Seborrheic Dermatitis of the Scalp: A Battle at the Top

What Is Dandruff and Seborrheic Dermatitis?

Seborrheic dermatitis of the scalp, commonly known as dandruff and medically as pityriasis capitis, is a very common dermatological condition prevalent among the general population. Dandruff is a milder form of seborrheic dermatitits. They are a continuous spectrum of the same disease characterized by forming yellow to white thick or thin flakes or corneocytes on the stratum corneum (the outermost layer of the skin), with associated pruritus and no visible inflammation of the scalp. The various contributory factors leading to the formation of dandruff on the scalp could be intrinsic or extrinsic, including fungal infection, bacterial superinfection, oily scalp, hormonal variations, excess sweating, neurological conditions, HIV infections, and other associated skin conditions.

Who Is More Commonly Affected by Dandruff?

Scalp seborrheic dermatitis affects about 50 percent of the general population. During the lifespan, three major peak incidences are noticed during infancy up to 3 months of life, during puberty, and adulthood. During infancy, the associated condition, rightly termed as cradle cap, is characterized by greasy, yellow, thick scales on the scalp along with other areas of the skin, including the face, groin area, and natal cleft. Puberty is associated with fluctuations in hormonal levels of androgen, leading to excess sebum secretion on the scalp for which fungal pathogens, specifically Malassezia furfur, have a high affinity leading to the formation of dandruff. Among adults, oily and sweaty scalps, climate change, stress, and the use of hair products can contribute to the formation of dandruff. Dandruff is more commonly seen among men in comparison to women.

Dandruff is very common among people suffering from neurological disorders, including parkinsonism, epilepsy, facial nerve palsy, spinal cord injury, brain damage, and depression. Other risk factors include HIV-infected patients, patients on antibiotics for underlying bacterial infection, chronic alcoholism, and also among patients with congenital disorders like Down’s syndrome. Dandruff is also associated with dermatological conditions like psoriasis, xerosis, and gynecological conditions like PCOS.

How Does Dandruff Form and What Are Its Causes?

Malassezia furfur is the most common fungal organism leading to the formation of scalp dandruff. Malassezia furfur is a fungal pathogen that is part of the normal commensal or flora over the human body. Certain conditions may trigger and flare up Malassezia's production to twice its normal range, like stress, seasonal variations, cold weather, hormonal fluctuations, neurological conditions, congenital disorders, and treatment for other medical conditions, especially with corticosteroids and antibiotics, nutritional deficiencies like Zinc deficiency, and weakened immunity. The excess production of Malassezia leads to the formation of scalp dandruff.

Apart from fungal dandruff, pruritus associated with dandruff causes trauma and abrasions due to incessant scratching leading to superinfection with bacterial pathogens. Although most fungal and bacterial dandruff results from the oily and sweaty scalp and are associated with irritation and itching, some dandruff could also be dry in nature.

Psoriasis is a chronic recurring multifactorial inflammatory dermatological condition leading to an absence of the granular layer of the skin and simply causes piling up of the skin due to increased turnover rate from 28-40 days to 5-7 days to form thick dry plaques in a generalized pattern but is also seen on the scalp most often below the hair line on the nape of the neck and below the frontal area of the scalp on the forehead. Dry dandruff is associated with this condition and is called sebopsoriasis, which is a milder variation of scalp psoriasis but associated with dry, flaky, and scaly lesions on the scalp with excessive itching and sometimes visible inflammation.

What Are the Symptoms of Dandruff and Seborrheic Dermatitis?

Dandruff may be mild, moderate, or severe based on the distribution, chronicity, and the type of flakes associated which is usually diagnosed clinically based on the history and physical examination of the patient.

The most common symptoms of scalp dandruff include

• Visible white to yellow flakes or scales, which may be thick or thin in consistency.

• Occasional to continuous itching or pruritus.

• Occasionally visible inflammation.

• Visible dry patches or plaques when associated with sebopsoriasis.

• Oily or sweaty scalp.

• Hair loss or fall.

• Scales on the pinna of ears, behind the ears.

• Papules and flakes on the forehead with visible erythema.

• Papules and pustules on the nape of the neck and back.

• Generalized skin dryness, mostly over bilateral elbows, knees and palms, and soles.

How to Treat Dandruff and Seborrheic Dermatitis?

