Yoshiharu Kawaguchi

Back muscle injury after posterior lumbar spine surgery. A histologic and enzymatic analysis.

Study Design Back muscle injury after posterior lumbar surgery was studied by muscle histology and serum creatine phosphokinase MM isoenzyme activity. Objectives To investigate intraoperative factors influencing the magnitude of back muscle injury after posterior lumbar surgery. Summary of Background Data The authors previously have reported iatrogenic back muscle injury in an animal model and in humans. Serious injury of the back muscle has been shown by short‐term and long‐term follow‐up evaluation. Methods The retraction pressure was monitored, and the retraction pressure‐time products were calculated in 24 patients. Early histologic changes of multifidus muscle, which were taken at completion of surgery, and serum creatine phosphokinase MM isoenzyme activity changes were examined. Results The magnitude of back muscle injury was significant as the pressure‐time product increased. Creatine phosphokinase MM isoenzyme activity increased after surgery and reached a plateau 1 day after surgery, followed by recovery to the normal value 1 week after surgery. Creatine phosphokinase MM isoenzyme activity tended to be high in cases with multilevel exposure and with high pressure‐time product. Conclusions Back muscle injury occurs in all patients who underwent posterior lumbar surgery, and these injuries are related to the retraction pressure time, and extent of exposure.

Serial changes in trunk muscle performance after posterior lumbar surgery.

STUDY DESIGN Serial changes in trunk muscle performance were prospectively studied in 20 patients who underwent posterior lumbar surgery. OBJECTIVE To evaluate the influence of back muscle injury on postoperative trunk muscle performance and low back pain, to clarify the significance of minimization of back muscle injury during surgery. SUMMARY OF BACKGROUND DATA The current investigators have reported examination of iatrogenic back muscle injury in an animal model and in humans. However, definite impairment caused by such back muscle injury has not been clarified. METHODS The patients were divided into a short-retraction-time group (< 80 minutes; n = 12) and a long-retraction-time group (> or = 80 minutes; n = 8). Before surgery and 3 and 6 months after surgery, the degree of back muscle injury was estimated by magnetic resonance imaging, and trunk muscle strength was measured. In addition, the incidence and severity of low back pain were serially analyzed. RESULTS Back muscle injury was directly related to the muscle retraction time during surgery. The damage to the multifidus muscle was more severe, and the recovery of extensor muscle strength was delayed in the long-retraction-time group. In addition, the incidence of postoperative low back pain was significantly higher in the long-retraction-time group. CONCLUSIONS Postoperative trunk muscle performance is dependent on the muscle retraction time. Thus, it is beneficial to shorten the retraction time to minimize back muscle injury and subsequent postoperative low back pain.

Association between an aggrecan gene polymorphism and lumbar disc degeneration.

STUDY DESIGN A case-control study using magnetic resonance imaging findings and a polymerase chain reaction assay to investigate the association between aggrecan gene polymorphism and lumbar disc degeneration. OBJECTIVE To analyze whether the aggrecan gene polymorphism is related to lumbar disc disease in young women. SUMMARY OF BACKGROUND DATA It has been suggested that a genetic factor or familial predisposition contributes to the development of lumbar disc herniation. However, the precise genetic component related to disc disease remains unclear. Recently, a polymorphism has been identified in the region of the human aggrecan gene. The expressed variable numbers of tandem repeat polymorphism occur in the highly conserved repeat region. METHODS The participants were 64 young women with or without low back problems. Magnetic resonance imaging was used to evaluate the degeneration and herniation of the intervertebral disc. Genomic deoxyribonucleic acid was extracted from all participants. A polymerase chain reaction assay was carried out to detect the alleles of the aggrecan gene. The association of intervertebral disc degeneration and herniation with the distribution of the aggrecan gene alleles was analyzed. RESULTS Findings showed an overrepresentation of alleles with small numbers of repeats in subjects with multilevel disc degeneration, thus indicating a significant distribution difference. There also was a significant difference between the distribution of alleles and the severity of disc degeneration. No significant association was found between any of the alleles either in number or type of disc herniation. CONCLUSIONS The current study showed that multilevel and severe disc degeneration was present in the participants with shorter variable numbers of tandem repeat length of the aggrecan gene. This suggests that subjects with shorter variable numbers of tandem repeat length of the aggrecan gene have a risk of having multilevel disc degeneration develop at an early age.

