Magnetic Resonance Imaging Evaluation of the Effects of Surgical Invasiveness on Paravertebral Muscles After Muscle-preserving Interlaminar Decompression (MILD).

STUDY DESIGN: This is a retrospective study. OBJECTIVES: The aim of this study was to determine the extent of damage to the paravertebral muscles after muscle-preserving interlaminar decompression (MILD) using magnetic resonance imaging to evaluate changes in the multifidus muscle (MF). SUMMARY OF BACKGROUND DATA: Short-term surgical outcomes of MILD for lumbar spinal canal stenosis (LSCS) are satisfactory; however, the extent of damage to the paravertebral muscles after MILD remains unclear. METHODS: Thirty-four patients (18 men/16 women; mean age: 72.6 y) who had LSCS treated with MILD were retrospectively investigated. A total of 61 decompressed disk levels [L2/3(5); L3/4(21); L4/5(30); L5/S(5)] and 34 nondecompressed levels (L1/2) were assessed. There was 1 decompressed disk level in 12 cases, 2 in 17 cases, and 3 in 5 cases. Magnetic resonance imaging scans were obtained before surgery and at 3 and 12-18 months after surgery, using the same scanner. The rate of paravertebral muscle atrophy was evaluated to compare the area of the MF in the T2-weighted axial plane (intervertebral disk level) preoperatively and postoperatively, using OsiriX Medical Imaging Software. Changes in muscle signal intensity were also recorded. Statistical analysis was performed using 3-way analysis of variance with the post hoc Fisher PSLD test. RESULTS: The rate of MF atrophy was 4.0% at the decompressed levels and 2.1% at the nondecompressed levels. There were no changes of signal intensity in the MF between the preoperative and postoperative periods. In decompressed levels, muscle atrophy and signal intensity were significantly improved from 3 months to 12-18 months after surgery. The number and level of the decompressed disks did not affect the extent of muscle injury. CONCLUSIONS: The extent of paravertebral muscle injury after MILD is satisfactory. The midline interlaminar approach used in this technique may prevent local denervation and irreversible damage to the paravertebral muscles. These results indicate that MILD is useful to treat LSCS less invasively.

Innovative Technique for the Placement of the Drainage Tube for Microendoscopic Spinal Decompression.

STUDY DESIGN: A technical note and retrospective study. OBJECTIVES: The objectives were to describe a new method of drainage tube placement during microendoscopic spinal decompression, and compare the positioning and fluid discharge obtained with this method and the conventional method. SUMMARY OF BACKGROUND DATA: To prevent postoperative epidural hematoma after microendoscopic decompression, a drainage tube must be placed in a suitable location. However, the narrow operative field makes precise control of the position of the tube technically difficult. We developed a method to reliably place the tube in the desired location. MATERIALS AND METHODS: We use a Deschamps aneurysm needle with a slightly curved tip, which we call a drain passer. With the microendoscope in position, the drain passer, with a silk thread passed through the eye at the needle tip, is inserted percutaneously into the endoscopic field of view. The drainage tube is passed through the loop of silk thread protruding from the inside of the tubular retractor, and the thread is pulled to the outside, guiding the end of the drainage tube into the wound. This method was used in 23 cases at 44 intervertebral levels (drain passer group), and the conventional method in 20 cases at 32 intervertebral levels (conventional group). Postoperative plain radiographs were taken, and the amount of fluid discharge at postoperative hour 24 was measured. RESULTS: Drainage tube positioning was favorable at 43 intervertebral levels (97.7%) in the drain passer group and 26 intervertebral levels (81.3%) in the conventional group. Mean fluid discharge was 58.4±32.2 g in the drain passer group and 38.4±23.0 g in the conventional group. Positioning was significantly better and fluid discharge was significantly greater in the drain passer group. CONCLUSION: The results indicate that this method is a useful drainage tube placement technique for preventing postoperative epidural hematoma.

