Added Value of Dynamic EMG in the Assessment of the Equinus and the Equinovarus Foot Deviation in Stroke Patients and Barriers Limiting Its Usage

So is this my ankle and foot problem? Of course my doctor told me nothing. And this is useless; NO SOLUTION.

Added Value of Dynamic EMG in the Assessment of the Equinus and the Equinovarus Foot Deviation in Stroke Patients and Barriers Limiting Its Usage

Isabella Campanini^1*, Michela Cosma², Mario Manca³ and Andrea Merlo^1,4

• ¹LAM-Motion Analysis Laboratory, Neuromotor and Rehabilitation Department, S. Sebastiano Hospital, Azienda USL-IRCCS di Reggio Emilia, Reggio Emilia, Italy
• ²Motion Analysis Laboratory, Department of Neuroscience and Rehabilitation, Azienda Ospedaliero Universitaria di Ferrara, Ferrara, Italy
• ³Rehabilitation Unit, Fondazione Poliambulanza, Brescia, Italy
• ⁴Merlo Bioengineering, Parma, Italy

Equinus (EFD) and     (EVFD) are the most frequent lower limb deformities in stroke survivors. The equinus component can be triggered by a combination of dorsiflexor deficits, plantar flexor overactivity, muscle stiffness, and contractures. The varus component is typically due to an imbalance between invertor and evertor muscle actions. An improvement in identifying its causes leads to a more targeted treatment. These deformities are typically assessed via a thorough clinical evaluation including the assessment of range of motions, force, spasticity, pain, and observational gait analysis. Diagnostic nerve blocks are also being increasingly used. An advantage of dynamic electromyography (dEMG) is the possibility of measuring muscle activity, overactivity or lack thereof, during specific movements, e.g., activity of both ankle plantar flexors and dorsiflexors during the swing phase of gait. Moreover, fine-wire electrodes can be used to measure the activity of deep muscles, e.g., the tibialis posterior. An impediment to systematic use of dEMG in the assessment of EFD and EVFD, as a complimentary tool to the clinical evaluation, is a lack of evidence of its usefulness. Unfortunately, there are few studies found in literature. In order to fill this void, we studied three pairs of patients suffering from chronic hemiparesis consequent to a stroke, with EFD or EVFD. At the initial evaluation they all displayed the same clinical traits, very similar walking patterns, and an overlapping gait kinematics. However, the patterns of muscle activity differed considerably. dEMG data acquired during walking provided information that was not available from the sole clinical assessment. The contribution of this information to the subsequent clinical and rehabilitation process was discusses along with the barriers that limit the use of dEMG as a routine tool in neurorehabilitation.

Introduction

Following an upper motor neuron lesion, patients may develop acquired deformities in the lower limbs that impair or inhibit walking. The most frequent lower limb acquired deformities in stroke survivors are the equinus (EFD) and the equinovarus foot deviation (EVFD) (1). They are characterized by a downward deviation and an internal rotation of both the ankle and foot (2, 3). Both are often associated with clawed toes. Ankle dorsiflexors (DF), plantarflexors (PF), invertor, and evertor muscles and toe flexors and extensors control ankle-foot movements and are typically involved with EFD/EVFD in various ways. These deformities are caused by several factors that are found in the different combinations of paresis, overactivity, and altered motor control (paresis, co-contractions, spasticity, dystonia, and other manifestations of muscle overactivity), changes in soft tissues that gradually result in stiffness, contractures and secondary joint limitations due to disuse (4, 5).

The combination of these phenomena is different in each patient and results in joint alterations during gait, which must be evaluated in dynamic conditions because they may not be detectable and measurable by a clinical evaluation. Clinical evaluation and observation of a patient's gait may not be sufficient to establish the causes responsible for the observed deviation and walking alterations. The contribution of gait analysis (GA), and in particular dynamic EMG (dEMG), can be used to discriminate between different causes and thus support the decision-making process in order to formulate the most appropriate therapeutic program (5–9). The presence/absence of EMG activity and the type of activation (e.g., continuous, with bursts) detected (9–15) leads to different choices in terms of focal neuromuscular blocks, non-pharmacological treatments, and neuro-orthopedic surgery.

Failure to use dEMG and GA during the decision-making process could be due to the presence of some barriers (13, 16). In this manuscript we tried to overcome this issue. We will present six patients with very similar gait patterns and different dEMG that provides information not available by the sole clinical assessment.