Kazutoshi Yokogushi

Mechanosensitive afferent units in the lumbar intervertebral disc and adjacent muscle.

The purpose of this study was to characterize the somatosensory units of the lumbar intervertebral disc and adjacent muscle. A laminectomy was performed on the lumbar spine of adult male Japanese White rabbits. Receptive fields of mechanosensitive afferent units were investigated in the intervertebral disc and adjacent muscle, and electrophysiologic recordings were obtained from filaments of the dorsal root. Thirteen mechanosensitive units were identified: three units in the intervertebral disc area, and 10 units in the psoas muscle. Of the three units in the disc area, one was identified at the surface of the L5-6 anulus fibrosus and two at the insertion of the anulus fibrosus to the L5 and L6 vertebral bodies. These three units belonged to Group III and had very high mechanical thresholds, more than 160 g. The 10 units in the psoas muscle belonged to Groups II, III, and IV, and had mechanical thresholds ranging from 0.22 to 12.6 g. The units in the disc area may serve as nociceptors sensitive to strong noxious stimulation that could traumatize the tissue. The units in the psoas muscle may contribute to nociception and proprioception.

Immunophenotypic analysis of the inflammatory infiltrates in herniated intervertebral discs.

Study Design. The herniated portion of the lumbar disc was analyzed immunohistochemically for inflammatory infiltrates to determine their immunophenotype. Objective. To investigate the pathomechanism behind spontaneous regression of herniated discs. Summary of Background Data. Spontaneous regression of herniated intervertebral discs has been increasingly reported. The inflammatory response of the host has been suggested as a factor in this phenomenon. However, whether the inflammation is induced from direct chemical irritation of the nucleus pulposus material or whether it is secondary to an autoimmune response to the nucleus pulposus remains controversial. Methods. The herniated portion of the disc was collected from 38 patients who underwent surgery for lumbar disc herniation. Thin cryostat sections were made, and the extent to which inflammatory cells had infiltrated the disc specimen was defined. Then the immunophenotype of cellular infiltrates in the herniated disc specimens was assessed by immunostaining using a series of antibodies for lymphocyte, monocyte, macrophage, and dendritic cell markers. Results. The inflammatory infiltrates in 14 of the 38 herniated discs were subjected to immunohistochemical analysis. None of them expressed the immunophenotypic markers of the lymphocyte (CD20, CD45RO, CD4, CD8, TCR&ggr;&dgr;), mature monocyte (CD33), or dendritic cell (CD1a, CD80, CD86, S100). Abundant infiltration of CD68-positive cells that lacked CD33 but had a variable amount of CD11b, CD11c, and CD40 likely represents a process of differentiation from monocytes to macrophages. Conclusions. These findings are consistent with an immunophenotype of inflammatory responses to tissue injury or chemical irritation rather than antigen-specific immune responses. Therefore, understanding the mechanism of tissue repair is fundamentally important in the management of patients with disc herniations.

Suspension effect and dynamic evaluation of the total surface bearing (TSB) trans-tibial prosthesis: a comparison with the patellar tendon bearing (PTB) trans-tibial prosthesis.

X-ray and cineradiography measurements were used to compare the suspension effect and stability of a TSB trans-tibial prosthesis with an Icelandic Roll-On Silicone Socket (ICEROSS) system to that of a PTB trans-tibial prosthesis. The suspension effect was measured by the distance between the tibia and the socket in both suspension position and weight-bearing position in both type of prostheses. The suspension effect of the TSB prosthesis (2.53 ± 0.90cm) was superior to that of the PTB prosthesis (3.60 ± 0.56cm) (p<0.05) by x-ray measurement. The suspension effect of the TSB prosthesis (0.1, 0.4, 0.72cm) was superior to that of the PTB prosthesis (0.3, 0.48, 1.03cm) (p<0.01, p<0.05) by cineradiographic measurement. The stability was measured as the angle between the axis of the tibia and the prosthesis at the time of heel contact and toe off. The angle change of the TSB prosthesis was statistically smaller than that of the PTB prosthesis.

Vertebral body ischemia in the posterior spinal artery syndrome: case report and review of the literature.