Prolonged Dysphagia due to a Combination of Cerebral Hemorrhage and Diffuse Idiopathic Skeletal Hyperostosis: A Case Report.

A 79-year-old man was diagnosed with left thalamic hemorrhage. On admission, the Functional Independence Measure (FIM) motor score was 13 points, and the Food Intake Level Scale (FILS) was Level 2, with the patient needing enteral nutrition. Six months after stroke onset, the FIM motor score had improved to 38 points and the dysphagia to FILS Level 7. The patient was able to ingest easy-to-swallow food orally three times a day, but only after postural adjustment with rotation of the head. Seven months after stroke onset, the FIM motor score had reached 45 points but without further improvement in swallowing function. Videofluoroscopic swallowing evaluation (VF) revealed that the persistence of dysphagia was due to osteophytes on the cervical vertebrae caused by diffuse idiopathic skeletal hyperostosis. On surgical removal of the osteophytes, swallowing function improved to FILS Level 9; the patient was able to ingest normal food in a seated position without postural adjustment. One year after stroke onset, the patient was discharged with an FIM motor score of 59 points and FILS Level 9. At the 2-year follow-up, there was minimal recurrence of the osteophytes, and both motor and swallowing functions were maintained at the same level as at discharge. This case suggests that dysphagia in elderly patients may be due to multiple disorders, and that surgical intervention may occasionally be effective.

Positive effect on bone fusion by the combination of platelet-rich plasma and a gelatin ß-tricalcium phosphate sponge: a study using a posterolateral fusion model of lumbar vertebrae in rats.

We developed a novel method for bone fusion by combining platelet-rich plasma (PRP) and a gelatin ß-tricalcium phosphate (ß-TCP) sponge. The PRP is an autologous concentration of platelets that includes several growth factors. The gelatin ß-TCP sponge comprises gelatin and ß-TCP, thus enabling the sustained release of growth factors and osteoconduction. To evaluate this method, we generated a posterolateral fusion model of lumbar vertebrae in rats and divided it into five groups by implanting the following materials between transverse processes of vertebrae, (1) the gelatin ß-TCP sponge with PRP (PRP sponge), (2) the gelatin ß-TCP sponge with platelet-poor plasma, (3) gelatin hydrogel with PRP, (4) autologous iliac bone (autograft), and (5) no material was implanted as a control. The assessment of bone fusion by a radiographic assessment, a biomechanical test, microcomputed tomography, and histological evaluations demonstrated that there were no significant differences between the PRP sponge and the autograft groups regarding the osteogenic effect. Subsequent examinations revealed that no significant differences existed between the PRP sponge and the autograft groups in either biomechanical stiffness or the bone volume over time; whereas the radiographic and histological composition underwent similar changes in the fusion process. These results indicate that the PRP sponge could, therefore, be potentially useful as an attractive and less invasive method for bone fusion.

Three-dimensional morphology and kinematics of the craniovertebral junction in rheumatoid arthritis.

STUDY DESIGN: A case-series study. OBJECTIVES: To measure the 3-dimensional (3D) morphology and kinematics of the craniovertebral junction (CVJ) using a 3D computed tomography (CT) model; to reveal abnormal patterns and the relationships between pathology and kinematics. SUMMARY OF BACKGROUND DATA: Evaluations using radiography, 2-dimensional (2D) CT and magnetic resonance imaging have limitations because of the complex 3D structure of the CVJ. METHODS: Twenty-four rheumatoid arthritis patients (21 females, 3 males) with cervical involvement underwent CT scanning of the cervical spine from the basilar process of the occipital bone to the first thoracic vertebra in neutral and flexed positions. The 3D morphology of the occipital condyle, atlas, and axis were classified based on the type of deformity observed. Periodontoid lesions (continuous bony lesions between the atlas and the odontoid process) were also noted. The 3D kinematics in the atlanto-occipital and atlantoaxial joints were evaluated using the volume merge method. RESULTS: Deformities in the atlanto-occipital joints appeared more frequently than those in the atlantoaxial joints. The most common instability pattern was flexural rotation during flexion at the CVJ. The direction of translational motions during flexion was posterior in the atlanto-occipital joint and anterior and caudal in the atlantoaxial joint. CONCLUSION: The results suggest that bilateral occipital condyle deformation, unilateral and bilateral mass collapse, and periodontoid lesions may affect flexion/extension rotational instability in the atlantoaxial joint. In addition, unilateral occipital condyle deformation and atlantoaxial joint stability may affect sagittal translational instability to the posterior side in the atlanto-occipital joint. The noninvasive 3D CT imaging technique employed here would be useful for predicting the prognosis of patients with rheumatoid deformities at the CVJ.

