Search Results

You are looking at 1 - 10 of 12 items for

  • Author or Editor: Nobuhiro Tanaka x
Clear All Modify Search
Restricted access

Kazuki Yunokawa, Yoshitaka Hagiyama, Yu Mochizuki, Nobuhiro Tanaka and Mitsuo Ochi

✓The authors present a case of concurrent hypertrophic spinal pachymeningitis (HSP) and heavy-chain disease (HCD). The patient was a 71-year-old woman presenting with leg paralysis and fever. Laminectomy was performed for thoracic HSP, and chemotherapy was administered for HCD. Because the dura mater was not surgically opened, marked hypertrophy remained postoperatively. Once the HCD was controlled by chemotherapy, the fever subsided and the hypertrophy was resolved. No previous reports have supported a link between the two diseases. Idiopathic HSP may be secondary to rare conditions such as HCD, and systemic examinations should be performed to the fullest extent possible to investigate the possibility of some underlying disease.

Restricted access

Kiyotaka Yamada, Nobuhiro Tanaka, Kazuyoshi Nakanishi, Naosuke Kamei, Masakazu Ishikawa, Toshiyuki Mizuno, Kazuhiro Igarashi and Mitsuo Ochi

Object

Oxidative stress contributes to secondary injury after spinal cord injury (SCI). The expression of heme oxygenase-1 (HO-1), which protects cells from various insults including oxidative stress, is upregulated in injured spinal cords. Mice deficient in Bach1 (Bach1−/−), a transcriptional repressor of the HO-1 and beta-globin genes, express high levels of HO-1 mRNA and protein in various organs. The authors hypothesized that HO-1 modulates the secondary injury process after SCI in Bach1−/− mice.

Methods

Male C57BL/6 (wild-type) and homozygous Bach1−/− C57BL/6 mice were subjected to moderate SCI, and differences in hindlimb motor function, and electrophysiological, molecular biological, and histopathological changes were assessed for 2 weeks.

Results

Functional recovery was greater, and motor evoked potentials were significantly larger in Bach1−/− mice than in wild-type mice throughout the observation period. The expression of HO-1 mRNA in the spinal cord was significantly increased in both mice until 3 days after injury, and it was significantly higher in Bach1−/− mice than in wild-type mice at every assessment point. Histological examination using Luxol fast blue staining at 1 day after injury showed that the injured areas were smaller in Bach1−/− mice than in wild-type mice. The HO-1 immunoreactivity was not detected in uninjured spinal cord, but 3 days postinjury the number of HO-1–immunoreactive cells was obviously higher in the injured area in both mice, particularly in Bach1−/− mice. The HO-1 was primarily induced in microglia/macrophage in both mice.

Conclusions

These results suggest that HO-1 modulates the secondary injury process, and high HO-1 expression may preserve spinal cord function in the early stages after SCI in Bach1−/− mice. Treatment that induces HO-1 expression at these early stages may preserve the functional outcome after SCI.

Full access

Kazuyoshi Nakanishi, Nobuhiro Tanaka, Naosuke Kamei, Ryo Ohta, Yuki Fujioka, Takeshi Hiramatsu, Satoshi Ujigo and Mitsuo Ochi

Object

Cervical laminoplasty is a surgical procedure for cervical compressive myelopathy (CCM), and satisfactory outcomes have been reported. However, few reports have examined the pathophysiology of improvements in spinal cord function. The aim of this study was to investigate the variation in central motor conduction time (CMCT) before and after cervical laminoplasty in patients with CCM.

Methods

Motor evoked potentials (MEPs) following transcranial magnetic stimulation and compound muscle action potentials (CMAPs) and F-waves following electrical stimulation of the ulnar and tibial nerves at the wrist and ankle were measured from the abductor digiti minimi muscle (ADM) and abductor hallucis muscle (AH) in 42 patients with CCM before and 1 year after cervical laminoplasty. The peripheral conduction time (PCT) was calculated as follows: (latency of CMAPs + latency of F-waves − 1)/2. The CMCT was calculated by subtracting the PCT from the onset latency of the MEPs. The CMCT recovery ratio was defined and calculated as the ratio of CMCT values 1 year after surgery to those before surgery. The CMCT data were analyzed as longer or shorter CMCT between the patients' right and left ADMs and AHs. The Japanese Orthopaedic Association (JOA) score for cervical myelopathy was obtained as a clinical outcome before and 1 year after surgery. The recovery rate (RR) 1 year after surgery was calculated using the following formula: (postoperative JOA score 1 year after surgery – preoperative JOA score)/(17 – preoperative JOA score) × 100. Correlations among CMCT parameters, patient age, JOA score, and RR were determined.

