Current Concepts In Diagnosing And Treating Drop Foot

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A Guide To Common Foot Drop Etiologies

• Hypothyroidism
• Lymphomas
(Hodgkin’s or non-Hodgkin’s)
• Guillain-Barré Syndrome
• HIV infection
• Cytomegalovirus infection
• Diabetes
• Megaloblastic anemia
• Intracranial tumors
• Brain lesions
• Tumors of the head and neck
• Trauma (direct injury)
• Antineoplastic drugs
• Spinal cord compression
• Direct peripheral
nerve invasion
• Autoimmunity
• Obesity or weight loss
• Idiopathic
• Local tumors such as ganglion or synovial cysts
• Nerve sheath tumors (schwannoma)
• Neurofibroma
• Bone tumors
• Postural (prolonged squatting, sitting or kneeling)
• Prolonged hospitalization
• Bed rest
• Internal surgery
(positioning on table)
• Ankle inversion/sprains
• Orthopedic (fibular fractures)
• Cast immobilization
• Tibial plateau repair/fracture
• Knee arthroplasty
• Hip surgery

Nicholas Romansky, DPM, Kelly Scollon-Grieve, MD, and James G. McGinness, CPO

   Negative aspects of conventional bracing include heaviness of the orthoses and the possible stigma of wearing braces. In general, patients quickly become accustomed to wearing this brace and find that the benefits outweigh the negatives.

A Closer Look At Medical Therapy Options

Alternative and adjunctive treatments may include oral antidepressants such as amitriptyline (Elavil, Merck), nortriptyline, gabapentin (Neurontin, Pfizer) and pregabalin (Lyrica, Pfizer). Other options are oral and topical non-steroidal anti-inflammatory drugs (NSAIDs) such as capsaicin, diclofenac, nabumetone (Relafen, GlaxoSmithKline), meloxicam (Mobic, Boehringer Ingelheim), a Flector patch (Pfizer) or a Lidoderm patch (Endo Pharmaceuticals).

   There are companies and local pharmacies that “compound” topicals to meet the specific needs of the patient. For example, one can also use customized topical components with ketoprofen, amitriptyline or gabapentin. Oral or transdermal narcotics are options but one should use them in a limited fashion. Optimizing the control of other comorbidities such as diabetes, hypothyroidism and vitamin deficiencies of B1, B6 and B12 can also be useful.

   One may also consider chemodenervation and nerve blocks in combination with AFOs.10 In the last few decades, chemodenervation has emerged as a treatment option, especially for intramuscular hyperactivity in upper motor neuron syndromes. This process helps clinicians to manage focal muscle or muscle activities through the use of agents such as botulinum toxin (Botox, Allergan), Myobloc (Solstice) or Dysport (Medicis). One can use phenol alone or phenol and alcohol combined and injected. These modalities have been in use in the last four decades.

   The agent one uses depends on the patient’s clinical entity and the strengths and weaknesses of the individual agents. One can use these agents for short-term or for sustained effort. Nerve blocks and regional anesthesia can be useful for both diagnostic and long-term therapeutic motor and sensory treatment.

   In addition to conventional therapy, more proximal involvement should occur on the contralateral side. Patients should perform proximal core strengthening and stability exercises including those for the gluteus medius and piriformis, and hamstring stretches in addition to Pilates and yoga.

Can Functional Electrical Stimulation Have An Impact?

Functional electrical stimulation can be beneficial for patients diagnosed with drop foot. Patients with intact peripheral nerves who have suffered from central nervous system disorders such as stroke, traumatic brain injury, multiple sclerosis, spinal cord injury or cerebral palsy are the most appropriate candidates for functional electrical stimulation.11 Also, if the patient has a history of poor adherence with AFOs or has rejected them in the past due to bulk, weight, heat or limitations in shoewear, functional electrical stimulation is an excellent alternative.

   Functional electrical stimulation systems such as the WalkAide® (Innovative Neurotronics) apply low-level electrical currents directly to the common peroneal nerve to help restore functional dorsiflexion during walking. The unit fits in a cuff that attaches to the proximal calf region just below the knee. The system has the ability to measure the position and speed of the lower limb through inclinometers and accelerometers, and the electrical current flows through self-adhesive electrodes that attach inside the cuff. A unique feature of the WalkAide system is the tilt sensor, which analyzes angular velocity during the gait cycle to know when to send the appropriate stimulus to the muscle. Other systems use a heel switch, which can complicate the triggering of the system and make for a more inefficient gait pattern.11

   After the initial training on donning and doffing of the self-contained cuff system, most patients are able to do this themselves. Placement of the electrodes within the cuff on the limb may require an initial marking on the skin for the patient to assist in placement but with time, patients can become proficient at knowing exactly where their “sites” are and how the electrodes must be aligned.

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