The clinical usefulness of preoperative dynamic MRI to select decompression levels for cervical spondylotic myelopathy.

The study subjects included 54 patients with cervical spondylotic myelopathy who underwent a selective laminoplasty. The patients were divided into three groups according to the number of decompressed levels: two levels, three levels and four or five levels. The number of cord compressions at every intervertebral level was determined in the flexion, neutral, and extension position using a dynamic magnetic resonance imaging (MRI) scan in consideration of both static and dynamic compressions. For each group, the clinical outcomes were evaluated. Moreover, the patients were divided into two groups according to their age. Then, the appearance ratios of cord compression between the neutral and extension position were compared at each intervertebral level. The clinical outcomes were satisfactory. There were no statistical differences among the three groups, except for the age and operation time. The position of the neck influenced the number of cord compressions. The appearance ratios of cord compression, which were especially prominent at C2/3, C3/4 and C4/5, showed high scores in the aged. The preoperative dynamic MRI scan was clinically useful. In the aged, attention should be given to C2/3, C3/4 and C4/5.

Characterization of in vivo effects of platelet-rich plasma and biodegradable gelatin hydrogel microspheres on degenerated intervertebral discs.

We have previously shown that administration of platelet-rich plasma-impregnated gelatin hydrogel microspheres (PRP-GHMs) into a degenerated intervertebral disc (IVD) markedly suppresses progression of IVD degeneration. In the current study, we characterized the in vivo effects of PRP-GHM treatment in a degenerated IVD model in rabbit. On magnetic resonance images, the IVD height was significantly greater after treatment with PRP-GHMs compared with phosphate-buffered saline-impregnated GHMs, PRP without GHMs, and needle puncture only. Water content was also preserved in PRP-GHM-treated IVDs. Consistent with this observation, the mRNA expression of proteoglycan core protein and type II collagen was significantly higher after PRP-GHM treatment compared with other treatment groups. No proliferating cells were found in the nucleus pulposus and inner annulus fibrosus in any groups, but the number of apoptotic cells in the nucleus pulposus after PRP-GHM treatment was significantly lower than that after other treatments. These results provide an improved understanding of the therapeutic effects of PRP-GHM treatment of degenerated IVDs.

Muscle-preserving interlaminar decompression for the lumbar spine: a minimally invasive new procedure for lumbar spinal canal stenosis.

