Notalgia paresthetica (NP) causes itching and, sometimes, pain on the back. It usually affects a specific patch of skin, rather than causing generalized pain or itching. The itch commonly appears under the shoulder blade, often on the left side.

NP is a type of nerve pain, meaning that it is a problem with how the body processes pain and itch signals. It does not always produce visible symptoms, such as a rash, but some people may present with hyperpigmentation of the affected area.

Keep reading to learn more about notalgia paresthetica, including its causes, symptoms, diagnosis, and treatment.

Causes

Nerve pain is a possible cause of NP.
Sometimes, dry skin, allergic reactions, or skin diseases cause itching. However, this is not the case with notalgia paresthetica.

Doctors do not fully understand what causes NP, but most research seems to indicate that it is a type of nerve pain, or sensory neuropathy. Some potential causes include:

• Spinal nerve compression: Degenerative diseases, such as arthritis, can damage the spinal column. When this happens, nerves can become trapped, generating abnormal sensations that include pain and itching. Spinal scans of people with NP frequently show trapped nerves.
• Chemically induced nerve damage: Medications and toxic chemicals can damage the nerves, causing itching and other unusual sensations.
• More nerves deep in the skin: Some research on NP suggests that people with the condition may have more nerves in the dermis, the second layer of skin. However, researchers do not know if this causes symptoms or is the result of them.
• Injuries: Injuries to either the spine, the nerves surrounding the spine, the muscles, or even the bones may also damage nerves. This nerve damage can result in painful or itchy sensations.

As doctors do not understand NP well, it may have multiple causes. There may be additional causes that researchers have yet to identify.

There are few reports of cases of NP, but doctors and researchers believe that this condition may be relatively common but underdiagnosed.

Symptoms
Symptoms of notalgia paresthetica include:

• itching on the back, usually on a specific patch of skin
• itching under the left shoulder blade
• itching that does not get better with time and that does not appear after an injury or allergic reaction
• increased sensitivity on the itchy patch of skin
• changes in skin color on the itchy patch, possibly due to scratching and inflammation
• pain on a specific portion of the back, usually on just one side

Diagnosis
To diagnose NP, a doctor will examine the itchy spot and take a complete medical history. They may ask the person questions about recent injuries, muscle pain, infections, or chronic skin problems. As some people develop patches from an allergic reaction called dermatitis, the doctor will need to know about any allergies or recent rashes.

Doctors must diagnose NP on the basis of medical history and symptoms, as no medical test can confirm it. While some people have patches of discolored skin, others do not.

In some cases, a doctor may recommend a skin biopsy to rule out skin cancer. Biopsies sometimes show deposits of a type of protein called amyloid. Doctors think that these deposits form because of the itching and scratching, rather than causing it.

As part of the diagnosis, the doctor may want to rule out macular amyloid (MA), another condition that causes itching. MA usually causes itching on the upper part of the middle back, as well as a grayish-brown patch. Nerve pain from herpes-related nerve damage may also cause itching, so a doctor might ask about any history of shingles.

Treatment
Several different treatments may help with notalgia paresthetica, including:

• Skin creams: Creams containing capsaicin, an ingredient in chili peppers, often reduce pain. When these creams do not work, a person may find that topical steroids, such as hydrocortisone, provide relief. A doctor will need to prescribe strong steroid creams, but weaker options are available over the counter.
• Medication: Medications may help ease symptoms, but a person may need to experiment — with the help of their doctor — with different drugs at various dosages. Antiseizure medications, such as gabapentin (Neurontin), may be particularly effective.
• Physical therapy: Physical therapy can help release trapped nerves, which may ease the symptoms of NP.
• Injections: Certain injections may help. For example, botulinum toxin (Botox) may help with pain and itching. A nerve block, which obstructs certain sensations, can reduce or eliminate symptoms.
• Surgery: When other treatments fail, and a compressed or trapped nerve causes symptoms, surgery to decompress the spine and free trapped and damaged nerves may offer relief.
• Less invasive medical procedures: Less invasive medical procedures may ease symptoms when surgery is ineffective, or a person wishes to avoid it. Laser therapy may change nerve sensations, while pulsed radio frequency and electrical muscle stimulation may ease pain.
• Alternative and complementary medicine: A 2009 case report of a woman with NP found that her condition improved with just 20 minutes of osteopathic spinal manipulation. Some people may find relief from other approaches, such as acupuncture, especially when they use them alongside conventional treatment.

Outlook
Notalgia paresthetica is a chronic condition. Although it may go away on its own or with treatment, it can sometimes last for many years. Some people have to experiment with several different remedies. A treatment that initially worked may stop working, requiring a change in approach.

The symptoms may also change with time, potentially getting better and then worse again or transitioning from itching to pain.

NP is not dangerous, and it does not increase the risk of serious illnesses, such as cancer. There is no evidence that it inevitably gets worse, and it will not progress to other areas.

Summary
Unexplained itching may trigger fears of skin cancer, an infection, or a serious neurological problem. However, although NP can be bothersome and may undermine a person’s quality of life, it is not dangerous.

Treatment focuses on relieving symptoms rather than curing the condition.

People who experience unexplained itching should see a doctor for help.