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Effects of neuromuscular electrical stimulation treatment of cerebral palsy on potential impairment mechanisms: a pilot study.

PURPOSE: This pilot study examined the effects of neuromuscular electrical stimulation (NMES) therapy on upper limb impairment in children with cerebral palsy, specifically addressing spasticity, heightened passive resistance to wrist rotation, coactivation, and weakness. METHODS: Eight subjects, aged five to 15 years, with spastic hemiparesis subsequent to brain injury, participated in three months of NMES therapy, targeting the wrist flexor and extensor muscles. Maximum voluntary wrist extension range of motion against gravity, spasticity, passive torque, maximum voluntary isometric torque, and coactivation were recorded prior to, during, and at the conclusion of the therapy. RESULTS: Seven of the eight subjects demonstrated a significant (>15 degrees) improvement in wrist extension range of motion against gravity following the NMES treatment, with an average gain of 38 degrees. Differences in spasticity (0.01 +/- 0.14 N-m, p = 0.80) and passive torque (0.03 +/- 0.11 N-m, p = 0.52) were not significant for these subjects. Isometric wrist extension torque, however, did increase significantly (p < 0.01), accompanied by a reduction in flexor coactivation (p < 0.01). CONCLUSIONS: Evidence suggests that the NMES treatment protocol affected wrist extension by improving the strength of the wrist extensor muscles, possibly through decreased flexor coactivation. Further studies are required, however, to determine whether electrical stimulation itself or other facets of the therapy paradigm played the key role in improvement.

Adolescent↗

Longitudinal study of fiber density and motor unit number estimate in patients with amyotrophic lateral sclerosis.

We examined fiber density, compound muscle action potential (CMAP) amplitude, and motor unit number estimate (MUNE) of the abductor digiti minimi and grip strength longitudinally. We sought to determine the effects of ALS on these measurements and to evaluate which of these tests may be more sensitive in evaluating progression of ALS and possibly predicting survival. Ten patients were examined at months 0, 3, and 6. A significant decrease in MUNE and increase in fiber density were observed at months 3 and 6 (p < 0.02) compared with baseline (month 0). Mean CMAP and grip strength declined, but not significantly. The decrease in MUNE over 6 months was significantly greater than that of CMAP and grip strength (p < 0.025). The significant changes in MUNE and fiber density over time suggest that they are more sensitive in measuring the rate of progression of ALS. To evaluate further the utility of these tests, we arbitrarily divided the patients into equal groups based on length of survival. MUNE declined significantly in the group with shorter survival (p < 0.01). Conversely, fiber density increased significantly in patients with longer survival (p < 0.01). With similar statistical analysis there were no significant differences in decline of CMAP or grip strength in either subgroup over 6 months. Our study suggests that MUNE and fiber density are more sensitive than CMAP and grip strength in detecting progression of ALS. Furthermore, we raise the hypotheses that a greater increase in fiber density identifies a group of patients with ALS who will have longer survival, and that a greater decline in MUNE identifies a group with a worse prognosis.

Action Potentials↗

Dynamic strength training in patients with early rheumatoid arthritis increases muscle strength but not bone mineral density.

