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Mononeuropathy: causes, symptoms, diagnosis, treatment
Last reviewed: 05.07.2025
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Mononeuropathy involves sensory disturbances and weakness in the distribution of the affected nerve or nerves. The diagnosis is made clinically but should be confirmed by electrodiagnostic tests.
Treatment of mononeuropathy is aimed at eliminating the cause; sometimes splints are applied, NSAIDs are used, glucocorticoid injections are used, and in severe cases of nerve entrapment, surgical treatment is used.
[ Causes of mononeuropathy
Trauma is the most common cause of acute mononeuropathy. Overuse or forced hyperextension of a joint, as well as minor repeated injuries (eg, working with small tools, vibration from air hammers), can cause focal neuropathy. Prolonged, continuous pressure on bony prominences can cause compression neuropathy involving the superficial nerves (ulnar, radial, peroneal), especially in thin individuals; such compression can occur during sleep, intoxication, cycling, or anesthesia. Compression of nerves in narrow canals leads to tunnel neuropathy (eg, carpal tunnel syndrome). Compression of a nerve by a tumor, plaster cast, crutches, hyperostosis, or prolonged compression while in one position (eg, gardening) can cause compression palsy. Neuropathy can be caused by bleeding into a nerve, exposure to cold or radiation, or direct tumor invasion.
Multiple mononeuropathy (mononeuritis multiplex) usually occurs as a complication of a systemic connective tissue disorder (eg, polyarteritis nodosa, systemic lupus erythematosus, Sjögren's syndrome, rheumatoid arthritis), sarcoidosis, metabolic disorders (eg, diabetes, amyloidosis), or infectious diseases (eg, Lyme disease, HIV infection, leprosy). Diabetes commonly causes sensorimotor distal polyneuropathy.
Symptoms of mononeuropathy
Single and multiple mononeuropathies are characterized by pain, weakness, and paresthesia in the distribution of the affected nerve or nerves. Motor nerve involvement begins with weakness without pain; sensory nerve involvement begins with sensory disturbances without weakness. Multiple mononeuropathy often begins asymmetrically; nerves may be affected all at once or gradually. Extensive involvement of many nerves may simulate polyneuropathy.
Ulnar nerve neuropathy often develops as a result of trauma in the ulnar groove due to frequent weight bearing on the elbow or asymmetric bone growth after a fracture in childhood (late ulnar nerve palsy). The ulnar nerve can also be compressed in the cubital canal. Compression at the elbow level can cause paresthesia or loss of sensitivity in the little finger and on the palmar surface of the ring finger; weakness and atrophy of the adductor muscle of the thumb, the muscle that abducts the little finger, and the interosseous muscles. Severe long-term ulnar nerve palsy leads to a claw-like deformity of the hand.
Carpal tunnel syndrome can be unilateral or bilateral. It develops as a result of compression of the median nerve between the transverse superficial ligament of the wrist and the tendons of the flexor muscles of the forearm. Compression causes paresthesia and pain along the palmar surface. Pain in the forearm and shoulder is possible, which usually intensifies at night. Impaired sensitivity on the palmar surface of the first, second and third fingers of the hand, as well as weakness and atrophy of the short muscle that abducts the thumb of the hand, may follow. Impaired sensitivity in this syndrome should be distinguished from dysfunction of the C5 root in radiculopathy; if necessary, EMG is performed.
Neuropathy of the peroneal nerve is usually associated with compression of the nerve by the lateral surface of the fibular neck. It is common among bedridden patients and thin individuals who are accustomed to crossing their legs. It manifests itself as weakness of the extensors of the foot (inability to extend the foot, abduct it outward, and pronate) and sometimes sensory deficits along the anterolateral surface of the leg and the dorsum of the foot.
Radial nerve neuropathy (synonyms: weekend palsy, lovers' palsy, garden bench palsy) is a consequence of the nerve being pressed against the humerus, for example, when the arm rests on the back of a nearby chair for a long time (for example, during intoxication or deep sleep). It manifests itself as a "drooping wrist" (weakness of the extensors of the forearm, hand and fingers) and loss of sensitivity in the area of the first dorsal interosseous muscle.
Treatment of mononeuropathy
Treatment of mononeuropathy should be directed at the cause of the disease. In case of constant compression (for example, by a tumor), surgery is considered. Symptoms of transient compression usually resolve with rest, warming, NSAIDs; the activity that causes them should be avoided. In carpal tunnel syndrome, glucocorticoid injections sometimes help. In all types, improvement can be expected from the use of corsets and splints. When the disease progresses despite conservative treatment, surgical intervention should be considered.