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PubMed2003

[Hang-back retroposition as a variation in oculomotor muscle weakness].

In a clinical study the authors evaluate efficiency of the operation on oculomotoric muscles by the hang-back retroposition method. A total of 70 children have been operated on, 52 of the patients suffering from esotropia and 18 from exotropia. The mean preoperation deviation in esotropia was 30 +/- 12 pdpt, the postoperation deviation was in the range of 6 +/- 7 pdpt. In the exotropia cases the preoperation deviation improved from original 76.9%, in the exotropia group being 77.8%. The overall success rate of the hang-back retroposition in all these patients was 77.1%. Ina group of children operated on by a traditional retroposition there was an overall success rate 78.7% (77.6% in esotropia and 82.4% in exotropia cases). Hang-back retroposition has been equally effective as the traditional retroposition of oculomotoric muscles. Its main advantages include visibility of the operation field, minimum risk of perforation of sclera and a fair time factor of the intervention. The authors discuss the development, indications, further advantages but also possible disadvantages or limitations of this acknowledged surgical procedure in strabology.

Child, Preschool↗
PubMed2002

Fatigue-related changes in torque output and electromyographic parameters of trunk muscles during isometric axial rotation exertion: an investigation in patients with back pain and in healthy subjects.

STUDY DESIGN: A cross-sectional case-control study. OBJECTIVES: To examine the effect of fatigue on torque output as well as electromyographic frequency and amplitude values of trunk muscles during isometric axial rotation exertion in back pain patients and to compare the results with a matched control group. SUMMARY OF BACKGROUND DATA: Back pain patients exhibited different activation strategies in trunk muscles during the axial rotation exertions. Fatigue changes of abdominal and back muscles during axial rotation exertion have not been examined in patients with back pain. METHODS: Twelve back pain patients and 12 matched controls performed isometric fatiguing axial rotation to both sides at 80% maximum voluntary contraction in a standing position. During the fatiguing exertion, electromyographic changes of rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum, and multifidus were recorded bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were also measured. RESULTS: No difference in the endurance capacity was found between back pain and control groups. At the initial period of the exertion, back pain patients demonstrated a statistical trend (P = 0.058) of greater sagittal coupling torque as well as lower activity of rectus abdominis and multifidus and higher activity in external oblique. During the fatigue process similar changes of coupling torque were demonstrated in both sagittal and coronal planes, but a smaller fatigue rate for right external oblique, increase in median frequency for latissimus dorsi, and lesser increase in activity for back muscles were found in the back pain group compared with the control group. CONCLUSIONS: Alterations in electromyographic activation and fatigue rates of abdominal and back muscles demonstrated during the fatigue process provide insights into the muscle dysfunctions in back pain and may help clinicians to devise more rational treatment strategies.

Abdomen↗
PubMed2002

EMG activity normalization for trunk muscles in subjects with and without back pain.

PURPOSE: The aims of the present study were to examine electromyographic (EMG) activity of six bilateral trunk muscles during maximal contraction in three cardinal planes and to determine the direction of contraction that gives maximal activation for each muscle, both for healthy subjects and back-pain patients. METHODS: Twenty-eight healthy subjects and 15 back-pain patients performed maximum voluntary contractions in three cardinal planes. Surface EMG signals were recorded from rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum, and multifidus bilaterally. Root mean square values of the EMG data were calculated to quantify the amplitude of EMG signals. RESULTS: For both healthy subjects and back-pain patients, one single direction of contraction was found to give the maximum EMG signals for most muscles. Rectus abdominis demonstrated maximal activity in trunk flexion, external oblique in lateral flexion, internal oblique in axial rotation, and multifidus in extension. For the latissimus dorsi and iliocostalis lumborum, maximal activity was demonstrated in more than one cardinal plane. CONCLUSION: This study has implications for future research involving normalization of muscle activity to maximal levels required in many trunk EMG studies. As the latissimus dorsi and iliocostalis lumborum demonstrate individual differences in the plane that gives maximal activity, these muscles may require testing in more than one plane.

Abdominal Muscles↗
PubMed2006

Low back pain patients demonstrate increased hip extensor muscle activity during standardized submaximal rotation efforts.

