Notalgia paresthetica


Notalgia paresthetica or notalgia paraesthetica is a chronic sensory neuropathy. Notalgia paresthetica is a common localized itch, affecting mainly the area between the shoulder blades but occasionally with a more widespread distribution, involving the shoulders, back, and upper chest. The characteristic symptom is pruritus on the back, usually on the left hand side below the shoulder blade. It is occasionally accompanied by pain, paresthesia, or hyperesthesia, which results in a well circumscribed hyperpigmentation of a skin patch in the affected area.

Causes

The causes of this condition have not yet been completely defined. Patients are usually older persons.
The correlation of notalgia paresthetica localization with corresponding degenerative changes in the spine suggests that spinal nerve impingement may be a contributing cause. According to Plete and Massey, "The posterior rami of spinal nerves arising in T2 through T6 are unique in that they pursue a right-angle course through the multifidus spinae muscle, and this particular circumstance may predispose them to harm from otherwise innocuous insults of a varied nature." Patients may have other conditions that predispose them to peripheral neuropathies.

Diagnosis

Possible differential diagnoses are:
Therapy for notalgia paresthetica is directed at controlling symptoms, as no cure exists for the condition. Available treatments include local anesthetics, topical capsaicin, topical corticosteroids, hydroxyzine, oxcarbazepine, palmitoylethanolamide and gabapentin. Paravertebral nerve block and botulinum toxin injections may also be helpful.
Some patients treated with low concentration topical capsaicin reported pain, burning, or tingling sensations with treatment, and symptoms returned within a month of ceasing treatment. Oxcarbazepine was reported to reduce the severity of symptoms in a few cases. One patient has been treated with "paravertebral nerve blocks, with bupivacaine and methylprednisolone acetate injected into the T3–T4 and T5–T6 intervertebral spaces" Hydroxyzine has also been used with considerable success in some cases as long as the pills are used daily.
High concentration topical capsaicin have been shown to be highly effective in treating neuropathic itch in some patients as well as in a recent proof-of-concept study.
Most recently intradermal injections of botulinum toxin type A have been tried with some success. Even though botulinum normally wears off in three to six months, the treatment appears to be long term, and it has been theorised that botulinum type A effects lasting change in pain signaling.