Case Report

Functional Electrical Stimulation to Assist Equinovarus Deformity during Gait for a Patient with a Foot Dystonia: A Case Report

Fechter BJ and Hayes HA^*
Department of Physical Therapy, University of Utah, USA

^*Corresponding author: Heather A. Hayes, Department of Physical Therapy, University of Utah, 520 Wakara Way, Salt Lake City, UT 84108, USA

Published: 07 Jul, 2016
Cite this article as: Fechter BJ, Hayes HA. Functional Electrical Stimulation to Assist Equinovarus Deformity during Gait for a Patient with a Foot Dystonia: A Case Report. Ann Clin Case Rep. 2016; 1: 1031.

Abstract

Functional Electrical Stimulation (FES) to address a walking difficulty associated with equinovarus deformity and foot drop has been shown to improve gait pattern and quality of life in populations with central nervous system disorders. To our knowledge, no research has been performed on the use of FES to address foot drop for a patient with a foot dystonia. The purpose of this single case study was to assess the use of FES for an individual with a foot dystonia on gait speed and quality of life (QOL). After 20 months of daily use of the FES system, clinically significant improvements were noted in 10m Walk Self Selected pace (10SS) and 10m Walk Fast Pace (10FP) both with and without the FES device. 10SS with FES increased +0.17 m/s (+15%); 10FP with FES increased +0.27 m/s (+19%); 10SS without FES increased +0.22 m/s (+19%); and 10FP without FES increased +0.27 m/s (+22%). In addition, improvements were seen in patient subjective report of QOL, which increased by 20%. The results of this case study demonstrate improvement in the gait speed and subjective QOL measures for an individual with an equinovarus deformity secondary to a focal dystonia.

Introduction

Individuals with an equinovarus deformity and foot drop often present with walking difficulty, which has a direct connection with, decreased quality of life (QOL), decreased gait speed, increased fall risk, and increased mortalitly [1]. Functional Electrical Stimulation (FES) to address a walking difficulty associated with equinovarus deformity and foot drop has been shown to improve gait pattern and QOL in populations with central nervous system (CNS) disorders associated with spasticity (i.e. Stroke [2] and Multiple Sclerosis [3]). FES to address foot drop is a neuromuscular electrical stimulation system that provides electrical stimulation to the anterior tibialis and peroneal muscles through surface electrodes. Activation of these muscles is coordinated through input from a pressure sensor in the heel of the shoe that activates the stimulation when the pressure is sufficiently decreased from the sensor (pre-swing through mid-swing). During initial fitting the intensity (mA) was adjusted until an appropriate muscle contraction was obtain resulting in adequate dorsiflexion and eversion of the foot. Research on FES and foot drop has been generally limited to Central Nervous System (CNS) related lesions, such as stroke or spinal cord injury [2,3]. However, limited research has addressed the use of a FES on a foot or hand. Barrett et al. [4]; showed improvements in balance and gait endurance with the use of surface FES in an individual with an isolated focal dystonia not combined with an additional movement disorder [4]. Dystonia is a neurological movement disorder presenting with muscles that contract involuntarily, often presenting as a twisting movement of the affected body part making it difficult for voluntary muscle contraction to occur [5]. Since central nervous system pathologies have successfully used FES to address equinovarus deformity and foot drop, we surmised that in an individual with a focal foot dystonia associated with a primary central movement disorder would also increase gait speed and QOL. The purpose of this single case study was to assess the use of FES on an individual with an equinovarus deformity and foot drop from a dystonia manifesting after CNS compromise on gait speed, QOL, and fear of falling.

Case Presentation

The subject is a 32-year-old female diagnosed with West Nile virus meningoencephalitis confirmed by an elevated level of IgM and pleocytosis via cerebral spinal fluid after a mosquito bite. The subject was hospitalized for 8 days at onset of diagnosis and presented with progressive weakness of bilateral limbs and difficulty feeding requiring a feeding tube (Table 1). During this acute hospitalization she underwent Intravenous Immunoglobulin treatment, which retarded the progression of symptoms. Following the acute hospitalization she presented to Inpatient Rehabilitation (IR) for Physical Therapy (PT) for limb muscle weakness and Speech Language Pathology to address bulbar muscle weakness. After two weeks of IR she was discharged home with almost full resolution of bulbar and muscle weakness. Six months later, she returned to neurology due to left foot weakness, pain, dysesthesias, hyperesthesia, swelling, skin changes and a dystonia. The subject was diagnosed at that time with Complex Regional Pain Syndrome (CRPS). Eight months later, without treatment for the CRPS, the pain resolved but the patient still presented with a dystonia of the left foot. To address the dystonia, she tried gabapentin and a series of onabotulinumtoxinA (Botox) injections with limited effect. Forty-six months later she presented to outpatient PT with difficulty walking longer distances, decreased QOL, and increased fear of falling because of the foot dystonia. The patient was assessed on gait speed via 10 meter walk self-selected and fast pace (10SS, 10FP respectively; with and without an FES system), QOL (subjective percentage), and fear of falling (subjective percentage). She was provided an FES system to address the equinovarus deformity and foot drop and a trial of a FES system was used (Bioness^®, Inc) in the clinic. A successful muscle contraction was achieved to warrant further training with the device. Settings for the program included a symmetrical sinusoidal waveform were used at phase duration of 200 μS and a pulse rate of 30 Hz. Patient was interested in using this technology full time for community ambulation. She purchased an FES system for community use (WalkAide^®, Reno, NV). She was educated on progressive use of the FES system to be worn daily during ambulation. Twenty months later, she returned for a follow up visit to assess gait speed, QOL and fear of falling.

Table 1

Table 2

Outcomes

At the twenty month follow up visit (post-intervention), the subject reported daily use of the FES system and clinically significant improvements were observed in 10SS and 10FP both with and without the FES system (Table 2); supplemental video of walking with and without FES both Initial and Post).
Initial/Post change with FES
Clinically significant improvements in 10SS (change, +0.17 m/s) and 10FP (change, +0.27 m/s) were noted with use of an FES system. Initial/Post change without FES
Additionally, clinically significant improvements in 10SS (change, +0.22 m/s) and 10FP (change, +0.27 m/s) were noted without use of an FES system. Immediate Initial change with FES
There was also an immediate clinically significant improvement observed in her gait speed on Initial 10FP (change, +0.15 m/s) with use of the FES system compared to without the FES system. No change in 10SS was noted during initial evaluation when using the FES system. Additionally, improvements were noted in subjective report of QOL comparing Initial to Post (improved, +20%), and Fear of Falling (reduced, -20%).

Conclusion

The purpose of this single case study was to assess the use of FES on an individual with a foot dystonia on gait speed and QOL. The results suggest a positive improvement in gait speed, QOL, and fear of falling with the use of FES for equinovarus deformity secondary to a focal dystonia. Improvements were observed both with immediate and long-term use with the FES system, which is consistent with other studies on other neurological conditions [6] Improvements were also observed long-term without an FES system, which may suggest an improvement in voluntary muscle control, which is consistent with other studies [7]. Other options exist for treatment of a foot dystonia, e.g. orthotics, deep brain stimulation, and orthopedic surgical interventions [8]; however, these results suggest that FES may be a feasible and less invasive option to address this impairment.
1. Limitations include the following: This is a single case study and future research is needed to determine the effectiveness of FES on a foot dystonia over a greater number of subjects
2. No measure of dystonia severity was used. Future research is warranted to understand the neurophysiologic response to FES with a foot dystonia. Additionally, future research is warranted to understand the long-term response and benefit of different treatment options compared with FES.

References

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