Mononeuritis multiplex

Painful asymmetric asynchronous sensory and motor peripheral neuropathy involving isolated damage to at least 2 separate nerve areas.

Multiple nerves can be affected.

As the disease process progresses it becomes less multifocal and more symmetric.

Mononeuropathy multiplex syndromes can be bilateral, distal, and proximal.

Refers to a group of disorders and not a true distinct disease entity.

Associated with systemic disorders such as diabetes, vasculitis, amyloidosis, direct tumor involvement, polyarteritis nodosa, rheumatoid arthritis, systemic lupus erythematosus, and paraneoplastic syndromes.

The most common cause of mononeuritis multiplex in the US are auto immune vasculitides: primary systemic, vasculitis, vascular neuropathy, or secondary vasculitis.

Mononeuritis multiplex occurs in 60% of patients with polyarteritis nodosa.

Autoimmune vasculitis causes blood vessel, inflammation, leading to compromised blood flow, ischemia, and infarction.

When vasculitis involves a nerve, the vasa nervorum is compromised, leading to ischemic injury to the axons.

The vasa nervorum is supplied by small and medium sized blood vessels, the most common type of vasculitis that causes mononeuritis multiplex, affecting small and medium sized vessels.

May be associated with Lyme disease, Wegener’s granulomatosis, Sjögren syndrome, cryoglobulinemia, hypereosinophilia, temporal arteritis, scleroderma, sarcoidosis, leprosy, acute viral hepatitis A, and acquired immunodeficiency syndrome (AIDS).

Can become progressively worse over time.

Damage to the nerves involves destruction of the axon interfering with nerve conduction.

Common causes include a lack of oxygen from decreased blood flow or vasculitis.

Approximately one third of cases of unknown cause.

The actual incidence not known due to the variety of associated processes.

Equal among the genders and no racial predilection.

Disability varies from none to partial to complete loss of function.

Age of onset determined by the age of occurrence of associated disease process.

Older individuals tend to have milder disease.

Diabetics typically present with acute onset of unilateral severe thigh pain that is followed rapidly by weakness and atrophy of the anterior thigh muscles and loss of the knee reflex.

Patients often present with low back or hip and spreads to the thigh and knee on one side.

Pain characterized as deep and aching with sharp pains that are most severe at night.

Patients complain of numbness, tingling, burning pain, weakness and lack of control of movement.

Clinical findings include loss of sensation and impaied movement with specific nerves.

Reflexes are preserved and strength preserved except in in areas where nerves are profoundly affected.

Common findings include dysfunction of the sciatic nerve, femoral nerve, common peroneal nerve, axillary nerve, radial nerve, median nerve, ulnar nerve, and autonomic nerve dysfunction.

Laboratory testing reflects consideration of underlying associated disease processes.

Imaging Studies are not helpful to make the diagnosis.

Physical and occupational therapy may be beneficial.

Medication therapy intended to decrease inflammation around the epineurium.

Treatment is directed to the disease condition implicated to be related to the etiology.

Corticosteroids may decrease inflammation by reversing the increased capillary permeability, and suppresses neutrophil activity by stabilizing lysosomal membranes.

Corticosteroids can suppress lymphocyte and antibody production.

Long-term corticosteroids may be required therapy.

Immunosuppressants may be useful in patients that can not tolerate corticosteroids.

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