STUDY DESIGN: A comparative study of trunk and hip extensor muscle recruitment patterns in 2 subject groups. OBJECTIVE: To examine for changes in recruitment of the hip and back extensor muscles during low level isometric trunk rotation efforts in chronic low back pain (CLBP) subjects by comparison with matched asymptomatic control subjects. SUMMARY OF BACKGROUND DATA: Anatomic and biomechanical models have provided evidence that muscles attaching to the thoracolumbar fascia (TLF) are important for providing stabilization to the lumbopelvic region during trunk rotation. This has guided rehabilitation programs. The muscles that link diagonally to the posterior layer of the TLF have not previously been examined individually and compared during low-level trunk rotation efforts in CLBP patients and matched controls. METHODS: Thirty CLBP patients and 30 matched controls were assessed using surface electromyography (EMG) as they performed low-level isometric rotation efforts while standing upright. Muscles studied included latissimus dorsi, erector spinae, upper and lower gluteus maximus, and biceps femoris. Subjects performed the rotation exertion with various levels of external trunk support, related to different functional tasks. RESULTS: EMG results demonstrated that subjects with CLBP had significantly higher levels of recruitment for the lower and upper gluteus maximus (P < 0.05), hamstrings (P < 0.05), and erector spinae muscles (P < 0.05) during rotation to the left compared with the control subjects. CONCLUSION: This study provided evidence of increased muscle recruitment in CLBP patients when performing a standardized trunk rotation task. These results may have implications for the design of therapeutic exercise programs for CLBP patients.

Adult↗
PubMed2005

Muscle activation imbalance and low-back injury in varsity athletes.

There are conflicting findings in the literature regarding erector spinae activation imbalance in people with low-back pain (LBP). Some studies have found asymmetric recruitment between muscle pairs in people with LBP, whilst other studies have not; some reported people with LBP recruit more lumbar muscles whilst other have reported greater thoracic activity. Using 242 varsity athletes, EMG activity of thoracic and lumbar erector spinae pairs was recorded during an isometric trunk extension. Activation imbalance among muscle pairs and levels was compared between athletes with and without a history of low-back injury (HxLBI). There were no group differences in the imbalance between sides, but the HxLBI group had greater activation imbalance between lumbar and thoracic levels than the No HxLBI group. Activation imbalance between levels was similar for individuals with No HxLBI and those who sustained first time injury suggesting that imbalance does not cause LBI. There was no difference between the athletes with single and multiple episode LBI, nor between short and long symptom duration suggesting that the presence of imbalance is not an impairment. Interestingly, activation imbalance occurred in both directions, meaning more thoracic activity for some, and more lumbar activity for others, which might be a functional adaptation related to pathology.

Adult↗
PubMed1995

Stiff-man syndrome: case report.

Stiff-man syndrome is a rare neurologic disorder characterized by progressive, fluctuating muscle rigidity with painful muscle contractions affecting predominantly the back and proximal extremities. In the ED, the diagnosis can be easily overlooked and misdiagnosed as acute or chronic low back pain and muscle spasm. This syndrome is often associated with diabetes, autoimmune diseases, and cancer. This report describes an illustrative case of a 39-year-old woman who presented to the ED with a two-year history of right leg spasms and low back pain that had become so severe in the preceding two days that she was unable to ambulate. Clues to the patient's proper diagnosis coincide with the diagnostic criteria for stiff-man syndrome: the presence of a slowly progressive stiffness of the axial muscles and proximal limb muscles, making ambulation difficult; hyperlordosis of the lumbar spine; episodic spasms precipitated by jarring or sudden movement; a normal intellectual, sensory, and motor examination when not in spasm; and a marked amelioration of symptoms with the IV administration of diazepam. High-dose oral diazepam is the maintenance drug of choice.

Adult↗
PubMed2004

Return-to-work status 1 year after muscle reconditioning in chronic low back pain patients.

OBJECTIVE: To evaluate return-to-work status 1 year after a physical deconditioning program in manual laborers with chronic low back pain. METHODS: In this open prospective study, a questionnaire was sent to 125 patients and their physicians (115 men and 10 women, mean age 40 years). Mean sick leave duration at program initiation was 4 months. All participants had followed a physical reconditioning program 12 months earlier. The program for the present study included 6 h of physical and occupational therapy each day, 5 d a week for 3 weeks. RESULTS: One hundred and nine questionnaires were evaluable. Fifty-seven patients (52.3%) were working, 39 (35.8%) full time and 18 (16.5%) part time. The remaining 52 patients were on disability leave. Among the study variables, only a favorable subjective evaluation by the patient at completion of the program and absence of clinical evidence of nonorganic pain at study inclusion significantly predicted return-to-work within 1 year. CONCLUSION: This intensive reconditioning program for low back pain patients had positive effects on return-to-work status after 1 year.

Adult↗
PubMed1999

Motor-evoked potentials elicited from human erector spinae muscles by transcranial magnetic stimulation.