OBJECTIVE: To assess the effects of 12 months' dynamic strength training on muscle strength and bone mineral density (BMD) at the lumbar spine and femoral neck in patients with early rheumatoid arthritis (RA). METHODS: Thirty-two subjects in the training group (EG) and 33 in the control group (CG) completed the study. EG carried out strength training 2 times a week with moderate loads of 50-70% of repetition maximum. They were also encouraged to do recreational physical activities. CG performed recreational physical activities and range of motion exercises. Maximal strength of the knee extensors, trunk extensors and flexors, and grip strength were recorded with dynamometers. BMD was measured using dual x-ray absorptiometry. Modified Disease Activity Score, erythrocyte sedimentation rate, and pain were used for the estimation of disease activity, and Stanford Health Assessment Questionnaire to measure functional disability. RESULTS: The 12 month resistance training in EG led to statistically significant mean increases of 22-35% in all muscle groups examined. CG patients were also able to increase their strength to some degree (3-24%), but at the end of the study strengths in CG were significantly lower than in EG. By the end of the study lumbar spine BMD had changed by +0.19% (4.24) in EG and by -1.14% (4.36) in CG. The corresponding changes of femoral BMD were +1.10% (3.71) and -0.03% (3.58). The changes in BMD were minor and statistically not significant in both groups. However, femoral BMD was found to be decreased among those patients treated periodically with oral glucocorticoids (n = 15, 3 subjects from EG and 12 from CG) compared with changes in BMD among those not treated with systemic glucocorticoids (n = 50). CONCLUSION: Minimally supervised strength training resulted in significant improvements in muscle strength without detrimental effects on disease activity. The detected annual changes in central BMD were minor and statistically insignificant in both groups. Special attention should be focused on those patients with RA with high disease activity and concomitant glucocorticoid treatment.

Arthritis, Rheumatoid↗

Tolerance and sensitization to inhaled 1,1,1-trichloroethane in mice: results from open-field behavior and a functional observational battery.

RATIONALE: 1,1,1-Trichloroethane (TCE), a representative abused solvent, has well described acute behavioral effects in animals. Much less is known about repeated high-concentration exposures as would be encountered in inhalant abusers. Tolerance has been demonstrated in some, but not all, studies with TCE while sensitization has also been seen with other abused solvents. OBJECTIVE: The present study was designed to further characterize changes in the effects of repeated exposure to TCE on a variety of mouse behaviors. METHODS: Mice were tested using locomotor activity as well as a functional observational battery (FOB) both before and after a regimen of daily exposures to various concentrations of TCE. RESULTS: The initial locomotor effects of acute 30-min exposures to TCE were biphasic with concentration-dependent increases in activity at lower concentrations and decreases observed at higher concentrations. The profile of acute effects as measured by the FOB included changes in posture, decreased arousal, disturbances in gait, delayed righting reflexes, and decreased sensorimotor reactivity. Animals were then divided into five groups and exposed 30 min/day to either air or one of four concentrations of TCE (2,000, 6,000, 10,000, or 13,300 ppm) for 15 consecutive days. The TCE concentration used primarily affected the magnitude of change, not whether tolerance or sensitization occurred. Tolerance developed on the measures of forelimb grip strength, inverted screen, and number of rears. Conversely, sensitization developed to measures of locomotor activity. CONCLUSION: Depending on the behavioral measure, both tolerance and sensitization can occur in mice with repeated exposure to TCE. Both of these phenomena are characteristic of drugs of abuse.

Administration, Inhalation↗

Optimum pinch grips in the handling of dies.

Handling roller-press dies has caused numerous work-related musculoskeletal disorders in the leather industry. The dies are quite large (0.61 x 0.30 m), heavy (3.5 kg) and are difficult to handle because of the large pinch span requirements (up to 16 cm). The purpose of this study was to determine the optimum pinch span and optimum crossbar angulation to minimize die handling forces. Five-finger pulp-pinch forces were measured on five males and five females with a force-sensitive-resistor instrumented glove while handling a simulated adjustable die. Maximum pinch forces occurred at pinch spans between 1.27 and 3.81 cm, with average female strengths being 57% of average male pinch strengths. Minimum pinch forces to hold the die occurred at a 45 degrees angulation and increased linearly as the angle approached 90 degrees or the normal vertical orientation. The simplest solution to redesigning the dies is to: (1) decrease the distance between the braces to less than 4 cm and (2) slant the braces at 45 degrees.

Ergonomics↗

Large index-fingertip forces are produced by subject-independent patterns of muscle excitation.

