Notalgia paraesthetica G58.8

The disease was first described in 1934 by the Russian neurologist Mikhail Astvazaturov (cited in Pleet AB et al., 1978). Since then, a large body of literature has been published on the etiology and pathogenesis of this disease, much of which is speculative.

Notalgia paraesthetica (from the Greek noton = back – algia = pain) is a chronic neuropathic dysesthesia ( a form of neuropathic pruritus) of unknown cause, characterized by a circumscribed, chronic, intermittent, or permanent itching (itch-pain), which is usually localized to the medial lower edge of the scapula. Clinically and morphologically, this area is characterized by a yellowish-brown discoloration that is usually poorly defined.    

The etiology of notalgia paraesthetica remains unclear. Most authors assume that notalgia paraesthetica is a form of neuropathic dysesthesia, although it remains unclear whether it is caused by radicular or peripheral neuropathy. 

Compression of the spinal nerves is most commonly cited as the underlying cause of the symptoms (thoracic polyradiculopathy of the posterior branches from Th2 to Th6; Raison-Peyron N et al., 1999), with degenerative spinal changes and intervertebral disc protrusions being the most commonly cited causes (radiologically, degenerative changes are found in the spinal segments of the affected regions in the majority of patients).

The hyperpigmentation of the area is understood to be an irritative response to constant friction at this site. In more than 10% of cases, (reactive) macularfriction amyloidosis is present.

The etiology is multifactorial and not yet fully understood. Neuropathic mechanisms play a primary role. It is believed that the sensation of itching is a complex process involving sensory neurons and adjacent cellular mechanisms that modulate it. Dysregulation of this process leads to abnormal activity in the nerve fibers that transmit the itching sensation in the absence of a typical physical stimulus that would normally trigger itching. This type of disorder is known as allokinesia (Andersen HH et al. 2018).

It is believed that this itching is transmitted via at least two different types of nerve fibers. Small, unmyelinated, histamine-sensitive nerve fibers, known as C-fibers, are considered the primary transmitters of itching. Other nerve fibers presumably transmit both itching and pain. This second bifunctional nerve fiber could explain why some patients with notalgia paresthetica experience additional sensations such as paresthesia and allodynia in addition to pruritus.

In addition, itch-sensitive fibers may have closely coupled thermoreceptors, which could provide a possible explanation for why heat exacerbates the itching.

Notalgia paraesthetica is most likely a multifactorial process in which a combination of physical nerve irritation and a disrupted itch control mechanism plays a role (Ikoma A et al. 2004; Howard M et al. 2018; Cohen PR 2017). At the core of this condition is functional or structural damage to, or irritation of, afferent somatosensory nerve fibers.

Specifically, degenerative spinal changes are implicated, such as:

• spondylosis of the cervical and thoracic spine
• Intervertebral disc degeneration and disc protrusions
• Facet joint osteoarthritis
• Foraminal stenosis

However, a causal relationship between radiological changes and clinical symptoms cannot be demonstrated in all patients.

Peripheral nerve compression or irritation: Mechanical irritation of small sensory nerve branches, particularly the dorsal branches of the thoracic spinal nerves, as they pass through paravertebral muscles and fascia (da Cruz CM et al. 2018).

Musculoskeletal factors:

• Chronic paravertebral muscle tension
• Postural abnormalities and kyphotic changes
• Changes in shoulder girdle mechanics
• Local mechanical stress

Genetic factors (rare): Rare familial or hereditary forms, particularly in association with multiple endocrine neoplasia type 2A (MEN2A) and pathogenic variants of the RET proto-oncogene. In children with notalgia paresthetica, particularly when there are additional clinical indications of MEN2A, this condition should be considered.

Other causes include metabolic disorders such as type 2 diabetes mellitus or infectious causes such as a previous episode of herpes zoster (Oaklander AL et al. 2003).

About 70% of those affected are women. The median age of onset is 57 years (range: 25–80 years).

Notalgia paraesthetica shows no ethnic prevalence (unlike other neuropathic pruritus syndromes such as brachioradial pruritus, which occurs primarily in people with lighter skin tones/He A et al. 2017).

