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A Pilot Study to Investigate the Combined Use of Botulinum Neurotoxin Type A and Functional Electrical Stimulation, with Physiotherapy, in the Treatment of Spastic Dropped Foot in Subacute Stroke

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A Pilot Study to Investigate the Combined Use of Botulinum Neurotoxin Type A and Functional Electrical Stimulation, with Physiotherapy, in the Treatment of Spastic Dropped Foot in Subacute Stroke
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  A Pilot Study to Investigate the Combined Use of Botulinum Neurotoxin Type A and Functional ElectricalStimulation, with Physiotherapy, in the Treatment of Spastic Dropped Foot in Subacute Stroke *Catherine A. Johnson, *Duncan E. Wood, *Ian D. Swain, †Anthony M. Tromans,‡Paul Strike, and §Jane H. Burridge *Department of Medical Physics and Biomedical Engineering, †Duke of Cornwall Spinal Treatment Centre, ‡Researchand Development Support Unit, Salisbury District Hospital, Salisbury; and §University of Southampton,Southampton, United Kingdom Abstract:  The objective was to inform sample size calcu-lations for a full randomized controlled trial (RCT). Thedesign included an RCT pilot trial with a 16 week studyperiod, including a 4 week baseline phase. The subjectswere adults within 1 year of first stroke, ambulant with aspastic dropped foot. Twenty-one participants were re-cruited from the stroke services of 4 centers. For interven-tion all participants received physiotherapy; the treatmentgroup also received botulinum neurotoxin Type A(BoNTA) intramuscular injections to triceps surae (800 UDysport) and functional electrical stimulation (FES) of the common peroneal nerve to assist walking. The mainoutcome measure was walking speed. The result was asignificant upward trend in median walking speed for boththe control (p  0.02) and treatment groups (nonstimu-lated p  0.004, stimulated p  0.042). Trend lines weredifferent in location (p    0.04 and p    0.009, respec-tively). In conclusion, there is evidence of an additional,beneficial effect of BoNTA and FES. Sufficient informa-tion has been gained on the variability of the primary out-come measure to inform sample size calculations for a fullRCT to quantify the treatment effect with precision.  KeyWords:  Electrical stimulation—Botulinum toxin—Stroke—Equinus. There are approximately 100,000 hospital admis-sions for stroke in the United Kingdom annually;20% are fatal, 20% make a full recovery, and 60%make a partial recovery but have a restricted lifestyle(1). Physiotherapists working with these patients aimto maximize the recovery of movement and functionthrough the reeducation of postural control and nor-mal activity. There are no statistics on how manypatients might benefit from the combined use of functional electrical stimulation (FES) and botuli-num neurotoxin Type A (BoNTA), but 20% (2)would be a conservative estimate of the proportionof patients suffering from a spastic drop foot. Thisgroup of patients experiences difficulty when walk-ing because the patients are unable to dorsiflex theirankle effectively during the swing phase of walking.The problem arises partly through an inability toactivate the anterior tibial muscles and partlythrough restraint from the calf muscles. In some, butnot all cases, the restraint is due mainly to inappro-priate (spastic) calf activity; in others the mechanicalresistance offered by the calf is the predominant fac-tor. Knuttson and Richards (3) described prematurecalf activity in one-third of the study group of pa-tients with spastic hemiparesis. Electromyographical(EMG) activity in the triceps surae began andpeaked earlier in the gait cycle, compared with nor-mal; peak activity was lower in the triceps surae andin the tibialis anterior.FES applied to the common peroneal nerve and Received October 2001.Presented in part at the Seventh Vienna International Work-shop on Functional Electrical Stimulation, held September 12–15,2001, in Vienna, Austria.Address correspondence and reprint requests to Catherine A.Johnson, Clinical Research Physiotherapist, Department of Medi-cal Physics and Biomedical Engineering, Salisbury District Hos-pital, Wiltshire, SP2 8BJ, United Kingdom. E-mail calj@mpbe-sdh.demon.co.uk  Artificial Organs 26(3):263–266, Blackwell Publishing, Inc.© 2002 International Society for Artificial Organs  263  timed to the swing phase of walking has been shownto be effective in patients with poor active ankledorsiflexion and calf spasticity (4,5). FES is thoughtto have an inhibitory effect on antagonist activityand thus reduce calf spasticity; it may also improvethe mechanical component of calf restraint throughstretching of the triceps surae muscle group. BoNTAalso has been shown to reduce inappropriate calf activity (6) particularly in patients with prematurecalf activation during walking. The presence of spas-tic dropped foot frequently causes stroke patients toadopt an abnormal gait pattern that may exacerbateextensor spasticity. Once established, such abnormalpatterns are difficult to correct. By applying thesecombined treatments during the recovery phase, thelong-term outcome of the mobility of stroke patientsmay