What Causes Neuropathic Itching?

When your skin itches, a good scratch can often make the discomfort go away. However, for people living with neuropathic itch, their feelings of itching don't go away by simply scratching the afflicted area, per Harvard Medical School. In a biological sense, pain and itching serve a primitive role in attracting our attention to parts of our bodies where a bug may be biting or a rash-inducing plant is making contact with our skin. But when itching isn't caused by an external source and instead is rooted in internal signals being sent from the brain that result in chronic and sometimes widespread itching, then the purpose of an itching sensation is defeated. The lasting result is continuous aggravation and pain that persists despite attempts to scratch the itch away.

Neuropathic itching, used interchangeably with the term neuropathic itch, is more akin to neuropathic pain than to traditional itching (via Dermatology Times). Neuropathic itch arises when an overabundance of peripheral neurotransmitters is fired from the brain, leading the body and skin to feel itchy. Despite their similarities, far more research has been performed on neuropathic pain than on how to relieve neuropathic itch, though it is known that neuropathic itching is often a symptom of underlying conditions, particularly disorders of the peripheral nervous system or damage to the nerves that serve as signal avenues from the brain to various body parts. Read on to find out more about what causes this chronic and often insatiable itching.

Common underlying conditions of neuropathic itching

Many underlying conditions that trigger neuropathic itching are related to nerves around the cervical spine, like notalgia paresthetica and brachioradial pruritus, per HealthCentral. Both of these conditions are mostly diagnosed in people over 40 years old. Notalgia paresthetica is generally rooted in injury or damage to the cervical spine, specifically at disc levels C4 through C6. The area of the spine affected by this underlying condition leads to neuropathic itching around the shoulder blades and back, which is frequently described as itching with a pins and needles feeling that won't go away. Brachioradial pruritus often leads to neuropathic itching on the arms due to injury of the cervical spine, peripheral cutaneous nerves, or both. Other underlying conditions that produce the perennial itching sensation of neuropathic itch include multiple sclerosis, scars, and a buildup of scar tissue

Due to the nerve damage that gives way for neuropathic itching to flourish, common treatments for brachioradial pruritus, notalgia paresthetica, and other conditions are medications that inhibit nerves, such as gabapentin, anticonvulsants, and benzodiazepines.

A 2012 study published in Seminars in Cutaneous Medicine and Surgery found that not all patients with underlying conditions that can induce neuropathic itch develop chronic itching. The study stated that while the neural circuits that lead to neuropathic itch aren't fully understood by researchers, it's known that lesions within the central and peripheral nervous systems lead to neuropathic itch. 

Underlying conditions precipitating neuropathic itching noted in the study include tumors, demyelinating disease, radicular compression, and stroke.

Neuropathic itch has its own symptoms

Neuropathic itch can be a confusing condition because it can result as a symptom of an array of underlying conditions while presenting its own symptoms. According to MedicalNewsToday, common symptoms of neuropathic itch include simultaneous sensations of burning, numbness, prickling, pins and needles, electric shocks, shooting pain, skin crawling, and chilling or cold feelings around the affected area. Since neuropathic itching is often a byproduct of nerve pain, it shares many of the same symptoms and sensations as nerve damage. If you notice one or more of these symptoms, consult with your healthcare provider to determine if there is an underlying condition causing neuropathic itch.

"People with chronic itch often feel as if insects are crawling all over them," says Anne Louise Oaklander, M.D., Ph.D., an associate professor of neurology at Harvard Medical School. When nerve cells and transmitters from the central nervous system or peripheral nervous system function improperly and misfire itch-causing neurons, widespread and chronic itch occurs. The result is a symptom that can be traced to neuropathic itch itself and to conditions with neuropathic itching as a symptom, like shingles, phantom limb syndrome, tumors in the brain, and spinal cord lesions. 

Because identifying and diagnosing neuropathic itch and potential underlying conditions can be difficult and frustrating, it's recommended that people seeking diagnoses also seek support from their family and friends since the process can often be overwhelming (via HealthCentral). Identifying neuropathic itching's cause can be trying, but awareness of symptoms is key.