STUDY DESIGN: Outcomes of muscle-preserving interlaminar decompression (MILD) for the lumbar spine are reported. OBJECTIVE: To verify the clinical findings of lumbar MILD. SUMMARY OF BACKGROUND DATA: A preliminary short-term follow-up study of lumbar MILD demonstrated satisfactory neural recovery and reduced invasiveness. METHODS.: The initial 105 consecutive patients with lumbar spinal canal stenosis were included in this study. A total of 210 intervertebral levels were decompressed. There were 48 women and 57 men, and the mean patient age was 68.8 years. The postoperative follow-up period ranged from 8 to 44 months (mean 21.3 months). Eighty-one patients showed cauda equina claudication, and 75 patients complained of radicular pain. Preoperative imaging studies demonstrated that all patients had moderate-to-severe spinal canal stenosis, 75 patients had degenerative spinal canal stenosis, and the remaining 30 had degenerative spondylolisthesis. Pre- and postoperative Japanese Orthopedic Association scores, intraoperative blood loss, surgical complications, and postoperative ambulation were recorded. RESULTS.: One hundred five patients underwent lumbar MILD procedure for 210 interspinous levels, 42 patients for 2 levels, 37 patients for 1 level, 17 for 3 levels, 7 for 4 levels, and 2 for 5 levels. Cerebrospinal fluid leakage due to dural tear occurred in 2 patients. Expansion of the operative field was not necessary to repair the dura mater. The mean operation time was 104.9 minutes per level, and mean intraoperative blood loss was 29.4 g per level. Neurologic improvement was demonstrated in all patients. The mean recovery rate calculated with pre- and postoperative Japanese Orthopedic Association scores was 64.9%. Patients started to stand or walk an average of 2.5 days after surgery. None of the patients presented with wound infection. There was no neurologic complication in this series. CONCLUSION: In MILD for the lumbar spine, damage to the posterior stabilizing structures such as the intervertebral facet joints, paravertebral muscles, thoracolumbar fascia, supra- and interspinous ligaments, can be minimized, while preserving the function of the spinous processes as lever arms for lumbar extension.

Evaluation of lateral instability of the atlanto-axial joint in rheumatoid arthritis using dynamic open-mouth view radiographs.

Upper cervical involvement is common in patients with rheumatoid arthritis (RA). Anterior atlanto-axial subluxation (aAAS) sometimes occurs at an early stage of the disease. We hypothesized that not only antero-posterior instability but lateral instability may occur with atlanto-axial involvement in RA. To prove this hypothesis, we evaluated the lateral instability of the atlanto-axial joint in RA, using dynamic open-mouth view radiographs. Thirty RA patients and a control group of 22 non-RA outpatients were enrolled in this study. The patients underwent lateral view radiographs of the cervical spine during flexion and extension, and antero-posterior (AP) open-mouth views during maximum right and left bending of the neck. The anterior atlanto-dental interval (AADI) was measured to evaluate antero-posterior instability of the atlanto-axial joint, and atlanto-dental lateral shift (ADLS) was defined to evaluate dynamic lateral instability. In the RA group, AADI averaged 3.2 mm in flexion, and in eight patients, it exceeded 3 mm in flexion (aAAS). In the control group, the AADI averaged 1.0 mm in flexion. The ADLS in the RA group averaged 14.8%, and this was significantly greater than in the control group, in which it averaged 6.1%. The ADLS averaged 20.6% in the RA subgroup with aAAS, and 12.7% in the RA subgroup without aAAS. In both subgroups, the ADLS was significantly greater than that of the control group. In this study, dynamic lateral instability of the atlanto-axial joint in RA was demonstrated. The results suggest that an evaluation of the dynamic lateral instability of the atlanto-axial joint can be useful for early diagnosis of atlanto-axial lesions in RA.

Intervertebral disc regeneration using platelet-rich plasma and biodegradable gelatin hydrogel microspheres.

This study evaluated the regenerative effects of platelet-rich plasma (PRP) for the degenerated intervertebral disc (IVD) in vivo. After induction of IVD degeneration in rabbits, we prepared PRP by centrifuging blood obtained from these rabbits. These PRP were injected into the nucleus pulposus (NP) of the degenerated IVDs after impregnation into gelatin hydrogel microspheres that can immobilize PRP growth factors physiochemically and release them in a sustained manner with the degradation of the microspheres. As controls, microspheres impregnated with phosphate-buffered saline (PBS) and PRP without microspheres were similarly injected. Histologically, notable progress in IVD degeneration with time courses was observed in the PBS control, PRP-only, and sham groups. In contrast, progress was remarkably suppressed over the 8-week period in the PRP group. Moreover, in immunohistochemistry, intense immunostaining for proteoglycan in the NP and inner layer of the annulus fibrosus was observed 8 weeks after administration of PRP-impregnated microspheres. Almost all microspheres were indistinct 8 weeks after the injection, and there were no apparent side effects in this study. Our results suggest that the combined administration of PRP and gelatin hydrogel microspheres into the IVD may be a promising therapeutic modality for IVD degeneration.

