Electromyography and clinical neurophysiology最新文献

The purpose of this study was to compare the electrical activity of the knee stabilizers, in patients with ACL (anterior cruciate ligament) reconstructed and uninjured individuals during different balance board stimuli. Eleven post-surgery individuals and eleven uninjured controls participated in the study. The muscular activity of the vastus medialis obliquus, vastus lateralis, semitendinosus, biceps femoris and gastrocnemius medial were analyzed by surface electromyography during the execution of six different balance board activities. All electromyographic data were reported as percentage of RMS mean values obtained in maximal voluntary isometric contractions (MVIC) for each muscle. When comparing the individuals with ACL reconstructed and uninjured controls, minor electromyographic activity was observed (MVIC %) for all the muscles in the surgery group (P < 0.05), however, when comparing each exercise between the groups, a statistically significant difference for vastus lateralis was demonstrated in the floor exercise (P = 0.02) and for gastrocnemius on the round board (P = 0.04). Individuals ACL reconstructed presented a decrease in muscular activity during different balance board stimuli, which suggests that compensatory alterations after ACL may still exist even after a surgery to repair an ACL rupture.

Purpose: Currently, to record underwater surface electromyography (EMG), electrodes are covered with waterproof tape. For short-term measurement, waterproof tape prevents electrical leakage. However, during long-term measurement, water or sweat can contact the electrodes, changing the measurement conditions and gradually affecting the EMG data. The purpose of present study was to devise a novel method for prolonged underwater EMG recording, which estimate dry-land EMG from underwater EMG recorded by non-waterproofed electrodes using system identification techniques.

Method: One healthy male participated in this study. System identification was used to convert underwater EMG signals to the estimated dry-land signals. Transfer functions were derived using two pairs of surface recording electrodes on the same muscle in parallel. System input was the EMG recorded using non-waterproofed electrodes; the output was the signal recorded underwater using waterproofed electrodes (supposed to be the same as dry-land signals). To examine the validity of the present method, three experiments were conducted.

Result: There was a high positive correlation between the estimated dry-land EMG based on the non-waterproofed electrodes and the EMG obtained using waterproofed electrodes. To test the validity of long-term recording using the novel method, the estimated dry-land EMG signals were measured during 30 minutes of underwater stepping and were stable.

Conclusion: The novel method using non-waterproofed electrodes with system identification techniques eliminated the effect of changes in measurement conditions and appears effective for long-term, underwater surface EMG recording.

This study aimed to compare the torque, torque ratio (Hamstrings: Quadriceps - H:Q), electromyographic (EMG) activity and EMG ratio (knee flexors: knee extensors EMG) in soccer players (SG, N = 10) and active subjects (AG, N = 10). Subjects performed three maximal voluntary isometric knee extensions and flexions at 45 degrees and 90 degrees to determine the peak torque and EMG activity. Torque and EMG activity of the knee flexor (biceps femoris [BF] and semitendinosus [ST]) were divided by the torque and EMG activity of the knee extensor (vastuls lateralis [VL] and rectus femoris [RF]) to calculate torque ratios (H:Q) and EMG ratios (BF:VL, BF:RF, ST:VL, ST:RF). The flexion torque was significantly higher for SG (p < 0.05) in 45 degrees and 90 degrees. EMG activity for SG was significantly higher in agonist contractions for VL, RF and ST and significantly lower in antagonist contractions for RF and ST when compared to AG. Torque and EMG ratios were similar between groups and there were good correlations between torque ratio and BF:VL ratio (r = 0.71, p = 0.02) and BF:RF ratio (r = 0.81, p = 0.004) at 45. The EMG results could overestimate the joint balance calculated using torque ratios. Differences in recruitment pattern between soccer players and non-athletes can be related to the training routines and the EMG ratios presents applicable in trained populations.

Objective: Ankle inversion injuries represent the most common trauma sustained by athletes. Muscle fatigue from activity may contribute to a delay in the response of the ankle proprioceptors and dynamic restraints during unexpected inversion. The purpose of this investigation was to determine if the electromechanical delay (EMD) of the peroneus longus is influenced by a task failure exercise.

Subjects: Sixteen subjects (age 20 +/- 1.1 y; mass 71.6 +/- 12.5 kg; height 173.0 +/- 8.7 cm; 9 male, 1 female) with no lower extremity injuries reported for data collection.

