Introduction

Notalgia Paresthetica (NP) is a condition that mainly affects women and leads to pruritus on the skin that is located on the upper back region. Pruritus refers to skin itchiness, and this is known to be unpleasant as individuals mainly relieve this by scratching. Alongside pruritus, those affected may also present with a tingling or a burning feeling in the affected areas, as well as hyperpigmentation. This is a neuropathic condition, which means it is caused by nerve dysfunction, unlike many other conditions that result in pruritus.¹ Although the pathophysiology of this condition is not known in great detail, NP is thought to be due to the spinal nerves (T2-T6) being damaged. This results in the middle part of the spine, known as the thoracic region, having compressed roots, which leads to the symptoms observed in NP.  NP is also thought to be due to musculoskeletal issues.

There have been some studies which suggest that NP is not purely due to these mechanisms; hence, there are many unknowns regarding the cause of this condition.² Acupuncture is a Traditional Chinese Medicine (TCM) intervention which involves nerve stimulation using needles and has been shown to excite nerve fibres.³ TCM's success in different conditions has resulted in it being a treatment of interest in instances of NP, with some case studies demonstrating positive results.⁴ This article is going to evaluate the effectiveness of acupuncture in treating NP through investigating its mechanism of action. The risks associated with this form of treatment will also be explored.

Overview of notalgia paresthetica

Notalgia Paresthetica is known to affect women more than men, with some studies demonstrating that women are affected twice or even up to three times more than men with this condition. It is also important to note that NP mainly affects middle-aged or older people, hence many of those with NP are middle-aged women.⁵ As aforementioned, the pathophysiology of this condition is not fully known; however, it is thought to be due to nerve damage in nerves T2-T6 within the spine. The nerve roots within the thoracic region being compressed is known as thoracic polyradiculopathy, and this is thought to lead to the pruritus and tingling sensation that those affected experience. The phenomenon that results in compressed nerves is known as nerve entrapment. The entrapment of the T2-T6 nerves alongside musculoskeletal changes is the most common theory for the symptoms experienced in NP instances.⁶ There are currently a few different treatment options available for NP patients. Topical agents such as lidocaine and capsaicin are known to interact with the nervous system in the affected areas and have been shown to treat NP associated pruritus. There are possible side effects, such as a prolonged burning sensation, which is counterintuitive.⁷ Oral medications, such as antihistamines, have also been utilised to treat NP. Although this disease is not caused by an allergic reaction, antihistamines do provide short-term relief in some cases. However, many studies have shown that antihistamines are not particularly effective as a long-term treatment option. Gabapentin is a preferred oral medication in most cases due to its direct effect on nerve impulses and electrical activity, therefore leading to largely positive results.² Physical therapy techniques, such as strengthening the back muscles and the weak muscles that are typically implicated in this condition, such as the scapular and pectoral muscles, are key way to treat this condition.⁸ Massaging the back and the areas around the spine is another way to improve nerve function and reduce the symptoms of NP.

Finally, transcutaneous electrical nerve stimulation (TENS) is used to treat NP, which involves using an electric current to stimulate the affected nerves and attempt to restore normal nerve function to alleviate NP symptoms. TENS may unintentionally exacerbate any symptoms; hence, it must be used in a very controlled manner and environment.⁹

Acupuncture as a treatment option

Recently, acupuncture has been utilised to treat those with NP. This TCM technique revolves around the concept of Qi, meaning energy flow and meridians. In the body, meridians are certain lines that carry energy and lead to proper muscle and tissue function. Acupoints are situated in certain parts of meridians and can be stimulated by using needles to ensure that the Qi is carried along the meridians.¹⁰ In acupuncture, needles inserted at certain acupoints have been shown to affect brain function and activation, and this is traditionally thought to restore energy balance throughout the body.¹¹ Certain acupoints are used during acupuncture, such as ST36 (stomach 36), LI4 (large intestine 4) and LR3 (liver 3),  although there are many different acupoints that are used.¹² Acupuncture sessions typically last less than an hour, and the majority of people have up to three sessions per week when undergoing acupuncture as a treatment form.¹³ Acupuncture is also used alongside other traditional medicine techniques, such as cupping therapy, which uses suction on certain parts of the body to lower pain in individuals.¹⁴ Electroacupuncture is similar to acupuncture; however, it uses electrical stimulation of acupoints by utilising currents travelling through needles. This form of acupuncture has been shown in some studies to be more effective than acupuncture that does not involve an electrical current and has been shown to stimulate nerve function and activity.¹⁵