Results

The longer and shorter CMCTs from the ADM (longer, p = 0.000; shorter, p = 0.008) and the longer CMCT from the AH (longer, p = 0.000) before surgery decreased significantly 1 year after surgery; the shorter CMCT from the AH did not significantly differ (shorter, p = 0.078). The mean JOA score before surgery was 10.1 ± 3.0 and improved significantly to 12.9 ± 2.7 at 1 year after surgery (p = 0.000). The mean CMCT recovery ratio and RR were 0.91 ± 0.18 and 0.43 ± 0.27, respectively. The longer/shorter CMCT parameters in the ADM and AH before or 1 year after surgery correlated significantly with the JOA score both before and 1 year after surgery. The CMCT recovery ratio from the longer CMCT in the ADM correlated significantly with the RR (r = − 3090, p = 0.011). There were no significant correlations between age and any CMCT parameters or CMCT recovery ratios.

Conclusions

These results suggest that cervical laminoplasty improves corticospinal tract function 1 year after surgery, which may be one of the reasons for the JOA score improvements in patients with CCM. The degree of improvement in corticospinal tract function did not correlate with patient age in this case series. The results demonstrated quantitative evidence of the pathophysiology of functional recovery in the corticospinal tract following cervical laminoplasty in patients with CCM.

Restricted access

Nobuhiro Tanaka, Masami Fujii, Hirochika Imoto, Joji Uchiyama, Kimihiko Nakano, Sadahiro Nomura, Hirosuke Fujisawa, Ichiro Kunitsugu, Takashi Saito and Michiyasu Suzuki

Object

The use of focal brain cooling to eliminate epileptic discharges (EDs) has attracted increasing attention in the scientific community. In this study, the inhibitory effect of selective hippocampal cooling on experimental hippocampal seizures was investigated using a newly devised cooling system with a thermoelectric (Peltier) chip.

Methods

A copper needle coated with silicone and attached to the Peltier chip was used for the cooling device. The experiments were performed first in a phantom model with thermography and second in adult male Sprague–Dawley rats in a state of halothane anesthesia. The cooling needle, a thermocouple, and a needle electrode for electroencephalography recording were inserted into the right hippocampus. Kainic acid (KA) was injected into the right hippocampus to provoke the EDs. The animals were divided into hippocampal cooling (10 rats) and noncooling (control, 10 rats) groups.

Results

In the phantom study, the cooling effects (9°C) occurred in the spherical areas around the needle tip. In the rats the temperature of the cooled hippocampus decreased below 20°C within a 1.6-mm radius and below 25°C within a 2.4-mm radius from the cooling center. The temperature at the needle tip decreased below 20°C within 1 minute and was maintained at the same level until the end of the cooling process. The amplitude of the EDs was suppressed to 68.1 ± 4.8% of the precooling value and remained low thereafter. No histological damage due to cooling was observed in the rat hippocampus.

Conclusions

Selective hippocampal cooling effectively suppresses the KA-induced hippocampal EDs. Direct hippocampal cooling with a permanently implantable system is potentially useful as a minimally invasive therapy for temporal lobe epilepsy and therefore could be an alternative to the temporal lobectomy.

Restricted access

Yasumu Kijima, Masakazu Ishikawa, Toru Sunagawa, Kazuyoshi Nakanishi, Naosuke Kamei, Kiyotaka Yamada, Nobuhiro Tanaka, Seiichi Kawamata, Takayuki Asahara and Mitsuo Ochi

Object

Despite intensive efforts in the field of peripheral nerve injury and regeneration, it remains difficult to achieve full functional recovery in humans following extended peripheral nerve lesions. In this study, the authors examined the use of blood-derived CD133+ cells in promoting the repair of peripheral nerve defects.

