Alopecias - Practical Evaluation and Management

D. Ioannides, A. Tosti

• Editore: S. Karger
• Anno: 2015
• ISBN:
  9783318027754
• Argomento: Medicina
• Categoria: Endocrinología y metabolismo

Hair is subject to either intrinsic (i.e. physiological) aging or extrinsic (i.e. premature) aging that can be attributed to external factors. The intrinsic factors can be associated with genetic mechanisms and are subject to individual variations, whereas external factors include ultraviolet radiation, air pollution, smoking, and possibly nutrition. Leading experts have contributed to this book which offers a practical approach to the evaluation and management of various forms of alopecia, including their pathogenesis, the diagnostic procedures involved, medical treatments, and nutritional issues. A completely new surgical technique for hair transplantation that leaves behind sufficient follicle unit tissue to regenerate hairs is also described. Being comprehensive and easy-to-read, this book should be very useful for dermatologists who wish to diagnose and treat their patients with hair problems more effectively.

Ioannides D, Tosti A (eds): Alopecias - Practical Evaluation and Management.
Curr Probl Dermatol. Basel, Karger, 2015, vol 47, pp 107-120 (DOI: 10.1159/000369411)

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Effect of Ultraviolet Radiation, Smoking and Nutrition on Hair

Ralph M. Trüeb

Center for Dermatology and Hair Diseases, Zürich-Wallisellen, and University of Zürich, Zürich, Switzerland

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Abstract

Similar to the rest of the skin, the hair is exposed to noxious environmental factors. While ultraviolet radiation (UVR) and smoking are well appreciated as major factors contributing to the extrinsic aging of the skin, their effects on the condition of hair have only lately attracted the attention of the medical community. Terrestrial solar UVR ranges from approximately 290 to 400 nm; UV-B (290-315 nm) reaches only the upper dermis, while the penetration of UV-A (315-400 nm) into the dermis increases with wavelength. The two most important chronic effects of UVR on the skin and bald scalp are photocar-cinogenesis and solar elastosis; however, the effects of UVR on hair have largely been ignored. As a consequence of increased leisure time and a growing popularity of outdoor activities and holidays in the sun, the awareness of sun protection of the skin has become important and should also apply to the hair. Besides being the single-most preventable cause of significant cardiovascular and pulmonary morbidity and an important cause of death, the association of tobacco smoking with various adverse effects on the skin and hair has also been recognized. Increasing public awareness of the association between smoking and hair loss seems to offer a good opportunity for the prevention or cessation of smoking, since the appearance of hair plays an important role in the overall physical appearance and self-perception of people. Finally, the quantity and quality of hair are closely related to the nutritional state of an individual. Normal supply, uptake, and transport of proteins, calories, trace elements, and vitamins are of fundamental importance in tissues with high biosynthetic activity, such as the hair follicle. In instances of protein and calorie malnutrition as well as essential amino acid, trace element, and vitamin deficiencies, hair growth and pigmentation may be impaired. Ultimately, important commercial interest lies in the question of whether increasing the content of an already adequate diet with specific amino acids, vitamins and/or trace elements may further promote hair growth. Unless the hair is impaired due to nutritional deficiency, there is only so much that nutrients can do to increase the size of individual hairs because hair thickness is largely genetic. Nevertheless, there are external factors that influence hair health to such a degree that micronutrients could boost hair that is suffering from these problems.

© 2015 S. Karger AG, Basel

Effect of Ultraviolet Radiation on Hair

A number of pathologic conditions of the scalp are evidently related to ultraviolet radiation (UVR), particularly photosensitive diseases that affect the balding scalp and disorders of the photodamaged bald scalp [1]. While the consequences of sustained UVR on unprotected skin, mainly photo-carcinogenesis and solar elastosis, are well appreciated, the effects of UVR on the hair have found little attention in the scientific community. However, some clinical and morphological observations as well as theoretical considerations suggest that UVR has some negative effects on hair [1].

The mechanisms by which UVR plays a role in the development of skin cancer are varied and represent a multistep process involving alterations in DNA structure that result from purine photoproducts, cytosine photohydrates, single-strand breaks, and sister chromatid exchange, as well as from reactive oxygen species that are generated during exposure of cells to UVR. Additionally, UVR induces deviations in tumor immunosurveillance mechanisms that eventually aid the survival and progressive growth of UVR-induced malignancies [2]. Finally, it has been found that telomerase activity plays a crucial role in the immortalization of human cells; telomerase activity is found in plucked hair follicles, is associated with the presence of stem cells in the follicle and is found in a high percentage of skin tumors. Evidence of UV-associated activation of telomerase in human skin further suggests that telomerase activation is involved in skin photocarcinogenesis [3].