Are fingertip forces produced by subject-independent patterns of muscle excitation? If so, understanding the mechanical basis underlying these muscle coordination strategies would greatly assist surgeons in evaluating options for restoring grasping. With the finger in neutral ad- abduction and flexed 45 degrees at the MCP and PIP, and 10 degrees at DIP joints, eight subjects attempted to produce maximal voluntary forces in four orthogonal directions perpendicular to the distal phalanx (palmar, dorsal, lateral and medial) and in one direction collinear with it (distal). Forces were directed within 4.7 +/- 2.2 degrees (mean +/- S.D.) of target and their magnitudes clustered into three distinct levels (p < 0.05; post hoc pairwise RMANOVA). Palmar (27.9 +/- 4.1 N), distal (24.3 +/- 8.3 N) and medial (22.9 +/- 7.8 N) forces were highest, lateral (14.7 +/- 4.8 N) was intermediate, and dorsal (7.5 +/- 1.5 N) was lowest. Normalized fine-wire EMGs from all seven muscles revealed distinct muscle excitation groups for palmar, dorsal and distal forces (p < 0.05; post hoc pairwise RMANOVA). Palmar force used flexors, extensors and dorsal interosseous; dorsal force used all muscles; distal force used all muscles except for extensors; medial and lateral forces used all muscles including significant co-excitation of interossei. The excitation strategies predicted to achieve maximal force by a 3-D computer model (four pinjoints, inextensible tendons, extensor mechanism and isometric force models for all seven muscles) reproduced the observed use of extensors and absence of palmar interosseous to produce palmar force (to regulate net joint flexion torques), the absence of extensors for distal force, and the use of intrinsics (strong MCP flexors) for dorsal force. The model could not predict the interossei co-excitation seen for medial and lateral forces, which may be a strategy to prevent MCP joint damage. The model predicts distal force to be most sensitive to dorsal interosseous strength, and palmar and distal forces to be very sensitive to MCP and PIP flexor moment arms, and dorsal force to be sensitive to the moment arm of and the tension allocation to the PIP extensor tendon of the extensor mechanism.

Adult↗

Capitolunate arthrodesis with scaphoid and triquetrum excision.

A retrospective two-center outcome study was designed to evaluate the results of capitolunate arthrodesis with scaphoid and triquetrum excision mainly for scapholunate advanced collapse patterns of arthritis. Fourteen wrists in 14 patients were evaluated objectively by standard parameters and subjectively by the Short Musculoskeletal Functional Assessment at an average of 28 months after surgery (range, 14-51 months). All patients were men between the ages of 20 and 70 years (average, 49 years). Two patients had a painful nonunion and one had persistent pain despite conversion to a solid wrist arthrodesis. One patient had x-ray evidence of progressive radiolunate narrowing, but only occasional pain. Postoperative wrist flexion-extension arc was 53 degrees and radioulnar deviation arc was 18 degrees. Grip and pinch strengths were 71% and 75%, respectively, of the normal contralateral wrist. The results of our study indicate that capitolunate arthrodesis with scaphoid and triquetrum excision is comparable to other motion-preserving operative procedures for scapholunate advance collapse.

Adult↗

The development of bone strength at the proximal radius during childhood and adolescence.

Current investigations of bone development mostly focus on bone mass, but bone strength may be functionally more important than mass. Therefore, we compared the developmental changes in cortical bone mass (BMCcort) and parameters of cortical bone strength [polar moment of inertia, section modulus, and strength strain index (SSI)]. Analyses were performed at the 65% site of the proximal radius using peripheral quantitative computed tomography. The study population comprised 469 healthy subjects, 6-40 yr of age (273 females). Both in prepubertal children (pubertal stage 1) and after puberty (pubertal stage 5 and adults) all studied parameters were significantly higher in males. During puberty (pubertal stages 2-4) the gender-specific differences were generally somewhat smaller. All of the measured parameters increased significantly with age and pubertal stage. However, although the percent increase in BMCcort between the youngest children and adults was similar between the genders, the increases in polar moment of inertia, section modulus, and SSI were higher in males. The ratio between section modulus and BMCcort was consistently higher in males after the age of 11 yr and after pubertal stage 2. Similar results were found for ratios between polar moment of inertia or SSI and BMCcort. These results show that for a given bone mass, males have stronger bones than females after pubertal stage 2. This reflects the fact that in puberty males add bone mostly on the periosteal surface, where the effect on bone strength is highest, whereas females add bone on the endocortical surface, which has a small effect on bone stability. The purpose of the mechanically inefficient endocortical apposition in female puberty might be to create a reservoir of calcium for future pregnancy and lactation.