Radiological grading of cervical destructive spondyloarthropathy in long-term hemodialysis patients.

On the basis of the radiological findings of dialysis patients, we made a radiological grading and analyzed the progression of destructive spondyloarthropathy (DSA) using this grading system. In this system, the radiological features of the vertebral endplates and intervertebral disc spaces were divided into 4 grades (grade 0 to grade III). Grades II and III were defined as DSA. In this study, out of the 787 dialysis patients (447 men and 340 women, mean age: 60.0 years) examined, 133 patients (16.9%) were diagnosed with DSA. During 7 years follow-up, 108 dialysis patients were examined to investigate the clinical characteristics of DSA. Fifteen of 90 non-DSA cases progressed to DSA. Six of 18 DSA cases showed grade progression. The duration required for progression of each grade was analyzed. A new classification of DSA, namely, degenerative DSA and classical DSA, was applied in this study. The degenerative DSA showed faster grade progression than the classical DSA. Therefore, great attention should be paid in the radiological follow-up of elderly patients with grade I who start dialysis at an old age.

Atlantoaxial subluxation in different intraoperative head positions in patients with rheumatoid arthritis.

BACKGROUND: Disorders of the cervical spine are often observed in patients with rheumatoid arthritis (RA). However, the best head position for RA patients with atlantoaxial subluxation in the perioperative period is unknown. This study investigated head position during general anesthesia for the patients with RA and proven atlantoaxial subluxation. METHODS: During anesthesia of patients with RA and proven atlantoaxial subluxation, the authors used fluoroscopy to obtain a lateral view of the upper cervical spine in four different positions: the mask position, the intubation position, the flat pillow position, and the protrusion position. Copies of the still fluoroscopic images were used to determine the anterior atlantodental interval, the posterior atlantodental interval, and the angle of atlas and axis (C1-C2 angle). RESULTS: The anterior atlantodental interval was significantly smaller in the protrusion position (2.3 mm) than in the flat pillow position (5.1 mm) (P < 0.05). The posterior atlantodental interval was significantly greater in the protrusion position (18.9 mm) than in the flat pillow position (16.2 mm) (P < 0.05). The C1-C2 angle was, on average, 9.3 degrees greater in the protrusion position than in the flat pillow position (P < 0.05). CONCLUSION: This study showed that the protrusion position using a flat pillow and a donut-shaped pillow during general anesthesia reduced the anterior atlantodental interval and increased the posterior atlantodental interval in RA patients with atlantoaxial subluxation. This suggests that the protrusion position, which involves support of the upper cervical spine and extension at the craniocervical junction, might be advantageous for these patients.

Clinical study of a modified Brooks technique for atlanto-axial subluxation using polyethylene tape.

