Search PubMed⌕ Search

Biomedical subjects

C Z Hong

Publications and source records attributed to C Z Hong.

At least 19 recordsLinked to original sources
PubMed2001

Inhibitory effect of dry needling on the spontaneous electrical activity recorded from myofascial trigger spots of rabbit skeletal muscle.

OBJECTIVE: Dry needling of myofascial trigger points can relieve myofascial pain if local twitch responses are elicited during needling. Spontaneous electrical activity (SEA) recorded from an active locus in a myofascial trigger point region has been used to assess the myofascial trigger point sensitivity. This study was to investigate the effect of dry needling on SEA. DESIGN: Nine adult New Zealand rabbits were studied. Dry needling with rapid insertion into multiple sites within the myofascial trigger spot region was performed to the biceps femoris muscle to elicit sufficient local twitch responses. Very slow needle insertion with minimal local twitch response elicitation was conducted to the other biceps femoris muscle for the control study. SEA was recorded from 15 different active loci of the myofascial trigger spot before and immediately after treatment for both sides. The raw data of 1-sec SEA were rectified and integrated to calculate the average integrated value of SEA. RESULTS: Seven of nine rabbits demonstrated significantly lower normalized average integrated value of SEA in the treatment side compared with the control side (P < 0.05). The results of two-way analysis of variance show that the mean of the normalized average integrated value of SEA in the treatment group (0.565 +/- 0.113) is significantly (P < 0.05) lower than that of the control (0.983 +/- 0.121). CONCLUSIONS: Dry needling of the myofascial trigger spot is effective in diminishing SEA if local twitch responses are elicited. The local twitch response elicitation, other than trauma effects of needling, seems to be the primary inhibitory factor on SEA during dry needling.

Animals↗
PubMed2000

Interexaminer reliability of the palpation of trigger points in the trunk and lower limb muscles.

OBJECTIVES: To determine the interexaminer reliability of palpation of three characteristics of trigger points (taut band, local twitch response, and referred pain) in patients with subacute low back pain, to determine whether training in palpation would improve reliability, and whether there was a difference between the physiatric and chiropractic physicians. DESIGN: Reliability study. SETTING: Whittier Health Campus, Los Angeles College of Chiropractic. PARTICIPANTS: Twenty-six nonsymptomatic individuals and 26 individuals with subacute low back pain. INTERVENTION: Twenty muscles per individual were first palpated by an expert and then randomly by four physician examiners. MAIN OUTCOME MEASURES: Palpation findings. RESULTS: Kappa scores for palpation of taut bands, local twitch responses, and referred pain were .215, .123, and .342, respectively, between the expert and the trained examiners, and .050, .118, and .326, respectively, between the expert and the untrained examiners. Kappa scores for agreement for palpation of taut bands, twitch responses, and referred pain were .108, -.001, and .435, respectively, among the nonexpert, trained examiners, and -.019, .022, and .320, respectively, among the nonexpert, untrained examiners. CONCLUSIONS: Among nonexpert physicians, physiatric or chiropractic, trigger point palpation is not reliable for detecting taut band and local twitch response, and only marginally reliable for referred pain after training.

Adult↗
PubMed1998

Myofascial trigger points in intercostal muscles secondary to herpes zoster infection of the intercostal nerve.

Chronic pain in the chest wall is a major complication after herpes zoster infection of intercostal nerves. It is usually difficult to control pain of such origin. Two cases are reported of postherpetic neuralgia after herpes zoster infection involving the intercostal nerves. Both patients had shooting, burning, aching, and localized pain in the muscle supplied by the involved intercostal nerves 1 to 3 months after onset. Compression palpation of a tender spot in one of these muscles induced a referred pain that followed the corresponding interspace, usually in the distal anterior direction. Local twitch responses could be elicited during injection of 0.5% or 1% lidocaine into one of these tender spots; the pain in the interspace was consistently eliminated immediately after injection. One patient had complete pain relief after three series of injections. The effect of pain relief for the other patient lasted for 1 to 2 weeks after the initial injection and lasted progressively longer (up to 2 months) after repeated injections. It appears that many of the tender spots formed in intercostal muscles after herpes zoster are myofascial trigger points that respond to injection with referred pain, local twitch responses, and immediate pain relief.

