Method: EMG-triggered electrical stimulation was applied to the extensor digitorum communis (EDC) of 8 chronic hemiplegics who showed no functional changes for more than 3 months. Stimulation was started when the amplitude of processed EMG signal from the same muscle exceeded the preset threshold. The therapeutic effect was evaluated by kinesiologic and clinical methods before and after 4 weeks. Quantitative EMG from EDC, excursion of second metacarpophalangeal joint, and functional measurements were used. We also evaluated cognitive and perceptual effect on recovery of arm function.

Results: Subjects treated with EMG-triggered electrical stimulation showed significant gain in amplitude of quantitative EMG and excursion sum during maximal exertion comparing to those of pre-treatment (p＜0.05). There was also an decrease of spasticity after treatment. But functional, perceptual and cognitive outcome were not changed significantly (p＞0.05).

Conclusion: These results suggest that EMG-triggered electrical stimulation might be an effective therapeutic modality to improve motor function of the hemiplegic arm of chronic brain injured patients. (J Korean Acad Rehab Med 2003; 27: 320-328)

Objective: This study was designed to investigate the effect of forearm position on the maximal isometric voluntary supination and pronation strengths and EMG activities in the related muscles.

Method: The maximal isometric supination and pronation strengths were measured in 14 normal male subjects using Work simulator^Ⱂ at 4 different forearm rotation position. EMG activities were simultaneously measured in supinator and biceps brachii during supination and pronator quadratus and pronator teres during pronation.

Results: The maximal isometric supination strength and EMG activities of biceps brachii and supinator were significantly higher as the forearm was more pronated (p＜0.05). The maximal isometric pronation strength and EMG activi-ties of pronator teres were significantly higher as the forearm was more supinated (p＜0.05). The maximal isometric supination and pronation strengths were higher in the dominant side than those of the nondominant side (p＜0.05) and EMG activities of pronator teres and supinator were higher in the dominant side than in the nondominant side (p＜0.05).

Conclusion: The supination and pronation strengths and EMG activities of related muscles were influenced by the forearm rotation position. Therefore the forearm position should be considered in evaluation of upper limb strength and function, and rehabilitation of upper extremity for improving strength and minimizing the overuse of supination and pronation. (J Korean Acad Rehab Med 2002; 26: 432-438)

Objective: The purpose of this study was to observe the characteristics of the clinical improvement and the electrodiagnostic study in non-traumatic facial nerve palsy.

Method: The clinical observation and the electrodiagnostic study were done in 57 of 266 patients who were treated at the Kyunghee Medical Center from December 2000 to July 2001. The initial study was done at 2 weeks from the onset time, and the follow-up study was done at 3 months later. The blink reflex, nerve conduction study and needle EMG were done, and made a statistical comparison between the initial and follow-up study.

Results: The clinical improvement and the change of the electrodiagnostic study between the initial and follow-up study were remarkable in the patients with expected to be good and fair prognosis. In the electrodiagnosis study, there were no statistical correlations on the % degeneration of the CMAP amplitude in the patients with expected to be poor prognosis.

Conclusion: Although the ideal electrodiagnostic study does not yet exist, the best method of evaluating the facial nerve is side-to-side evoked amplitude comparison, and not only the initial study but also the follow-up, this method would be very useful. (J Korean Acad Rehab Med 2002; 26: 420-425)

Objective: To investigate the clinical feature and quantitative electromyographic (QEMG) findings in the patients with post-polio syndrome (PPS).

Method: Eleven patients who had clinical evidences of antecedent poliomyelitis were evaluated with standardized clinical history, physical examination and QEMG study. If a patient had fulfilled provisional criteria for PPS, he was regarded as PPS and six patients had fulfilled the criteria. Other patients were treated as control group with stable poliomyelitis. Manual muscle testing and needle EMG study including quantitative motor unit analysis was performed at the tibialis anterior and vastus medialis muscles. The existence of abnormal spontaneous activity and parameters of quantitative motor unit analysis, mean duration and amplitude of motor unit action potentials (MUAPs), were compared between PPS and control groups. The correlation between the muscle strength and parameters of QEMG was investigated.

Results: Abnormal spontaneous activities were noted in 4 out of 11 patients (36.4%) and three of these 4 patients were PPS. Mean duration and amplitude of MUAPs of tibialis anterior and vastus medialis muscles were not different significantly between the PPS and stable poliomyelitis group (p＞0.05). The parameters of MUAPs were poorly correlated with muscle strength.

Conclusion: Distribution of abnormal spontaneous activities and parameters of QEMG study were not different in PPS and stable poliomyelitis patients. QEMG study may not have additional benefit in differentiating PPS from stable poliomyelitis.

