Sensitive scalp.

Sir,

Sensitive skin, also referred to as reactive, hyperreactive, intolerant, and irritable skin, is defined as the onset of prickling, burning, or tingling sensations with or without pain or pruritus. It is triggered by various factors, which may be physical (ultraviolet radiation, heat, cold, and wind), chemical (cosmetics, soap, water, and pollution), psychogenic (stress), or hormonal (menstrual cycle).[1-3]

Sensitive skin is often seen on the face but it can also involve other areas.[4] A recent study has shown that sensitive skin can occur on the scalp and hands apart from the face.[56]

Scalp sensitivity is characterized by presence of prickling burning or tingling sensation on the scalp. Earlier, it was said to be a vague syndrome but epidemiological study reveals that such is a distinct entity.[5] Sensitive scalp is an extension of concept of sensitive skin on other anatomical areas such as face, commonly with atopic dermatitis.

Ethnic variations are noted in scalp sensitivity. A study from French population has shown that 44.2% of the population suffers from scalp sensitivity. The main triggering factors identified were pollution, heat, emotive factors, and shampoos.[5]

We present two cases as follows:

Case 1: A 35-year-old female presented with the complaint of hair loss of two-month duration. She further complained of pain in scalp while combing the hair and stinging sensation in the vertex area. She treated herself with massage with a herbal oil on the scalp. Her symptoms worsened. Hence, she consulted us.

Skin examination was grossly normal except for mild erythema due to scratching. But, scalp was highly tender to touch. Hair pull test was positive. Her baseline investigations including hemoglobin, urinalysis, blood sugar, and thyroid function tests were normal. Investigations: A few follicular pustules on the scalp were noted after a few days on vertex and occipital lymph nodes were also palpable and non-tender. Oral cephalexin and anti-inflammatory medicines healed the pustules and reduced lymph node size but scalp symptoms largely persisted.

Case 2: A 30-year-old male presented with complaint of stinging and burning sensation on the scalp of three-week duration. He used herbal oil for male pattern baldness. His previous consultant had prescribed him an alcohol-based minoxidil lotion for topical application, which could not be tolerated by his sensitive scalp. On examination, erythema and pustules were noted on the scalp [Figure 1]. His baseline investigations were normal. We asked the patient to stop herbal oil. We also temporarily withdrew minoxidil and prescribed antihistamine and topical fluticasone lotion for a week, which resulted in good clinical improvement.

Figure 1

Scalp with pustules and erythema

Common symptoms of sensitive scalp are burning, stinging, dry scalp, vague discomfort in the scalp, and sometimes, the trichodynia. The latter is defined as “discomfort, pain, or paresthesia of the scalp.” Patients often perceive it as unpleasurable combing of hair.

Scalp sensitivity may be varied according to scalp characteristics and was clearly more frequent and intense in patients with greasy or dry scalps. Scalp sensitivity, probably, belongs to sensitive skin syndrome and most patients declared sensitive skin in another area.[6-8]

In our experience, sensitive scalp is often seen in the individuals with atopic background.[56] Psychogenic factors[67] or sudden alteration in weather, especially during winter, may precipitate the symptoms in Indian patients. Erythema may be sometimes observed[5] but we believe, pustule formation is rare in untreated sensitive scalp. Local scalp diseases of scalp may occasionally play a role in exacerbation. Practice of head massage with herbal oils is common in India. This involves vigorous rubbing of hair oil in the scalp, which might result into pustule formation due to mechanical and microbial factors (secondary bacterial invasion), as it happened in our patient.

The pathogenesis of sensitive scalp is poorly understood. Frequent shampooing is an important predisposing factor for scalp sensitivity, which could be due to disturbance of barrier function resulting from excessive transepidermal water loss, thus permitting increased exposure to detergents.[5]

Trichodynia could be part of scalp sensitivity, which is defined as “discomfort, pain, or paresthesia of the scalp.”[10] The presence of abnormal sensations clinically and histologically observed vasodilatation in sensitive skin disorder suggest role of nervous system. Neurogenic inflammation probably results from the release of neurotransmitters such as substance P, calcitonin gene-related peptide, and vasoactive intestinal peptide, which induce vasodilatation and mast cell degranulation. Non-specific inflammation may also be associated with the release of interleukin (IL)-1, IL-8, prostaglandin E2, prostaglandin F2, and tumor necrosis factor-alfa. The only proteins that can be activated by both chemical and physical factors belong to the transient receptor potential (TRP) family, such as TRPV1.[11-14]

In both of our patients, all three things were noted including hair loss, sensitive scalp, and application of hair oil. It may be argued that their condition could be irritant dermatitis rather than sensitive scalp because it is well known that herbal oils frequently cause contact dermatitis.[10] In these patients, history of sensitivity existed before application of anything on scalp. Intolerance to number of unrelated products also existed, which points to consideration of sensitive scalp. However, if the sensitivity had begun after the application of hair oil, it is rational to think of contact dermatitis. Hence, we believe that a good history taking is important in making a preliminary diagnosis of sensitive scalp.

To summarize, sensitive scalp is often an overlooked entity in our patients and the condition may be worsened or triggered by hair loss. Vigorous herbal hair oil massage may worsen the problem in certain individuals.[15] There are no studies from India on this subject and hence, it may be worth studying it further.