Peroneal nerve disease

Article by Master, Doctor Vu Duy Dung - Doctor of Neurology - Department of General Internal Medicine - Vinmec Times City International Hospital

Compression of the common peroneal nerve at the tip of the fibula is the most common single nerve disease of the lower extremities. Common causes are weight loss, prolonged immobility, and frequent sitting with legs crossed. Other causes include prolonged squatting, knee dislocation, ankle sprain, intracranial ganglion cyst, fibula goiter, and acute compression after wearing tight pants. Patients with common peroneal neuralgia often present with difficulty walking. While some patients describe drooping feet, many report "toes dragging," "foot flapping," or often tripping. Paresthesia is sometimes present in the lower lateral leg and instep but it is often overlooked in the setting of significant weakness. Pain may also manifest at the site of compression.
A detailed physical examination may reveal a Tinel sign in the proximal peroneal nerve. Drooping feet can be clearly seen when walking or walking with drooping feet. In mild cases, gait may not be affected, but weakness is only seen when the patient walks on the heel. Motor examination will reveal weakness in the dorsal flexors of the ankle, lateral tilt of the foot, and extensor of the toes. Loss of sensation may be unstable but is usually dorsolaterally preserved V. Any weakness of the lateral foot, toe flexion, or hip abduction will suggest an L5 radiculopathy other than a neurologic disease. separate label.

Isolated cases of deep peroneal neuropathy are uncommon. Causes include trauma, compression, and ganglion cysts. The lesion preserves lateral tilt of the foot and sensation on the lateral side of the lower leg and foot. There is loss of sensation between toes I and II. Superficial peroneal neuropathy is also relatively rare. Depending on the extent of the lesion, it may present with motor or sensory-only symptoms. Weakness of the lateral foot is found in proximal disease, while loss of sensation on the lateral side of the lower leg and in the dorsal surface of the foot may be present in proximal or proximal lesions. The space between toes I and II preserves sensation, because the deep peroneal nerve innervates this area.

Peroneal motor nerve conduction exploration is performed with recording electrodes placed over the extensor extensors of the toes with stimulation at the anterior ankle, fibular head, and popliteal fossa. If there is no motor response, the recording electrode can be placed into the anterior tibial muscle with stimulation at the fibula tip and the popliteal fossa. A sensory response to the superficial peroneal nerve may also be performed to assist in localizing the lesion.
Needle EMG is necessary to assess severity and aid in prognosis. A minimal assessment includes the anterior tibialis, fibula, and biceps femoris. The other muscles innervated by the sciatic nerve and the L4 and L5 roots should also be examined to distinguish solitary peroneal nerve disease from sciatica, lumbar-sacral plexus disease, and radiculopathy. waist life. For example, abnormalities on the needle insertion EMG of the posterior tibial muscle can help differentiate L5 radiculopathy from peroneal neuropathy.

On neuromuscular ultrasound, the cross-sectional area is increased at the sites of compression; Early studies suggested that increased nerve cross-section was associated with axon loss. The nerve is usually less than 12 mm2 at the level of the fibula tip. Neuromuscular ultrasonography in peroneal neuropathy of the fibula tip can reveal structural causes, especially in patients without risk factors for nerve compression. In one study, neuromuscular ultrasonography demonstrated ganglion cysts compressing nerves at the tip of the fibula in 18% of patients. A 2015 analysis found anatomical abnormalities of the biceps femoris, ganglion cysts, and lipomas in a case series of 21 patients with drooping feet due to common peroneal neuropathy. Information of this type cannot be obtained if electrodiagnostic testing alone is essential in guiding appropriate treatment. The case illustration below describes how electrodiagnostic and neuromuscular ultrasound can be used together in clarifying complex cases of peroneal nerve compression.

Treatment of peroneal neuralgia is based on the cause. Surgery is often needed after an injury. Compressing intracranial ganglion cysts must be resected to prevent recurrence and further nerve damage. In cases of equivocal compression at the fibula tip with no or only minor electrodiagnostic changes, time and control of risk factors may be sufficient for recovery. For more severe cases such as axonal loss, surgery is indicated. This is complicated by the lack of a standard approach and the many different places where compression can be. The majority of patients have improved function and pain after the intervention, but published studies are small and lack standardization. Microsurgical decompression, with only removal of the fibrous band between the superficial head of the long peroneal muscle and the soleus muscle, may be an equally effective approach when compared to more invasive surgical decompression.

Illustrated clinical case
A 79-year-old male lung cancer patient experiences weakness in his left foot after participating in a rehabilitation program after 2 months in hospital. The patient often tripped his left foot, and the patient's wife said that the patient's steps were "too noisy". The patient had no trauma to the leg and was painless but had intermittent pins and needles sensation on the instep of the left foot. The patient does not have low back pain.
Examination is notable for weakness and mild diffuse weakness of the muscles of the upper and lower extremities bilaterally. The patient also has weakness with only antigravity motion with left instep flexion, left lateral tilt, and toe extension. Bilateral lower extremity tendon reflexes are absent, and the patient has a bilateral glove-stocking distribution.
Electrodiagnostic exploration revealed evidence of a diffuse sensory axonal polyneuropathy. Loss of peroneal motor response was noted in the extensor extensors of the toes on both sides. The bilateral superficial peroneal nerve response is lost, along with loss of calf nerve sensory response. A needle-stick EMG showed loss of distribution and redistribution in the bilateral anterior tibialis and medial abdominal muscles, but the changes were most pronounced in the left anterior tibialis. The peroneal nerve motor response recorded on the left anterior tibial muscle showed reduced amplitude and delayed conduction through the fibula tip. Ultrasonography of the left peroneal nerve at that site showed a marked increase in the local size of the nerve. The patient was diagnosed with left peroneal neuropathy at the tip of the fibula superimposed on an underlying disease of motor-sensory polyneuropathy.
Comment
The patient in this case has a pre-existing polyneuropathy that complicates the evaluation of mononeuropathy. Peripheral neuropathy of the fibula tip is of great concern in patients with clinical presentation and risk factors of immobility and marked weight loss. Use of needle-stick EMG, variable recording sites of peroneal nerve motor response, and ultrasound allow for an accurate diagnosis.
Currently, Vinmec International General Hospital has implemented surgery for nerve compression diseases. In particular, with the pioneering of electrical diagnostic techniques. Vinmec is one of the few addresses that deploys specialized techniques, with modern equipment of NATUS (USA), the specialist doctor after performing the examination, recording and reading the results will provide a method to diagnose the disease. accurately, giving patients a chance to recover, safe treatment and no complications.

References:
Hobson-Webb LD, Juel VC. Common Entrapment Neuropathies. Continuum (Minneap Minn) 2017;23(2, Selected Topics in Outpatient Neurology):487-511.