Methods

The authors transplanted phosphate-buffered saline (control), mononuclear cells, or CD133+ cells embedded in atelocollagen gel into a silicone tube that was used to bridge a 15-mm defect in the sciatic nerve of athymic rats (12 animals in each group). At 8 weeks postsurgery, molecular, histological, and functional evaluations were performed in regenerated tissues.

Results

The authors found that sciatic nerves in which a defect had been made were structurally and functionally regenerated within 8 weeks after CD133+ cell transplantation. From macroscopic evaluation, massive nervelike tissues were confirmed only in rats with CD133+ cell transplantation compared with the other groups. Morphological regeneration in the samples after CD133+ cell transplantation, as assessed using toluidine blue staining, was enhanced significantly in terms of the number of myelinated fibers, axon diameter, myelin thickness, and percentage of neural tissue. Compound muscle action potentials were observed only in CD133+ cell–treated rats. Furthermore, it was demonstrated that the transplanted CD133+ cells differentiated into Schwann cells by 8 weeks after transplantation.

Conclusions

The results show that CD133+ cells have potential for enhancement of histological and functional recovery from peripheral nerve injury. This attractive cell source could be purified easily from peripheral blood and could be a feasible autologous candidate for peripheral nerve injuries in the clinical setting.

Restricted access

Nobuhiro Tanaka, Kazuyoshi Nakanishi, Yoshinori Fujimoto, Hirofumi Sasaki, Naosuke Kamei, Takahiko Hamasaki, Kiyotaka Yamada, Risako Yamamoto, Toshio Nakamae and Mitsuo Ochi

Object

In this prospective analysis the authors describe the clinical results of surgical treatment in patients > 80 years of age in whom spinal function was evaluated with motor evoked potential (MEPs) monitoring.

Methods

The authors included 57 patients > 80 years of age who were suspected of having cervical myelopathy. The mean age of the patients was 83.0 years (range 80–90 years). The central motor conduction time (CMCT) was calculated from the latencies of the MEPs following transcranial magnetic stimulation and from M and F waves following peripheral nerve stimulation.

Results

Preoperative electrophysiological evaluation demonstrated significant elongation of CMCT or abnormalities in MEP waveforms in 37 patients (65%), and 35 patients of these underwent laminoplasty. In 30 patients cervical spondylotic myelopathy was diagnosed and 5 patients ossification of the posterior longitudinal ligament was diagnosed. The preoperative mean Japanese Orthopaedic Association Scale score was 8.6 (range 3–12.5) and the mean postoperative score was 12.6 (range 6–14.5) with an average recovery rate of 45% (range −21 to 100%). There were no major complications in any of the patients during the operative period and there were no cases of death resulting from operative intervention.

Conclusions

Sufficient clinical results are expected even in patients with myelopathy who are older than 80 years of age, provided the patients are correctly selected by electrophysiological evaluation with MEPs and CMCT.

Restricted access

Kazuyoshi Nakanishi, Nobuhiro Tanaka, Naosuke Kamei, Toshio Nakamae, Bun-ichiro Izumi, Ryo Ohta, Yuki Fujioka and Mitsuo Ochi

Object

The pathophysiology of occult tethered cord syndrome (OTCS) with no anatomical evidence of a caudally shifted conus and a normal terminal filum is hard to understand. Therefore, the diagnosis of OTCS is often difficult. The authors hypothesized that the posterior displacement of the terminal filum may become prominent in patients with OCTS who are in a prone position if filum inelasticity exists, and they investigated prone-position MRI findings.

Methods

Fourteen patients with OTCS and 12 control individuals were examined using T2-weighted axial MRI with the patients in a prone position on a flat table. On each axial view, the distance between the posterior and anterior ends of the subarachnoid space (A), the distance between the posterior end of the subarachnoid space and the terminal filum (B), the distance between the posterior end of the subarachnoid space and the dorsal-most nerve among the cauda equina (C), and the distance between the posterior end of the subarachnoid space and the ventral-most nerve (D) were measured. The location ratios of the terminal filum, the dorsal-most nerve, and the ventral-most nerve were calculated by the ratio of A to B (defined as TF = B/A), A to C (defined as DN = C/A), and A to D (defined as VN = D/A), respectively. Patients underwent sectioning of the terminal filum with the aid of a surgical microscope. The low-back pain Japanese Orthopaedic Association score was obtained before surgery and at the final follow-up visit.