Adolescent↗

Acute percutaneous scaphoid fixation. A pilot study.

Fractures of the scaphoid are most common in young men; immobilisation in a cast usually means a long period away from work and athletic activities. Early rigid fixation has been shown to promote a rapid functional recovery, but open reduction and internal fixation is technically demanding with the dangers of damage to the radiocarpal ligaments, the scaphotrapezial joint, and the blood supply of the scaphoid. For minimally displaced or undisplaced B1 or B2 fractures, these problems can be overcome by percutaneous fixation. We report our technique and the results of a pilot study in 15 patients. There was no immobilisation; patients were allowed movement soon after operation, but union was obtained in all at a mean of 57 days (38 to 71). The range of movement after union was equal to that of the contralateral limb and grip strength was 98% of the contralateral side at three months. Patients were able to return to sedentary work within four days and to manual work within five weeks. Our initial results show that percutaneous scaphoid fixation for acute fractures is satisfactory and gives rapid functional recovery.

Acute Disease↗

Quadriceps and grip strength are related to vitamin D receptor genotype in elderly nonobese women.

Osteoporotic fragility fractures are related to bone density and injury, which are both related to muscle strength. The influence of genetic factors, such as the vitamin D receptor (VDR) polymorphism on bone mineral density (BMD), is documented but still controversial, and is not known for muscle strength. In the present study, we investigated the association between the VDR BsmI polymorphism and BMD (femoral neck [FN], lumbar spine [LS], and proximal forearm [FA]) and muscle strength (quadriceps and grip strength) in 501 healthy women older than 70 years. No association was found between the VDR genotypes and BMD in elderly women. However, in nonobese women (body mass index <30 kg/cm2), the BMD in the FN was 5% higher in women with the bb BsmI genotype than in women with the BB genotype (p < 0.05). After correction for muscle strength, no association was found. A significant association between the VDR genotypes and quadriceps and grip strength was observed. In nonobese women, a 23% difference in quadriceps strength (p < 0.01) and 7% in grip strength (NS) was observed between the bb and BB genotype of the VDR. After correction for confounding factors and BMD, this association was significant for quadriceps and grip strength. These results indicate a major association of an allelic variant at the VDR locus with muscle strength in elderly nonobese women, which could explain a small association between VDR polymorphism with BMD in the femoral neck in nonobese women. No such associations were found in obese women, suggesting that factors related to obesity obscure such an association.

Aged↗

Anthropometric and performance variables discriminating elite American junior men weightlifters.

The purpose of this study is to identify physical and performance variables that discriminate elite American junior-aged men weightlifters from nonelite performers. Using a cross-sectional design, multiple discriminant analysis was used to determine field tests identifying elite male junior weightlifters. Young men who were participants (n = 115) at the Junior National and Junior Olympics Weightlifting Championships volunteered as subjects (mean +/- SD age = 14.8 +/- 2.3 years). Elite weightlifters (n = 20) were identified as the top 17.5% of national-level competitors when weightlifting performances were adjusted for body mass using the Sinclair equation. All other weightlifters were classified as nonelite (n = 95). Test batteries were performed immediately upon completion of a national-level weightlifting competition. Variables measured included easily-administered field tests of physical dimensions and body composition, muscular strength and power, flexibility, and gross motor control. The resulting regression equations correctly classified 84.35% of the weightlifters as elite or nonelite. Five variables significantly contributed to the discriminant analysis (Wilks Lambda = 0.6637392, chi(2) = 44.880, df = 5, p < 0.0001, adjusted R(2) = 0.67). Body mass index accounted for 23.13% of the total variance, followed by vertical jump (22.78%), relative fat (18.09%), grip strength (14.43%), and torso angle during an overhead squat (0.92%). The use of these 5 easily administered field tests is potentially useful as a screening tool for elite American junior men weightlifters.

