Neuroscience Clerkship at UH/VA
 

MONONEURITIS MULTIPLEX

 

The pattern of a mononeuropathy multiplex is one of the most important patterns to recognize and differentiate from the length-dependent, dying-back, axonal polyneuropathy. The clinical presentation is distinctive: there is an asymmetric, stepwise progression of individual cranial and/or peripheral neuropathies often over days to weeks. Over time, a confluent pattern may develop, which may be difficult to distinguish from a generalized polyneuropathy. When the etiology involves inflammation, the term mononeuritis multiplex is used.

In most cases, the individual neuropathies are of named nerves (i.e., median, ulnar, peroneal, etc.) as opposed to small nerve twigs. Mononeuropathy multiplex is associated with a limited differential diagnosis (see list below) and most often occurs in the setting of VASCULITIS and vasculitic neuropathy. As each subsequent nerve is infarcted, pain develops (often severe), followed hours or days later by weakness and numbness in the nerve’s distribution. Although other organ systems are often involved, the initial clinical presentation of systemic vasculitis may involve only the peripheral nervous system. Indeed, there are well-recognized cases in which vasculitis remains confined to the peripheral nervous system.

Above: The most common pattern of mononeuritis multiplex is an asymmetric neuropathy, that affects medium and large nerves. This is in contradistinction to the typical pattern of most peripheral neuropathies that are symmetric and length dependent ("stocking-glove pattern").
 

Differential Diagnosis of Mononeuropathy Multiplex

Vasculitis

Polyarteritis nodosa

Churg-Strauss syndrome

Wegener's syndrome

Hypersensitivity

Cryoglobulinemia

Systemic lupus erythematosus

Rheumatoid arthritis

Sjögren’s syndrome

Chronic active hepatitis

Diabetes

Inflammatory demyelinating polyneuropathy

Multiple entrapments (hereditary and acquired)

Infection (e.g., Lyme, leprosy, HIV)

Infiltration

◊ Granulomatous disease (e.g., sarcoid)

◊ Neoplasm (e.g., lymphoma, leukemia, carcinoma)


Evaluation
 

Serology for autoimmune disorders (ANA, ESR, RF, ANCA, Hep B, Hep C, cryoglobulins)

• EMG

Nerve. muscle or other involved tissue biopsy

Above: Muscle biopsy in a patient with mononeuritis multiplex. The biopsy demonstrates an inflammatory infiltrate and fibrinoid necrosis of small vessel, consistent with vasculitis.

 

Serology for Lyme, HIV (selected patients)

• Systemic Evaluation for malignancy or sarcoid (depending on risks and other symptoms)


Treatment

The treatment ultimately depends upon the etiology. Mononeuritis multiplex from vasculitis requires urgent treatment to prevent further progression and disability. In the case of systemic vasculitis (e.g., polyarteristis nodosa), delay in therapy can result in renal, mesenteric and cardiac ischemia, and its accompanying morbidity and risk of mortality. Mononeuritis multiplex from vasculitis is typically treated with immunosuppressive therapy, usually with steroids, often with the addition of cytoxic drugs, such as cyclophosphamide.