By Gary M. White, MD
The area outlined here itches.
Notalgia paresthetica (NP) is the condition in which there is a very itchy, fixed spot on the midback, usually just to one side of the midline. The itch is neuropathic in origin, not cutaneous. The nerves that innervate this area are at the medial cutaneous branches of the dorsal primary rami of the thoracic spinal nerve.
In one study, the striking correlation of notalgia paresthetica localization with radiographic degenerative changes in the spine suggests that spinal nerve impingement may contribute to the pathogenesis of this entity. In another report, a patient developed NP of the right upper back and shoulder caused by a large osteophyte in the C3/C4 intervertebral space, impinging on the right C4 nerve root (visualized by magnetic resonance imaging). Another report suggested injury to the long thoracic nerve and resulting dysfunction of the serratus anterior muscle. In cases where no radiographs changes are seen, tissue abnormalities such as cervical fibrous bands or muscle spasms have been theorized.
Interestingly there has been found an association between NP and multiple endocrine neoplasia 2A (MEN2A). Patients with MEN2A may develop NP at a younger age, even as low as age 6.
A very itchy, fixed spot on the midback, usually just to one side of the midline is typical. Pigmentation from the constant rubbing may occur. Historically, this was called "puzzling posterior pigmented pruritic patches".
Inquiry should be made about any previous neck trauma, motor vehicle accident. vertebral fracture, cervical neoplasm or malignancy, cervical disc disease or history of osteoarthritis. In the absence of specific neurologic changes, neither referral to neurology nor imaging is usually done [JAAD 2016;74;215].
For most patients, effective treatment is too complex or involved. Some may just want to scratch! If however, the itching is severe or very bothersome, the following may be tried:
If cervical disc disease is present or suspected, the following may be considered: transcutaneous electrical stimulation (TENS), acupuncture, electrical muscle stimulation (EMS), cervical traction, spinal manipulation, physical therapy, massage, cervical muscle strengthening and range of motion enhancing routines. For example, physical therapy with the goal of strengthened the rhomboids and latissimus dorsi muscles as well as stretched the pectoral muscles greatly helped two patients [Acta Derm Venereol. 2011 May;91(3):356-7].
Botulinum toxin injection appears to have no beneficial effect (JAAD 2013:70:1140)
It is common to get a brown spot where the itch is do to repeated rubbing/scratching (frictional melanosis).
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