Vasculitic Neuropathy

How vasculitis damages nerves

Peripheral nerves receive blood through a network of tiny vessels (vasa nervorum). In vasculitis, immune cells attack the walls of these vessels, causing inflammation, narrowing and blockage. Parts of the nerve that lie in "watershed" zones with the poorest blood supply, such as the mid-thigh and mid-upper arm, are especially vulnerable. The affected nerve fibers die (axonal damage), causing loss of feeling and strength in the area that nerve supplies.

Patterns of nerve involvement

Causes

Systemic vasculitis

• polyarteritis nodosa
• ANCA-associated vasculitis: eosinophilic granulomatosis with polyangiitis (often with asthma), microscopic polyangiitis, granulomatosis with polyangiitis
• cryoglobulinemic vasculitis, often linked to hepatitis C

Connective tissue diseases

• rheumatoid arthritis (rheumatoid vasculitis)
• lupus
• Sjögren's disease

Infections

• hepatitis B (polyarteritis nodosa) and hepatitis C (cryoglobulinemia)
• HIV and others

Other

• nonsystemic vasculitic neuropathy: vasculitis confined to the nerves, often with a slower, more benign course
• diabetic radiculoplexus neuropathy (inflammatory microvasculitis affecting the thigh nerves in diabetes)
• drug-induced vasculitis and cancers

Symptoms

• sudden onset of burning or deep aching pain in a limb
• numbness and tingling in the area supplied by a single nerve
• weakness: foot drop, wrist drop, weak grip
• new symptoms appearing in other nerves over days to weeks
• systemic symptoms with systemic vasculitis: fever, fatigue, weight loss, joint pain, rash, kidney or lung problems

Diagnosis

• Neurological examination to map which nerves are affected.
• Nerve conduction studies and EMG: show patchy axonal damage in multiple nerves.
• Blood tests: inflammatory markers (ESR, CRP), ANCA, rheumatoid factor, ANA, complement, cryoglobulins, hepatitis B and C, HIV, kidney function, blood count, urinalysis.
• Nerve and muscle biopsy: usually of the superficial peroneal or sural nerve with a muscle sample; shows inflamed vessel walls and nerve fiber loss. This is the key test, particularly for nonsystemic disease.
• Imaging and other organ assessment if systemic vasculitis is suspected.

Diabetic and other non-vasculitic neuropathies are ruled out, though diabetes and vasculitis can coexist.

Treatment

• Corticosteroids (prednisone), often starting with high doses.
• Cyclophosphamide or rituximab for systemic vasculitis and severe or progressive disease.
• Maintenance with azathioprine, methotrexate or rituximab for 18 months or more in systemic vasculitis.
• Antiviral treatment for hepatitis B- or C-associated vasculitis.
• Nonsystemic vasculitic neuropathy: corticosteroids alone may be enough for mild disease; add other immunosuppressants for progressive cases.
• Neuropathic pain treatment: gabapentin, pregabalin, duloxetine or amitriptyline.
• Rehabilitation: physical and occupational therapy, ankle-foot orthoses for foot drop.

Outlook

With treatment, most people stabilize and many improve over months to years as nerves slowly regrow. Some weakness, numbness or pain may persist. Relapses can occur, particularly in systemic vasculitis, so long-term follow-up is needed.

Frequently asked questions

What is vasculitic neuropathy?

It is nerve damage caused by inflammation of the small blood vessels that supply the nerves. Reduced blood flow injures the nerves, causing pain, numbness and weakness, often in one nerve after another.

What is mononeuritis multiplex?

Mononeuritis multiplex is a pattern of nerve damage in which two or more separate nerves are affected, usually at different times, causing patchy numbness and weakness. Vasculitis is a common cause; diabetes and some infections are others.

How is vasculitic neuropathy diagnosed?

Doctors use nerve conduction studies to map the damage, blood tests to look for vasculitis and its causes, and usually a nerve and muscle biopsy to confirm inflammation in the blood vessels.

Can vasculitic neuropathy be cured?

The vasculitis can usually be brought into remission with steroids and immune-suppressing medicines. Nerve recovery is slow and may be incomplete, but early treatment improves the chance of regaining strength and sensation.