Notalgia Paresthetica: An Enigmatic Condition
A 55-year-old woman presented with a history of pruritus and sporadic pain between her shoulder blades. Her husband noticed a slight discoloration around the area of pain. The patient’s medical history was negative for any systemic diseases. She was not taking any medications and denied having any allergies. She tried over-the-counter moisturizers, which did not help to decrease her itching or pain. Physical examination revealed a hyperpigmented patch between her scalpulae. A biopsy demonstrated only post-inflammatory hyperpigmentation.
What is your diagnosis?
Notalgia paresthetica is a relatively common, but under-reported, condition within the spectrum of cutaneous dysesthesias (abnormalities of cutaneous sensation). Although the condition was probably mentioned previously under different names, it was a neurologist from St. Petersburg, Russia, who, in 1934, thoroughly described and introduced the term notalgia (“notos” – back, “algia” – pain; from Greek).1
The condition is characterized by neuropathic pruritus and episodic pain occurring on either the left or right side of the middle to upper back. Notalgia paresthetica is 2 to 3 times more prevalent in women than men, and usually occurs after 50 years of age. While not life threatening, notalgia paresthetica can cause discomfort (due to the itch) and pain, as well as decreased quality of life.
Notalgia paresthetica usually is located in the scapular region (T2-T6 dermatomes) and is characterized by pruritus and occasional painful sensations. Despite the name, itch is more common than pain, which is observed in ≤30% of patients.2 Up to 10% of cases are bilateral.2 Hyperpigmentation and secondary changes due to itching (excoriations, lichenification) are seen commonly, and lichen amyloidosis most likely represents secondary amyloid deposition in the setting of notalgia paresthetica (Figure 1).
Nerve entrapment is the most likely causative mechanism, and evidence exists that notalgia paresthetica may be associated with cervical and thoracic spinal pathology.2,3 Savk et al noted that 61% of patients with notalgia paresthetica have spinal cord pathology (mainly herniated nucleus pulposus and degenerative changes) in a distribution corresponding to the skin lesions.2 Several cases of an association of notalgia paresthetica with Sipple’s syndrome (multiple endocrine neoplasia type 2a) are known.4
The histopathology of notalgia paresthetica demonstrates secondary changes related to scratching, including post-inflammatory hyperpigmentation with diffuse melanophages in the papillary dermis (Figure 2).5 Mild hyperkeratosis may be seen.
Inaloz et al reported an increased number of nerve endings found in lesional and perilesional skin of patients with notalgia paresthetica, which also may represent a reactive phenomenon in response to the associated itch.6 Neural proliferation was positive for S-100 staining within the dermis. Some authors have reported the deposition of amyloid in patients with notalgia paresthetica and proposed that cutaneous amyloidosis (lichen amyloidosis) and notalgia paresthetica represent two ends of the same spectrum. Not all authors have accepted this hypothesis.5,7 Savk et al reported an absence of amyloid, even in some patients suffering from notalgia paresthetica for decades.5 No immunohistochemical findings were reported to be helpful in diagnosis of notalgia paresthetica.5
Diagnosis and Management
A biopsy is helpful to exclude other possible conditions (early mycosis fungoides, morphea, fungal infection, lichen sclerosus, etc). Twice daily application of over-the-counter capsaicin topical therapy in conjunction with biweekly osteopathic manipulative treatments consisting of soft tissue and myofascial technique can result in improvement within 2 weeks.
Notaliga paresthetica is a chronic condition that may last for decades, causing significant discomfort for patients. Multiple treatment options, including topical and systemic treatments, as well as non-medical modalities are used with variable results. There is no FDA-approved treatment for notalgia paresthetica. The efficacy of available pharmacologic treatments for this disease has been assessed only in small studies and case reports, and long-term effects are unknown. The treatment plan should be based on the severity of itch/pain and patient preferences. Usually, topical therapy and physical therapy provide some benefit. A review of current treatment modalities is presented below.
Capsaicin was among the first topical treatments for notalgia paresthetica.8 Early research found that use of capsaicin (0.025%) (Axsain, Capsagel, others) for 4 months led to 90% relief of symptoms in about 70% of cases.9 In essence, capsaicin is a naturally derived molecule that acts as a transient receptor potential vanilloid receptor agonist. It binds to this heat-activated channel receptor on the membranes of cutaneous nerves and causes activation at temperatures below the normal range at which the channel operates, producing a sensation of heat, causing relief to the applied area.10 In addition to capsaicin, topical corticosteroids may lead to the temporary relief of notalgia paresthetica. Local anesthetics, such as lidocaine, may be used as well.
Antiseizure medications, such as oxcarbazepine (Trileptal, others) and gabapentin (Gralise, Neurontin, Horizont, others), have been studied as a treatment for notalgia paresthetica. They act on the neural pathway and have shown benefit in other neuropathic conditions. Oxcarbazepine inhibits sodium channels on pain-producing neurons and has been shown to relieve the itch and pain in patients with notalgia paresthetica.11 Gabapentin, on the other hand, binds to receptors to prevent the release of neurotransmitters involved in producing symptoms.12 The tricyclic antidepressant amitriptyline also has been used to treat itch and pain in patients with notalgia paresthetica, with variable results.13
Since the pathophysiology of this condition lies in nerve entrapment, exercises that increase the patient’s range of motion have been shown to be beneficial. Fleischer et al have found that exercise caused relaxation and pliability of surrounding musculature, in turn decreasing the compressive forces placed on the nerves.14 In a similar fashion, osteopathic manipulative treatment also has been used to treat notalgia paresthetica.15 Certain passive indirect techniques, such as counter-strain or articulatory techniques of the spine in addition to rib raising, may offer dual therapy, to not only relieve the muscular strains but also to decrease sympathetic tone, resulting in a decreased neural output to the involved dermatomes.