Notalgia paresthetica. This condition might also cause neuropathic pruritus as a consequence of nerve impingement. The itch of notalgia paresthesia is located on the skin, medial to the scapular border on the upper or mid-back.2 It has been postulated that the itch is caused by nerve entrapment of the posterior rami of spinal nerves arising from T2-T6.9 However, another theory suggests that the itch is caused by damage to peripheral nerves.9 The itch of notalgia paresthetica can wax and wane.2
Poststroke pruritus. Brain lesions, most often caused by stroke, can cause neuropathic itch. One of the best-known syndromes related to poststroke itch is Wallenberg syndrome (ischemia from a lateral medullary infarction), which typically presents with itch, thermalgic hypoesthesia of the face, cerebellar dysfunction, nausea, and vomiting.7
Shingles. More than one-half of patients who develop postherpetic neuralgia as a consequence of a herpes zoster infection also develop neuropathic pruritus.9 It is thought that postherpetic pruritus shares a comparable pathophysiology with postherpetic neuralgia, in which neurons involved in itch stimuli become damaged.7
Diabetes mellitus. Pruritus from diabetes can be classified as systemic or neuropathic. Diabetes is one of the most common causes of small-fiber polyneuropathy, which can cause neuropathic pruritus.13
Multiple sclerosis. Central nervous system lesions that affect sensory pathways can lead to neuropathic itch in multiple sclerosis. Patients can have severe episodes of generalized pruritus. It has been hypothesized that the neuropathic itch in multiple sclerosis is induced by activation of artificial synapses in demyelinated areas.2
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