[Sensory polyneuropathy and neural conduction block as an initial manifestation of polyarteritis nodosa].

Polyarteritis nodosa (PAN) is a systemic necrotising vasculitis which affects middle calibre arteries and which has a tendency to form aneurysms. It may appear as one of a great variety of clinical forms depending on the vascular territory afflicted. Almost any organ may be involved although the lung is usually unaffected. Neurological manifestations are very frequent in this disease (global incidence being around 80%), especially at the peripheral nervous system level. Multiple mononeuritis is the most usual manifestation classically associated with this type of vasculitis, but it may also appear as distal sensorimotor polyneuropathy, this being its most infrequent form of presentation. The presence of nerve conduction blocks has also been recently described, usually associated with demyelinating processes. However peripheral nerve affectation in vasculitis has its origins in small ischaemic infarcts in the sensorimotor conduction fibres. It may well be that segmentary demyelination and axonal degeneration reflect different levels of ischaemic damage.