Naoto Takahashi

Pathomechanisms of nerve root injury caused by disc herniation: an experimental study of mechanical compression and chemical irritation.

Study Design. An electrophysiologic and histologic study on nerve roots after mechanical compression and/or local application of nucleus pulposus (NP) was performed. Objective. To assess the effects of mechanical compression and/or chemical irritation caused by NP. Summary of Background Data. It has been shown that application of NP to nerve roots without compression induces histologic and functional changes in nerve roots and the dorsal root ganglia. In clinical situations, however, mechanical compression has also been considered an important factor in disc herniation. Methods. Eighteen dogs (9–15 kg) were used in this study. Four groups were used to assess the effect of each factor: 1) sham group (n = 3); 2) NP group (NP applied under the S1 lamina) (n = 5); 3) comp group (a plastic balloon placed under the S1 lamina) (n = 5); and 4) comp+NP group (a balloon and NP placed under the S1 lamina) (n = 5). Ascending cauda equina action potentials (CEAPs) and cauda equina–sensory nerve conduction velocity (SCV) were recorded before, immediately after, and 1 week after treatment. Histologic changes were also assessed by light microscopy. Results. There were no significant differences in CEAP and SCV among the four groups immediately after the treatment. However, 1 week after treatment, the amplitudes in the NP group, comp group, and comp+NP group were statistically significantly lower compared with those in the sham group. The comp+NP group showed significantly lower amplitude than did the NP group and comp group. Immediately after treatment, SCV in the NP group and comp group did not show significant differences compared with that in the sham group. However, 1 week after treatment, SCV in the comp+NP group was significantly lower compared with that in the sham group. Histologic changes such as intraneural edema, Schwann cell edema, and nerve fiber injury seemed to be more pronounced in the comp+NP group than in the other groups. Conclusions. It was shown that each of the assessed factors induces nerve dysfunction. However, the combination of mechanical compression (mass effect of herniated NP) and chemical irritation (inflammation around nerve root) may induce more nerve root injury than each factor per se.

TNF-α and Phosphorylation of ERK in DRG and Spinal Cord : Insights Into Mechanisms of Sciatica

Study Design. Characterize extracellular signal-regulated kinase (ERK) and its phosphorylation (pERK) in neural tissues after topical application of tumor necrosis factor-alpha (TNF-α) to L5 nerve root. Objective. Identify time-course, localization, and expression of pERK. Summary of Background Data. TNF-α has a key role in disc herniation and sciatica as an inflammatory component of the nucleus pulposus. ERK is associated with neuronal signal transduction and nociception. Methods. We studied tissue from naive rats, vehicle-treated rats, and rats receiving rat recombinant TNF-α using Western blots of total and phosphorylated ERK (pERK). We used immunohistochemistry of pERK with neuronal nuclear (NeuN) antibody to identify its cellular distribution. Results. Topical application of TNF-α to rat nerve root increased pERK in ipsilateral dorsal root ganglion (DRG) neurons and glia within 5 hours. pERK was not expressed in DRG during the first hour after TNF-α application, nor was it seen at anytime in spinal cord dorsal horn. DRG satellite cells had increased pERK 5 hours after TNF-α or vehicle treatment. TNF-α treatment increased pERK in small- and medium-sized DRG neurons and to a lesser degree in large neurons. Conclusions. These findings suggest that ERK signaling plays a role in the activation of DRG cells following inflammatory injuries to nerve roots and further documents the importance of inflammation in the pathogenesis of painful spine disorders.

Diagnostic value of the lumbar extension-loading test in patients with lumbar spinal stenosis: a cross-sectional study

BackgroundThe gait-loading test is a well known, important test with which to assess the involved spinal level in patients with lumbar spinal stenosis. The lumbar extension-loading test also functions as a diagnostic loading test in patients with lumbar spinal stenosis; however, its efficacy remains uncertain. The purpose of this study was to compare the diagnostic value of the lumbar extension-loading test with that of the gait-loading test in patients with lumbar spinal stenosis.MethodsA total of 116 consecutive patients (62 men and 54 women) diagnosed with lumbar spinal stenosis were included in this cross-sectional study of the lumbar extension-loading test. Subjective symptoms and objective neurological findings (motor, sensory, and reflex) were examined before and after the lumbar extension-loading and gait-loading tests. The efficacy of the lumbar extension-loading test for establishment of a correct diagnosis of the involved spinal level was assessed and compared with that of the gait-loading test.ResultsThere were no significant differences between the lumbar extension-loading test and the gait-loading test in terms of subjective symptoms, objective neurological findings, or changes in the involved spinal level before and after each loading test.ConclusionsThe lumbar extension-loading test is useful for assessment of lumbar spinal stenosis pathology and is capable of accurately determining the involved spinal level.