Anesthetics, Local↗
PubMed1998

Bilateral femoral neuropathy after vaginal hysterectomy.

A case of bilateral femoral neuropathy as a complication of vaginal hysterectomy is presented. A 45-year-old woman developed weakness of both quadriceps, absence of bilateral knee jerks, and numbness over bilateral anteromedial thighs and medial lower legs after a vaginal hysterectomy. Electromyographic examination revealed evidence of denervation in the bilateral quadriceps. A nerve conduction study showed prolonged distal latencies and markedly reduced amplitude of the compound muscle action potentials in bilateral femoral nerves. It is suggested that this complication is caused by a microvascular and/or local mechanical injury of the femoral nerve, which is compressed beneath the tough inguinal ligament in a sustained posture with the hip joint in an extreme abduction and external rotation position. The prognosis was excellent with almost complete recovery within 10 weeks. The complication may be preventable by minimizing operating time, changing the patient's posture, and limiting the degree of flexion, abduction, and external rotation of the hip.

Electromyography↗
PubMed1998

Phentolamine effect on the spontaneous electrical activity of active loci in a myofascial trigger spot of rabbit skeletal muscle.

OBJECTIVE: To investigate the effect of phentolamine, a sympathetic blocking agent, on the spontaneous electrical activity (SEA) recorded from a locus of a myofascial trigger spot (MTrS), equivalent to a human trigger point, in rabbit skeletal muscle. DESIGN: Randomized control trial. SETTING: A university medical laboratory. PATIENTS OR OTHER PARTICIPANTS: Nine adult New Zealand rabbits. INTERVENTION: In the experimental group phentolamine mesylate (1mg/kg) was injected into the external iliac artery, followed by flushing with normal saline. The control group was treated with normal saline instead of phentolamine using the same procedure. MAIN OUTCOME MEASURES: SEA was recorded from multiple active loci of MTrSs in the biceps femoris muscle: initially SEA in the same locus was recorded before and immediately after phentolamine (or normal saline) injection; then SEA was recorded from 25 different active loci. The mean of the average integrated signal (AIS) of SEA was analyzed, comparing the effects of phentolamine and normal saline on SEA. RESULTS: In the same active locus, the AIS of SEA showed statistically a linear decay with time after phentolamine injection, with a correlation coefficient of .56 at p < .05. However, no statistical relationship could be derived for the control group data with time by using regression analysis, probably because of large variations among the rabbits and movement artifacts during the experiment. In 25 different loci in the phentolamine group, the mean of the AIS of SEA (7.92 microV) was significantly lower than that of the control group (9.89 microV) at p < .05. CONCLUSIONS: The results support the hypothesis that the autonomic nervous system is involved in the pathogenesis of myofascial trigger points. The application of the AIS as an evaluation index seems to be feasible in the quantitative measurement of SEA.

Adrenergic alpha-Antagonists↗
PubMed1998

Pathophysiologic and electrophysiologic mechanisms of myofascial trigger points.

OBJECTIVE: To review recent clinical and basic science studies on myofascial trigger points (MTrPs) to facilitate a better understanding of the mechanism of an MTrP. DATA SOURCES: English literature in the last 15 years regarding scientific investigations on MTrPs in either humans or animals. STUDY SELECTION: Research works, especially electrophysiologic studies, related to the pathophysiology of MTrP. DATA SYNTHESIS: (1) Studies on an animal model have found that a myofascial trigger spot (MTrS) in a taut band of rabbit skeletal muscle fibers is similar to a human MTrP in many aspects. (2) An MTrP or an MTrS contains multiple minute loci that are closely related to nerve fibers and motor endplates. (3) Both referred pain and local twitch response (characteristics of MTrPs) are related to the spinal cord mechanism. (4) The taut band of skeletal muscle fibers (which contains an MTrP or an MTrS in the endplate zone) is probably related to excessive release of acetylcholine in abnormal endplates. CONCLUSION: The pathogenesis of an MTrP appears to be related to integrative mechanisms in the spinal cord in response to sensitized nerve fibers associated with abnormal endplates.

Acetylcholine↗
PubMed1998

Association of active myofascial trigger points and cervical disc lesions.