Forty-four patients, 15 males and 29 females (3-71 years old; mean age, 52.9), were treated for the control of cervical instability with a modified Brooks operation using Tekmilon tape (an ultrahigh molecular weight polyethylene tape) instead of metal wires. Forty of the patients had rheumatoid arthritis (RA) with atlanto-axial subluxation (AAS), three patients had os odontoideum, and one patient had a cervical spine injury. The mean follow-up period was 8 years and 4 months. These patients were divided into three groups: 30 years or less, 31 to 60 years, and over 60 years. Atlanto-dental interval (ADI), inclination angle of atlanto-axial vertebrae (A-A angle), and bone fusion were examined on plain radiographs. The proportion of patients with reduced neck pain (Ranawat's grade 0 or grade 1) increased from 42.5% to 97.9% at the time of postoperative evaluation. Surgical complications, such as dural tear, lamina fracture, and spinal cord injury did not occur in any cases. Thirty-nine patients (88.6%) achieved bone union. ADI in the maximum flexed position improved from 10.3 to 2.5 mm. There was no statistical difference between ADI in males and females. ADI did not change in any age group both before and after surgery. A-A angle also improved from 9.4 to 24.4 degrees. The polyethylene tapes, used for internal fixation, caused no neurologic complications during sublaminar wiring and produced no MR artifacts. This modified Brooks technique using Tekmilon tape was proved to be a simple and safe treatment of AAS.

Is posterior spinal cord shifting by extensive posterior decompression clinically significant for multisegmental cervical spondylotic myelopathy?

STUDY DESIGN: Posterior cervical spinal cord shifting after selective single laminectomy associated with partial laminotomies was compared with that after bilateral open-door laminoplasty between the C3 and C7 levels in relation to the clinical results of each procedure. OBJECTIVES: To investigate the clinical significance of posterior spinal cord shifting after extensive cervical laminoplasty. SUMMARY OF BACKGROUND DATA: Current techniques used for cervical laminoplasty for multisegmental cervical spondylotic myelopathy (CSM) are consecutively performed between the C3 and C6 or C7 levels with expectation that the spinal cord will shift backward to keep it clear of anterior compression. However, the clinical significance of the posterior spinal cord shifting remains controversial, and there has been no report verifying it by comparing limited posterior decompression procedures with conventional extensive ones. METHODS: Twenty-six patients with consecutive 2- to 3-level CSM who underwent selective laminoplasty (Group A) were enrolled in the study, and among 56 CSM patients who underwent bilateral open-door laminoplasty between the C3 and C7 levels, 25 who had consecutive 2- or 3- level stenosis identified by preoperative magnetic resonance imaging were used as controls (Group B). The recovery rate was calculated using preoperative and postoperative Japanese Orthopedic Association (JOA) scores for each patient, and for each patient's magnetic resonance imaging, the postoperative cervical curvature index was obtained according to Ishihara's method and the magnitude of postoperative backward shifting of the spinal cord was measured. RESULTS: There was no significant difference between the subjects in Groups A and B with respect to the spinal curvature index, preoperative JOA scores, and recovery rate, but the magnitude of the postoperative posterior shifting of the spinal cord was greater for those in Group B than for those in Group A. There was no correlation between the recovery rate and posterior shifting of the spinal cord for each group, and no correlation was also found between the curvature index and posterior shifting of the spinal cord. CONCLUSIONS: The outcome of posterior decompression surgery for multisegmental CSM is not correlated with the magnitude of postoperative backward shifting of the spinal cord. Extensive and consecutive decompression performed in conventional cervical laminoplasties is therefore not always necessary for multisegmental CSM.

Classification of vertebral compression fractures in the osteoporotic spine.

OBJECTIVE: The purpose of this study was to clarify the relationship between initial radiographs of osteoporotic vertebral compression fractures (VCFs) and clinical results. METHODS: Of the 135 VCFs in the elderly, 73 consecutive patients (84 vertebrae) were reviewed retrospectively. All patients were treated without rigid immobilization. The subjects consisted of 15 men and 58 women. The mean age was 75.0 years with a range from 61 to 91 years. The early radiographic features were classified into five types based on lateral radiographs. Radiographic results during follow-up were evaluated according to the number of collapsed vertebrae and vacuum clefts. Clinical results were evaluated by Visual Analog Scale and activities of daily living. RESULTS: Of the five types, swelled-front-type, bow-shaped-type, and projecting-type fractures had a poor prognosis with late collapse and often showing a vacuum cleft. On the other hand, concave-type and dented-type fractures had a good prognosis and almost achieved fusion. Clinical results of 28 patients with vacuum clefts were fair at the final follow-up. Nineteen patients had little back pain, and nine patients experienced moderate back pain. Regarding the activities of daily living, four patients had difficulty walking.

