Scalp itch and its management continue to be a major issue for dermatologic patients, and a greater understanding of the pathomechanisms of itch in the hair follicle is needed to provide more targeted approach for treatment, according to Dr. Gil Yosipovitch. Dr. Yosipovitch spoke about therapeutic options for the treatment of scalp itch during a session at the American Academy of Dermatology Scientific Sessions in Orlando, Fla.
“The data we have obtained from our itch centres [suggests] that older populations have a higher prevalence of scalp itch,” added Dr. Yosipovitch, professor of dermatology and director of the Itch Center at Miller School of Medicine in Miami.
Seborrheic dermatitis is the most common presentation of scalp pruritus. “It [occurs] in adolescents and in our older population of patients,” added Dr. Yosipovitch. “If you look closely in older populations, [however], a lot of times they don’t have seborrheic dermatitis.”
Dr. Yosipovitch cited a study involving older patients of Hispanic origin. Data showed that 28% of the subjects reported having an itchy scalp but the majority had no rash. “What was interesting about this analysis was that patients with diabetes had a more than two-fold increase of itching of the scalp in comparision to non-diabetics. These findings suggest that scalp itch in old age [might be] associated with diabetic neuropathy,” he said.
Scalp and itch stimuli
He noted that when treating the scalp, “it is important to remember that the scalp is extremely highly innervated. There are actually two types of innervations—one is coming from the trigeminal nerve and the other one from the cervical nerve.”
“[Also], the hair follicle is highly innervated with receptors that are known to also be receptors for itch.”
To determine if the scalp is more sensitive to itch stimuli Dr. Yosipovitch and colleagues conducted a study to examine the two major pathways for itch induction—histaminergic and non-histaminergic (using spicules of Cowhage) in 16 healthy individuals.
“To our surprise [we found] induction in the scalp is almost very minimal, both with histamine and with Cowhage,” he said. “The scalp has a significantly lower itch intensity even though the scalp is a very itchy anatomic location. The main exogenous pruritogens do not cause significant itch.”
Dr. Yosipovitch added that there are possibly endogenous molecules that reduce itch sensation in the scalp that “possibly protect us and prevent us from external induction that induces itch,” he said.
Topical Tx for scalp itch without rash
For the treatment of scalp itch without a rash Dr. Yosipovitch recommended the following therapies:
• Pramoxine 1 to 2% with a moisturizing shampoo
• Salicylic acid 6% with a topical steroid
• ASA topical solution 3%
• Topical ketamine 5 to 10% with amitryptiline 5%
• Lidocaine 5% in a lipoderm base or foam base
Dr. Yosipovitch added, however, that he does not find oral ASA to be effective for scalp itch.
“Other preparations that we have tried due to the fact that we think the neurosystem has a significant impact on scalp itch is the use of gabapentin 6 to 12% in the lipoderm base,” he said. “Another option is using an overthe-counter compound containing strontium gel 4%.”
Scalp itch with inflammation
When inflammation accompanies scalp itch, he suggested a number of different therapeutic options including coal tar shampoo, and topical corticosteroids as an occlusive therapy
Other treatment options for scalp itch with inflammation include:
• Salicylic shampoo or lotion plus topical corticosteroids
• Pramoxine lotion with or without a topical steroid
Scalp itch and oral treatments
For patients with severe scalp itch without a rash, Dr. Yosipovitch recommends gabapentin (at higher doses) up to 3000 mg daily.
He added that pregabalin (up to 300 mg daily) is another option, but “unfortunately it is difficult to get pregabalin covered by insurance companies [in the U.S.]”
Another treatment option is mirtazapine, 15 mg daily, Dr. Yosipovitch said. “[Mirtazapine] enables our patients to sleep better because when a patient is itchy at nighttime and they cannot sleep it is a major quality of life issue and further aggravates their condition.”
Another condition that can cause scalp itch is central centrifugal cicatricial alopecia (CCCA). It mainly occurs in African Americans and symptoms consist of varying degrees of itch, pain and burning sensations, Dr. Yosipovitch explained.
He cited findings from a study published in the British Journal of Dermatology (Feb. 2013; 168(2):253– 256) that he conducted with his colleagues. A total of 15healthy AfricanAmerican women and 16 AfricanAmerican female patients with CCCA participated in the study and underwent quantitative computerized thermosensory testing to assess warmth and heat pain thresholds.
As part of the evaluation, the researchers indicated that itch was induced using histamine iontophoresis and application of cowhage spicules, and the intensity of each association between itch intensity and CCCA severity score was also examined.
“We found that patients with scarring alopecia had more significant activation of itch intensity in comparison to the healthy controls,” he said. “It was interesting to [discover] that there was a correlation between the stage and the severity of the CCCA and the itch involvement.”
Dr. Yosipovitch noted that the treatment of CCCA often consists of the following:
• Clobetasol 0.05% foam or solution
• Topical pramoxine 2% foam or solution with clobetasol 0.05% foam
• Intralesional injection of Kenalog
Oral tetracycline 500 mg b.i.d. can be usefulbecause it is an inhibitor of protease-activated receptors involved in non-histaminergic itch, he said.
“This is more of an out-of-the-box treatment, but lately it has beendifficult to get tetracycline in the market. We have tried with minocycline, but I cannot tell you at the moment if [minocycline] works because I do not have enough experience with it,” he said.
Originally published in The Chronicle of Skin & Allergy (Aug. 2017; 23(5):page 1,12)
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