Neuro Disorders: Mononeuritis Multiplex

Mononeuritis Multiplex is a type of neuropathy (nerve pathology) where as the name implies multiple nerves are affected by the same pathological process.

The affected nerves are randomly distributed in an asymmetric fashion. Peripheral neuropathy, also called as polyneuropathy is also a pathological condition of the nerves but there nerves are affected bilaterally and in a symmetric fashion in both limbs.

Vasculitis is the commonest cause for this type of neuropathy. Vasculitis means inflammation of the the arteries and following are the usual causes;

• SLE (systemic lupus erythematosus) or lupus
• Rheumatouid arthritis
• PAN (poly arteritis nodosa)
• Cryoglobunins
• Neurosarcoidosis
• Vasculitis confined to the nerves without systemic involvement.

Non vasculitic condition like DM an also cause this type of neuropathy.

The tiny branches that supply the nerves are called as vasa nervorum and due to inflammatory process they develop thrombosis (clot) or get obliterated and this cuts of blood supply to these nerves and causes something like strokes of the nerves. (microinfarcts). In addition to this the inflammatory cells that infiltrate the nerves can also cause some direct damage to the nerves.

Patient will complain of multiple neurological usually a combination of motor and sensory, in an asymmetric fashion. These episodes may not all manifest at the same time; means different nerve may get affected at different times. Muscle weakness (foot drop, wrist drop, muscle wasting etc), numbness, pins & needles (tingling), loss of sensation over a limb are the common manifestations.

If the underlying cause is a systemic inflammatory process then there may be additional constitutional manifestations like fever, loss of appetite, weight loss, joint pains etc.

High degree of clinical suspicion & EMG/NCS (electromyography & nerve conduction study) are the mainstay in the diagnosis.

Blood tests including ESR/CRP, serum complements, RA factor, ANA, cryoglobulins, Anti Ro, Anti La antibodies are frequently ordered. More tests may be required depending upon the suspicion.

Nerve biopsy is sometimes needed too.

The following therapeutic interventions are generally necessary;

• Steroids
• Other immunosuppressive agents
• Rarely immunoglobulins, plasmapheresis
• Symptomatic treatments e.g. nerve pain pills like gabapentin, duloxetine, pregabalin fo pain, numbness/tingling sensations
• Physical therapy etc.

A neurologist s commonly involved in the care of Mononeuritis Multiplex patients.