Sensitive Skin Syndrome: A Low-Noise Small-Fiber Neuropathy Related to Environmental Factors?

Background and Objectives: Patients frequently complain of mild, transient, unpleasant skin sensations that cannot be diagnosed as common neuropathies. Dermatologists have termed these symptoms "sensitive skin syndrome." This narrative review was performed for a better knowledge by other specialists. Databases and Data Treatment: Publications on pain in sensitive skin syndrome were obtained from PubMed. Results: There is a growing body of data supporting the concept that sensitive skin is a type of small-fiber neuropathy. The arguments are based on clinical data, a decrease in intra-epidermal nerve fiber density, quantitative sensory testing abnormalities and an association with irritable bowel syndrome and sensitive eyes. Sensitive skin is triggered by environmental factors. Sensitive skin is a frequent condition, with a lifetime prevalence of ~50% according to self-reports. Conclusions: Mild levels of skin pain or itch are frequently experienced by patients, who rarely report them. There is a need for a better knowledge of sensitive skin because it can be the first level of small-fiber neuropathies.

Pruritus, Pain, and Depression Associated with the Most Common Skin Diseases: Data from the French Study "Objectifs Peau".

BACKGROUND: The prevalence and impact of pruritus, pain, and other sensory symptoms in skin diseases are poorly known. OBJECTIVE: To assess the frequency of these symptoms with dermatoses and their association with depression using data from the "Objectifs Peau" survey. METHODS: A representative sample of 20,012 French individuals was created using the usual quota method. RESULTS: When patients suffered from both pruritus and skin pain, they had a higher relative risk of psychological suffering (2.9) than those who suffered only from pruritus (1.4) or skin pain (1.2). Pruritus was reported in 48.55% of patients with acne, 43.24% with mycoses, 44.35% with warts, and 36.51% with rosacea. For skin pain, the results were 11.22%, 27.59%, and 16.13% for atopic dermatitis, acne, and warts, respectively. Other unpleasant sensations, such as tingling or burning, were also frequently reported. CONCLUSION: Pruritus, pain, or other sensory symptoms were found to be common not only in classic pruritic skin diseases but also in acne, rosacea, or warts. The association of pruritus and pain dramatically increased psychological suffering. These symptoms must be systematically searched for in patients, especially since new therapeutic possibilities are emerging for the symptomatic treatment of pruritus.

Pain in Atopic Dermatitis: An Online Population-based Survey.

Pruritus in atopic dermatitis has been studied extensively; however, evaluation of skin pain has been very limited. The aim of this study was to evaluate the presence, frequency and characteristics of skin pain in patients with atopic dermatitis. A survey was conducted of a representative sample of 5,000 18-80-year-old individuals selected from the French population according to sex, age, geographical area and socioprofessional status. Data on socio-demographic status and the presence of any skin disease were collected. Pain in the past month and health-related quality of life were evaluated. Average intensity of skin pain during the previous month was assessed with a horizontal visual analogue scale (0-10). Skin pain was reported by more than half of the patients with atopic dermatitis, at a pain intensity of almost 6/10. A neuropathic component was suggested by the Douleur Neuropathique - 4 questions (DN4) questionnaire (a tool for detection of neuropathic pain), as well as the presence of pain inside and outside of skin lesions. Severe alterations to health-related quality of life were assessed with the Dermatology Life Quality Index and Short Form 12 Health Survey (SF-12). Pain is reported frequently by patients with atopic dermatitis. Healthcare professionals should question patients about pain and provide effective treatments. Future clinical trials must take skin pain into account.

Pruritus in Autoimmune and Inflammatory Dermatoses.

Pruritus in autoimmune and inflammatory dermatoses is a common symptom that can be severe and affect the quality of life of patients. In some diseases, pruritus is related to disorders activity and severity or may occur independent of the disease. Despite the high prevalence, the symptom is still underrated and there are only a few trials investigating the efficacy of drugs for disease-specific pruritus. In this review, the characteristics and possible pathomechanisms of pruritus in various dermatoses like autoimmune bullous diseases, connective tissue diseases as well as autoimmune-associated dermatoses (atopic dermatitis, psoriasis vulgaris) is illustrated. Additionally, studies analyzing the antipruritic treatment are discussed. Summarizing, the prevalence of pruritus in these diseases demonstrates the importance for symptom recognition and the need for an efficient antipruritic therapy.

Sensitive skin is a neuropathic disorder.

Sensitive skin is defined by the occurrence of unpleasant sensations such as tingling, burning, tautness, itching or pain. Mechanisms explaining sensitive skin are controversial, and many hypotheses have been proposed. Because sensitive skin is primarily characterized by a wide variety of neuropathic-like symptoms, it is highly likely that neurosensory dysfunction in the skin represents one of the pathological mechanisms of sensitive skin. This hypothesis does not exclude other explanations like role of keratinocyte, transient receptor potential channels, vasculature or environmental factors. Nevertheless, the role of the nervous system in the development of sensitive skin is crucial, and growing evidence supports this hypothesis. Pain and pruritus described by patients with sensitive skin correspond to neuropathic component, and its assessment shows an increase in neuropathic measures (DN-4, Douleur Neuropathique 4) compared with control. These sensations are similar to the sensations observed in small-fibre neuropathy (SFN), which is a group of disorders that affect thin nerve fibres. One study on the pathophysiology of sensitive skin demonstrated that intra-epidermal nerve fibre density, especially of peptidergic C-fibres, was lower in the sensitive skin group. A recent study showed a modification in heat-pain detection threshold in patients with sensitive skin. All these results indicate that C-fibre damage can help explain sensitive skin. Consequently, the role of the nervous system is increasingly obvious. Nevertheless, keratinocytes and other epidermal cells closely participate in sensory transduction. Therefore, the results of neurophysiological studies should be interpreted in the light of this information that the whole epidermis represents a huge polymodal nociceptor.