We investigated the occurrence of active myofascial trigger points in specific muscle groups in relation to the existence of cervical disc bulging at various levels. One hundred and five patients (48 men, 57 women; mean age, 45.8 +/- 12.1 yr) who had active trigger points in the neck or upper back after trauma were divided into two groups on the basis of magnetic resonance imaging (MRI) evidence of bulging disc(s). The discN group consisted of 46 patients who had normal MRI findings in the cervical spine. The other 59 patients, with mild cervical disc bulging, were assigned to the disc' group. The correlations between specific muscles with active trigger points (clinical finding) and cervical disc lesions at specific levels (MRI finding) were analyzed. There were significant associations between the level of disc lesion and the muscles with trigger points, namely C3-4 lesions with levator scapulae and latissimus dorsi trigger points; C4-5 lesions with splenius capitis, levator scapulae, and rhomboid minor trigger points; C5-6 lesions with splenius capitis, deltoid, levator scapulae, rhomboid minor, and latissimus dorsi trigger points; and C6-7 lesions with latissimus dorsi and rhomboid minor trigger points. For each disc level, the average pain intensity (assessed using a numerical analog scale) of trigger points in certain correlated muscles (as indicated above) in the disc group was significantly higher than that in the discN group (p < 0.05 for all disc levels). We conclude that active trigger points are more likely to occur in certain muscles in the presence of cervical disc lesions at specific levels.

Adult↗
PubMed1997

Referred pain elicited by palpation and by needling of myofascial trigger points: a comparison.

OBJECTIVE: To investigate the occurrence of referred pain (ReP) elicited by palpation (Pal-ReP) or by needle injection (Inj-ReP) of myofascial trigger point (MTrP), and to assess the correlated factors, including the pain intensity of an active MTrP and the occurrence of local twitch response (LTR). DESIGN: Correlational study. PATIENTS: Ninety-five patients who were treated with MTrP injections. INTERVENTION: MTrP injections. MAIN OUTCOME MEASURE: Pain intensity of MTrP and occurrence of Pal-ReP, Inj-ReP, and LTR. RESULTS: Both Pal-ReP and Inj-ReP were elicited in 53.9% of MTrPs, Inj-ReP, but not Pal-ReP, was elicited in 33.7% of MTrPs. Both Pal-ReP and Inj-ReP were unobtainable in 12.3% of MTrPs. The occurrence of ReP was significantly correlated to the pain intensity of active MTrP and the occurrence of LTR. CONCLUSION: ReP could be elicited more frequently by needling than by palpation. The frequency of occurrence in ReP mainly depends on pain intensity of an active MTrP.

Adult↗
PubMed1997

Interrater reliability in myofascial trigger point examination.

The myofascial trigger point (MTrP) is the hallmark physical finding of the myofascial pain syndrome (MPS). The MTrP itself is characterized by distinctive physical features that include a tender point in a taut band of muscle, a local twitch response (LTR) to mechanical stimulation, a pain referral pattern characteristic of trigger points of specific areas in each muscle, and the reproduction of the patient's usual pain. No prior study has demonstrated that these physical features are reproducible among different examiners, thereby establishing the reliability of the physical examination in the diagnosis of the MPS. This paper reports an initial attempt to establish the interrater reliability of the trigger point examination that failed, and a second study by the same examiners that included a training period and that successfully established interrater reliability in the diagnosis of the MTrP. The study also showed that the interrater reliability of different features varies, the LTR being the most difficult, and that the interrater reliability of the identification of MTrP features among different muscles also varies.

Adult↗
PubMed1996

Difference in pain relief after trigger point injections in myofascial pain patients with and without fibromyalgia.

