Tetraplegic Abstracts

Clinical Experience Of The Neurocontrol Free Hand Neuro Prosthesis For Tetraplegic Hand Function.

Deltoid Triceps Transfer And Functional Independence Of People With Tetraplegia.

A portable system for closed loop control of the paralysed hand using functional electrical stimulation.

Clinical Experience of the NeuroControl Freehand System.

Electrical stimulation of abdominal muscles for control of blood pressure and assisted cough in a C4 level tetraplegic.

Pattern of use and user satisfaction of Neuro Control Freehand System.

Restoration of tetraplegic hand function by use of the NeuroControl Freehand System.

J Esnouf, P Taylor, J Hobby

Salisbury District Hospital, Salisbury, Wiltshire, SP2 8BJ

5th IPEM Clinical FES Meeting, Salisbury, March 1997

Introduction

Much can be done to improve the hand function of tetraplegic patients who have C6 lesions and below with international classifications 3 or better by the use of tendon transfers. However, those with weak C6 and C5 lesions present a greater problem to the hand surgeon as these patients have insufficient muscles under voluntary control for tendon transfer. The NeuroControl Free Hand System attempts to produce a useful grasp by means of an implanted FES (Functional Electrical Stimulation) device. Epimysial electrodes are implanted on to up to 8 muscles to produce finger flexion and extension, abduction, adduction, flexion and extension of the thumb. C5 subjects who have no voluntary wrist extension use the 8th channel to provide wrist extension. In subjects who have wrist extension, the 8th electrode can be used to provide sensory feedback by stimulating the skin sensory receptors at the shoulder, an area where all the subjects will have normal sensation. The frequency of stimulation is increased in five stages as the hand moves from open to a tight grip.

Control signals and power are propagated by radio telemetry through the skin from an induction coil taped to the skin, to the implant receiver, implanted just below the shoulder. The user controls the hand by moving the contralateral shoulder, detected by a twin axis goniometer on the skin surface. The control can be programmed to respond to protraction and retraction or elevation and depression of the shoulder. For example, a user might retract their shoulder to open his hand and protract to close the hand. If the user wishes to hold an object for an extended time, the hand can be locked in position by making a quick movement with the shoulder. If a velocity threshold is exceeded the hand is locked in that position until the velocity threshold is exceeded a second time.

Materials and methods

Patients are assessed using the GRT (Grasp Release Test), ADL assessment, grip strength, range of motion (ROM) and usage by questionnaire. 5 subjects have received the implant (tables 1 and 2). Subjects are assessed prior to implant. Following the operation the arm is immobilised in plaster for three weeks. Once the plaster is removed electrical stimulation training exercises are commenced. The duration of the exercises is doubled weekly.

Table 1.

*Sensory ability: O - eye sight but no skin sensation, OCu - eye sight and skin sensation.

Transferable muscles: 0 - no muscle below elbow, 1 - Br only, 2 Br and one wrist extensor.

Table 2.

four weeks exercise are of eight hours duration and carried out at night. At this point the

shoulder controller is tried and if successfully used, taken home to practice hand control. At 11 weeks post op the subjects are re-assessed and trained to complete there self selected ADL tasks. Once the training is completed, the subjects are again assessed. Follow up assessments are made at six and twelve months.

Results

At the time of writing three subjects have reached or completed the training stage of the programme. One subject will enter it in four weeks time and the fifth subject in three months time. Of the three patients who have reached the training stage:

1. All have achieved their self chosen ADL tasks.

2. All have achieved improved scores in the GRT.

3. All three patients have achieved a greater ROM when using the system.

4. All patients have achieved grip strength measurements where no grip was possible before.

5. All patients have use the system on a daily basis preferring to use the device rather than previously used splints and aids.

6. One patient (3) has suffered radial nerve dysfunction preventing finger, thumb and wrist extension due to an unrelated cause, preventing the full use of the device. This may be temporary dysfunction due to a Neuropraxia.

