Rare Diagnostic Case of the Month: Notalgia Paresthetica

The next time you buy an orthopaedic textbook take a look at the chapter list. You will probably find the shortest chapter to be on the thoracic spine. With that said the list of differentials  for T Spine and interscapular pain is usually short for most manual therapist. This is why although perhaps rare, reading about Notalgia Paresthetica sparked my interest.

What is it?

Notalgia Paresthetica (A.K.A Hereditary Localized Pruritis, Posterior Pigmented Pruritic patch and Subscapular pruritus) is a sensory neuropathy which involves dorsal spinal nerves. The neuropathy usually first presents itself with extreme itchiness and then may progress to pain, paresthesia, hyperesthesia and eventually a hyperpigmented patch of skin.

What causes it?

The flaw in research regarding NP is there are multiple causes which are purposed. Most studies looking into NP denote one specific cause and only investigate that particular pathophysiology. NP has been deemed to be due to hereditary conditions, chemical toxicity, increased dermal innervations and spinal nerve pathology either due to trauma or entrapment.

The hereditary and toxicity notion is often dismayed because of the rare reports and anecdotal evidence. However, there seems to be a strong correlation with spinal changes and NP.  Firstly, dorsal spinal nerves in the upper thoracic spine appear to pierce the Multifidus in a right angled manner. Such an anatomical position leaves the nerves exposed to trauma and easily being impinged.

In addition, recent small cased studies have found the majority of NP patients to have some form of T Spine pathology (7/10 & 9/12). These pathologies consist of degeneration, bulging disc and past history or prior upper back and neck complaints. Interestingly enough the dermatological pattern of patients symptoms correlated with their imaging findings. For example if a patient presented with symptoms from T1-T3 it was found they had degeneration in this particular area. In addition, these findings were discovered by a radiologist blinded to the patient's complaint.

How do I treat it?

Multiple forms of treatment have been performed on NP patients. Majority of treatment options consist of dealing with hypersensitive nerves and skin. These options are limited to paravertebral nerve blocks, epidural injections, topical creams, acupuncture and botuline toxin injections.

However, what does one do when these forms of treatment are not at their disposal? How do you treat an area which is to painful to even touch?

A recent experimental form of treatment has been published. This treatment is based on the premise that NP may be due to the long thoracic nerve being injured. Thus with such an injury the Serratus Anterior is dysfunctional and now needs to be rehabilitated.

In this particular study subjects carry out Electrical Muscle Stimulation (EMS) of the Serratus Anterior.  Although results were recorded anecdotally, an improvement of 70% was found in some subjects.
More importantly this study provides insight into options for rehabilitative practitioners into treating NP.

Consider the following: If the Serratus Anterior is dysfunctional then the scapula may be positioned in a slightly retracted manner. The Trapezium and Rhomboids are now pulled under tension. This tension may apply traction or impingement to dorsal spinal nerves. This ideology may purpose a relationship between NP and Serratus Anterior dysfunction. If such a relationship is proven then this gives a rehabilitative premise for manual therapist to work with NP patients.

Additional research has also attempted to show analgic effects of using transcutaneous electrical nerve stimulation (TENS) amongst NP patients. However, results of this study were minimal displaying 30% improvement at best.

In addition, if one does find a correlation of T Spine pathology with an NP patient they should focus on the actual pathology. Degenerative changes could be treated with glucosamine supplementation and disc herniations with Mckenzie exercises.

So Remember

-Attempt to discover the cause of your patients NP.  Consider taking radiographs.
-Work with other professionals such as dermatologist to relieve symptoms such as pruritis.
-Incorporate Serratus Anterior rehab exercises into your treatment plan.
-Attempt to re-educate nerves with EMS and numb them with TENS.
-Focus on the actual T Spine pathology such as a herniated disc or degeneration which may be causing symptoms.

In summary manual therapist should be knowledgeable in the diagnosis of NP. Knowing such a diagnosis allows one to consider it in their differential list. Furthermore, NP allows us more insight into other causes of neuropathic pruritis which is often forgotten and not known about. Dr. Wayne Button, BSc, D.C

References:

SAVK, O., & SAVK, E. (2005). Investigation of spinal pathology in notalgia paresthetica Journal of the American Academy of Dermatology, 52 (6), 1085-1087 DOI: 10.1016/j.jaad.2005.01.138

Raison-Peyron, N., Meunier, L., Acevedo, M., & Meynadier, J. (1999). Notalgia paresthetica: clinical, physiopathological and therapeutic aspects. A study of 12 cases Journal of the European Academy of Dermatology and Venereology, 12 (3), 215-221 DOI: 10.1111/j.1468-3083.1999.tb01031.x

Wang CK, Gowda A, Barad M, Mackey SC, & Carroll IR (2009). Serratus muscle stimulation effectively treats notalgia paresthetica caused by long thoracic nerve dysfunction: a case series. Journal of brachial plexus and peripheral nerve injury, 4 PMID: 19772656

Savk E, Savk O, & Sendur F (2007). Transcutaneous electrical nerve stimulation offers partial relief in notalgia paresthetica patients with a relevant spinal pathology. The Journal of dermatology, 34 (5), 315-9 PMID: 17408440