OBJECTIVE: To compare responses to trigger point (TrP) injection between patients having both myofascial pain syndrome (MPS) caused by active TrPs and fibromyalgia syndrome (FMS) and patients with MPS due to TrPs but without FMS. DESIGN: Prospective design blinded measurement, before- after trial. SETTING: A pain control medical clinic. PATIENTS: Group 1: MPS + FMS; Group 2: MPS only. All patients (9 in each group) had active TrPs in the upper trapezius muscle. INTERVENTION: Myofascial TrP injection with 0.5% xylocaine. MAIN OUTCOME MEASURES: Subjective pain intensity (PI), pain threshold (PT), and range of motion (ROM) were assessed before, immediately after, and 2 weeks after TrP injection. RESULTS: In a comparison of preinjection measures to immediate postinjection measures, only ROM was significantly improved (p < .05) in Group 1 patients; all three parameters were significantly improved (p < .05) in the Group 2 patients who had only MPS. Two weeks after injection, both groups showed significant improvement (p < .05) in all three measured parameters as compared to preinjection measurements. In a comparison of the two groups, the immediate effectiveness of TrP injection was significantly less (p < .05) in Group 1 than in Group 2 for all three parameters. Two weeks after injection, the degree of improvement in PT or ROM (but not PI) was not significantly different between two groups. Postinjection soreness (different from myofascial pain) was more severe, developed sooner, and lasted longer in Group 1 than in Group 2. CONCLUSION: Trigger point injection is a valuable procedure for pain relief for patients in both group. Patients with FMS are likely to experience significant but delayed and attenuated pain relief following injection of their active TrPs compared to myofascial pain patients with similar TrPs but without FMS. Also, FMS patients are likely to experience significantly more postinjection soreness for a longer period of time.

Adult↗
PubMed1996

Splinting and local steroid injection for the treatment of ulnar neuropathy at the elbow: clinical and electrophysiological evaluation.

OBJECTIVE: To compare the effects of splinting alone in the treatment of ulnar nerve lesion at the elbow with the effects of applying a local steroid injection in addition to splinting. DESIGN: Twelve nerves of 10 patients were randomly assigned into two groups: 5 nerves in Group A were treated with elbow splinting only; 7 nerves in Group B were treated with local steroid injection in addition to splinting. Therapeutic effects were assessed 1 and 6 months after treatment. SETTING: Patients were selected from an outpatient clinic of a VA Medical Center. PATIENTS: Ten patients (12 nerves) with ulnar neuropathy at the elbow confirmed by electrodiagnostic tests. INTERVENTIONS: Elbow splint was given to patients of both Groups A and B. A single dose of 40 mg triamcinolone plus 1 mL of 1% lidocaine was injected around the ulnar nerve at the elbow of Group A patients. MAIN OUTCOME MEASURES: Clinical evaluation of symptoms and signs, and ulnar motor and sensory nerve conduction studies were performed before, 1 month after, and 6 months after treatment. RESULTS: There was significant improvement in symptoms in both groups at 1 and 6 months after treatment. Ulnar motor nerve conduction velocity across the elbow improved at 1 month in Group A only, but showed improvement at 6 months in both groups. There was no significant change in the other parameters either at 1 or 6 months in both groups. In comparing the differences between Groups A and B regarding the changes at 1 or 6 months after treatment, there was no significant difference between the two groups in all parameters. CONCLUSIONS: Splint application alone is adequate to improve the symptoms and ulnar nerve conduction across the elbow. The addition of a steroid injection did not provide further benefit in the treatment of cubital tunnel syndrome.

Adult↗
PubMed1996

Pathophysiology of myofascial trigger point.

Myofascial trigger point is a sensitive spot in a palpable taut band of skeletal muscle fibers. Two important clinical characteristics of trigger points, referred pain and local twitch response, can be elicited by mechanical stimulation (palpation or needling). The trigger point is usually activated by acute or chronic injury to a muscle, tendon, ligament, joint, disc or nerve. Recent human and animal studies have suggested that the pathogenesis of either referred pain or local twitch response is related to integration in the spinal cord. It has been proposed that there are multiple sensitive loci in a trigger point region. A sensitive locus may contain one or more sensitized nociceptive nerve endings. Mechanical stimulation of a sensitive locus can elicit a local twitch response which is frequently associated with characteristic referred pain. Theoretically, sensitive loci can be found in any site of a skeletal muscle, but is usually distributed with highest concentration near the endplate region where a trigger point is frequently found. The trigger point is a common pathogenic pathway of muscle pain from different causes.

Humans↗
PubMed1995

Most dorsal root ganglion neurons of the adult rat survive nerve crush injury.