Conclusions

1. The Free Hand System provides useful function for C5/C6 tetraplegics.

2. Provision of wrist extension is important for use of the system with C5 patients.

Address for correspondence: Department of Medical Physics and Biomedical Engineering, Salisbury District Hospital, Salisbury, Wiltshire, SP2 8BJ. 0122 336262 Ex 4121 / 4065

Reference

Keith MW, Peckham PH, Thrope GB, Stoh KC, Smith B, Buckett JR, Kilgore KL, Jatich JW. Implantable functional neuromuscular stimulation in the tetraplegic hand. J Hand Surg 14A:524-530, 1989

Dunkerley AL. MSc BSc (Hons) MCSP SRP

Research Physiotherapist at Salisbury District Hospital.

16th Guttmann Multi-Disciplinary Meeting, 1999

Abstract

Introduction: Surgical restoration of active elbow extension in patients with cervical spinal cord injury is thought beneficial in increasing functional ability, but has been poorly evaluated. The aim of this study was to compare the functional ability of spinal injured patients, post deltoid triceps transfer, with matched control subjects.

Setting: Two regional spinal units - Salisbury (surgical centre) and London (control centre).

Subjects: Two matched groups of subjects with tetraplegia, resulting in triceps paralysis. The surgical group consisted of 5 of the 6 patients who had undergone deltoid triceps transfer at Salisbury. The control group (n=6) had not undergone surgical intervention but were comparable with respect to level of lesion, age, age at injury and duration of disability.

Method: A Matched Case Control Study was conducted. All subjects completed standardised assessments of activities of daily living (Functional Independence Measure - FIM) and wheelchair mobility (10 metre Push & Figure of 8 Push). Surgical subjects completed additional questions, regarding the perceived effects of surgery on function.

Results: Surgical subjects tended towards higher scores than controls in two FIM areas (grooming & upper body dressing). Two surgical subjects completed the 10 metre Push more quickly than their controls. All subjects performed similarly in the Figure of 8 Push. Statistically significant differences were not found using paired sample t-tests and Wilcoxon Matched Pairs Signed Ranks Tests. All surgical subjects cited specific functional improvements since surgery and recommended the procedure.

Conclusion: Further investigation of the functional outcome of deltoid triceps transfer in tetraplegia is warranted. Development of more sensitive outcome measures would be useful.

SE Crook, PH Chappell

Medical Engineering and Physics 20 (1998) 70-76

A Portable and closed-loop system is described for the paralysed hand using transcutaneous electrical stimulation. It is implemented using a modest microprocessor which receives data from force sensors mounted in a glove on the hand. A display shows parameter values and a menu for the user to sequentially select control states. For the grip, the control loop is basically proportional plus a two stage integral response (gain adaptation). Eight channels can be accommodated in the stimulator. The system was evaluated with the help of a tetraplegic who managed to hold everyday objects in a stable grip.

J Esnouf,* P Taylor, J Hobby**

Department of Medical Physics and Biomedical Engineering, *The Duke of Cornwall Spinal Treatment Centre, **The Odstock Centre for Burns, Plastic and Maxillo-Facial Surgery, Salisbury District Hospital, Salisbury, Wiltshire SP2 8BJ. Tel. 01722 429 121, Fax. 01722 425 263. E-mail j.esnouf@mpbe-sdh.demon.co.uk Web page www.mpbe-sdh.demon.co.uk.

6th IPEM Clinical FES Meeting April 12,13 2000 University of Surrey.

Introduction

The NeuroControl Free Hand System from Cleveland Ohio, is an implanted FES device intended for the restoration of hand function in C5 and C6 level tetraplegics. The subject controls the device by movement of the opposite shoulder, using a skin surface mounted position detector. The strength of the grasp is proportional to the distance moved by the shoulder. Both palmar and lateral grasps are possible, selected by pressing a button on the shoulder controller. This paper reports on the first nine Freehand users in Salisbury.