Back Muscle Injury After Posterior Lumbar Spine Surgery: Part 2

Study Design Back muscle injury caused by retractor application during posterior spine surgery in rats was examined histologically and histochemically according to the postoperative time with reference to the retraction time-pressure relationship. Objectives The results were correlated to provide the risk factors for back muscle injury during posterior spine surgery. Summary of Background Data Back muscles were examined histologically and histochemically after application of quantitative pressure and retraction time. No previous study has assessed this relationship. Methods Five groups were studied: Group 1, 1-hour low-pressure load group: Group 2, 1-hour high-pressure load group; Group 3, 3-hour low-pressure load group; Group 4, 3-hour high-pressure load group: and sham group. In each group, the multifidus muscle was evaluated 3 hours, 48 hours, 1 week, 3 weeks, and 6 weeks after surgery. Results In all groups except the sham group, degeneration of the muscle and neuromuscular junction was found at a very early postoperative time, but regeneration began at 1 week, 3 weeks, and 6 weeks after surgery. Results In all groups except the sham group, degeneration of the muscle and neuromuscular junction was found at a very early postoperative time, but regeneration began at 1 week, and recovery was attained by 6 weeks. The extent of muscle fiber necrosis and the severity of degeneration of the neuromuscular junctions showed a parallelism with the magnitude of the pressure load and retraction time. As the duration and pressure load increased, the time required for regeneration also increased. The fiber type grouping in group 3 and 4 was consistent with the severity of degeneration of neuromuscular junctions. Conclusions The muscular degeneration and the regeneration was largely dependent on the retraction pressure-time product. These results suggest that denervation muscle injuries are likely secondary responses to muscle retraction injury in any case of posterior spine surgery.Study Design The histologic and histochemical changes in back muscle were studied in virgin surgery patients with lumbar spine disorders and in patients who underwent repeat posterior lumbar surgery. Objectives The results were correlated to provide the evidences of histologic changes of back muscle after posterior lumbar surgery. Summary of Background Data Back muscles were examined histologically and histochemically after posterior lumbar surgery. No previous study has assessed these changes. Methods Back muscles were obtained before and after retraction from 18 virgin surgery cases with lumbar spine disorders. In four patients, the retraction pressure was monitored and the retraction pressure-time products ([P][T]) were calculated. In 21 repeat lumbar surgery cases, muscle samples were obtained before muscle retraction. Samples were evaluated by histologic and histochemical methods. Results Abnormal findings were slight in virgin surgery cases. Early back muscle injury tended to depend on operation time and ([P][T]) products. Late back muscle injury in reoperated patients was marked. Various types of neurogenic changes were observed more than 10 months after the first operation. Conclusions Histologic damages of back muscle due to previous surgical intervention were long-lasting. To avoid permanent muscle injury, the retraction time and pressure should be shortened or the pressure on the back muscle should be monitored during posterior surgery.

A functional SNP in CILP , encoding cartilage intermediate layer protein, is associated with susceptibility to lumbar disc disease

Lumbar disc disease (LDD) is caused by degeneration of intervertebral discs of the lumbar spine. One of the most common musculoskeletal disorders, LDD has strong genetic determinants. Using a case-control association study, we identified a functional SNP (1184T → C, resulting in the amino acid substitution I395T) in CILP, which encodes the cartilage intermediate layer protein, that acts as a modulator of LDD susceptibility. CILP was expressed abundantly in intervertebral discs, and its expression increased as disc degeneration progressed. CILP colocalized with TGF-β1 in clustering chondrocytes and their territorial matrices in intervertebral discs. CILP inhibited TGF-β1–mediated induction of cartilage matrix genes through direct interaction with TGF-β1 and inhibition of TGF-β1 signaling. The susceptibility-associated 1184C allele showed increased binding and inhibition of TGF-β1. Therefore, we conclude that the extracellular matrix protein CILP regulates TGF-β signaling and that this regulation has a crucial role in the etiology and pathogenesis of LDD. Our study also adds to the list of connective tissue diseases that are associated with TGF-β.

