Multijoint reflex responses to constant-velocity volitional movements of the stroke elbow.

Multijoint reflex coupling could impact the voluntary control of functional arm movements in people post stroke. The multijoint responses to active-assist, constant-velocity movements of the elbow joint were measured in 14 individuals post stroke and 9 neurologically intact controls. Resulting responses in the stroke group illustrated a change in the reflex coupling of the elbow and shoulder muscles compared with passive perturbations of the spastic elbow. Voluntary effort during constant-velocity elbow extension resulted in reflex shoulder abduction, differing from the reflex coupling observed between the elbow flexors and shoulder adductors observed during passive elbow extension. These results suggest that post stroke, voluntary drive alters reflex coupling of the elbow and shoulder. Flexion of the elbow during active-assist also resulted in reflex coupling. Shoulder abduction torque decreased with constant-velocity flexion of the elbow; however, no net adduction was observed at the end of the perturbation. Shoulder flexion/extension and internal/external rotation torque responses demonstrated similar modulations to imposed active-assist perturbations of the elbow in subjects post stroke. Responses were absent during passive perturbations of the control elbow; however, shoulder torque modulations were observed during constant-velocity, active-assist tasks. The active-assist response patterns in controls were similar to stroke subjects during the extension task but opposite during flexion of the elbow. This study provides evidence of a neural coupling between elbow and shoulder muscles and a modulation of this coupling during voluntary drive of the spastic arm.

Multijoint reflexes of the stroke arm: neural coupling of the elbow and shoulder.

The reflex torque responses of the elbow and shoulder to constant velocity angular extensions of the full comfortable range of the spastic elbow were measured in 16 people with unilateral stroke and 6 neurologically intact controls in order to identify the interjoint reflex coupling that occurs after stroke. The resulting responses showed a substantial reflex torque at the elbow and shoulder in subjects with stroke, with 12 of the 16 subjects producing adduction of the shoulder in response to passive extension of the elbow. The presence of simultaneous shoulder flexion torque with elbow flexion torque and with an identical waveform indicated an active role of biarticular elbow/shoulder flexors, such as the biceps. As the biceps muscle produces a shoulder abduction moment, shoulder adduction produced during elbow extension was thought to be associated with neural rather than biomechanical coupling. These results suggest that spasticity in people with stroke is more complex than its traditional perception as a hyperexcitable stretch reflex, and includes potent heteronymous reflex pathways. The reflex coupling observed between the shoulder and elbow should be considered in the diagnosis and clinical management of spasticity. The potential impact of this reflex on the coordination of volitional arm movements will be examined in future studies.

Reliability of biomechanical spasticity measurements at the elbow of people poststroke.

OBJECTIVE: To determine the minimum number of measurements required to obtain a reliable estimate of upper-extremity spasticity using biomechanic assessment across multiple testing trials and dates. DESIGN: Single-center, longitudinal study with repeated measurements of spastic upper-extremity torque measures taken 1 week apart. SETTING: A hospital-based laboratory with an isokinetic testing system. PARTICIPANTS: Sixteen subjects more than 6 months poststroke with upper-extremity spasticity. INTERVENTION: Elbow flexor hypertonia was assessed with a custom-made manipulandum attached to a 6-axis load cell and a Biodex System 3 isokinetic testing machine. Movements into extension were imposed at 4 speeds: 6 degrees /s, 30 degrees /s, 60 degrees /s, and 90 degrees /s. MAIN OUTCOME MEASURES: The resistive torque and electromyographic response to these imposed movements were measured. The torque response at the slowest speed (6 degrees /s) was attributed solely to the passive elements of the elbow and was subtracted from the torque response at the higher speeds (30 degrees /s, 60 degrees /s, 90 degrees /s), leaving only reflex torque. The reflex torques at 30 degrees /s, 60 degrees /s, and 90 degrees /s were used for further analysis. Peak torque, peak joint stiffness, and onset angle of reflex torque responses were found; repeatability and daily variability of these measures were statistically examined. The variabilities due to the subject, test day, and trial number were computed. The overall reliability of each parameter at the 3 higher test speeds using different testing schemes was also calculated. RESULTS: Ninety percent reliability in the measurement of all parameters was obtained after at least 2 days of testing during which 3 tests a day were performed. The variability in between-subjects measurements was at least 4 times greater than the intertrial variability when testing at the highest speeds; daily variability that was up to 50% of the intersubject variability was also observed. The biomechanic measures correlated well with the Ashworth Scale (Spearman rho=.84, P<.005), a clinical measure of hypertonia. CONCLUSIONS: We recommend at least 2 test dates to account for the daily variability in the spastic reflex response and to ensure reliable spasticity measurements.

Management of postsurgical hyperhidrosis with direct current and tap water.

BACKGROUND AND PURPOSE: Excessive sweating, known as hyperhidrosis, involves the eccrine sweat glands of the axillae, soles, palms, and/or forehead. The use of iontophoresis to reduce or eliminate excessive sweating has been described since 1952. The purpose of this case report is to describe the use of tap water galvanism (TWG) using direct current (DC) with a patient who had postsurgical hyperhidrosis. CASE DESCRIPTION: The patient was a 36-year-old male electrician with traumatic phalangeal amputation and postsurgical development of hyperhidrosis. Tap water galvanism was administered using a DC generator, 2 to 3 times per week for 10 treatments. The patient's hands were individually submerged in 2 containers of tap water with the electrodes immersed directly into the containers. Each hand was treated with 30 minutes of TWG at 12 mA. Hyperhidrosis was measured by a 5-second imprint and subsequent tracing of the left hand placed on dry paper toweling. OUTCOMES: The patient's hyperhidrosis decreased from the full left palmar pad, with a surface area of 10.3x12.0 cm, to a reduced area of wetness that covered a 2.2-x2.7-cm area. The patient returned to work as an electrician without needing absorbent gloves, which had prevented him from performing electrical work. DISCUSSION: Following use of TWG, the patient's palmar hyperhidrosis returned to normhidrosis.