Results

On prone-position axial MRI, the terminal filum was separated from the cauda equina and was shifted caudally to posterior in the subarachnoid space in all patients with OTCS. The locations of the caudal cauda equina shifted to ventral in the subarachnoid space. The TF values in the OTCS group were significantly lower than those in the control group at the L3–4 (p = 0.023), L-4 (p = 0.030), L4–5 (p = 0.002), and L-5 (p < 0.001) levels. In contrast, the DN values in the OTCS group were significantly higher than those of the control group at the L-2 (p = 0.003), L2–3 (p = 0.002), L-3 (p < 0.001), L3–4 (p < 0.001), L-4 (p = 0.007), L4–5 (p = 0.003), and S-1 (p = 0.014) levels, and the VN values in the OTCS group were also significantly higher than those of the control group at the L2–3 (p = 0.022), L-3 (p = 0.027), L3–4 (p = 0.002), L-4 (p = 0.011), L4–5 (p = 0.019), and L5–S1 (p = 0.040) levels. Sections were collected during surgery for histological evaluation, and a decreased elasticity within the terminal filum was suggested. Improvements in the Japanese Orthopaedic Association score were observed at the final follow-up in all patients.

Conclusions

The authors' new method of using the prone position for MRI shows that the terminal filum is located significantly posterior and the cauda equina is located anterior in patients with OTCS, suggesting a difference in elasticity between the terminal filum and cauda equina.

Full access

Kazuyoshi Nakanishi, Nobuhiro Tanaka, Naosuke Kamei, Takeshi Hiramatsu, Satoshi Ujigo, Norihiko Sumiyoshi, Takanori Rikita, Atsushi Takazawa and Mitsuo Ochi

OBJECT

The occurrence of compressive cervical myelopathy (CCM) increases in adults over 50 years of age. In addition, diabetes mellitus (DM) is a frequent comorbidity for people of this age and may impact the severity of CCM. The authors assessed motor pathway function in diabetic patients with CCM to investigate the correlation between electrophysiological parameters and clinical symptoms.

METHODS

Motor evoked potentials (MEPs) were measured from the abductor digiti minimi muscle (ADM) and the abductor hallucis muscle (AH) following transcranial magnetic stimulation, as were M- and F-waves following electrical stimulation of the ulnar and tibial nerves, in 22 patients with CCM and diabetes mellitus (DM) who had not experienced symptomatic diabetic neuropathy (CCM-DM group), in 92 patients with CCM alone (CCM group), and in 24 healthy adults (control group). The peripheral conduction time (PCT; measured from the ADM and AH) was calculated as follows: (M-wave latency + F-wave latency −1)/2. The central motor conduction time (CMCT; measured from the ADM and AH) was calculated by subtracting the PCT from the onset latency of the MEPs. The Japanese Orthopaedic Association (JOA) score for cervical myelopathy was obtained before and 1 year after surgery as a clinical outcome measure.

RESULTS

MEP, PCT, and CMCT parameters in the CCM-DM and CCM groups were significantly longer than those in the control group (p = 0.000−0.007). The PCTs in the CCM-DM group were significantly longer than those in the CCM group (p = 0.001−0.003). No significant differences were detected in the MEP and CMCT parameters between the CCM-DM and CCM groups (p = 0.080–1.000). The JOA score before surgery in the CCM-DM group was 10.7 ± 2.0 points and was significantly lower than that in the CCM group (12.2 ± 2.5 points, p = 0.015). In the CCM-DM group, JOA scores before surgery correlated with MEP-AH (r = −0.610, p = 0.012) and PCT-AH (r = −0.676, p = 0.004) values, but not with CMCT values, while the JOA scores were related to both MEP and CMCT parameters in the CCM group. The JOA scores improved to 13.8 ± 2.2 points after surgery (p = 0.001) and correlated with MEP-AH (r = −0.667, p = 0.005) and PCT-AH (r = −0.611, p = 0.012) in the CCM-DM group.