Development and implementation of an inpatient multidisciplinary pain management program for patients with intractable chronic musculoskeletal pain in Japan: preliminary report

Introduction Multidisciplinary pain management is a useful method to treat chronic musculoskeletal pain. Few facilities in Japan administer a multidisciplinary pain management program, especially an inpatient program. Therefore, we implemented a multidisciplinary pain management program in our hospital based on biopsychosocial factors guided by the recommendations of the International Association for the Study of Pain. The purpose of this study is to describe our inpatient pain management program for Japanese patients, which uses the biopsychosocial method of pain self-management. Materials and methods Fourteen patients with intractable chronic musculoskeletal pain, who were implemented a multidisciplinary pain management program in our hospital, were studied using the evaluation of the pain and associated factors and physical function. Results Significant improvement in outcomes were seen in the brief pain inventory, the pain catastrophizing scale (rumination, magnification, and helplessness), the pain disability assessment scale, the hospital anxiety and depression scale (anxiety and depression), the pain self-efficacy questionnaire, the EuroQol five dimensions questionnaire, and muscle endurance and physical fitness. We found no statistically significant differences in static flexibility or walking ability. Conclusion We developed an inpatient chronic pain management program for Japanese patients. Our results suggest that our program improves chronic musculoskeletal pain coping mechanisms, and that the program can improve patients’ quality of life and some physical function. This inpatient pain management program is being expanded to better help intractable chronic musculoskeletal pain patients.

Therapeutic efficacy of nonsteroidal anti-inflammatory drug therapy versus exercise therapy in patients with chronic nonspecific low back pain: a prospective study

Therapy for chronic, nonspecific low back pain is mainly conservative: medication and/or exercise.　Pharmacotherapy, however, has side effects, and the quantities of concomitant drugs in older persons require attention.　Although exercise promises improved function, its use to alleviate pain is controversial.　Thus, we compared the efficacy of pharmacotherapy versus exercise for treating chronic nonspecific low back pain.　The pharmacotherapy group (n=18: 8 men, 10 women) were prescribed celecoxib monotherapy.　The exercise group (n=22: 10 men, 12 women) undertook stretching exercises.　Because of drop-outs, the NSAID group (n=15: 7 men, 8 women) and the exercise group (n =18: 8 men, 10 women) were finally analyzed.　We applied a visual analog scale, Roland-Morris disability scores, and the 36-Item Short Form Health Survey.　We used a paired t-test for within-group analyses and an unpaired t-test for between-group analyses.　Pain relief was achieved after 3 months of pharmacotherapy or exercise.　Quality of life improved only in the exercise group.　Recovery outcomes for the two groups were not significantly different.　Efficacy of exercise therapy for strictly defined low back pain was almost equivalent to that of pharmacotherapy and provided better quality of life.

FOUR-YEAR FOLLOW-UP OF PREGNANCY-ASSOCIATED OSTEOPOROSIS : A CASE REPORT

A 22-year-old woman presented with complaints of severe pain in a wide region of the thoracolumbar spine. She developed severe pain in the thoracolumbar spine region 2 months after her first delivery and was referred 1 month later. A lateral thoracic X-ray showed depressed degenerative vertebrae (T7, T9). One month after the initial examination, thoracic sagittal magnetic resonance imaging showed low intensity areas on T1-weighted imaging and iso-high intensity areas on T2-weighted imaging at T5, 7, 8, 9 and 11. Bone mineral density measured by ultrasound was low (%YAM 76%). The bone metabolic markers were high, suggesting accelerated osteoclast activity. These findings prompted a diagnosis of pregnancy-associated osteoporosis. She was asked to stop breastfeeding and to wear a lumbar brace, and treatment with nutritional calcium, activated vitamin D3, and risedronate sodium was started. Her low back pain almost disappeared after treatment. Bone metabolic markers showed normalization 8 months after the initial examination. Risedronate sodium was stopped 2 years and 2 months after the initial examination. Teriparatide treatment was started because her bone mineral density remained low; however, the osteoblast marker P1NP was not increased 5 months after the start of teriparatide treatment.