Measurements: Data were collected from each subject's dominant leg using surface electromyography (EMG). Electrodes were applied over the peroneus longus (PL) using a standard protocol. A stimulating electrode was applied to the common peroneal nerve. Subjects were placed in a monopedal stance on a force platform. A low amplitude, short duration stimulus was applied to the common peroneal nerve. The EMG was used to determine timing of the M wave and the force platform was used to determine the onset of foot pronation. Once 6 trials were recorded, subjects completed 2 sets of an isotonic activity that isolated the peroneals. The task was completed to failure for each set. Immediately following the task failure exercise, subjects returned to the force platform for 6 additional trials recorded as before. Analysis of data was performed by determining the onset of the M wave as the beginning of positive EMG activity following the end of the imposed stimulus response. This point was superimposed on the force platform curve and the point at which a 10 N.m force change occurred was used to calculate the EMD (time difference between the force platform indicator and the M wave indicator).

Results: Average EMD prior to the task failure exercise was 13.35 +/- 3.47 ms. Following the task failure exercise, the average EMD was 12.67 +/- 3.86 ms. A paired samples t test revealed no significant differences with regard to EMD between pre- and post-task failure exercise for the PL (p = 0.448).

Conclusion: We concluded that the task failure exercise did not affect the electromechanical delay of the PL.

The purpose of this study was to examine the patterns of responses for mechanomyographic (MMG) amplitude versus isometric torque in different frequency bands for the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) muscles. Eleven men (mean +/- SD age = 20.1 +/- 1.1 yrs) performed submaximal to maximal isometric step muscle actions of the dominant leg extensors from 10% to 100% of the maximum voluntary contraction (MVC). During each muscle action, three separate surface mechanomyographic (MMG) signals were detected from the VL, RF and VM. Each MMG signal was decomposed into 9 different frequency bands (5-15, 15-25, 25-35, 35-45, 45-55, 55-65, 65-75, 75-85, and 85-95 Hz), and the root-mean-square amplitude of the signal in each frequency band was calculated. The results showed that for the VL and RF muscles, MMG amplitude plateaued from 80-100% MVC in the 15-25 and 25-35 Hz frequency bands. For the VM, however, the plateau in MMG amplitude from 80-100% MVC occurred in the 5-15 and 15-25 Hz bands. These findings indicated that there were both muscle- and frequency-specific discrepancies in the MMG amplitude versus isometric torque relationship that could be due to differences in muscle architecture and/or fiber type composition.

Objective: To evaluate the diagnostic value of ultrasonography in patients with electrophysiologically confirmed carpal tunnel syndrome.

Design: A prospective ultrasonographic study of 70 wrists with electrophysiologically confirmed carpal tunnel syndrome and of 80 normal wrists. Receiver-operating-characteristics curves for the ultrasonographic measurements of median nerve were plotted to identify the most optimal cutoff values.

Results: The ultrasonographic measurements of median nerves were found to be increased significantly in patients with carpal tunnel syndrome when compared with controls, particularly in terms of cross-sectional area (P <0.001). According to receiver-operating-characteristics curve results, the most optimal cutoff value for the cross-sectional area of the median nerve was obtained at the level of middle carpal tunnel, which was 9.3 mm2, with a sensitivity of 80% and specificity of 77.5%.

Conclusion: Ultrasonographic examination of the median nerve seems to be a promising method in the diagnosis of carpal tunnel syndrome, evaluating the morphologic changes of the median nerve in patients with clinical signs and symptoms. Further studies with wider series are needed to confirm our preliminary results.

Examination of the orbicularis oculi reflex (OOR) has been used for many years in the diagnostic algorithm of multiple sclerosis (MS) in a few aspects: to define existence and specific location of the lesions and to follow-up dynamic changes in pontine and supranuclear structures of the CNS. Correlation between MRI and electrophysiological data from OOR has not been widely studied in the patients with MS. The aim of the present study is to assess the changes of OOR in patients with MS and their relation to clinical and MRI brainstem findings. Forty-six patients were examined by complex EMG, MRI, and clinical protocol, aged from 21 to 55. Two groups were formed: first group of 40 patients with relapsing remitting MS (RRMS) and second group of six patients with secondary progressive (SPMS). About one third of the patients had neither clinical nor OOR or MRI brainstem abnormal changes. In 22.5% of the cases a clinical, EMG and MRI correlation, showing brainstem lesions, was found We observed different changes in OOR responses in about three fourths of all patients, respectively in 75% of patients with RRMS and in 83.3% of those with SPMS. OOR examination gives us evidence of additional brain lesions in 15% of our patients, whose MRI and clinical findings were unremarkable. Prolonged latency of the first and second component of OOR, additionally with asymmetry or lack of response, was more commonly related to the clinical manifestation.