Severe crush of the rat sciatic nerve does not result in any significant cell death among motor neurons (Swett et al., 1991a). The present study reports on the survival of the dorsal root ganglion (DRG) neurons in the same experiments. From 15 to 187 days after crush of the left sciatic nerve, the common peroneal or sural nerve was cut and labeled distal to the injury with a mixture of horseradish peroxidase (HRP) and its wheatgerm agglutinin conjugate (WGA:HRP). In other cases, the crush injury was made far enough distally on a peroneal or sural branch to permit labeling several millimeters proximal to the injury. The procedures for reconstructing the regenerated DRG neuron populations were identical to those used in an earlier study describing the normal sciatic DRG neuron populations in the rat (Swett et al., 1991b). The normal peroneal nerve contains 2699 +/- 557 DRG neurons. When the peroneal nerve was crushed near its point of origin from the sciatic and labeled 10 mm distal to the injury, 2186 +/- 163 DRG neurons were counted, suggesting a decrease of about 19% (p < 0.01). However, when the entire sciatic nerve was crushed, distal labeling of the peroneal nerve revealed a mean number of 2578 +/- 291 DRG neurons, an insignificant reduction (p > 0.2). When the peroneal nerve was labeled proximal to a peroneal crush site, a similar number of DRG neurons (2563 +/- 412) was counted. Results following sural nerve crush were similar. The sural nerve normally contains 1675 +/- 316 DRG neurons. When the nerve was labeled distal to the injury, 1558 +/- 64 DRG neurons were counted--a number almost identical to that found (1529 +/- 240) when this nerve was labeled proximal to the injury. The results demonstrate that within 6 months of severe crush injury of the rat sciatic nerve, the vast majority of DRG neurons survive and regenerate new axons distally beyond the injury site, presumably to reinnervate their original targets.

Animals↗
PubMed1995

Prediction of reflex sympathetic dystrophy in hemiplegic patients by electromyographic study.

BACKGROUND AND PURPOSE: This study was designed to investigate the correlation between reflex sympathetic dystrophy syndrome (RSDS) in hemiplegic patients and spontaneous electromyographic (EMG) activity, as well as to determine the predictive value of spontaneous EMG activity in early diagnosis of RSDS. METHODS: An EMG and nerve conduction velocity study of the weak upper limb was conducted on 70 hemiplegic patients at 3 to 4 weeks after cerebrovascular disease (either cerebral hemorrhage or infarction). Clinical assessment for development of the RSDS was done during the following 6 months. The correlation of RSDS development with the presence of spontaneous EMG activity and certain clinical parameters (including sex, age, side affected, cause of stroke, sensory impairment, spasticity, and shoulder subluxation) was analyzed statistically. RESULTS: Of the 46 patients who exhibited spontaneous activity, 30 (65%) developed clinical RSDS in their hemiplegic upper extremity, whereas only 1 (4%) of the other 24 patients with no spontaneous EMG activity developed clinical RSDS within 6 months after the onset of hemiplegia (P < .001). The correlation of RSDS development with the presence of shoulder subluxation and sensory impairment in the hemiplegic side was statistically significant. Neither age, sex, severity of spasticity, nor etiology of stroke had a significant correlation with the development of clinical RSDS. CONCLUSIONS: There is significant correlation between the presence of spontaneous EMG activity and the development of clinical RSDS in the hemiplegic upper extremity after stroke. It is concluded that spontaneous EMG activity in the hemiplegic hands of stroke patients might be a good predictor of the future development of clinical RSDS.

Adult↗
PubMed1994

Persistence of local twitch response with loss of conduction to and from the spinal cord.

A local twitch response (LTR) is a brisk contraction of a taut band of skeletal muscle fibers elicited by snapping palpation of a trigger point (TrP) in that band. The LTR is a clinically valuable objective sign that confirms the presence of a myofascial TrP. A transient burst of electromyographic (EMG) activity can be recorded from taut band fibers when an LTR is elicited by snapping palpation of TrP. A previous study of the human extensor digitorum muscle during ischemia suggested that both central and local pathways can be involved in the propagation of LTRs. In this study, EMG activity of LTRs in the third finger extensor muscle were recorded bilaterally in a patient with a unilateral brachial plexus lesion. This patient had complete loss of nerve conduction involving the posterior cord of the right brachial plexus as confirmed by EMG and nerve conduction studies and by neurological examination at 6 months after injury. EMG activity (measured as discharge duration and maximal amplitude) on the paralyzed side was significantly reduced (p < 0.01) as compared with the unaffected side, but had not disappeared. Three more studies were done at 7, 8, and 17 months after injury when the motor and sensory functions were recovered progressively. The EMG activity of LTRs recovered on the paralyzed side in parallel with the motor and sensory recovery. These findings indicate that the transmission of LTR depends mainly on the central nervous system with a possible minor degree of local transmission.

