Search

NARRATIVE REVIEW: Patients with focal hand dystonia and upper extremity entrapment neuropathies may present with similar symptoms and risk factors making it difficult to distinguish between the two diagnoses. Evaluating for the presence of neuromuscular findings and abnormal movement patterns can help assist the hand therapist in identifying the presence of focal hand dystonia or peripheral motor axon involvement in the absence of pronounced muscle atrophy. The purposes of this review article are twofold. First, to describe selected neuromuscular signs and symptoms characteristic of patients presenting with repetitive overuse syndromes of the upper limb leading to either a nerve entrapment syndrome or a focal hand dystonia. The selected topics will be limited to an overview of ectopic neuronal activity with an emphasis on fasciculations, muscle spasms/cramps, and sensation (including pain). Second, the article will conclude with a brief synopsis of focal hand dystonia and compression neuropathies, highlighting general assessment and treatment principles.

The purpose of the current study was to examine motion enslaving characteristics of multiple fingers during isolated flexion of the distal interphalangeal joints. Because the distal interphalangeal joints are flexed by multiple tendons of the single flexor digitorum profundus, the current experimental design provided a unique advantage to understand inter-finger enslaving effects due to the flexor digitorum profundus. Eight subjects were instructed to flex the distal interphalangeal joint of each individual finger from the fully extended position to the fully flexed position as quickly as possible. Maximal angular displacements, velocities, or accelerations of individual fingers were used to calculate the enslaving effects. An independence index, defined as the ratio of the maximal displacement of a master finger to the sum of the maximal displacements of the master and slave fingers, was used to quantify relative independence of each finger. The angular displacements of the index, middle, ring, and little fingers were 68.6° (±7.7), 68.1° (±10.1), 68.1° (±9.7), and 74.7°(±13.3), respectively. The motion of a master finger was invariably accompanied by motion of 1 or 2 slave fingers. Angular displacements of master and slave fingers increased to maximum values with time monotonically. Velocity curves demonstrated bell-shaped profile, and the acceleration curves were sinusoidal. Enslaving effects were generated mainly on the neighboring fingers. The amount of enslaving on the middle and ring fingers exceeded more than 60% of their own maximum angular displacements when a single adjacent finger moved. The index finger had the highest level of independence as indicated by the lowest enslaving effects on other fingers or by other fingers. The independence indices of the index, middle, ring, and little fingers were 0.812 (±0.070), 0.530 (±0.051), 0.479 (±0.099), and 0.606 (±0.148), respectively. In all tasks, motion of slave fingers always lagged with respect to the master finger. Time delays, on average, ranged from 7.8 (±5.0) to 35.9 (±22.1) ms. Our results suggest that there exist relatively large enslaving effects among the compartments of the flexor digitorum profundus, and functional independence of fingers in daily activities is likely enhanced through synergistic activities of multiple muscles, including flexors and extensors. [ABSTRACT FROM AUTHOR]