Notalgia paresthetica: a study on pathogenesis.

BACKGROUND: Notalgia paresthetica is a sensory neuropathy involving the dorsal spinal nerves. The characteristic symptom is pruritus on the back, occasionally accompanied by pain, paresthesia, and/or hyperesthesia, which results in a well-circumscribed hyperpigmented patch in the symptomatic area. The etiology of this condition has not yet been completely defined.

OBJECTIVE: Possible mechanisms that could explain the pathogenesis of notalgia paresthetica were investigated through clinical examination and various diagnostic tests.

METHODS: Ten cases of notalgia paresthetica underwent dermatologic, neurologic, and orthopedic examination. This was followed by skin biopsy, electrodiagnostic investigation, and radiography of the spine.

RESULTS: All patients had a typical symptomatology and dermatologic picture. Neurologic examination and standard electrodiagnostic investigation results were normal in all cases. Histopathology was compatible with postinflammatory hyperpigmentation; there were no amyloid deposits. In seven cases, degenerative changes in the vertebrae were observed and, in all of these cases, these changes were most prominent in the vertebrae which corresponded to the dermatome of the cutaneous lesion.

CONCLUSIONS: The striking correlation of notalgia paresthetica localization with degenerative changes in the spine suggests that spinal nerve impingement may contribute to the pathogenesis of this entity.