Where and why does the nerve suffer?
The peroneal nerve arises from the sciatic nerve in the popliteal region and bends around the neck of the fibula almost under the skin. Here, between the bone and the dense muscular arch, it is not protected by soft tissues, so even moderate but prolonged pressure disrupts its nutrition. The nerve further divides into a deep branch, which elevates the foot, and a superficial branch, which is responsible for outward rotation of the foot and sensitivity. The set of symptoms depends on which branch is affected. It is important to remember that a similar picture occurs with a herniated lumbar disc, so the level of damage needs to be clarified.
- Compression at the head of the fibula
- Knee injury, fracture, dislocation
- Tight cast, bandage, high shoes
- Prolonged position cross-legged or squatting
- Operations under anesthesia with a forced position of the leg
- Tumors and cysts of the popliteal region
Causes and risk factors
Separately, there is the so-called cotton picker's paralysis and similar professional variants associated with long periods of squatting, as well as neuropathy after rapid weight loss, when the fat layer that protects the nerve disappears. Diabetes, alcohol abuse, B vitamin deficiency and thyroid disease make the nerve more vulnerable, so normal pressure, which a healthy person can tolerate without consequences, causes permanent damage in them.
- The habit of sitting cross-legged
- Working in a squatting position
- Sharp loss of body weight
- Diabetes mellitus and polyneuropathy
- Prolonged bed rest and anesthesia
- Knee injuries and surgeries
- Vasculitis and systemic diseases
Symptoms
The main manifestation is weakness of extension of the foot and fingers. The foot hangs down, the toe clings to the floor, so the person develops a characteristic gait with the knee raised high, and the foot slams on the floor when lowered. Numbness and tingling are added along the outer surface of the lower leg and on the back of the foot. The pain does not always occur and is usually moderate, which distinguishes this neuropathy from sciatica. Over time, the muscles on the front surface of the lower leg lose weight, which is noticeable when compared with the other leg.
- Inability to lift the foot and toes
- Slap gait
- Numbness of the outer leg and dorsum of the foot
- Rolling of the foot when walking
- Losing weight in the lower leg muscles
- Usually minimal pain
Survey
The neurologist checks muscle strength, sensitivity and reflexes, which makes it possible to distinguish nerve damage from root damage in the lumbar region: with a herniated disc, there is usually severe back pain and other areas of numbness. The main tool is electroneuromyography, which shows the level, nature and severity of damage, as well as the prognosis for recovery. An ultrasound scan of the nerve can help see compression, scarring, or a cyst. If a problem in the spine is suspected, an MRI is performed, and if there is no obvious cause, metabolic disorders are looked for.
- Neurological examination with assessment of muscle strength
- Electroneuromyography
- Ultrasound of the peroneal nerve
- MRI of the lumbar spine for suspected hernia
- Glucose, glycated hemoglobin
- Vitamin B12 and thyroid function indicators according to indications
Treatment and recovery
The first and mandatory step is to eliminate pressure on the nerve: change position, loosen the bandage, change working conditions. Further, physical therapy and proper fixation of the foot are of primary importance. A special orthosis keeps the foot at a right angle, restores normal gait and prevents shortening of the Achilles tendon. Physiotherapy and electrical stimulation are used as an adjunct. Medicines are prescribed by a doctor taking into account the cause: for diabetes and vitamin deficiency, the underlying disorder is treated. If the nerve is torn or compressed by a cyst, surgery is required, and it cannot be postponed for a long time.
- Eliminating the cause of compression
- Foot orthosis and comfortable shoes
- Physical therapy and stretching of the calf muscles
- Physiotherapy and electrical stimulation as prescribed
- Correction of diabetes and vitamin deficiency
- Surgical decompression or nerve suture when indicated
- Control ENMG after a few months