Current pharmaceutical developments in atopic dermatitis.

Atopic dermatitis (AD) is an inflammatory, pruritic, chronic or chronically relapsing skin disease that typically begins in early childhood and is occurring frequently in families with other atopic diseases (bronchial asthma and/or allergic rhino-conjunctivitis). Thanks to immunological and neurobiological research, the era of new treatments is coming as well as it occurred with psoriasis 15 years ago. Many treatments targeting cytokines (IL-4, IL-13, IL-31, TSLP) or neurotransmitters (substance P, opioids) or their respective receptors as well as phosphodiesterase-4 or the Jak/Stat pathways are under development. Antagonists of cytokines and anti-jak have promising effects on pruritus while it is more difficult to discriminate the effects of other drugs from the placebo effect on itch, which is known to be high.

Association between two painful and poorly understood conditions: Irritable bowel and sensitive skin syndromes.

BACKGROUND: Irritable bowel and sensitive skin syndromes are common painful conditions that are poorly understood, with alterations of the peripheral (and possibly central) nervous system that lead to a lowering of perception thresholds as the main pathophysiological mechanism. METHODS: A cross-sectional epidemiological study was carried out on a representative sample of French people, according to the quota method using a questionnaire. RESULTS: Among the 5,000 respondents, 48.9% were men and 51.1% were women. According to the adapted Rome questionnaire, 14.6% suffered from irritable bowel syndrome. A total of 59.1% declared very sensitive or sensitive skin. A total of 73.1% of subjects had irritable bowel syndrome versus 52.3% in the other group without an irritable colon (p < 0.001). Similarly, the frequency of irritable bowel syndrome symptoms was associated with the severity of sensitive skin syndrome. The presence of sensitive skin was highly associated with the presence of abdominal pain or discomfort, with an OR of 1.93 after adjustment for sex and age. CONCLUSIONS: This study is the first study showing an association between sensitive skin and irritable bowel syndromes. Sensory symptoms are predominant in these two syndromes and transit disorders in one case and vasomotor disorders in the other could probably be considered as pathophysiological equivalents. SIGNIFICANCE: The demonstration of the association between these two syndromes can open new pathophysiological or even therapeutic pathways, since dysfunctional nerve endings and/or increased release of some neurotransmitters are likely involved.

Characteristics of Pruritus in Relation to Self-assessed Severity of Atopic Dermatitis.

The objective of this study was to explore characteristics of pruritus in atopic dermatitis (AD) in relation to the severity of AD. A web-questionnaire was used, which included the Patient-Oriented SCORing Atopic Dermatitis index, the 5-D itch scale and the Brest questionnaire. A total of 170 participants were included (86.5% women, mean age 30.9 years). Severity of AD was mild for 8.2% of patients, moderate for 38.2% and severe for 53.5%. Mean 5-D itch scale was 13.2. The mean intensity of pruritus was 5.8, and mean sleep loss was 4.7 (from 0 to 10). The participants frequently described burning (61.8%) and stinging (58.8%); these symptoms suggest a neuropathic component. Pruritus was worse in severe AD compared with moderate AD, exhibiting a higher impact on sleep and more associated symptoms. The majority of participants reported sleep disturbance as a result of pruritus. The characteristics of pruritus varied depending on the severity of AD.

Clinical Characteristics of Pruritus in Systemic Sclerosis Vary According to the Autoimmune Subtype.

Pruritus is a frequent symptom in systemic sclerosis (SSc), with a prevalence of 40-65%, but its pathophysiology is poorly understood. This study investigated the immunological component of pruritus. Fifty-six patients with SSc responded to a standardized questionnaire regarding both SSc disease and pruritus characteristics. Among patients with SSc, those with pruritus did not display a particular immunological profile (inflammatory, humoral, and/or cellular factors), but pruritus was, in most cases, concomitant with the development of SSc. Thus, pruritus characteristics were evaluated further, according to the detection of anti-centromere autoantibodies (ACA), into ACA+ (n = 17) and ACA- (n = 19). The ACA+ subgroup was characterized by a longer evolution of SSc and pruritus, pruritus present outside the sclerotic area, and a shorter daily duration of pruritus. In conclusion, the concomitant appearance of the 2 processes and the differences observed between ACA+ and ACA- subgroups support the presence of an immunological component in pruritus.

Pathophysiological Study of Sensitive Skin.

Sensitive skin is a clinical syndrome characterized by the occurrence of unpleasant sensations, such as pruritus, burning or pain, in response to various factors, including skincare products, water, cold, heat, or other physical and/or chemical factors. Although these symptoms suggest inflammation and the activation of peripheral innervation, the pathophysiogeny of sensitive skin remains unknown. We systematically analysed cutaneous biopsies from 50 healthy women with non-sensitive or sensitive skin and demonstrated that the intraepidermal nerve fibre density, especially that of peptidergic C-fibres, was lower in the sensitive skin group. These fibres are involved in pain, itching and temperature perception, and their degeneration may promote allodynia and similar symptoms. These results suggest that the pathophysiology of skin sensitivity resembles that of neuropathic pruritus within the context of small fibre neuropathy, and that environmental factors may alter skin innervation.