Adolescent↗

The functional results of ulnar nerve repair. Defining the indications for tendon transfer.

The subjective, objective and functional outcome following repair of isolated ulnar nerve injuries was assessed in 50 patients, 1 to 7 years after repair. We tried to identify those patients who may benefit from early tendon transfer. This study confirmed a satisfactory functional result in sedentary workers, but not in manual labourers. Intrinsic muscle power, grip strength, key pinch and sensation continued to improve following repair of high injuries for at least 2 years, and of low injuries for at least 3 years. Early tendon transfers are only recommended in manual workers who complain of poor grip or key pinch.

Adolescent↗

The implication of repeated versus continuous strain on nerve function in a rat forelimb model.

We studied the effect of repeated and continuous nerve strain using a rat forelimb model to investigate whether an innocuous level of strain applied continuously affects nerve function when applied repeatedly. We used the rat medial cord of the brachial plexus and assessed the effects of strain by studying nerve histology (blood-nerve barrier), function (grasping strength), and electrophysiology. Continuous stretching was applied to the rat forelimb for 1 hour at 2 N. After this strain neither histologic analysis, grasping strength, nor electrophysiologic analysis revealed any effect. We then applied repeated strain at both 60 and 120 times per hour; after the latter strain abnormalities in histology, grasping strength, and nerve conduction were identified. There results suggest that a small nerve strain applied repeatedly results in nerve dysfunction. Our data may help explain the cause of nonspecific neural symptoms in the upper extremities of patients with no objective findings.

Animals↗

[Simultaneous management of multi-fragment distal radius fractures with palmar and dorsal approach].

Reconstruction of the articular anatomy can be extremely difficult in distal radius fractures with severe comminution of both the dorsal and palmar cortices. In these cases, neither open reduction using an unilateral approach nor closed reduction with ligamentotaxis and fixateur externe will be successful. Reconstruction of both the dorsal and palmar cortical column is necessary. Sixteen of nineteen patients with unstable bicolumnar distal radius fractures treated by a combined plate osteosynthesis were studied retrospectively. Follow-up time averaged 32.5 months (8 to 74). At the time of re-examination the average grip strength and range of motion were reduced by 30% compared with the uninjured side. The average DASH-score was 11.2 points. Radiographic measurements revealed a satisfactory restoration of the radius concerning length and form. There were no signs of higher graded arthrosis.

Adult↗

Upper body contribution during leg cycling peak power in teenage boys and girls.

This study investigated gender differences in upper-body contribution to cycle muscle power in 23 adolescents. All subjects performed two 5-s and one 20-s cycling sprint, using two protocols: with handgrip (WG) and without handgrip (WOG). Maximal handgrip strength was assessed for each individual. Absolute peak and mean cycling power was corrected for total fat-free mass (FFM) and for lean leg volume (LLV). Males showed higher cycling performance than females. Peak power and 20-s mean power (flywheel inertia included), but not optimal velocity, were higher WG than WOG. Especially for peak power, absolute differences between both protocols were higher in males than in females, and were significantly related to handgrip strength. The significant contribution of the upper body suggested that, for standardisation of cycle muscle power, total FFM is a more relevant variable compared with LLV. Furthermore, in adolescents, the higher contribution of the upper body musculature in males partly explained gender differences in peak power.

Adolescent↗

Physical and performance measures for the identification of mild to moderate frailty.