STUDY DESIGN: The compound muscle action potentials elicited from the erector spinae muscles by transcranial magnetic stimulation was studied in 15 healthy adults. OBJECTIVE: To describe the recording procedure for consistent compound muscle action potentials elicited from the human erector spinae by transcranial magnetic stimulation and to establish the normal latency ranges of the responses, at respective spinal levels, for the practical use of this test. SUMMARY OF BACKGROUND DATA: Although recording of the compound muscle action potentials from limb muscles after transcranial magnetic stimulation has been extensively studied, the use of the erector spinae as the target muscle has not, probably because of the difficulty of consistently evoking compound muscle action potentials. METHODS: Compound muscle action potentials from the erector spinae muscles were recorded with the subject prone during tonic voluntary background contraction of the back extensor muscles at approximately 20% of maximum effort. The compound muscle action potentials were recorded concurrently at multiple levels after magnetic stimulation to the brain with a round coil centered over the vertex. RESULTS: The onset and peak latencies (mean +/- SD) of the major negative potential increased progressively toward the caudal level from 13.4 +/- 2.2 msec and 17.6 +/- 2.2 msec at T5-T6 to 20.8 +/- 1.5 msec and 26.3 +/- 3.0 msec at L4-L5 in healthy subjects. The latencies changed significantly between two adjacent segments from T5-T6/T6-T7 through T12-L1/L1-L2. CONCLUSIONS: The compound muscle action potential was elicited from the voluntarily contracted erector spinae at all spinal levels from T5-T6 through L4-L5 in all subjects tested. This noninvasive test has potential for evaluating the functional integrity of the motor pathway in the thoracic spinal cord, the spinal nerves, or both.

Adult↗
PubMed1996

[Biomechanical heart and cardiovascular support].

A surgical association between skeletal muscle and heart muscle dates back to experiments at the beginning of this century. Initially, the use of skeletal muscles aimed at plastic reconstructions of myocardial defects and enhancement of myocardial blood flow. The application of the contractile force of the skeletal muscle failed because of skeletal muscle fatigue. In the late sixties, investigations in muscle physiology demonstrated the "functional plasticity" of muscle tissue: Chronic electrical stimulation induces a transformational process of the cellular organelles, the metabolism, the fiber proteins and the calcium regulatory systems which results in "fatigue resistance" of the muscle. This was is a prerequisite for the application of skeletal muscles for continuous support of the circulation. Biomechanical support of the heart and the circulation is experimentally performed as skeletal muscle ventricles, chronic extraaortic counterpulsation and ventricular and atrial cardiomyoplasty. The electrical stimulation is performed with "burst" impulses, in order to increase the force and the length of contraction. The first clinical application of ventricular cardiomyoplasty is attributed to the French surgeon Alain Carpentier. Clinical investigations show that cardiomyoplasty results in an impressive symptomatic improvement of the patients clinical condition with only moderate changes of objective hemodynamic parameters. Further research will investigate the clinical applicability of the other, thus far only experimental techniques of biomechanical support. The introduction of cardiomyoplasty has induced great scientific interest in all forms of skeletal muscle circulatory support. Close collaboration between basic researchers and clinical investigators is of utmost importance for further developments in this field. The combined international research effort can be expected to yield considerable progress within the forthcoming years.

Animals↗
PubMed1984

Comments on the reliability of muscle activity comparisons in EMG biofeedback research with back pain patients.

The underlying assumption in comparing muscle activity levels in back pain research is the reliability of the documented biological record. Surface-recorded EMG data are often used as "objective" indicators in treatment outcome studies. The present paper questions the reliability of this somatic measure. Three sources of error variance that interfere with the reliability of the recorded biological signal are discussed: movement of the body, replacement of electrodes, and electronic equipment instability. It is argued that surface-recorded EMG activities of the back are unreliable and unsuited for comparing the efficacy of a back pain treatment program.

Back Pain↗
PubMed1999

Investigation of anthropometric and work-rate profiles of Rugby Sevens players.

BACKGROUND: To describe anthropometric and match performance profiles of international Rugby Sevens players and explore correlations between anthropometric characteristics and work-rates in matches. METHODS: Profiles were compared by means of multivariate analysis and correlation techniques. SETTINGS: measurements were made on players participating in the 1996 International Rugby Sevens tournament in Uruguay. SUBJECTS: Thirty male players. MEASURES: work-rate analysis during matches (n = 30) and a comprehensive anthropometry profile of 27 of the 30 players. RESULTS: Forwards had more mass (whole-body, adipose tissue, muscle) than backs, jogged more frequently and paused more often. High intensity activity was negatively correlated with muscle mass and with mesomorphy. CONCLUSIONS: Anthropometric features are related to components of match play in Rugby Sevens but do not necessarily determine whether a game is won or lost.

Anthropometry↗