Notalgia paraesthetica is typically a unilateral condition that frequently occurs on the side opposite the dominant hand. The majority of the population is right-handed. Therefore, left-sided parascapular itching that the patient can reach with their dominant hand strongly suggests notalgia paraesthetica.

Above or between the shoulder blades (segments C7–Th6). See figure.

Studies involving larger groups describe symptoms of “pruritus of varying intensity and localized distribution” as well as a well-defined, blurred, brown-gray patch on the skin (likely caused by friction and rubbing of the affected areas, melanosis maculosa; see also friction amyloidosis).

Additionally, the following are reported (less commonly):

• intermittent pain (30%)
• paresthesias (28%)
• hyperesthesia (11%).

The diagnosis is typically made clinically based on the characteristic location and symptoms. In most cases of notalgia paraesthetica, further evaluation beyond the medical history and physical examination is not necessary.

Dermatological findings (see above): Well-defined hyperpigmentation in the absence of primary inflammatory skin changes.

Neurological examination: Assessment of sensation to touch, pain, and temperature in the affected area; if indicated, examination of the spine and paravertebral muscles.

Imaging: MRI of the cervical or thoracic spine in cases of neurological abnormalities, radicular symptoms, or a well-founded suspicion of a relevant structural lesion. Routine imaging is not necessary if the findings are typical.

Histology: Not mandatory. A skin biopsy may be indicated in cases of unclear pigmentation or suspicion of another dermatosis. Typical but nonspecific changes include epidermal acanthosis, pigment incontinence, and dermal melanophages.

Biopsies are generally not necessary for diagnosis, but they can help rule out other conditions such as contact dermatitis, parapsoriasis, early cutaneous amyloidosis, and tinea versicolor.

In a larger study, histological examination revealed single-cell necrosis in the epidermis in 71.4% of cases, epidermal hyperpigmentation in 74.3%, and dermal hyperpigmentation in 80%.

Amyloid deposits in the papillary body were detectable in 11.4% of patients (possibly due to chronic scratching, which damages keratinocytes and leads to the breakdown of keratin into amyloid). 5.7% of patients did not exhibit any of the aforementioned histological features (see also friction amyloidosis; see below: cutaneous amyloidosis)

An increased nerve fiber density (S-100 staining) is under discussion.

The diagnosis of notalgia paresthetica is primarily based on the patient’s medical history and a physical examination. A thorough examination is essential to avoid excessive and unnecessary testing. Symptoms suggestive of notalgia paresthetica may include a long-standing, intermittent itching sensation of varying intensity that occurs medially in the lower two-thirds of the scapula on the side opposite the dominant hand. Although most cases are unilateral, notalgia paresthetica can also occur bilaterally. In addition, patients may report sensations such as pain, heat, cold, a foreign body sensation, tingling, and numbness.

Pigmented contact dermatitis: usually superficial scaling, scattered lesions; histology: spongiotic dermatitis; consistent history of exposure

Small-focal parapsoriasis: a single lesion would be unusual; itching is less pronounced. No hyperpigmentation of the lesions 

Lichen simplex chronicus ( LSC): Localization on the “back” is uncommon. Composed of papules that aggregate into plaques; a three-zone pattern is typical of LSC

Macular cutaneous amyloidosis(lichen amyloidosus): reticular or wavy hyperpigmentation; dermal amyloid deposits

Tinea versicolor: Fine scaling; detection of Malassezia

Post-inflammatory hyperpigmentation: Pigment changes following a prior inflammatory reaction

Radiculopathy: Dermatome-related neurological symptoms, possibly including motor deficits

Brachioradial pruritus: Neuropathic pruritus primarily affecting the dorsolateral forearms

There are a variety of treatment options for notalgia paresthetica. Oral and topical medications, botulinum toxin A, transcutaneous electrical nerve stimulation (TENS), and physical therapy have been used with varying degrees of success. Before treatment, it is essential to reassure the patient and explain that this is a benign condition. Often, this alone provides sufficient relief, and patients with mild or intermittent itching may not require treatment.

Botulinum toxin A: Mixed reports on treatment success. Early reports suggest that botulinum toxin was a viable option that led to a significant improvement in patient-reported itching. Later studies attempted to replicate these results, but found little to no improvement (Weinfeld PK 2007).