The Association of Lumbar Disc Disease with Vitamin-D Receptor Gene Polymorphism

Background: Although the etiology of lumbar disc disease is unknown, it has been suggested that a genetic factor contributes to its development. Recently, some genetic polymorphisms have been found to be related to clinical disorders. We investigated the association between vitamin-D receptor gene and estrogen receptor gene polymorphisms and lumbar disc disease in young adults.Methods: The participants included 205 young adults (166 women and thirty-nine men) with or without low-back problems. A magnetic resonance imaging scan of the lumbar spine was performed for all subjects, and the grade of disc degeneration was determined, according to the four-grade classification system of Schneiderman et al. The presence or absence of disc herniation was also evaluated. Genomic DNA was extracted from peripheral blood samples. The polymorphisms of the vitamin-D receptor and estrogen receptor genes were detected with use of a polymerase-chain-reaction assay. The restriction fragment length polymorphisms (RFLPs) for the vitamin-D receptor gene were analyzed by TaqI and ApaI restriction enzymes. XbaI and PvuII restriction enzymes were used for the estrogen receptor gene analysis. The distribution of polymorphism in subjects with disc degeneration and/or disc herniation was compared with that in the normal subjects.Results: The allelic frequencies of both vitamin-D receptor gene and estrogen receptor gene polymorphisms were similar to those in previous analyses of Japanese subjects. The allelic variation in the vitamin-D receptor gene was associated with multilevel and severe disc degeneration and disc herniation. The Tt allele was found to be more frequently associated with multilevel disc disease, severe disc degeneration, and disc herniation than was the TT allele. No additional associations were found.Conclusions: This study revealed that the Tt allele of the vitamin-D receptor gene was more frequently associated with multilevel and severe disc degeneration and disc herniation than was the TT allele, pointing to an increased risk of disc disease at an early age in subjects with the Tt allele in the vitamin-D receptor gene.

Minimum 10-year Follow-up Study of Anterior Lumbar Interbody Fusion for Isthmic Spondylolisthesis

The aims of the current study were to evaluate the long-term clinical and radiologic results of anterior lumbar interbody fusion (ALIF) for isthmic spondylolisthesis. Between 1981 and 1988, a total of 35 patients underwent ALIF for isthmic spondylolisthesis. Of these, 23 patients were followed clinically and radiographically for more than 10 years (average, 13.3 years). The Japanese Orthopaedic Association low-back pain score was used to evaluate the outcome of subjective symptoms and clinical signs. The preoperative and postoperative percentage of slip, preoperative and postoperative intervertebral disk height, interbody graft union, and pars defect union were evaluated by serial radiographs. The adjacent disk degeneration was also evaluated by radiographs and magnetic resonance imaging. Although the low-back pain score worsened after 5 years, ALIF provides satisfactory overall long-term clinical results. The preoperative percentage of slip and the disk height were corrected after surgery, but at the time of interbody graft union, slip and disk height recurred as a result of grafted bone collapse. The rate of union in the grafted area was 83%. In the nonunion cases, the scores gradually deteriorated with time, but the overall results were not different from those of union cases. Radiographs showed adjacent disk degeneration in 52% of cases in the upper adjacent level and in 70% of cases in the lower adjacent level, but these changes were not correlated with clinical outcomes.