Effectiveness of acupuncture for NP

Acupuncture has been somewhat successful when treating notalgia paresthetica. Some studies have demonstrated that acupuncture results in reducing pruritus; however, it is key to note that some patients have had symptoms that worsen, therefore leading to further acupuncture being required. In those whose symptoms resolve, many of these symptoms do not reappear after the treatment cycle is complete.¹⁶

It is widely accepted that acupuncture is a safe treatment form and leads to pain reduction and a better quality of life in those affected, although long treatment periods are required in those who do not respond to this treatment form quickly.¹⁷ The most common outcome for those receiving acupuncture treatment with NP is reduced itching, which is the key issue in NP instances. Many patients have all of their symptoms resolved; however, relapse is a potential issue for these individuals.¹⁸ Although acupuncture is a promising treatment form and has shown potential, there have not been many randomised controlled trials conducted at the time of writing, and the way that acupuncture is utilised differs between trials in many cases.¹⁶

Possible mechanisms of action

Acupuncture is thought to resolve NP due to a few different mechanisms. Firstly, acupuncture can act through the central nervous system when different acupoints are stimulated and resulting in improved nerve function. This means that T2-T6 nerve compression leading to NP symptoms can be resolved through acupuncture. This has been effective in patients who have undergone surgical procedures to correct nerve compression with unsuccessful outcomes.¹⁹ Acupuncture also has a positive effect on the sympathetic and parasympathetic nervous systems due to acupuncture helps the autonomic nervous system (ANS) function. This means that the peripheral nervous system, which is not located in the spine, also benefits from acupuncture, therefore improving musculoskeletal function around the body. The ANS is key in allowing neurotransmitter function such as serotonin, gamma aminobutyric acid and acetylcholine, which are important in regulating nerve cell function. Acupuncture has also been shown to reduce oxidative stress levels and inflammation in studies, resulting in potentially lower pruritus, although this is not necessarily due to inflammation.²⁰ This technique has also been shown to improve blood flow around different organs, therefore improving musculoskeletal issues.  As well as this, improved blood flow reduces possible tension caused by the muscles on the nerves implicated in NP.²¹ A theory known as the gate control theory suggests that sensory neurones detect stimuli that may cause pain; hence, acupuncture leads to these stimuli and nerve signals not being transmitted. This, in theory, leads to a reduction in symptoms.²²

Risks and considerations

There are some issues associated with the use of acupuncture. When acupuncture is carried out by trained professionals, it is generally safe. There are risks, however, as some patients may have soreness or pain in the acupoints that have been targeted, as well as some degree of bruising.²³ As well as this, it has been reported that some patients experience complications such as bleeding and some skin conditions, which contradicts the notion that acupuncture is always safe. There needs to be more research on the potential issues associated with acupuncture to ensure that it is safe to use for those with NP.²⁴

Summary

In summary, acupuncture has shown some promise in treating NP due to its neurological and anti-inflammatory effects as well as potentially improving blood flow and modulating pain and itch mechanisms. It is imperative that there is better research regarding the use of acupuncture for those with NP. There is a lack of trials that demonstrate the effectiveness of acupuncture in treating NP, but the outcomes thus far have shown that it may be useful in the future. Acupuncture should be used in conjunction with other treatments such as topical agents and oral medications. Acupuncture utilisation, alongside readily available interventions and techniques, will improve outcomes in the near future for those suffering from notalgia paresthetica.