaneous spinal cord herniation. The mean blood loss was 219 g and the mean duration of surgery was 3 h and 54 min. The mean postoperative follow-up period was 2 years and 1 month. All eight patients started to sit with a soft brace within the second postoperative day, and were able to walk within the fifth postoperative day. There were no cases of spinal deformity, an invasion of hematoma or scar tissue into the spinal canal on magnetic resonance imaging, or back pain. TPL simultaneously enables surgeons to obtain sufficient field of vision and rigid early fixation of the reduced lamina at the time of surgery. Moreover, our novel technique also simplifies the postoperative treatment, while preserving the posterior arch of the spine, and also preventing an invasion of a hematoma and scar tissue, postoperative instability, subluxation, and kyphotic deformities.

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.

Evaluation of cervical spondylotic myelopathy using somatosensory-evoked potentials.

Fourteen patients who had cervical spine surgery for cervical spondylotic myelopathy with median-nerve short-latency somatosensory-evoked potentials (SSEP) were followed preoperatively and until six months postoperatively. We evaluated the N18 latency and compared it with the JOA score recovery rate for each period. Seven patients demonstrated improvement in the N18 latency immediately following the operation and showed improvement of upper- as well as lower-extremity function 12 weeks postoperatively. We found a statistically significant correlation between improvement in the SSEP during the early decompression period and a good surgical outcome at 12 weeks postoperatively. We conclude that evaluating the median nerve SSEP is useful for prediction of the prognosis in patients with cervical spondylotic myelopathy treated surgically.

Intraoperative measurements of nerve root blood flow during discectomy for lumbar disc herniation.

STUDY DESIGN: Nerve root blood flow was intraoperatively measured before and after discectomy for lumbar disc herniation and compared with clinical features. OBJECTIVE: To investigate the relation between nerve root blood flow changes and symptoms associated with lumbar disc herniation. SUMMARY OF BACKGROUND DATA: Several authors have reported that recovery of intraneural blood flow, which restores the supply of oxygen and other nutrients to the nerve tissue, is strongly related to the rapid improvement of nerve function after discectomy for lumbar disc herniation. However, no previous study has quantitatively assessed blood flow in the human nerve root. METHODS: Nerve root blood flow was monitored in 21 patients with lumbar disc herniation using laser Doppler flowmetry (ALF 21 N; ADVANCE, Tokyo, Japan) during discectomy. Possible correlations were investigated between the blood flow rates and the following clinical features: age, duration of sciatica, presence or absence of neurologic deficits, latency to pain relief, and morphology of herniated discs. RESULTS: The blood flow rate in 16 patients who reported immediate relief after discectomy was much greater than in 5 patients whose pain was not relieved immediately after surgery (141% 8%, = 0.0364). The increase in the blood flow rate after discectomy was five times greater in patients with neurologic deficits than in patients without neurologic deficits (158% 36%, = 0.0638). CONCLUSIONS: The results of the current study suggest that immediate relief from pain and resolution of neurologic deficits soon after surgery are the result of early recovery from nerve root ischemia after discectomy, and that ischemia caused by mechanical nerve root compression is mainly related to the mechanisms underlying sciatic pain production and neurologic deficits.

A combined thoracoscopic and posterior-spinal approach for "dumbbell" neurofibroma minimizes the anatomical destruction of the vertebrae: report of a case.

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.