Minimum 10-year followup after en bloc cervical laminoplasty

The long-term outcome (> 10 years) after cervical laminoplasty was assessed and the postoperative problems were clarified. One hundred thirty-three patients had laminoplasty between 1981 and 1989 for treatment of cervical myelopathy and 126 patients were available for the current study. The clinical results were evaluated using the Japanese Orthopaedic Association score. The radiologic findings were analyzed by postural anomalies and range of motion. The average preoperative score was 9.1 points, and the postoperative score improved to 13.7 points within a year. The Japanese Orthopaedic Association score and recovery rate were maintained at 13.4 points and 55.1% at the last followup. In 20 patients, the Japanese Orthopaedic Association score worsened during the followup. The causes of deterioration were axial spread of ossification of the posterior longitudinal ligament, other spinal lesions, cerebral infarction, and peripheral neuropathy. Postoperative cervical radiculopathy occurred in nine patients. Postoperative radiculopathy resolved in five patients, but remained in four patients. Kyphotic changes were observed in eight patients. The recovery rate in patients with kyphosis was poor. The postoperative range of motion decreased to 25.1% of preoperative range of motion. Sixty one percent of patients had a reduction of range of motion. Satisfactory results of cervical laminoplasty were maintained for more than 10 years after surgery; however, there were several postoperative problems, such as neurologic deterioration, postoperative radiculopathy, progression of kyphosis, and range of motion limitation.

Back muscle injury after posterior lumbar spine surgery. Topographic evaluation of intramuscular pressure and blood flow in the porcine back muscle during surgery.

Study Design Intramuscular pressure and blood flow of the back muscles were evaluated topographically during posterior lumbar spine surgery. The topographic damage of the back muscle after surgery was studied. Objective To investigate the relationship between intramuscular pressure or blood flow during posterior lumbar surgery and the back muscle injury after surgery. Summary of Background Data Iatrogenic back muscle injury in an animal and human model has been reported previously. Changes of intramuscular pressure and blood flow during surgery might be related to the muscle injury. No previous study on this issue has been published. Methods The contact pressure between the retractor blade and muscle tissue was monitored in 10 pigs during posterior surgery of the lumbar spine. On one side, intramuscular pressure at 5, 10, and 20 mm lateral to the retractor and on the other side blood flow of the back muscle at 5 and 20 mm during surgery were measured. Histologic changes of the back muscle at 5, 10, and 20 mm to the midline were evaluated 3 hours after surgery. Results The contact pressure decreased exponentially with time. Intramuscular pressure 5 mm lateral to the retractor was 114 ± 31 mm Hg and was significantly higher than at 10 mm and 20 mm. Blood flow markedly decreased during surgery and recovered incompletely after releasing the retractor at 5 mm and 20 mm lateral to the retractor. Blood flow at 5 mm was significantly lower than at 20 mm throughout surgery. The muscle damage 3 hours after surgery was more severe near the retractor blade. Conclusions The back muscles were exposed to pathophysiologic condition by a retractor during posterior lumbar spine surgery. External compression by a retractor increases intramuscular pressure to levels that impede local muscle blood flow. The muscle degeneration after surgery could be explained by direct mechanical damage and by the increased intramuscular pressure of muscle tissue by the retractor.

Direct and indirect activation of human corticospinal neurons by transcranial magnetic and electrical stimulation

Corticospinal volleys and surface electromyographic (EMG) responses evoked by magnetic and electrical transcranial stimulation were recorded simultaneously in three conscious human subjects. For magnetic stimulation, the figure-of-eight coil was held on the hand motor area either with the induced current through the brain flowing in a postero-anterior direction (P-A stimulation) or in a latero-medial direction (L-M stimulation). For electrical stimulation, the anode was placed 7 cm lateral to the vertex and cathode at the vertex (anodal stimulation). The P-A stimulation that was generally used preferentially evoked I waves, whereas the L-M and anodal stimulation preferentially evoked D wave. The results suggested that the mode of activation by transcranial magnetic stimulation altered, depending on its current direction, and the difference between P-M magnetic and electrical stimulation can be explained by the context of the D and I hypothesis.