Date Published: June 12, 2019
Publisher: Public Library of Science
Author(s): Helleana Eschmann, Martin E. Héroux, James H. Cheetham, Stephanie Potts, Joanna Diong, Sunghoon Ivan Lee.
Hand motor impairment is common after stroke but there are few comprehensive data on amount of hand movement. This study aimed to compare the amount of thumb and finger movement over an extended period of time in people with stroke and able-bodied people. Fifteen stroke subjects and 15 able-bodied control subjects participated. Stroke subjects had impaired hand function. Movement of the thumb and index finger was recorded using stretch sensors worn on the affected hand (stroke subjects) or the left or right hand (control subjects) for ∼4 hours during the day. A digit movement was defined as a monotonic increase or decrease in consecutive sensor values. Instantaneous digit position was expressed as a percentage of maximal digit flexion. Mixed linear models were used to compare the following outcomes between groups: (1) average amplitude of digit movement, (2) digit cadence and average digit velocity, (3) percentage of digit idle time and longest idle time. Amplitude of digit movement was not different between groups. Cadence at the thumb (between-group mean difference, 95% CI, p value: -0.6 movements/sec, -1.0 to -0.2 movements/sec, p = 0.003) and finger (-0.5 movements/sec, -0.7 to -0.3 movements/sec, p<0.001) was lower in stroke than control subjects. Digit velocity was not different between groups. Thumb idle time was not different between groups, but finger idle time was greater in stroke than control subjects (percentage of idle time: 6%, 1 to 11%, p = 0.02; longest idle time: 375 sec, 29 to 721 sec, p = 0.04). Rehabilitation after stroke should encourage the performance of functional tasks that involve movements at faster cadences, and encourage more frequent movement of the digits with shorter periods of inactivity.
Motor impairment at the hand is common after stroke . At 6 months after severe stroke, one third of people develop wrist and hand contracture (loss of passive joint range of motion)  and more than 50% of people with hand impairments do not regain function . The loss of functional hand movement is disabling and can persist for many years . The neurophysiological mechanisms underlying the recovery of hand function are complex, interdependent, and occur at different periods of time after onset of stroke; see reviews [5–7]. For example, hand impairments in chronic stroke are related in part to a decreased ability to control voluntary muscle activity [8, 9] and the abnormal recruitment of contralateral cortico-reticulospinal pathways . Greater understanding on the mechanisms of recovery after stroke is needed to develop effective interventions to improve hand function after stroke.
This was a cross-sectional observational study. The procedures conformed to the Helsinki Declaration and were approved by South Eastern Sydney Local Health District Human Research Ethics Committee (16/095). To enhance transparency of data analysis, all de-identified data and computer code used to analyse the data are available in the project folder on the Open Science Framework. Written consent was obtained from all subjects.
Characteristics of subjects are shown (Table 1). Stroke subjects had impaired hand function, were older than control subjects, and the range of time since stroke was broad. There was no difference between groups in sex. On average, stroke subjects wore the sensors for median 3.3 hours (interquartile range 2.1 to 3.7 hours) and control subjects for 3.1 hours (2.3 to 3.7 hours). Inspection of the raw data showed sensor values were outside of the physiological range of raw values for the thumb sensor in some subjects (1 control, 2 stroke subjects). We excluded thumb sensor data for these subjects.
We used stretch sensors to compare thumb and index finger movement over an extended period of time in people with stroke and able-bodied people. While the amplitudes of digit movement and digit velocities were not different between groups, people with stroke had lower thumb and finger cadences, and the finger was idle more often than the thumb. Exploratory findings show that in general, digit cadences and velocities ranged from slow to medium speeds.
Our findings add new information to the literature by providing the first comprehensive description of thumb and finger movement over an extended period of time in people with stroke. The clinical implications from this study are that rehabilitation after stroke should encourage the performance of functional tasks that involve movements at faster cadences, and encourage more frequent movement of the digits with shorter periods of inactivity. These strategies aim to improve and restore hand function after stroke.