Diagnosis:
The diagnosis is made based on clinical features +Peripheral neuropathy, +evidence of vasculitis, +evidence of other organ involvement
Clinical features:
acute, mononuritis multiplex or less commonly mononeuritis simplex or symetric polyneuropathy, sensorimotor
+Peripheral neuropathy
+evidence of vasculitis
+evidence of other organ involvement
Findings on investigations:
+NCS/EMG:
NCS:
- Axonal neuropathy
- Conduction block: often transient
- CMAP: reduced
- Motor conduction velocity: normal or slightly reduced
- SNAP: reduced
EMG: fibrillation potentials occasionally,
Pathology, nerve biopsy:
Sural nerve or superficial peroneal nerve biopsy
- Arterioles of the epineurium:
- Inflammation: Infiltrate of lymphocytes
- Necrosis of intima and media
- Endothelial cell changes
- Fibrinoid necrosis: a definite sign
- Axons: loss of axons in the periphery of the fascicle i.e. subfascicular ischemic change
Immunohistochemistry: CD3 for T cells