Scalp dysesthesia: a neuropathic phenomenon

Abstract

Scalp dysesthesia is an abnormal sensation of the scalp in the absence of cutaneous disease. It is characterized by a burning and/or itching sensation and can be related to a variety of neurogenic or psychogenic causes. This condition is extremely bothersome and is also common-especially among the geriatric population, in women, in patients with diabetes mellitus, and patients with psychiatric history. However, despite its prevalence in many populations, there are limited data about its causes and characteristics. Given its limited cutaneous manifestations, it is also easily misdiagnosed and an underrecognized cause of scalp pruritus in the dermatological community. Therefore, education on scalp dysesthesia is paramount to helping physicians identify and provide appropriate treatment for these patients. This review focuses predominantly on the neurogenic causes (with a brief review of psychogenic itch) of scalp dysesthesia and the therapeutics that have been found to be effective for this condition. Neurogenic causes of scalp dysesthesia occur with damage to the central or peripheral pathways of itch sensation, resulting in modification and heightened sensitivity of nerves that result in abnormal sensations in the absence of or out of proportion to external stimuli. A comprehensive review of etiologies is provided here, ranging from lesions to the central nervous system caused by cervical spine disease, trigeminal trophic syndrome, tumor, stroke, and multiple sclerosis, to small-fiber neuropathies caused by diabetes, brow lifts, keloid, and burn scarring. Recently, there have also been reports of scalp dysesthesias associated with post-infectious COVID-19. Treatment options tailored toward disease severity and different causes of disease will also be discussed. By elucidating the different mechanisms and therapeutic treatments of scalp dysesthesia, we hope to provide clinicians with the tools to identify and treat this condition as well as encourage further research into its etiologies and therapeutics.

Neuropathic Pruritus: An Underrecognized and Often Misdiagnosed and Difficult to Treat Medical Condition

“…It is estimated that up to 30% of people with Rare Diseases -Recent Advances postherpetic neuralgia have pruritus [17,18]. Postherpetic pruritus is also a common cause of NP in the dermatomal area affected by the peripheral nerve region damaged by the varicella zoster virus [19][20][21].…”

“…The intensive, persistent, and subconscious desire to scratch, which usually occurs during sleep, causes chronic and deep excoriations on the scalp. The resulting wounds can sometimes even reach the bones [20][21][22]. These patients often refer to dermatologists, but neurologists should be consulted to identify and treat the underlying cause [14,16].…”

“…In addition, it may be associated with brain malignancy (such as brainstem tumors, tumors infiltrating the trigeminal ganglion, cervical intramedullary glioma), multiple sclerosis, and stroke. Diabetic and geriatric patients have also been found to have higher rates of scalp pruritus [21,42]. Cosmetic procedures such as face and brow lift can also cause NP when they cause local nerve damage.…”

“…Symptoms of trichodynia appeared an average of 1-2 weeks after the diagnosis of COVID-19, lasting 4-5 weeks, and regressed in 44% of patients. These patients reported relief of trichodynia with sleeping, cold water washing, application of superpotent topical steroids, combing, massage, and scratching [21,45].…”

“…Age-related neuropathic changes and disruption of pruritus-inhibiting fibers, as well as the frequent occurrence of degenerative spine diseases in geriatric patients, make these individuals prone to neurogenic pruritus [46]. In these patients, besides the secondary lesions due to scratching, complaints such as burning, stinging, and numbness called dysesthesia may also be encountered [21,46].…”