Objective: To evaluate working condition in way of measuring working posture and muscle tension using the desktop personal computer and notebook personal computer having different screen height.

Method: Seventeen healthy men performed wordprocessing task in three workstation: desktop PC on the conventional computer table (DPC (on)); desktop PC under the 'inside' type computer table (DPC (under)); notebook PC on the table (NPC). The viewing distance and angle, head and neck angle, thoracic bending and trunk inclination were measured. Muscle tension of right posterior neck muscle, upper trapezius, sternocleidomastoid (SCM), and upper back muscle was also measured by integrated electromyogram (IEMG).

Results: 1) The viewing distance was the longest in DPC (under). 2) The lower the screen height, the more downward viewing angle and more flexed position in upper neck. 3) The posterior neck muscle tension was the lowest in DPC (on). 4) Stooped position was most frequently seen in NPC and the highest tension of posterior neck muscle and upper back muscle was shown in NPC. 5) In relation between postural analysis and muscle tension, muscle tension decreased with increasing backward reclining position, and the neck and thorax became more erect with increasing in viewing distance.

Conclusion: These results suggest that the stooped posture was worst and most frequently seen in NPC. If neck flexion is avoided, DPC (under) position could lessen the visual and musculoskeletal problem. More Ergonomical study would be needed about working posture using computer.

This study was designed to evaluate the usefulness of pudendal nerve block in the dorsal approach under EMG monitoring. The patient is placed in the prone position. The location of pudendal nerve is identified using the both ischial tuberosities and greater trochanter. We have performed the pudenal nerve block with 5% phenol solution, under the EMG monitoring. The patient was able to void with percussion method. There has been no impairment in urinary continence.

We experienced an excellent effect of bilateral pudendal nerve block in the dorsal approach, under EMG montoring, using 5% phenol solution in detrusor sphincter dyssynergia of neurogenic bladder.

Objective: Inappropriate neural control of the quadriceps femoris muscle group has been implicated in patellofemoral pain syndrome (PFPS) and the methods of biomechanical assessment of PFPS has been developed recently. The aims of the present investigation were to evaluate the effects of therapeutic exercise in the alleviation of PFPS and to develope objective clinical test for PFPS.

Method: We investigated the onset time of the isometric contraction of vastus medialis oblique muscle (VMO) and the vastus lateralis muscle (VL) under four different conditions: knee flexion and extension in weight bearing (standing) and non-weight bearing (sitting on chair) situations. For each condition, onset times of EMG activities and onset times for VMO and VL were determined from five trials of isometric contraction. In addition, we compared knee flexor and extensor torques in control group and subjects with PFPS. To evaluate the effects of the exercise we compared the onset time difference (onset time of VL-onset time of VM) and quadriceps muscle torque at pre- and post- exercise in PFPS groups.

Results: In PFPS group, onset time of VMO during knee extension was significantly longer than the onset time of VL and the knee extensor torque was considerably weaker in comparison with normal group. Although onset time difference was not changed after exercise program, there were significant increase in knee extensor torque in subjects with PFPS.

Conclusion: The role of exercise in the rehabilitation of quadriceps functions is to reduce the pain, to strengthen the knee extensor, and further accurate diagnostic tools and methods for the result of therapeutic exercise in PFPS are needed.

Objective: The aim of this study was to develop objective evaluation method which reflect the velocity dependent increase of stretch reflex in spasticity using the pendulum test and dynamic electromyography.

Method: Kinematic analysis for knee angle and angular velocity measurement, and dynamic electromyography were performed simultaneously during pendulum movement of spastic lower extremity in supine position for nineteen spastic hemiplegia patients and ten normal control subjects. Angular relaxation index (ARI), Maximum angular velocity (MAV), Angular threshold (AT) and Angular velocity threshold (AVT) were used for the evaluation of spsticity.

Results: 1) ARI was 1.64⁑0.04 in normal, 1.28⁑0.14 in modified Ashworth scale (MAS) I, 1.18⁑0.16 in MAS II, 1.02⁑0.13 in MAS III, 2) MAV was 325.0⁑29.4 in normal, 301.7⁑37.8 in MAS I, 269.2⁑29.7 in MAS II, 232.4⁑28.2 in MAS III, 3) In normal subjects EMG activity did not occur, whereas in spastic hemiplegic patient a stretch reflex appears in thigh muscle. AT and AVT were 57.39⁑4.45, 256.24⁑14.07 in MAS I, 38.59⁑4.26, 184.45⁑12.7 in MAS II, 19.13⁑7.13, 136.06⁑12.88 in MAS III, respectively, 4) Correlation coefficients of the ARI (r=⁣0.786), AT (r=⁣0.960), AVT (r=⁣0.949) showed significantly negative correlations with the MAS.

