A PILOT STUDY IN PREPARATION FOR AN INVESTIGATION INTO THE EFFECTS OF ELECTRICAL STIMULATION ON RECOVERY OF HAND SENSATION AND FUNCTION IN STROKE PATIENTS

Mann G.E.,¹ Malone L.¹Taylor P.N.¹ Burridge J.H.,²

¹Department of Medical Physics and Biomedical Engineering, Salisbury District Hospital, Salisbury, Wiltshire, SP28BJ

²Department of Rehabilitation and Health Sciences, University of Southampton,

Southampton, SO17 1BJ

SUMMARY

An important aim of rehabilitation therapy for the upper limb following stroke is the recovery of motor function. Recovery of sensation is also thought to have an effect on functional recovery.

The aim of this study is to investigate the effect of electrical stimulation on motor and sensory recovery in the upper limb and to establish their relative contributions to functional ability.

Subjects, within one year following a first stroke, were randomised into treatment and control groups. The treatment group received electrical stimulation of elbow and wrist extensors and the control group, elbow, wrist and finger extension exercises. Upper limb function was assessed using the Action Research Arm Test. In addition the Jebsen Taylor Hand Function Test was performed and hand sensation was assessed using the static Two Point Discrimination Test. Twelve subjects have completed the treatment stage of the study, 6 in the stimulation group and 6 in the control group.

This paper presents the results of the Action Research Arm Test for 12 subjects who have completed the treatment phase of the study.

STATE OF THE ART

There are nearly 150,000 first strokes a year in the United Kingdom. About half of these have impaired function of one upper limb and of these only 14% will regain any useful function.

The main focus of therapy for most patients following stroke is on recovery of motor function rather than any associated sensory deficits. However, it is well documented that these deficits have an adverse effect on functional outcome although the degree of functional impairment is not necessarily related to the extent of sensory loss.

Some physiotherapy treatment includes specific re-education of sensation in addition to motor retraining to improve function but few attempts have been made to promote recovery of sensation directly following stroke.

There has been little work with electrical stimulation to re-educate sensation in the hand of the hemiplegic patient with identified sensory deficit. Baker et al /1/ stimulated the wrist and finger extensors of 16 subjects over a 4 week period but recorded no changes in sensation using the 2 point discrimination test.

Prada /2/ found that use of ‘contingency stimulation’, that is, electrical stimulation to the hemiplegic forearm triggered by movement of the unaffected arm, resulted in significant improvement in awareness of the affected arm measured by the Rivermead Perceptual Assessment Battery and that this improvement was maintained.

Taylor et al /3/ conducted a retrospective analysis of 20 patients who had suffered a stroke at least 6 months prior to commencement of electrical stimulation treatment for the upper limb. These patients had restricted hand function but were able to take the hand to the mouth. They received electrical stimulation to the wrist and finger extensors reciprocally with either the lumbricals, the finger flexors or a rest period. Exercises were carried out twice daily for up to an hour a session. Tests of hand function using the Jebsen-Taylor hand function test, grip strength and the 2 point discrimination test for sensation were carried out.

Improvements in function were recorded and sensation tested in 11of the original 20 subjects showed improvement in 7 and no change in 4 subjects.

Few studies have quantified functional changes following therapy. Kraft et al /4/ compared three groups who received proprioceptive neuromuscular facilitation therapy, bias balance electrical stimulation therapy or EMG initiated stimulation to wrist extensors, with a control group. Assessments using the Fugl-Meyer (FM) post stroke recovery test showed significant improvements in all treatment groups, with the greatest gain in the EMG triggered stimulation group. Those in the treatment groups who could complete a Jebsen –Taylor hand function test also showed improvement. Controls showed no improvement.

MATERIALS AND METHODS

Subjects within a year of recovery from a first stroke leading to hemiplegia were recruited following admission to an acute inpatient rehabilitation unit, a neurological outpatient service or an Elderly Care Day Hospital. They were at least 18 years old with no upper age limit, medically stable, able to give informed consent and to comply with assessment procedures. Subjects who had evidence of sensory impairment and who were able to carry the hemiplegic hand towards the mouth were included.

Subjects were excluded if they had cognitive or psychiatric problems affecting their ability to understand or comply with treatment procedures, had a history of cardiac problems or wore a cardiac pacemaker.

Ethical approval for the study was obtained and subjects signed informed consent. Subjects were randomly assigned to the electrical stimulation group or the control group, using computer generated sealed allocation codes. All subjects continued with their standard physiotherapy, occupational and speech therapy.

Subjects in the electrical stimulation group received stimulation to the triceps and extensor carpi radialis and extensor digitorum communis muscles simultaneously to achieve a quasi functional movement. Stimulation was applied initially for 10 minutes twice a day, increasing to two 30 minute sessions a day.

Stimulation was delivered by a Microstim 2 neuromuscular stimulator, powered by a PP3 9 volt battery and producing a train of pulses of 300 microseconds duration at a frequency of 40Hz. Stimulation is applied for 8 seconds alternately with a rest period of 8 seconds with ramps of 2 seconds. The stimulation was applied using Pals skin surface self-adhesive electrodes. Current amplitude was adjusted to achieve full elbow, wrist and finger extension at a comfortable level.

Subjects in the control group were instructed in self-administered passive stretches of the elbow, wrist and fingers. These were carried out for the same length of time as the electrical stimulation exercises.