Action Potentials↗
PubMed1991

All peroneal motoneurons of the rat survive crush injury but some fail to reinnervate their original targets.

This is a quantitative study of the motoneuronal population of the rat's common peroneal nerve following severe crush injury of the sciatic nerve or its component branches. The crush was performed unilaterally under anesthesia for 60 seconds with hemostat jaws covered with tubing to form a smooth, 2 mm long, injured zone. Recovery from injury was allowed for 14 to 188 days. It was measured behaviorally using the sciatic functional index (SFI) and electrophysiologically by comparing the conduction velocity and amplitudes of evoked muscle action potentials prior to injury, and again after injury just before the nerve was labeled with horseradish peroxidase (HRP), and/or its wheat germ agglutinin conjugate (WGA-HRP), 48-72 hours before sacrifice. The motoneurons were retrogradely labeled on both sides so that the uninjured side might serve as a control. On the injured side the nerves were labeled either distal or proximal to the crush site. The tibialis anterior muscles on both sides were removed and weighted. Spinal segments L2 to L6 were cut in serial, frozen cross-sections. HRP reaction products were formed using TMB as the chromogen. The normal peroneal nerve was found to contain 634 +/- 26 motoneurons (22 cases). The number of motoneurons labeled 5-15 mm distal to the injury site (22 cases) was 535 +/- 69 or 84.4% of normal. In 12 cases in which the nerve was labeled 5 mm proximal to the injury normal population numbers (648 +/- 30) were found. These counts demonstrated that the unlabeled 15.6% in the distal labeled cases had not vanished as a result of cell death. Instead, the unlabeled group was composed mainly of small motoneurons whose axons probably had not regenerated distal to the crushed zone. Mean soma size of injured neurons increased to maximum 3-6 weeks after injury and then gradually decreased in size over the following weeks to nearly normal values. This transient increase in size was due to two factors: 1) soma swelling in response to axonal injury, and 2) absence of many small motoneurons, presumably gamma-motoneurons, which were either incapable of, or prevented from, regenerating beyond the injury zone long after larger motoneurons had reinnervated their targets. SFI scores, muscle weights, and amplitude ratios of evoked potentials recovered to control values by 70-80 days post-injury. Conduction velocities remained 20-25% below normal at the end of 80 days.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Effects of a topically applied counterirritant (Eucalyptamint) on cutaneous blood flow and on skin and muscle temperatures. A placebo-controlled study.

This study was designed to investigate the effects of a new product of counterirritant, Eucalyptamint, on the cutaneous circulation and on skin and muscle temperatures. Ten normal subjects (six males and four females, with an average age of 34 +/- 6 yr) were involved in this study. Eucalyptamint was applied to the anterior forearm skin of one side, and placebo was applied to the contralateral forearm. The subjective feelings, cutaneous blood flow, and skin temperature were measured before and periodically (5-min intervals) after the application of the compound. Muscle temperature was measured before and 30 min after the application of the Eucalyptamint. There was no significant effect on the subjective sensation. However, there were statistically significant (P less than 0.05) increases in cutaneous blood flow (up to 4 times base-line) and skin temperatures (up to 0.8 degrees C higher than base-line) after the application of Eucalyptamint with the effects lasting up to 45 min after the application. The muscle temperature was also increased (0.4 degrees C) significantly (P less than 0.05) 30 min after application of the Eucalyptamint. There were no significant changes in the placebo application. The results of this study suggested that the new product of counterirritant, Eucalyptamint, produced significant physiologic responses that may be beneficial for pain relief and/or useful to athletes as a passive form of warm-up.

Adult↗