Conclusion: 1) AT and AVT are more sensitive parameters than ARI for documenting spasticity in hemiplegic patients. 2) An evaluation of spasticity using pendulum test and dynamic electromyography would provide consistent results with little error and would not be influenced by the change of examiner or environment. Thus we can get very reliable results using this method.

Objective: The purpose of this study is to evaluate the searching stimulus intensity at each pedicle and to identify the most vulnerable roots in transpedicular screw fixation of lumbosacral spine.

Method: Thirty-two patients with unstable lumbosacral vertebra were treated with intrapedicular screw fixation. Small holes were made by an air drill on the pedicle from L2 to S1 for screw fixation. Constant current stimulation pulses(0.2 msec duration) were delivered through a ball-tipped nasopharyngeal probe used to palpate the walls of each pedicle, and observation was made of electromyogram(EMG) evoked lower extremity muscles. The probes were placed in each pedicular wall manually, and evaluated for searching stimulus intensity, the current necessary to evoked EMG.

Results: The cases that the searching stimulus intensity was above 5 mA were 99 cases(97%), above 10 mA were 61 cases(59.8%) and below 5 mA were 3 cases(2.9%). The vastus medialis muscle is most sensitive in L2(100%) and L3(78.9%), tibialis anterior is in L4(81.8%), Peroneus longus is in L5(50.5%) and gastrocnemius is in S1(87.5%).

Conclusion: We can regard the searching stimulus intensity as 5 mA and the root located at Infero-medial side of pedicle is most vulnerable in transpedicular screw fixation. Furthermore, stimulus-evoked EMG monitoring during transpedicular spine instrumentation is helpful to avoid neural tissue injury.

The purpose of this study was to detect the motor neuron losses in progressive neurologic diseases before the weakness or wasting of muscles became apparent using the motor unit number estimation technique. Method for estimating the number of motor units based on electrical stimulation of motor nerves was introduced first by McComas. The author describe the method which was applied to the median nerve innervated thenar muscles in healthy subjects. This study showed that the results of motor unit number estimation were 196.9⁑56.2 in male, 187.6⁑79.2 in female, and the most influencing factor for the number of motor unit was the size of amplitude or area of compound muscle action potential.

The reference values of motor unit action potentials(MUAP) of first dorsal interosseous and tibialis anterior muscles were measured in 50 healthy subjects. The MUAPs were recorded with a concentric needle electrode and extracted with a decomposition method. Sixty six patients with neuropathy were also studied in the same way with a count of outliers and measurement of mean values.

The mean values of amplitude, area, duration and thickness were 667.74±204.34 ՌV, 992.26±253.18 ՌVms, 9.75±1.95 ms and 1.49±0.26 ms, respectively in the first dorsal interosseous muscles, and 612.88±140.13 ՌV, 1172.84±199.21 ՌVms, 11.41±2.48 ms and 1.93±0.34 ms respectively in the tibialis anterior muscles. There was no significant difference in age and gender of normal subjects. The amplitude was the most sensitive parameter to detect abnormality in a count of outliers and measurement of mean values. The outliers count in duration showed a higher sensitivity than the measurement of mean values(p＜0.05), but not in amplitude, area or thickness.

Based on the results of this study, the count of outliers was more sensitive than the measurement of mean values in the diagnosis of patients with neuropathy. Further more, less numbers of MUAPs were needed for the evaluation of the outliers count. Through this method we could save the evaluation time and the patients felt more comfortable.

Palatal tremor is a rare disorder characterized by involuntary rhythmic movements of the soft palate. Palatal tremor is devided into symptomatic palatal tremor(SPT) and essential palatal tremor(EPT) on the basis of clinical features. SPT is associated with brain stem or cerebellar disease, whereas the EPT has no known etiology. Reverberant neural activity in the region of the brain stem or cerebellum within the Guillain-Mollaret triangle is believed to underlie SPT. We present a case of SPT associated with cerebellar lesion. Electromyographic recording from the levator veli palatini muscle and voice spectrogram analysis showed abnormal bursting activity time locked to the palatal movements. Botulinum toxin was injected into the levator veli palatini muscle to reduce the voice tremor. The pathology and management of this condition is briefly discussed.

