Mononeuritis multiplex

Mononeuritis multiplex (MNM) consists of a heterogeneous group of peripheral nerve disorders.

MNM presents with sensory and motor deficits in the distribution of specific peripheral nerves, and may be acute, sub-acute, or (rarely) chronic.

MNM is most commonly caused by vasculitis, which may be either systemic or isolated to the nerves. Other causes include hypersensitivity reactions to drugs or infections, or direct viral or bacterial infection of nerves.

Diagnosis is based on clinical picture, electrophysiological evidence of axon destruction, and characteristic changes seen on nerve biopsy.

Therapy varies with underlying MNM aetiology. Most vasculitic neuropathies are treated initially with corticosteroids. Oral cyclophosphamide may also form part of first-line treatment, depending on disease severity. Intravenous cyclophosphamide and oral methotrexate are further treatment options if the response to initial treatment is insufficient.

Plasma exchange and intravenous immunoglobulin may be useful adjunctive treatments for some forms of refractory MNM.

Azathioprine, oral cyclophosphamide, or methotrexate may be used for chronic maintenance therapy for vasculitic neuropathy once remission is achieved.

MNM is a term used to describe a distinctive clinical presentation of progressive motor and sensory deficits in the distribution of specific peripheral nerves. MNM is essentially an asymmetrical, asynchronous sensory and motor peripheral neuropathy involving isolated damage to at least two separate limb or cranial nerves. Multiple nerves in random areas of the body can be affected simultaneously or sequentially. As the condition worsens, it becomes less multifocal and more symmetrical, mimicking distal dying-back symmetrical polyneuropathy. However, a history of asymmetrical onset and clinical and electrophysiological findings of some asymmetry at all stages are generally present in almost all cases. Pain is a frequent symptom in MNM, often with both neuropathic pain within the area of sensory loss impairment and a deep pain in the affected extremity. A heterogeneous group of conditions lead to MNM.