Actinic keratosis is the most common precancerous epidermal lesion resulting from chronic UVR-exposure and usually occurs on sun-exposed body regions of middle-aged or older people, including the balding scalp or bald scalp area. It presents as a skin-colored to reddish, ill-defined macule with a dry adherent scale. Actinic keratoses of the scalp are often multiple, and although these lesions are usually asymptomatic, the patient may note mild local tenderness. At times, multiple, confluent lesions of the centroparietal scalp may be misinterpreted as refractory seborrheic dermatitis [4, 5].

The number of recognized photosensitive dermatoses that localize to the scalp is essentially limited to light-exacerbated endogenous eczema, dermatomyositis (DM), and cutaneous lupus erythematosus (LE). Additionally, scalp rosacea has been identified as a disorder of the balding scalp [6], and more recently, its relation to (diffuse) red scalp (disease) has become the focus of current attention. Finally, erosive pustular dermatitis represents a peculiar entity that is localized to the photodamaged bald scalp.

Patients with either atopic or seborrheic dermatitis occasionally report nonspecific exacerbation of their condition following sun exposure, also on the scalp, where it may be difficult at times to differentiate from the exacerbation of itch through heat-induced sweating. A high prevalence of seborrheic dermatitis on the scalp has been described in sun-exposed mountain guides in Austria, Switzerland, and Germany [7]. Moreover, it has been calculated that exposure of the scalp to UVR in mountain climbers is in a range up to 17 minimal erythema doses/day [8].

While LE represents a well-known photosensitive disorder with frequent scalp lesions, localization of DM to the scalp is often overlooked or misdiagnosed as seborrheic dermatitis or scalp psoriasis [9]. While photosensitivity is often underestimated in DM, it is overestimated in discoid LE, and in over 50% of patients with discoid LE, standardized UV testing does not induce skin lesions [10]. Particularly, isolated lesions in the hair-bearing scalp and external auditory canal are examples where this form of cutaneous LE is not related to light exposure. In any case, the inflammation of the scalp may lead to hair loss. Moreover, a late sequel squamous cell carcinoma may occasionally arise in chronic smoldering discoid LE of the scalp [11].

Red scalp was first described by Thestrup-Pedersen and Hjorth in 1987 [12] and was subsequently commented on by Moschella, who commented on the difficult problem of ‘diffuse red scalp disease which can also be itchy and burning.... non responsive to any therapy including potent topical steroids or anti-seborrhoeic therapy’ [13]. Patients frequently report aggravation in the sun or repeated episodes of sunburn of the scalp. Grimalt et al. [14] presented their findings on 18 patients with ‘red scalp syndrome’ at the 2000 Annual Meeting of the European Hair Research Society in Barcelona, Spain. They found that the majority of patients were middle-aged females who were consulting for hair loss. By definition, no specific dermatologic disease was found. The scalp redness was associated with alopecia in 13 of 18 patients, and three of the 10 biopsies that were performed were compatible with cicatricial alopecia (not otherwise specified). Some patients reported associated discomfort of the scalp. The most prevalent speculations with respect to the pathogenesis of scalp discomfort in the absence of a specific dermatologic disease were perifollicular inflammation and increased expression of the neuropeptide substance P in the vicinity of the affected hair follicles. In a series of 403 patients complaining of hair loss who were examined for trichodynia (painful scalp), Willimann and Trüeb [15] found that the dermatoscopic finding of scalp telangiectasia strongly correlated with the presence of trichodynia. An interesting analogy to rosacea exists where patients with the telangiectatic variant of rosacea more frequently reported a stinging sensation upon the topical application of 5% lactic acid on the cheeks than patients with the papulopustular type of rosacea or normal controls [16]. On the one hand, these findings suggest a connection between sensory or subjective irritation and cutaneous vascular reactivity. On the other hand, dilated and tortuous vessels are typically found in photodamaged skin. Ultimately, Oberholzer et al. [17] reported patients with red scalp disease and clinical and histopathologic findings consistent with rosacea and a response to oral tetracycline therapy.

Erosive pustular dermatosis of the scalp was first described by Pye et al. [18] and was subsequently delineated by Burton et al. [19] as a distinctive clinical entity producing chronic extensive pustulation that was confined to the scalp of elderly individuals and led to erosion and scarring alopecia. A high incidence of antecedent local trauma strongly suggests that scalp injury may be important in initiating dermatosis in a susceptible elderly person with atrophic skin changes of the scalp, particularly due to prolonged exposure of long-standing androgenetic alopecia to UVR [20]. No recognized cause of pustulation is present, and the histology is nonspecific. The response to antibiotics is poor, but the condition is suppressed by potent topical steroids, suggesting an inflammatory rather than infective etiology. The condition has been observed following contusion, laceration, blistering sunburn, shingles, synthetic fiber implantation, craniotomy, and skin grafting of the scalp [21], as well as following treatment of acti...