Peroneal nerve paralysis is a paralysis on the common fibular nerve that affects the patient’s ability to lift the foot at the ankle. It is also known as Zenker's paralysis, named after Friedrich Albert von Zenker. Peroneal nerve paralysis usually leads to neuromuscular disorder, peroneal nerve injury, or foot drop which can be symptoms of more serious disorders such as nerve compression. The origin of peroneal nerve palsy has been reported to be associated with musculoskeletal injury or isolated nerve traction and compression. Also it has been reported to be mass lesions and metabolic syndromes. Peroneal nerve is most commonly interrupted at the knee and possibly at the joint of hip and ankle. Most studies reported that about 30% of peroneal nerve palsy is followed from knee dislocations. Peroneal nerve injury occurs when the knee is exposed to various stress. It occurs when the posterolateral corner structure of knee is injured. Relatively tethered location around fibular head, tenuous vascular supply and epineural connective tissues are possible factors that cause damage on the common peroneal nerve. Treatment options for nerve palsy include both operative and non-operative techniques. Initial treatment includes physical therapy and ankle-foot orthosis. Physical therapy mainly focuses on preventing deformation by stretching the posterior ankle capsule. A special brace or splint worn inside the shoe (called an Ankle Foot Orthosis) holds the foot in the best position for walking. Orthosis stretches posterior ankle structures. Physical therapy can help patients to learn how to walk with a foot drop.
Signs and symptoms
Signs and symptoms of peroneal nerve palsy are related to mostly lower legs and foot which are the following:
Decreased sensation, numbness, or tingling in the top of the foot or the outer part of the upper or lower leg Foot drops (unable to hold the foot straight across) Toes drag while walking Weakness of the ankles or feet Prickling sensation Pain in shin Pins and needles sensation Slapping gait (walking pattern in which each step makes a slapping noise) Patients may need pain relievers to control pain. Other medications that are used to reduce pain include gabapentin, carbamazepine, or tricyclic antidepressants such as amitriptyline. Whenever if possible, patients need to avoid or limit the use of medication to reduce the risk of side effects. If the pain is severe, a pain specialist can help patients to explore all options to relieve the pain. Physical therapy exercises may help patients to maintain muscle strength. Also, orthopedic devices may improve patient's ability to walk and prevent contractures. Orthopedic devices may include braces, splints, orthopedic shoes, or other equipment. Vocational counseling, occupational therapy, or similar programs may help patients to maximize their mobility and independence.
Causes Causing factors of peroneal nerve palsy are such as musculoskeletal or peroneal nerve injuries. Usually paralysis occurs at the outside of the leg and the top of the foot. Palsy causes decrease of muscle strength to lift the foot, twist ankle outside, and move toes around. Major cause of palsy is due to dislocation of knee. Other possible causing factors are metabolic dysfunction of lower part of knee or disorientation of hip or pelvis. Damages on peroneal nerves destroy the myelin sheath that covers the axon or the whole nerve cell. There might be a loss of feeling, muscle control, muscle tone, and eventual loss of muscle mass because the nerves aren't stimulating the muscles after they are damaged. Dysfunction of a single nerve such as the common peroneal nerve is called a mononeuropathy. Mononeuropathy means the nerve damage is occurred in one area. However, certain conditions may also cause single nerve injuries. Common causes of damage to the peroneal nerve include the following:
Traumatic injury on the knee Fracture of the fibula Using a tight plaster cast (or other long-term constriction) of the lower leg Crossing the legs regularly Regularly wearing high boots Pressure to the knee from positions during deep sleep or coma Long period of resting on bed Broken leg bone Common peroneal nerve injury is more common in people:
Who are very thin (for example, from anorexia nervosa) Who have conditions such as diabetic neuropathy or polyarteritis nodosa Who are exposed to certain toxins that can damage the common peroneal nerve Prolonged pressure on nerve may occur because of:
Sitting position Blood clots, tumors Casts on lower leg due to tightness
Diagnosis For partial nerve palsy, more than 80% of patients will recover completely. For complete nerve palsy, less than 40% of patients will have complete recovery. Peroneal nerve in continuity arises from defined cause will be recovered better than those arise from unknown causes. Examinations are required for following reasons:
Considering lumbar radiculopathy during the examination Possibility of foot drop Sensory loss that may be difficult to determine because of variable and small autonomous zone of sensation Tinel's sign over the fibular neck that can help localize the site of nerve compression Checking for direct compression that reproduces nerve symptoms
Electromyography Electromyography is used to observe peroneal nerve palsy within one month of injuries. And if it is partial peroneal nerve palsy, patients have higher chance to recover fully from the palsy. More than 70 to 80 percent of patients with partial paralysis recovered completely, but those with complete paralysis have chances less than 30 percent to recover completely. If the symptom does not get any better in few months, surgery is required to decompress the nerve.
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