TENS: Successes have been reported with TENS (transcutaneous electrical nerve stimulation). TENS devices are typically used to treat neuropathic pain. It is believed that an afferent itch pathway transmits both itch and pain; and this is the most likely target for TENS treatment. A small study in which TENS was applied five times a week for 20 minutes resulted in a 60 percent reduction in itching in one-third of the patients. In the same study, one-fifth of the patients treated with TENS reported no change, and one patient reported a worsening of their itching during TENS treatment. Since notalgia paresthetica can involve other neuropathic symptoms—such as pain, tingling, and numbness—in addition to itching, TENS could be a particularly effective treatment for patients suffering from multiple neuropathic sensations (Savk E et al. 2007).

Nerve blocks: This treatment method is worth considering in therapy-refractory cases with corresponding neurological findings; very limited evidence.

Capsaicin 0.025–0.075%: Several times a day; desensitization of TRPV1-expressing sensory nerve fibers. Clinical efficacy has been demonstrated, although local burning and recurrence after discontinuation are common.

8% capsaicin patch: For treatment-resistant cases; use under medical supervision. Limited evidence from small studies.

Lidocaine 5%: Patch or topical preparation; symptomatic inhibition of neuronal conduction. Limited evidence.

Lidocaine, intracutaneous: Local injection therapy; positive results from small studies, but long-term efficacy is unconfirmed.

Topicalamitriptyline/ketamine: Experimental treatment of neuropathic dysesthesia; case reports and small case series.

 Doxepin: Experimental treatment of neuropathic dysesthesia; case reports and small case series (Wallengren J et al. 1995).

Tacrolimus 0.1%: Partially effective in small studies; not an established standard therapy.

Menthol 5% / cooling agents: Short-term symptomatic relief; no causal effect.

Topical glucocorticosteroids:Topical glucocorticosteroids vary in efficacy and are only indicated in the presence of inflammation. 

Narrowband UVB: A few positive case series; no established treatment.

Gabapentin: Dosage: Adults: Titration over 3 days (Day 1: 300 mg orally once daily; Day 2: 300 mg orally twice daily; Day 3: 300 mg orally three times daily). Alternatively: Initial dose 900 mg/day in 3 equal doses; usual dose range 900–1,800 mg/day; maximum total daily dose: 3,600 mg/day, divided into 3 equal doses. Caution: Dose adjustments are required in patients with chronic renal insufficiency and in elderly patients. Gabapentin is a commonly used treatment option for severe neuropathic pruritus. Small studies show an improvement in symptoms. Patients with notalgia paresthetica who are treated with gabapentin may report mild gastrointestinal discomfort; however, this generally does not lead to discontinuation of the medication (Loosemore MP et al. 2007).

Pregabalin: Dosage: maximum 600 mg/day; alternative to gabapentin; limited specific evidence.

Amitriptyline(antidepressant): Effective in individual cases, particularly for painful dysesthesias; be aware of anticholinergic side effects. 

Oxcarbazepine: Isolated positive case reports; insufficient evidence for a general recommendation.

Antihistamines do not provide significant relief from itching; however, the sedative effect of first-generation antihistamines may help reduce paroxysmal nocturnal or unconscious scratching.

Note: The systemic treatments mentioned are generally used off-label for this indication. In older patients in particular, sedation, dizziness, the risk of falls, and renal function must be taken into account.

The best results are achieved with 0.025–0.05% capsaicin ointment(e.g., Dolenon, Capsamol, Capsagamma Dolor 0.05%) applied 3–5 times a day over a treatment period of several months. The application of capsaicin initially causes a burning sensation and itching at the application site (inform the patient!).

Treatments with antipruritic substances such as camphor ormenthol may be tried.

Other localized conditions involving sensory changes/paresthesias include:

• Brachioradial pruritus (forearms)
• Cheiralgia paresthetica (radial nerve compression syndrome, sensory disturbances on the back of the hand, dysesthesia, and pruritus)
• Meralgia paresthetica (anterolateral thigh)
• Gonyalgia paraesthetica (knee and lower leg)

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