Study Design. A case of posterior spinal cord syndrome in which magnetic resonance images showed predominant T2 hyperintense signal in the adjacent vertebral body is reported. Objectives. To present the case for abnormal bone marrow magnetic resonance signal in the radiologic diagnosis of posterior spinal cord syndrome and to review its significance. Summary of Background Data. Infarction in the region of posterior spinal arteries has been rarely described. This is attributable not only to the infrequent occurrence of infarction of posterior spinal arteries, but also to a lack of well-established diagnostic procedures. It is of clinical value to define diagnostic images of posterior spinal cord syndrome, especially early in the course of the disease. Methods. The subject was a 52-year-old man who was presented with acute nontraumatic myelopathy. Magnetic resonance imaging, performed serially after onset of the disorder from 5 hours to 11 months, was evaluated in comparison with neurologic findings. The literature was reviewed to discuss the magnetic resonance images of spinal cord infarction. Results. The neurologic findings were consistent with posterior spinal cord syndrome. A magnetic resonance image taken at 5 hours after onset of the syndrome showed T2 hyperintense signal in the T12 vertebral body. At 3 days after onset, T2 hyperintense signal became obvious in the posterior portion of the spinal cord at T9–T12 vertebral levels. Follow-up magnetic resonance imaging at 41 days, 8 months, and 11 months showed a decrease in the size and intensity of the T2 signal change in the spinal cord and T12 vertebral body. In the literature, T2 hyperintense bone marrow signal was defined in one case of posterior spinal cord syndrome and seven cases of anterior spinal cord syndrome. Conclusions. Associated bone marrow abnormalities likely reflect the underlying pathology of the blood supply to the vertebral body, and may be an additional key sign for radiologic diagnosis of posterior spinal cord syndrome.

Correlation between progression of spinal deformity and pulmonary function in Duchenne muscular dystrophy

The purpose of this study was to investigate how age at and value of the plateau of vital capacity (VC plateau) correlate with the severity of the progression of spinal deformity in patients with Duchenne muscular dystrophy (DMD). Changes in spinal deformity and pulmonary function in 36 DMD patients were examined in a retrospective longitudinal study. Patterns of progression of spinal deformity were classified into three types according to Odas classification. Of the 32 patients who showed spinal deformity, six were classified as type 1, 19 as type 2, and seven as type 3. The correlation between the patterns of progression of spinal deformity and the VC plateau was examined using a discriminant analysis. Rapid and severe progression of spinal deformity could be expected in patients whose VC plateau was less than 1,900 mL and in those in which it occurred before age 14 years. Thus VC plateau may be an indicator of the severity of the progression of spinal deformity in DMD patients.

Prediction of progression of spinal deformity in Duchenne muscular dystrophy: a preliminary report.

Study Design. Discriminatory power was statistically estimated for multiple combinations of risk indicators for the progression of spinal deformity in Duchenne muscular dystrophy (DMD). Objective. To differentiate DMD cases in which spinal deformity will rapidly and severely progress from those with lesser progression of spinal deformity. Summary of Background Data. Early surgical intervention using instrumentation has recently been advocated for DMD patients to prevent the progression of spinal deformity. However, early determination of cases needing surgical intervention is difficult because of variations in the severity of the clinical courses of DMD patients. Methods. Charts and spinal radiographs of 12 DMD patients were reviewed retrospectively. Patterns of progression in spinal deformity were classified into three types according to Oda’s classification. Discriminant analysis was conducted to categorize the patients into either a severe progression group (type-1 and type-2 patients) or a less severe progression group (type-3 patients and patients without spinal deformity) on the basis of four predictors: 1) vital capacity at the age of 10 years, 2) the age at which ambulation ceased, 3) curve pattern of spinal scoliosis, and 4) Cobb angles of spinal scoliosis at the age of 10 years. Results. Eleven of the twelve DMD patients showed spinal deformity. Three were classified as type 1, six were classified as type 2, and two were classified as type 3. The remaining patient showed no spinal deformity. Multiple discriminant analysis correctly predicted the severity of the clinical course of 91.7% of the DMD patients. Vital capacity at age 10 was found to be the strongest predictor among the variables. Conclusions. Through multiple discriminant analysis, the clinical course of spinal deformity in DMD patients was correctly predicted in 92% of subjects. This method would be useful to determine early which DMD cases need surgical intervention for treatment of spinal deformity.

Synovial chondromatosis presenting with cervical radiculopathy: a case report.

