Anaesthesia of the region supplied by the ulnar nerve with contractures of the fourth and fifth fingers may be signs directing our attention to the true nature of the disease and in those cases where the appearance of smooth yellowish-brown spots precedes the neuritis manifestations we may here also find anaesthesia, provided the eruption has lasted for some time.
In brief the fully developed case of nerve leprosy shows anaesthetic spots, trophic lesions of the skin and bone, together with muscular palsies. The spots often appear singly and may be from ½ to several inches in diameter. They are not raised, have a sunburnt color and do not sweat. Instead of having a preference for the exposed parts they most frequently appear on the covered portion of the body or limbs as trunk, buttocks, scapular region, thighs or arms, although the first appearance of spots may be on the face.
Fig. 80.—Nerve leprosy, showing deformities, perforating ulcer, etc. (From U. S. Naval Medical Bulletin.)
These spots often look like ringworm lesions, as they have an erythematous border with a paler center, but they are oval in outline rather than round and there is no scaling. Bullous eruptions, which are most frequently noted about the knuckles, are rare manifestations of nerve leprosy. They are often followed by ulceration.
Fig. 81.—Nerve or maculo-anaesthetic leprosy showing anaesthetic spots on back (U. S. Naval Medical Bulletin.)
About this time the nerve trunks begin to enlarge, especially the ulnar at the elbow and the great auricular as it crosses the sterno-mastoid muscle. The characteristic nerve enlargement is spindle-shaped or beaded.