The evaluation of peripheral nerve disorders has traditionally relied on clinical history, physical examination and electrodiagnostic studies. The electrodiagnostic study is currently the most popular procedure to analyse the nerve lesion, but it is painful and its result is operator dependent. The purpose of this study is to evaluate the significance of MRI signal change of denervated muscle in peripheral nerve as an adjuvant study of electrodiagnostic study. After the compression of sciatic nerves in 20 rabbits and severance of scitic nerve in 10 rabbits, the signal change of both T1WI(TR; 450 msec, TE; 15 msec) and T2WI(TR; 3,000 msec TE; 90 msec) of calf muscles were compared with EMG findings of the same muscles. Signal intensity ratio(SIR) of calf muscles was measured and compaired with the grade of abnormal spontaneous activity in the same muscles in needle EMG study. Serial studies were done on 4th day, 1 week, 2 weeks, 3 weeks, 4 weeks, 6 weeks, 8 weeks, 10 weeks after sciatic nerve injury. Among 25 rabbits showing abnormal spontaneous activity in needle EMG, the signal intensity of both T1WI and T2WI was increased in 13 rabbits. The signal intensity began to increase at 1 week in 10 rabbits and 2 weeks in 3 rabbits following nerve injury which was about 1 week later than appearance of abnormal spontaneous activity in needle EMG study. There were no signal intensity increase in rabbits which showed no abnormal spontaneous activity in needle EMG study. The signal intensity ratio and grade of abnormal spontaneous activity had a good correlation(Spearman's correlation coefficiency : 0.635). The signal intensity of 3 rabbits which showed regeneration evidence in needle EMG study returned to normal. These findings suggest that MRI study of denervated muscle can be used as an evaluation method for severe peripheral nerve injury, howeverits value is doubtful in mild peripheral nerve injury.

In this study, we measured the intervertebral foramina on the plain radiographs of cervical spine of fifty three patients who were over forty-year-old, and with single or multiple unilateral cervical radiculopathies on EMG. In order to determine if the foraminal stenosis on plain radiographs can determine the presense of radiculopathy, four parameters such as vertical diameter, mid-transverse diameter, inferior transverse diameter, and area were measured by a digital caliberator(CD-15C, Mitutoyo, Japan) and an image analyzer(VIDAS 2.0, Kontron, Germany) in 194 foramina of both sides(affected and unaffected groups). Another 80 foramina were also measured as control group in ten age-matched patients who did not show any abnormality on EMG.

In control group, C4/5 intervertebral foramen showed maximal values of the parameters among foramina, with vertical diameter of 10.55⁑0.35 mm(mean⁑S.D.), mid-transverse diameter of 6.22⁑0.33 mm, inferior transverse diameter of 5.09⁑0.19 mm and area of 0.77⁑0.05 cm². The minimal values were noted in C6/7 foramen except those of the vertical diameter which were noted in C4/5 foramen. The mid-transverse diameter and area of C7/T1 intervertebral foramen of affected group were significantly smaller than those of control and unaffected groups(p＜0.05). The other values in affected group were also smaller among the groups but they did not reach statistical significance.

In conclusion, the mid-transverse diameter and area of intervertebral foramen on plain cervical radiographs are somewhat useful to determine the encroachment of nerve root within the intervertebral foramen, especially in the lower cervical spine, in patients with cervical radiculopathy.

Since the myofascial trigger point(MFTrP) has been described fifty years ago, its underlying pathophysiology has been remained unclear. The diagnosis also depends on the characteristic pain, tenderness and physical findings, which is very subjective. In recent years, some physicians investigated the objective findings of MFTrP, using the pressure algo meter and thermography. We investigated the electromyographic findings of MFTrP to evaluate the clinical usefulness of local twitch response(LTR) and sympathetic skin response(SSR), and to evaluate the electrophysiologic characteristics of MFTrP.

21 patients, diagnosed as myofascial trigger point syndrome on upper trapezius and so on, were evaluated for the triggering pain with visual analog scale(VAS), pressure threshold(THpr) using pressure algometer(Dolorimeter), LTR with concentric needle electrode and SSR on the palm. There was a significant negative correlation between VAS and THpr, but no significant correlation with electromyographic findings of LTR. Thus LTR could support the existence of MFTrP electrod iagnostically, but, could not explain the clinically correlated severity of MFTrP. There were only 3 patients showing abnormal SSR, who were all complaining the sympathetic symptoms on the affected arm with reffered pain. Even though referred pain to arm and hand existed, SSR was normal because suggested autonomic dysfunction of MFTrP is localized mechanism.

Among the 13 patients underwent the trigger point block, 8 patients who showed no residual LTR immediate after MFTrP block, had a great symptomatic improvement of MFTrP in a week, but 5 patients who showed the residual LTR did not. Regardless of complaint of pain and soreness immediate after block, loss of LTR would be predicted as a good treatment result.

In some cases, spontaneous EMG activity exist within the 3-4mm sized focus of MFTrP, although the taut band of MFTrP is 3-4cm length and depth. But this focus of MFTrP is a electrophysiologic changes within a muscle, not a structural changes seen by ultrasonography.