BACKGROUND: The relative importance and association of factors contributing to physical frailty in elderly persons are unclear. METHODS: Physical measures of upper and lower extremity strength, range of motion, balance, coordination, sensation, and gait were evaluated in relation to scores obtained on a 36-point physical performance test (PPT) in 107 elderly subjects. RESULTS: Scores on the PPT were significantly associated with the measures of strength and balance, gait, several range of motion values, and sensation. Subjects were also grouped according to score on the PPT as not frail (32-36 points), mildly frail (25-31 points), or moderately frail (17-24 points). ANOVA followed by Bonferroni post hoc analyses were used to examine the relationships of physical measures to this index of frailty. Balance measures, an obstacle course, the Berg scale, the full tandem portion of the Romberg test, and fast gait speed were significantly different among the three groups. Multiple stepwise regression analyses indicated that the strongest combination of variables, explaining 73% of all the variance in the PPT, included obstacle course performance, hip abduction strength, the semitandem portion of the Romberg test, and coordination (pegboard). CONCLUSIONS: Results provide further insight into the relative importance of factors that contribute to frailty and factors that should be considered in treatment planning for the remediation of physical frailty in old adults.

Aged↗

Preliminary results of double nerve transfer to restore elbow flexion in upper type brachial plexus palsies.

BACKGROUND: Restoration of elbow flexion is the main objective in the treatment of brachial plexus palsies affecting the upper roots. Transfer of the ulnar nerve to the nerve of the biceps has given satisfactory results, but the restored biceps is often weak in cases with avulsions of the C5-C6-C7 roots, in elderly patients, and after long preoperative delays. The authors decided to investigate a double nerve transfer: one or more fascicles of the ulnar nerve to the nerve to the biceps and a fascicle of the median nerve to the motor branch to the brachialis muscle. METHODS: The authors operated on 15 patients using this technique. The authors have follow-up of more than 6 months in 10 of them. Six had C5-C6 injuries, three had C5-C6-C7 palsies, and one had sustained an infraclavicular injury. The average age was 27.2 years. The average delay before surgery was 6.6 months. The average follow-up was 12.1 months. RESULTS: Grade 4 elbow flexion was restored in each of the 10 patients. In 10 cases, the patients were able to lift 1 to 5 kg. There was no secondary deficit in grip strength or sensation. CONCLUSIONS: The results of this technique compare favorably with those of other methods. The percentage of success and the strength of elbow flexion restored were increased without any morbidity. This technique will probably reduce the need for secondary procedures to augment elbow flexion. The authors propose double nerve transfer as a standard procedure in C5-C6 and C5-C6-C7 injuries.

Adult↗

Skeletal muscle mass and muscle strength in relation to lower-extremity performance in older men and women.

OBJECTIVE: Low muscle strength is associated with poorer physical function, but limited empirical evidence is available to prove the relationship between muscle mass and physical function. We tested the hypothesis that persons with lower muscle mass or muscle strength have poorer lower-extremity performance (LEP). DESIGN: A cross-sectional, population-based study. PARTICIPANTS: A cohort of 449 men and women aged 65 years and older living in Amsterdam and its surroundings participating in the second examination (1995-1996) of the Longitudinal Aging Study Amsterdam. MEASUREMENTS: Leg skeletal muscle mass was measured using dual-energy X-ray absorptiometry (DXA). Grip strength was used as an indicator of muscle strength. Timed functional performance tests, including walking and repeated chair stands, were used to assess LEP. RESULTS: After adjustment for body height and age, leg muscle mass was positively associated with LEP in men (regression coefficient 0.178 [95% confidence interval 0.013-0.343], P = .035). In women an inverse association was observed, which became positive after additional adjustment for body mass index (BMI) (0.202 [-0.001-0.405], P = .052). Grip strength was positively associated with LEP in men and women. After additional adjustment for behavioral, physiological, and psychological variables, the associations between leg muscle mass and LEP disappeared, whereas grip strength remained to be independently associated with LEP in men (0.079 [0.042-0.116], P = .0001), with a tendency in women (0.046 [-0.009-0.101], P = .11). Results were similar when quartiles of leg muscle mass or grip strength were used. CONCLUSIONS: These results suggest that low muscle strength, but not low muscle mass, is associated with poor physical function in older men and women. However, prospective studies are needed to investigate the association between loss of muscle mass and physical function.

Absorptiometry, Photon↗