Various treatment modalities are used for the treatment of dandruff:

Anti-Fungal Shampoos: Ketoconazole is the most commonly used shampoo which works by preventing ergosterol synthesis on the fungal pathogens leading to preventing the growth of fungal elements. Zinc pyrithione is added to the Ketoconazole shampoo for action augmentation. It acts by damaging the iron-sulfur protein clusters, which are essential for fungal metabolism and growth. It also increases the efficacy of Ketoconazole and is thereby used together.

The application usually ranges from 3 to 4 times per week, lathering with water, keeping it for 5 to 10 minutes on the scalp after massaging, and rinsing it off. Apart from Ketoconazole, other variants, including Sertaconazole, Luliconazole, Piroctone olamine, Climbazole, Clotrimazole, and Selenium sulfide shampoos, are also used.

Anti Fungal Topicals: Ketoconazole, Terbinafine, Clotrimazole, Miconazole, and Sertaconazole topical creams, gels, ointments, and sprays are also used for local application at least twice daily on the scalp. It is only used in case of local lesions and flakes on the scalp, along with flakes on the pinna and back of ears and nape of the neck and forehead.

Treatment of Moderate Dandruff

Moderate amounts of flakes, mostly confined to the scalp, can be seen and sometimes might show up on the forehead, nape of the neck, and ear pinna as well. Salicylic acid shampoos, lotion (2 or 3 %), and Ketoconazole may be used against moderate dandruff. It should be used 2 to 3 times a week, massaged, and kept for 5 to 10 minutes before rinsing off in the case of shampoo, while lotions and creams require overnight applications on a daily basis in small quantities. Clobetasol propionate is also used in combination with salicylic acid in a 0.05 % dosage of Clobetasole at night for a maximum of two weeks. Clobetasol is a corticosteroid that helps with the inflammation and irritation associated with dandruff only on the locally present indurated lesions.

Treatment of Severe Dandruff

Severe dandruff may be associated with flakes not only on the scalp but also on other areas of the body. Scalp dandruff, in this case, would be characterized by severe flakes and extreme dryness. Although mild dandruff may be treated with antifungals, severe dandruff may require more potent medications and shampoos, including ones containing 2 to 6 % Salicylic acid and coal tar combination mostly used for sebopsoriasis and scalp psoriasis. As a lipophilic agent, Salicylic acid removes the intercellular lipids linked covalently to the cornified surrounding surface, thereby providing moisture to the dry flakes, reducing their thickness, and softening them. Clobetasol with salicylic acid may also be used for local overnight application.

Systemic anti-fungal tablets and capsules may be used along with topical treatment for severe dandruff. Itraconazole tablets of 100 to 200 mg dosage, once daily for two weeks intake, is essential for anti-fungal therapy and reduction of itching and growth of fungal elements. Terbinafine, with 250 to 500 mg dosage, once daily, may be provided instead of Itraconazole for two weeks. Fluconazole tablets in the strength of 400 mg in a single dose may be repeated for two weeks or may be given later in case of dandruff along with pityriasis on other parts of the body. Fluconazole 150 mg once a week for four weeks may also be provided in case of dandruff associated with tinea capitis, tinea barbae, and tinea corporis. Daily fluconazole consumption in a dosage of 100 to 150 mg for two weeks may be used in severe cases but is not usually recommended.

Hair Treatment

Platelet-rich plasma treatment, also known as PRP, is a blood component obtained after centrifuging the patient’s own blood. 10 to 30 ml or sometimes 60 ml, depending on the area to be treated, is drawn in a syringe and placed in a centrifugal machine which prepares platelet-rich plasma, which is later injected into the scalp. This is done in 6 to 9 sessions on a monthly basis. PRP is known to augment hair growth as platelet is a growth factor. Besides, it also helps alleviate dandruff and is therefore used in mild to moderate dandruff cases.

Conclusion

Although very common among the general population, Dandruff can be managed if not cured with the right treatment and medication, used religiously with doctor’s advice, and under constant supervision. Proper daily hydration, sweat control, and management of underlying medical conditions by using good quality hair products and frequent washing of hair at least three times a week will help prevent dandruff formation. Stress is a common factor that leads to dandruff in today’s world. Adopting proper measures to manage stress will counteract dandruff formation and possible adverse effects. Timely treatment in the initial stage and following the doctor's advice properly will help alleviate even the early formation of dandruff and reduce the chances of hair loss. Prevention is always better than cure. So, following preventive measures, however common a condition may be, can help stabilize health and associated issues of scalp dandruff, which precipitates due to a lack of immunity.

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