Method

Prior to implantation, the muscles of the hand and forearm are conditioned using surface electrical stimulation for a period of 4 to 8 weeks. Following the 6 hour operation, the arm was in plaster for three weeks. Muscle training is then commenced using the implant. After four weeks the shoulder controller is fitted and training in the use of the system commenced. Good independent function was usually achieved after a 2 to 4 weeks of practice.

Assessments

Outcome was assessed using a standardised hand function test called the Grasp Release Test. It consists of the following 6 tasks:

This device is intended to simulate the act of stabbing with a fork and is calibrated to the standard baked potato. The number of times each task is repeated in 30 seconds is recorded.

Grip strength is measured using a modified Gaymar dynamometer. Three grips are recorded, a lateral grasp, a Palmer grasp and a five finger grasp. ADL

(Activities of Daily Living) is assessed by patient goals. The subject chooses eight activities that they can not perform or wish to improve, prior to receiving the implant. Tasks are scored to record the amount of assistance or aids required in the set up, performance, and take down stages of each task. A questionnaire was also sent in a single mail shot to determine the user opinions about the system.

Sensory ability was monitored using static two-point discrimination. The medial and lateral side of each finger and thumb pulp was recorded.

Outcome measure assessments are made prior to receiving the implant and after 1 year of functional use of the system. Additionally, the GRT and grip strength measurements were made at the end of the training period. ADL re-assessments were only made at the post training stage. Statistical significance was shown using the Wilcoxon signed rank test.

Results

Two subjects discontinued using the system. The first developed a lesion of the post interosseus nerve as it passes under the supinator, after three months of system use. The lesion, which prevented finger, thumb and wrist extension, was of unknown origin but is not thought to be directly related to the system. The second subject reported problems with bowel motility, experienced after 2 to 4 days of use, leading to severe constipation. This was thought to be due to autonomic nervous system disturbance and as yet the problem remains unsolved preventing the subject from using the system.

System users:

There were statistically significant increases in the number of types of task achieved and the number of repetitions of those tasks in the grasp release test. Subjects could perform on average 5.1 types of task (max 6) post implant with the system compared with 1.4 (p=0.010) pre implantation and 1.5 (p=0.011) post implantation without the implant. Subjects could perform on average 37.4 repetitions post implant with the system compared with 12.7 (p=0.028) pre implantation and 20.2 (p=0.046) post implantation without the implant. Improvement in tenodesis grip of the C6 subjects post op, lead to an improvement in the tasks requiring little force when the system was not used.

The system produced a functionally strong grasp where no grip strength at all was possible prior to implantation. Four subjects had sufficient tenodesis grip to produce a measurable grip pre implant. They had a mean lateral, Palmer and five finger grasp of 0.93 N, 0.96N and 1.04N respectively. This was not significantly changed post implantation when the implant was not used in this sub group. With the implant post implantation the mean lateral, palmer and five finger grasp had increased to 11.2N, 9.5N and 10.4N respectively, all changes shown to be significant (p=0.012)

Three of the four subjects who had sensory ability prior to implant showed improvements in two-point discrimination.

Most of the selected tasks were achieved in the Activities of Daily Living Assessment indicating a significant improvement in independence. Out of eight selected tasks, on average 3.8 new tasks could be performed by each Free Hand System user with adaptive equipment being eliminated from 1.8 tasks. Carer assistance was eliminated from an average of 0.9 tasks while self-assist techniques were discontinued in 1.5 tasks indicating that they were performed in a more normal manner. On average, Free Hand users preferred to use their system in 6.5 tasks each.

Seven of the subjects are currently daily users of the device. Some problems had been experienced with equipment reliability and skin allergy to the tape used to secure external components. The system did not significantly alter the amount of carer time required, although two subjects believed the burden on family members was lessened. Six users felt more confident when using the system and seven felt their quality of life had improved.

Conclusion

The Free Hand system can significantly improve the functional ability and perceived level of independence of C5 and C6 lesion tetraplegics.

Acknowledgements

Thanks to Jonathan Norton of University College for assistance with the questionnaire. Thanks also to the INSPIRE Foundation who funded this work.