A correlative electrophysiologic study of nerve fiber involvement in carpal tunnel syndrome using current perception thresholds.

OBJECTIVE: To relate clinical severity of idiopathic carpal tunnel syndrome (CTS) to current perception threshold (CPT). METHODS: Subjects were 51 patients with CTS (involving 51 hands), and 50 healthy control subjects (50 hands). Involved hands were grouped into three clinical grades (mild, moderate, severe). Using a neurometer (Neurotron, Baltimore, MD), we investigated the relationship between clinical grade and CPT abnormalities. RESULTS: In the mild CTS group, most hands showed CPT abnormalities only at 2000 Hz stimulation. The moderate group included a higher percentage of hands showing abnormalities at both 2000 and 250 Hz stimulation increased. The severe group included the highest percentage of hands with abnormal values at all frequencies tested. CONCLUSIONS: CPT showed abnormalities appear progressively from 'higher to lower' frequency stimulations relative to the increasing severity of CTS. SIGNIFICANCE: Sensory nerve fiber dysfunction apparently begins in larger fibers, extending stepwise to smaller fibers as the clinical grade of CTS progresses.

Objective evaluation of sensory function in patients with carpal tunnel syndrome using the current perception threshold.

The purpose of this study was to determine the sensitivity and specificity for the current perception threshold (CPT) test during clinical examination of idiopathic carpal tunnel syndrome (CTS). We studied 71 patients (102 hands) with CTS; 50 healthy individuals (100 hands) served as a control group. Using a neurometer, we investigated standard CPT values to obtain the sensitivity and specificity of the CPT test in the clinical examination of CTS. In the CTS group, cases that had abnormal values in the range analysis, the ratio analysis, or both were called "true-positive CPTs"; in the control group cases that had normal values in the range and ratio analyses were called "true-negative CPTs." We defined the sensitivity as the percentage of true-positive CPTs in the CTS group and the specificity as the percentage of true-negative CPTs in the control group. The sensitivity of the CPT test using both range and ratio analyses was 73%, and its specificity was 74%. Based on these results we concluded that the CPT test is a reliable quantitative sensory function test.

Electrophysiologic evaluation of lumbosacral single nerve roots using compound muscle action potentials.

Transcutaneous electrical stimulation applied to the vertebral column produces compound muscle action potentials (CMAPs) from the leg muscles. Using this method, we evaluated the efferent pathways of the lumbosacral nerve roots. The subjects were 26 healthy volunteers and 31 patients with lumbar disc herniation (LDH). CMAP recordings were obtained from the bilateral vastus medialis, tibialis anterior, extensor digitorum brevis, and abductor hallucis muscles using low-output-impedance stimulation. In normal subjects, the CMAP latency increased linearly with the distance between the stimulating electrode and the recording electrode, with little difference in latency between the left and the right sides in each subject. The CMAP amplitude was significantly lower in the patients with LDH, and the latency was also prolonged when the stimulating electrode was placed above the lesion. This technique may thus be a useful noninvasive method for assessing lumbosacral nerve root function in patients with LDH.

Evaluation of sensory function after median nerve decompression in carpal tunnel syndrome using the current perception threshold test.

The recovery level for sensory function after carpal tunnel release for the treatment of idiopathic carpal tunnel syndrome (CTS) was assessed with the current perception threshold (CPT) test. Seventeen CTS patients (21 hands) were followed, and the CPTs at the index finger of each patient was measured preoperatively and at 1, 3, and 6 months postoperatively. After carpal tunnel release, there was significant recovery of CPT at all stimulation frequencies, indicating improvement of all sensory functions including sensations of temperature, pain, touch, and vibration.