be improved. PATIENTS AND METHODS Twenty-one patients were recruited from thestroke services of 4 National Health Service Trusts inEngland according to the following selection criteria:single stroke of vascular srcin with hemiplegia dur-ing the previous 12 months; inability to achieve aheel strike, correctable by FES; between 3 and 6inclusive on the Hauser Ambulation Index; an in-creased calf stretch response on examination; andpremature calf activation during gait identified byEMG activity. Patients were excluded who had anyadditional medical condition that might influence re-sponse to treatment; were prescribed antispasticmedication; were prescribed medication that mayhave influenced heart rate measurements, either atthe time of recruitment or during the 4 weeks priorto recruitment; had severe psychological problems;and were unable to give informed consent.Participants were randomized into 2 groups; eachselected a sealed opaque envelope containing an ex-planatory letter allocating them into 1 of the groups.The control group received physiotherapy. Thetreatment group received physiotherapy and thecombined use of FES and BoNTA. Both groups con-tinued with their physiotherapy program throughoutthe study period. In-patients received a minimum of 3 sessions per week and outpatients 2 sessions perweek.Subjects in the treatment group received BoNTAinjections at Week 0. The medial and lateral heads of the gastrocnemius each were injected with 200 U of Dysport and the tibialis posterior with 400 U. Thisdose was modified for less spastic muscles or smallerpatients. Injections were given under EMG guid-ance.FES was used by the treatment group patients im-mediately following BoNTA injections. An OdstockDropped Foot Stimulator mark III (ODFS III) wasset up by the research physiotherapist following thestandard protocol with a full explanation and a copyof the user instruction manual. The device delivereda train of electrical impulses at a frequency of 40 Hz,pulse width of 0 to 350   s, and maximum amplitudeof 100 mA, via surface electrodes. The common pe-roneal nerve was stimulated and timed to the per-son’s walking speed by a footswitch. Patients wereasked to use the system on a daily basis to assist theirwalking and for most of each day. Cyclic exercisestimulation was used in patients with higher levels of calf spasticity and where mechanical constraint of the triceps surae was present to maximize the pa-tient’s response to the use of the ODFS III.Assessments for the study were carried out by theresearch physiotherapist in the patient’s local phys-iotherapy department at Weeks −4, −2, 0, 2, 4, 8, and12. The primary outcome measures were nonstimu-lated (both groups) and stimulated (treatmentgroup) walking speed and Physiological Cost Index(PCI) of gait. The walking tests were performed overa 10 m walkway with stand-by assistance only. Pa-tients were permitted to use a walking aid but noother type of orthosis. Patients were asked to  walkbriskly  to produce a constant response. Two meterswere given for acceleration behind the start line andbeyond the finish line for deceleration. The meanscore of 3 tests was recorded where possible. In thetreatment group, the sequence of recording non-stimulated walking was randomized to avoid a biasfrom fatigue: 2 nonstimulated, 3 with stimulation,and 1 nonstimulated. A Polar heart rate monitor wasused to record heart rate at rest and immediatelyfollowing each 10 m walk to measure the energyefficiency of walking as calculated by the PCI. RESULTS Of the 21 patients recruited, complete data wereavailable on 18 patients. One participant of the con-trol group suffered a subsequent stroke and waswithdrawn from the study. Two participants from thetreatment group did not complete the study period.The first did not fulfil the selection criteria at Week0 and was withdrawn, and the second participantwithdrew after experiencing headaches during thefirst few days of using stimulation. A total of 32 sub- jects had been advised at the outset, but this was notachieved within the time scale. Eleven other patientswere screened: 5 did not fulfil the selection criteria,and consent was not given for 6. C.A. JOHNSON ET AL. 264  Artif Organs, Vol. 26, No. 3, 2002  Descriptive statistics based on the demographicdata of the study participants are tabulated in Table1. Results of the primary outcome measure, walkingspeed, and PCI are presented. Statistical methodsincluded graphical plots of individual patient re-sponse curves, nonparametric test statistics (Mann-Whitney and Wilcoxon paired-sample tests), and asummary measures approach to assessing betweengroup differences using regressions of median walk-ing speed and PCI and median change in walkingspeed and PCI on time.A similar pattern of response for walking speedand PCI was seen under both nonstimulated andstimulated test conditions. In the nonstimulatedwalking tests, a significant upward trend in medianwalking speed for both the control group (p  0.02)and the treatment group (p  0.004) was seen, thetrend lines being significantly different in location(p    0.04). Comparison of median walking speed(nonstimulated) in the control group (p  0.02) withmedian stimulated walking speed (treatment group,p    