Study Design. A case report is presented. Objectives. To report a case of synovial chondromatosis of a cervical facet joint and describe the appearance with magnetic resonance imaging and computed tomography myelography. Summary of Background Data. Synovial chondromatosis is an uncommon disorder characterized by the presence of multiple cartilaginous or osteocartilaginous nodules in the synovium of a joint space. Synovial chondromatosis in the cervical facet joint is rare. Method. A 52-year-old woman experienced the sudden onset of severe pain in the dorsal shoulder girdle and in the ulnar side of her right arm and forearm. This refractory pain only responded to an epidural nerve root block. Neurologic examination showed right nerve root signs that ranged from the C7 to Th1 segments of the spinal cord. Radiologic and electrophysiological examinations were carried out. Result. A mass was found in the right facet joint between C7 and Th1 with magnetic resonance imaging and computed tomography myelography. These investigations clearly indicated the location, size, and extent of the lesion accompanying the irregularity of the joint and osteolytic change. Somatosensory-evoked potentials with right ulnar nerve stimulation indicated a significant conduction block in the lower right cervical nerve roots. After surgical removal of this lesion, the neurologic symptoms markedly improved. The histopathology diagnosed synovial chondromatosis. Conclusion. Synovial chondromatosis should be included in the differential diagnosis of radiculopathies of unknown etiology.

Biomechanical and clinical evaluation of a newly designed polycentric knee of transfemoral prosthesis

We have designed a new polycentric knee adopting a hydraulic unit and an intelligent mechanism. The biomechanical parameters of this prototype, such as the stance duration, peak knee flexion angle in stance and swing, peak hip flexion angle, and peak hip extension moments were analyzed at three different cadences (88, 96, 104 steps/min) in three amputees, and then compared to those of polycentric hydraulic knees currently in use. The same parameters were also measured for 10 healthy volunteers and subsequently analyzed. In the prototype, almost all the values of the parameters showed no significant variety in individuals at the different cadences. The situation was the same with the healthy volunteers. However, the values of the parameter for the conventional knee varied significantly with the individual at the different cadences. The prototype may be of practical use, contributing to a stable walk even at different cadences.

Investigating Parental Caregiver Burden for Children with Disabilities using a Japanese version of the Zarit Caregiver Burden Interview (J-ZBI)

障害児の介護負担は高齢者とは違う特徴があると予想される．障害児を介護する保護者の負担を調査するために，肢体不自由養護学校就学児の保護者135 人を対象として，日本語版Zarit介護負担尺度（J-ZBI）などを用いて，アンケート調査を行った．有効回答が得られた69 人の回答結果から，全体のJ-ZBIの平均点は，25.6 点（SD 13.0）で，CES-Dの平均得点は10.8 点（SD 7.1）であった．保護者のSF-36の得点は，同年代の国民平均よりも低く，QOLが低下していた．保護者にとって障害児の介護負担は，精神的負担よりも身体的負担が強く感じられていた．J-ZBIで保護者を2 群に分けると，点数が高く，より介護負担が重いと考えられた保護者群は，CES-Dでうつ状態と判定される人数の割合が多く，同群の障害児のADL自立程度が低かった．保護者の身体的負担を軽減するサービスの利用で，介護負担は軽減される可能性がある．

Insufficiency fracture of the spine: a prospective analysis based on radiographic and scintigraphic diagnosis

Abstract. To investigate the clinical characteristics of insufficiency fracture of the spine, patients aged 65 years or older, who had been hospitalized for acute low back pain without either an acute traumatic event or a previous history of malignant disease, were examined by plain radiographs and technetium-99m methylene disphosphonate bone scanning. Fifteen patients were diagnosed as having a vertebral insufficiency fracture on the basis of: (a) radiographic oseteopenia of the vertebra; (b) positive bone scan images; and (c) no episode of newly identified malignant disease in a subsequent 1 year follow up. These patients were analysed with respect to age, gender, bone mineral density, the number and distribution of the affected vertebrae, the extent of vertebral deformity, and consistency between radiographic and bone scan findings. Vertebral insufficiency fractures exhibited: (a) strict female predominance; (b) concave deformity of the affected vertebra; (c) a wide range of the vertebral height ratios and fracture distribution; and (d) low consistency between the vertebral deformity assessed by the lateral radiograph and positive activity on bone scanning. These findings represent a unique clinical feature of vertebral insufficiency fracture, and also emphasize the difficulty of radiographic diagnosis, as well as the importance of a comprehensive diagnostic approach.