Mononeuritis multiplex (MNM) consists of a heterogeneous group of peripheral nerve disorders.
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 and characteristic changes seen on biopsy.
Therapy varies with underlying MNM aetiology, with most vasculitic neuropathies treated with intravenous methylprednisolone, oral corticosteroids, and oral cyclophosphamide.
Plasma exchange and intravenous immunoglobulin may be useful in some forms of MNM.
Azathioprine and oral cyclophosphamide are used for chronic maintenance therapy.
Mononeuritis multiplex (MNM) is a term used to describe a distinctive clinical presentation of progressive motor and sensory deficits in the distribution of specific peripheral nerves. A heterogeneous group of diseases lead to MNM. Involvement of each nerve occurs either sequentially or simultaneously. Pain is a frequent symptom in MNM, often with both neuropathic pain within the area of sensory loss and a deep pain in the affected extremity.
History and exam
Key diagnostic factors
- presence of risk factors
- sicca symptoms
- parotid gland enlargement
- rash, ulcerations, or pigment changes
- wheeze, cough, other pulmonary signs
- fever, weight loss, and malaise
Other diagnostic factors
- predisposing conditions causing vasculitis, inflammation, or other nerve damage
- age over 50 years
- hepatitis C
- hepatitis B
- connective tissue disease
- primary vasculitis
- drug use
- HIV infection
- non-HIV, non-hepatitis infections
- recreational intravenous drug use
- genetic predisposition
1st investigations to order
- electromyogram (EMG)
- FBC with differential
- erythrocyte sedimentation rate (ESR)
- C-reactive protein (CRP)
- serum creatinine
- serum glucose
- serum complement
- hepatitis B surface antigen
- hepatitis C antibodies or RNA
- anti-HIV antigens or HIV RNA
- Lyme disease antibodies
- cytoplasmic and perinuclear antineutrophil cytoplasmic antibodies (c-ANCA and p-ANCA)
- rheumatoid factor
- antinuclear antibodies (ANA)
- antidouble-stranded (ds) DNA
- anti-SSA or SSB antibodies
- serum angiotensin-converting enzyme
- protein electrophoresis and immunofixation
- chest x-ray
- muscle and nerve biopsy
Investigations to consider
- anti-Smith (anti-Sm) antibodies
- antitopoisomerase I (anti-Scl 70) and anticentromere (ACA) antibodies
- skin biopsy
- lip biopsy
- anti-Hu antibodies
- cerebrospinal fluid analyses
- CT of chest, abdomen/pelvis
- positron emission tomography (PET) scan of chest, abdomen, or pelvis
- conventional angiography
- magnetic resonance angiography
hepatitis B-associated polyarteritis nodosa
hepatitis C-associated cryoglobulinaemic vasculitic neuropathy
HIV-associated vasculitic neuropathy
cancer-associated vasculitic neuropathy
classic polyarteritis nodosa or eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)
granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis) or microscopic polyarteritis
secondary vasculitis associated with connective tissue disease
non-systemic vasculitic neuropathy
hepatitis C: remission achieved
classic polyarteritis nodosa or eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome): remission achieved
granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis) or microscopic polyarteritis: remission achieved
non-systemic vasculitic neuropathy: remission achieved
Kevin R. Scott, MD
Colorado Springs Neurological Associates
KRS declares that he has no competing interests.
Milind J. Kothari, DO
Professor of Neurology
Penn State College of Medicine
MJK declares that he has no competing interests.
Dr Kevin Scott and Dr Milind Kothari would like to gratefully acknowledge Dr Jenice Robinson, the previous contributor to this topic. JR declares that she has no competing interests.
John J. Kelly, MD
Professor and Chairman
Department of Neurology
The George Washington University Medical Center
JJK declares that he has no competing interests.
Cory Toth, BSc, MD, FRCP(C)
Assistant Professor of Neurosciences
Hotchkiss Brain Institute
University of Calgary
CT declares that he has no competing interests.
Jeremy Bland, FRCP
East Kent Hospitals NHS Trust
Kings College Hospital NHS Trust
JB declares that he has no competing interests.
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