CONCLUSIONS

The results suggest that MEP, PCT, and CMCT parameters each reveal abnormalities in the upper and lower motor neurons even in patients with DM. The results also show a prolonged PCT in CCM-DM patients, despite having no history of diabetic neuropathy. Corticospinal tract impairments are similar between CCM and CCM-DM patients, while the JOA score of the CCM-DM patients is lower than that in the CCM patients. The JOA score in CCM-DM patients may be influenced by additional impairments in peripheral nerves or other diabetic complications. These electrophysiological studies may be useful for screening motor pathway function for CCM in patients with DM.

Restricted access

Naosuke Kamei, Nobuhiro Tanaka, Yosuke Oishi, Masakazu Ishikawa, Takahiko Hamasaki, Koji Nishida, Kazuyoshi Nakanishi, Norio Sakai and Mitsuo Ochi

Object

The transplantation of bone marrow stromal cells (BMSCs) is considered to be an alternative treatment to promote central nervous system regeneration, but the precise mechanisms of this regeneration after transplantation of BMSCs have not been clarified. In the present study, the authors assessed the effects of BMSC transplantation on corticospinal axon growth quantitatively, and they analyzed the mechanism of central nervous system regeneration in the injured and BMSC-treated spinal cord using the organotypic coculture system.

Methods

Bone marrow stromal cells derived from green fluorescent protein–expressing transgenic Sprague–Dawley rats were transplanted to the organotypic coculture system in which brain cortex and spinal cord specimens obtained in neonatal Sprague–Dawley rats were used. The axon growth from the cortex to the spinal cord was assessed quantitatively, using anterograde tracing with 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate. To identify the differentiation of transplanted BMSCs, immunohistochemical examinations were performed. In addition, BMSCs were analyzed using reverse transcriptase polymerase chain reaction (RT-PCR) for mRNA expression of the growth factors.

The transplantation of BMSCs beneath the membrane, where the transplanted cells did not come into direct contact with the cultured tissue, promoted corticospinal axon growth to the same extent as transplantation of BMSCs on the tissues. The RT-PCR showed that the transplanted BMSCs expressed the mRNA of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF).

Conclusions

These findings strongly suggest that humoral factors expressed by BMSCs, including BDNF and VEGF, participate in regeneration of the central nervous system after transplantation of these cells.

Restricted access

Nobuhiro Tanaka, Yoshinori Fujimoto, Tadayoshi Sumida, Hideki Manabe, Kazuyoshi Nakanishi, Yasushi Fujiwara, Naosuke Kamei, Toshio Nakamae, Bunichiro Izumi and Mitsuo Ochi

Object

In this retrospective analysis the authors describe the long-term clinical results of microsurgical transdural discectomy with laminoplasty (MTDL) in patients with cervical disc herniation (CDH).

Methods

Thirty patients (21 males, 9 females; mean age at surgery 55 years) with CDH had surgical treatments consisting of MTDL between 1990 and 1998. All patients demonstrated signs or symptoms of cervical myelopathy and/or radiculomyelopathy. Clinical outcomes were evaluated by the Japanese Orthopaedic Association (JOA) scoring system and by recovery rate (RR). The degenerative grades of the intervertebral discs were also evaluated based on preoperative, postoperative, and final follow-up MR images. The average follow-up period was 14.1 years (range 10–22 years).

Results

Twenty (67%) of the 30 patients completed the follow-up in this study. The preoperative JOA scores in these patients averaged 11.8, and the postoperative scores at the final follow-up averaged 15.5 (average RR 69.6%). None of these patients required reoperation after MTDL. Although disc degeneration progressed during the follow-up period, there were no cases of clinical deterioration, recurrence of disc herniation, or postoperative kyphotic deformity.

Conclusions

Sufficient clinical results were obtained after the MTDL for a long-term follow-up period exceeding 10 years. The MTDL may be an option for an alternative procedure if the patients are correctly selected and the procedure is safely performed.