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy. The aim of the present study was to determine the relationship between patients reported symptoms and clinical tests with electrodiagnostic findings. Three hundred and nine patients with a mean age of 48.35 +/- 12.26 (range = 19-81 years) participated. Patients were assessed clinically and electrophysiologically. The main outcome measures were CTS related symptoms of pain and paraesthesia, Tinel sign, Phalen's test, distal sensory latency, and distal motor latency. The symptoms of presence of pain and diurnal paraesthesia showed a statistical relationship with the distal sensory latency. No relationship was found between the Tinel sign and either the distal sensory latency or the distal motor latency. Furtheremore, no relationship could be shown between Phalen 60 s, Phalen 45 s and distal sensory and motor latency. The Phalen 30 s had a significant relationship with both sensory and motor distal latency. The findings of this study indicate that both CTS related symptoms of pain, diurnal paraesthesia, and Phalen 30 s are associated with electrodiagnostic tests.

Purpose: Quadriceps weakness following anterior cruciate ligament reconstruction (ACLR) is prevalent despite intensive rehabilitation. Diminished neuromuscular excitability is one potential factor that may limit muscular recovery following injury or surgery. The H-reflex provides a measure of alpha motorneuron (neuromuscular) excitability in the sensory-motor pathway of the respective muscle and nerve. To date the vastus medialis (VM) and soleus (SOL) H-reflexes have been examined primarily in control subjects with induced knee joint effusion. This prospective, randomized clinical trial evaluated the affect of ACLR, utilizing hamsting (HS) or bone-patellar tendon-bone (BTB) autograft, on VM and SOL H-reflex latency and amplitude in twenty subjects.

Methods: Preoperatively bilateral VM and SOL H-reflex tests were conducted. VM and SOL H-reflexes were subsequently conducted on the involved lower extremity at 1 and 3 months post surgery. At each test session subjects completed visual analog scales and knee girth was measured.

Results: The VM H-reflex amplitude increased in the HS group at 3 months compared to 1-month post surgery (p<.05). Significant changes over time were also noted in the visual analog pain and functional scales and the mid-patella girth.

Conclusions: The increased VM H-reflex amplitude at 3 months following HS autograft ACLR demonstrates an increase in VM neuromuscular excitability. Increased VM neuromuscular excitability was not evident in patients following BTB reconstruction. The increased neuromuscular excitability, observed only in the HS group, warrants consideration when selecting graft type for patients with extensive preoperative quadriceps dysfunction.

Background: Previous studies have shown that enhancement of blink reflex (BR) excitability exists in various movement disorders, notably those involving the cranio-cervical area. In this study the BR recovery curve of the late component (R2) and R2 area was evaluated to determine what changes occur under different conditions and the significance of these changes.

Methods: The recovery curve of the blink reflex (BR) was studied in patients with hemifacial spasm (HFS), post-facial syndrome (PFS), blepharospasm (BS), segmental cranio-cervical dystonia (SD), cervical dystonia without BS (CD), and healthy control subjects. Following initial comparisons between six groups where the increased excitability observed in BS, SD and CD were assumed to be of central origin and that of HFS and PFS of peripheral origin; two additional groups were established and compared in terms of recovery times.

Results: Recovery values of 200, 400, 600, 800, 1000 ms and grades for all groups were significantly different when compared to the control group. The most significant difference observed between the groups was at 200 msn and the smallest at 800 msn interstimuli intervals. The subjects within the group referred to as the 'central origined group' recovered faster than those in the 'peripherally origined group' although no statistical difference was found between the two groups at stimulus interval.

Conclusion: Our findings suggest that the excitability changes observed among the groups can be attributed to a number of factors. Although the nature and anatomical substrate of the primary pathology involving the reflex cycle leads - to some extent - to differently enhanced excitability patterns, such differences were not considered statistically significant.