All inpatient treatments were supervised by a trained therapist. On discharge, treatment was supervised by a carer or carried out independently. Subjects carried out treatment for 12 weeks.

Demographic data was recorded for all subjects (Tables1 & 2).

Upper limb motor function was assessed using the Action Research Arm Test /5/ and hand function using the Jebsen-Taylor Hand Function Test /6/. The 2 point discrimination test was used to assess sensation in the hand /7/.

Assessments were carried out by a trained therapist at week 0 (start of treatment), week 6 (treatment) week 12 (end of treatment) and week 24, (12 weeks post treatment). Results of the assessments at from weeks 0-12 were analysed using paired t tests.

RESULTS

Results are presented for the Action Research Arm Test (ARAT) /6/only.This test consists of sections for Grasp, Grip, Pinch and Gross Movements. Each section is scored separately and the scores added. The maximum possible total score is 57.

Twelve subjects, 8 female and 4 male, mean age 71.9 years (+/-10.1) have completed the treatment phase of the study (seeTable1). Six subjects received electrical stimulation and 6 were in the control group.

	FES group	Control group
Mean Age (SD) yrs.	68.2 ( 9.1)	75.7 ( 10.3)
Age range yrs.	58 - 80	63 - 88
Sex	3 Female – 3 Male	5 Female – 1 Male
Side of hemiplegia	3 Right – 3 Left	1 Right – 5 Left
Mean time since stroke (SD)	7.2 (5.0) months	8.8 ( 2.8)
Cause of stroke	5 Infarct – 1Haemorrhage	5 Infarct – 1 Haemorrhage

Table1: Demographic data

Following randomisation it was observed that initial Action Research Arm Test scores for the stimulation group were higher than those for the controls. All subjects showed improved scores over the treatment period from weeks 0-12. Changes in weeks 0-6 of treatment were significant in both groups – FES: p<0.010, :Controls p<0.042. Improvement continued in both groups during weeks 6-12 but was only significant in the stimulation group FES p<0.001, Controls p< 0.094 (see Table 2).

Mean ARAT Scores FES

Mean ARAT Scores Controls

Week

Mean score(SD)

23.0(17.2)

32.7(15.1)

40.0(14.0)

8.8(7.7)

13.7(9.2)

16.5(11.0)

p-value at 95% C.I

Confidence interval

0-6weeks p<0.010

0-12weeks p<0.001

0-6weeks p<0.042

0-12weeks p<0.094

-15.88, -3.45

-23.74, -10.26

-9.77,-0.023

-14.02,+1.45

Table 2 SD = Standard Deviation

DISCUSSION

These preliminary results indicate that although improvement in Action Research Arm Test scores is achieved by both stimulation and control groups between the first 2 assessments between weeks 0 and 6 of treatment , there is greater improvement in the stimulation group Between the second and third assessments at weeks 6 and 12 there is continued improvement in both groups but this is significant only in the stimulation group. There are a number of possible reasons for this. Despite randomisation the initial Action Research Arm Test scores for the FES group at week 0 were lower for the control group than for the stimulation group. The mean age of the control subjects was greater and they had a longer time interval since onset of stroke. These factors need to be examined further for their possible contribution to the differences in level of improvement in the 2 groups.

Clinically, subjects require at least some active movement at the shoulder to be able to perform the tasks in each section of the Action Research Arm Test successfully. It was evident that some subjects who were able to perform the hand movement to initiate a task were unable to complete it because of lack of active movement at the shoulder. The criteria for inclusion in the study did not identify poor shoulder movement as a limiting factor and this could be a reason for the poorer performance of some subjects who were able to achieve the required hand movements.

Although the title of this study states that it is concerned with hand function and sensation, it will be necessary in a future trial to include assessment of the shoulder as an essential component of the upper limb in performance of function.

Therefore, in addition to informing sample-size calculations for a larger trial in the future, this study is also important to identify the most appropriate outcome measures for recovery of upper limb function and sensation following stroke.

REFERENCES

Baker LL, Yeh C, Wilson D, Waters RL. Electrical stimulation of wrist and fingers for hemiplegic patients. Physical Therapy 1979; 59 (12):1495 – 1499.

Prada G, Tallis R. Treatment of the neglect syndrome in stroke patients using a contingency stimulator. Clinical Rehabil 1995; 9:304 – 313.

Taylor PN, Burridge JH, Hagan SA, Chapple P & Swain ID. Improvement in hand function and sensation in chronic stroke patients following electrical stimulation exercises. A retrospective clinical audit.Pro Vienna 5^th. International Workshop on Functional Electrostimulation ISBN3-900928-03-7 pp359-362.

Kraft GH, Fitts SS & Hammond, MC. Techniques to improve function of the arm and hand in chronic hemiplegia. Arch. Phys. Med. Rehabil. 1992; 73: 220-227.

Carroll, D. A Quantitative Test of Upper Extremity Function, Journal of Chronic Diseases,1965 Vol.18: 479-491.

Jebsen RH, Taylor N et al. An objective and standardised test of hand function. Arch. Phys. Med. and Rehabil. 1969; June: 311 – 319.

Lee Dellon, A. The Sensational Contributions of Eric Moberg. Journal of Hand Surgery, 1990 15B: 14-24.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the contribution of the Physiotherapy Research Foundation in part funding this study.

AUTHOR’S ADDRESS

Geraldine E. Mann

Dept. Medical Physics

Salisbury District e-mail: G.Mann@mpbe-sdh.demon.co.uk