PN Taylor, A Tromans*, ID Swain.

Department of Medical Physics and Biomedical Engineering, *The Duke of Cornwall Spinal Treatment Centre, Salisbury District Hospital, Salisbury, Wiltshire SP2 8BJ. Tel. 01722 429 040, Fax. 01722 425 263. E-mail p.taylor@mpbe-sdh.demon.co.uk Web page www.mpbe-sdh.demon.co.uk.

IFESS 2000 18-20th June 2000

Purpose

It has been shown by several groups that electrical stimulation can cause autonomic dysreflexia in tetraplegics and high level paraplegics. This effect has been used by a C4 ventilator dependent tetraplegic to raise and maintain blood pressure following postural hypotension, particularly after meals. Additionally the system assists coughing function by stimulation of the abdominal muscles.

Method

A dual channel stimulator was designed that allowed selection and initiation of two predetermined stimulation intensities using a chin controlled joystick. Two sets of 70mm dia electrodes were placed either side of the abdomen. Approximately 80mA, 300ms, 40 Hz was required for assisted cough while about 40mA was required for maintenance of blood pressure. After eating the lower level stimulus is self-administered every 3-5min gradually increasing the time between groups of burst to once every hour over 90 minutes.

Results

Following eating a blood pressure of 60 / 45 mmHg was recorded. After five 1 second bursts of stimulation in quick repetition, this was increased to 133 / 92 mmHg. After 2 minutes blood pressure had fallen to 124 / 86 mmHg and to 93 / 66 after a further 4 minutes. The electrical stimulation was then repeated, returning the blood pressure to the previous higher level. Measurement of peak expiratory flow showed an increase from 275 l/min for an unassisted cough to 425 l/min when using the device.

Conclusion

The device is used every day. The user is now independent in coughing function and no longer requires suction or manual assistance. Maintenance of blood pressure has significantly improved his quality of life.

Taylor P, Esnouf J, Hobby J. Pattern of use and user satisfaction of Neuro Control Freehand System. J. Spinal Cord 2001 39, 156 - 160

Paul Taylor, Julie Esnouf and John Hobby

J. Spinal Cord 2001 39, 156 - 160

Abstract

Objectives: Evaluation of the use and acceptability of the Neuro Control Free Hand system.

Study design: A questionnaire was sent in a single mail shot to users of the system. Administration was by a 3rd party with anonymous returns.

Setting: A supra regional spinal unit in the UK.

Methods: The Freehand system is an implanted Functional Electrical Stimulation (FES) device for restoration of lateral and palmar grasps following C5 or C6 tetraplegia.

Results: Replies were received from 7 users of the system who had an average experience of 23 months use. All used the system daily and had increased their range of activities of daily living skills. Some problems had been experienced with equipment reliability and skin allergy to the tape used to secure external components. 6 users felt more confident when using the system and 7 felt their quality of life had improved.

Conclusion: The Free Hand System provides increased function that is considered by its users to be of benefit.

Sponsorship: This study was funded by the charity INSPIRE.

Key words: Freehand, FES, and tetraplegia, ADL, user satisfaction survey.

J Hobby, PN Taylor, J Esnouf

J. Hand Surgery 2001 26B 5 pp 459-464

Abstract

Nine tetraplegic subjects with C5 or C6 level spinal cord lesion received an eight channel implanted Functional Electrical Stimulation device for provision of hand opening and grasp, known as the Freehand System. This paper describes the surgical implementation of the system and describes the challenges encountered. Seven of the subjects are currently daily users of the device. One subject is unable to use the system due to disruption of bowel function when the system is used, thought to be related to disturbance of the autonomic system. A second subject suffered a lesion of the posterior interosseus nerve, but this was not thought to be related to system use. Additionally, one subject exhibited symptoms of autonomic dysreflexia, which were alleviated by reduction of the strength of the stimulus. Despite problems the Freehand system can significantly improve the functional ability of C5 and C6 lesion tetraplegics.