Published: 18 Jun 2025

ICD9: 354.5      ICD10: G58.7      ICD11: 8C12.1

Mononeuritis multiplex is a neurological disorder characterized by damage to multiple individual peripheral nerves in a seemingly random pattern.
This means that it affects different nerves in different parts of the body, rather than a single nerve root or a generalized neuropathy affecting all nerves.

Here's a breakdown of what that means:

"Mono": Refers to a single nerve.
"Neuritis": Inflammation or damage to a nerve.
"Multiplex": Meaning multiple.

Key Characteristics:

Asymmetrical: The symptoms typically affect different sides of the body differently.
Patchy: The pattern of nerve involvement is not uniform. For example, it might affect the median nerve in one arm and the peroneal nerve in the other leg.
Variable: The severity and types of symptoms can vary greatly depending on which nerves are affected.
Progressive: Symptoms can appear acutely and then resolve, or they can accumulate over time.

Symptoms:

Because mononeuritis multiplex can affect any peripheral nerve, the symptoms can be diverse. Common symptoms include:

Pain: Sharp, stabbing, burning, or aching pain in the distribution of the affected nerves.
Weakness: Muscle weakness or paralysis in the areas supplied by the damaged nerves.
Sensory Loss: Numbness, tingling, burning, or loss of sensation in the affected areas.
Loss of Reflexes: Diminished or absent reflexes in the affected limbs.
Muscle Wasting (Atrophy): Over time, the muscles controlled by the damaged nerves may waste away.

Causes:

Mononeuritis multiplex is often associated with underlying systemic conditions. The most common causes include:

Vasculitis: Inflammation of the blood vessels, which can damage the nerves by restricting their blood supply. Examples include polyarteritis nodosa, Churg-Strauss syndrome, and microscopic polyangiitis.
Diabetes: Although diabetic neuropathy usually presents as a symmetrical polyneuropathy, it can sometimes manifest as mononeuritis multiplex.
Connective Tissue Diseases: Conditions like rheumatoid arthritis, systemic lupus erythematosus (SLE), and Sjogren's syndrome.
Infections: Lyme disease, hepatitis B, hepatitis C, HIV, and herpes zoster (shingles).
Sarcoidosis: A disease characterized by the formation of granulomas (clumps of inflammatory cells) in various organs, including nerves.
Amyloidosis: A condition in which abnormal proteins (amyloid) accumulate in tissues and organs.
Certain Medications: Some drugs can, in rare cases, cause mononeuritis multiplex.
Cryoglobulinemia: Presence of abnormal proteins in the blood that can precipitate and damage small vessels.
In some cases, the cause is unknown (idiopathic).

Diagnosis:

Diagnosing mononeuritis multiplex typically involves:

Detailed Neurological Examination: Assessing muscle strength, sensation, reflexes, and coordination.
Electrodiagnostic Studies (EMG/NCS): Electromyography (EMG) and nerve conduction studies (NCS) to assess the function of the nerves and muscles. These studies can show which nerves are affected and the extent of the damage.
Blood Tests: To look for underlying systemic conditions such as vasculitis, diabetes, connective tissue diseases, and infections. Specific tests might include complete blood count (CBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), antinuclear antibodies (ANA), rheumatoid factor (RF), cryoglobulins, hepatitis serologies, and Lyme disease testing.
Nerve Biopsy: In some cases, a biopsy of an affected nerve may be necessary to confirm the diagnosis and identify the underlying cause, particularly in suspected cases of vasculitis.
Imaging Studies: MRI or CT scans may be used to rule out other causes of nerve damage, such as tumors or compression.

Treatment:

Treatment of mononeuritis multiplex focuses on:

Treating the Underlying Cause: This is the most important aspect of treatment. For example, if vasculitis is the cause, immunosuppressant medications (e.g., corticosteroids, cyclophosphamide) are used to control the inflammation. If diabetes is the cause, controlling blood sugar is crucial. Treating the infection, if present.
Pain Management: Medications such as NSAIDs, opioids, gabapentin, pregabalin, or tricyclic antidepressants may be used to manage pain.
Physical Therapy: To help maintain muscle strength and range of motion.
Occupational Therapy: To help adapt to any functional limitations.
Supportive Care: Braces or splints may be used to support weakened limbs.

Prognosis:

The prognosis of mononeuritis multiplex depends on the underlying cause and the severity of nerve damage. If the underlying condition can be effectively treated, the prognosis is generally better. However, if the nerve damage is severe or if the underlying condition is difficult to control, there may be permanent neurological deficits. Early diagnosis and treatment are important to improve the chances of a good outcome.