0.042) shows a significant upward trend, thetrend lines being significantly different in location(p  0.009). Figure 1 illustrates median walking speedin meters per second using box and whisker plots.In nonstimulated walking tests, a significant down-ward trend was demonstrated in median PCI for thetreatment group (p  0.007) but not for the controlgroup (p  0.292), the trend lines being significantlydifferent in location (p  0.038). In stimulated walk-ing tests, a significant downward trend in medianPCI was evident for the treatment group (p  0.02)but not for the (nonstimulated) control group (p  0.292), the trend lines being significantly different inlocation (p  0.016). Figure 2 illustrates the resultsof median PCI in heart beats per meter walked usingbox and whisker plots. DISCUSSION Analysis of the results of the primary outcomemeasures suggests that physiotherapy alone and thecombined use of BoNTA and FES with physiother-apy may have a beneficial effect on walking speedand PCI. The study has provided us with data thatare sufficiently convincing of an additional effect of BoNTA and FES to pursue a larger scale random-ized controlled trial (RCT) and to inform the samplesize calculation.The study was designed as a feasibility study toinvestigate the combined effect of BoNTA and FESwhich allowed the number of subjects required toremain comparatively small. A weakness of thestudy is that the individual contribution of the effectsof BoNTA and FES is not possible. A 4 arm RCTwould allow direct comparison of the separate andcombined effects of BoNTA and FES and should bea consideration in planning a subsequent study.The failure to recruit the recommended number of subjects to the study may, in part, be due to thenumbers of patients developing spasticity levels suf-ficient to indicate the use of BoNTA within the sub-acute stage. It may be useful to consider extendingthe time since stroke beyond 1 year to increase thepopulation base for recruitment in a future RCT. CONCLUSIONS This pilot study has provided evidence of a signifi-cant treatment effect. It has also given sufficient in- TABLE 1.  Demographic data Control TreatmentNumber of subjects 8 10Age (years) mean (SD) 59.3 (12.46) 58.2 (12.72)Age (years) range 44–78 41–78Sex 4 female, 4 male 2 female, 8 maleSide of hemiplegia 4 right, 4 left 7 right, 3 leftNumber 0–6 monthspoststroke 3 6Number 6–12 monthspoststroke 5 4 FIG. 1.  Shown are results of median walking speeds in meters per second. BoNTA AND FES FOR EQUINUS FOOT IN STROKE 265  Artif Organs, Vol. 26, No. 3, 2002  formation on the variability of the outcome measureto facilitate sample size calculations for a subsequentstudy and to clarify the magnitude of the treatmenteffect with a meaningful degree of precision. Given abaseline median walking speed of 0.2 m/s with apooled standard deviation for median change inwalking speed of 0.106 m/s, a test significance levelof 5% (assuming the use of a nonparametric teststatistic) and test power set at 80%, 470 subjects pergroup would be required to detect a 10% difference(0.02 m/s) between the treatment and control groups(as defined above) in respect of median change inwalking speed from baseline (at 12 weeks), 120 sub- jects per group to detect a 20% difference (0.04 m/s),55 subjects per group to detect a 30% difference(0.06 m/s), and 32 subjects per group to detect a 40%difference (0.08 m/s). Acknowledgments:  This work was supported by a grantfrom Ipsen Limited, 1 Bath Road, Maidenhead, Berkshire,SL6 4 UH, United Kingdom, including the supply of BoNTA (Dysport). The authors thank colleagues at theDepartment of Medical Physics and Biomedical Engineer-ing, Salisbury District Hospital; the research team, includ-ing medical consultants, pharmacists, and physiotherapistsin the participating National Health Service Trusts; theResearch and Development Support Unit at Salisbury Dis-trict Hospital; and especially the participants themselvesand their families. REFERENCES 1. Royal College of Physicians. Stroke: Towards better manage-ment. Summary and recommendations of a report of theRoyal College of Physicians.  J R Coll Physicians  1989;24:15–7.2. Merletti R, Adina A, Galante M, Furlan I. Clinical experienceof electronic peroneal stimulators in 50 hemiparetic patients. Scand J Rehab Med  11:111–21.3. Knutsson E, Richards C. Different types of disturbed motorcontrol in gait of hemiparetic patients.  Brain  1979;102:405–30.4. Burridge JH, Taylor PN, Hagan SA, Wood DE, Swain ID.The effects of common peroneal stimulation on the effort andspeed of walking.  Clin Rehabil   1997;11:201–10.5. Burridge JH, Taylor PN, Wood DE, McLellan DE. Indices todescribe different muscle activation patterns during treadmillwalking, in people with spastic dropped foot.  Med Eng Phys-ics  1997;23:427–34.6. Hesse S, Krajnik J, Luecke, Jahnke MT, Gregoric M, MauritzKH. Ankle muscle activity before and after botulinum toxintherapy for lower limb extensor spasticity in chronic hemipa-retic patients.  Stroke  1996;27:455–60. FIG. 2.  Shown are the results of median PCI in heart beats per meter walked (PCI: Physiological Cost Index). C.A. JOHNSON ET AL. 266  Artif Organs, Vol. 26, No. 3, 2002

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