Scalp dysesthesia

Scalp dysesthesia also called trichodynia or cutaneous dysesthesia syndrome, is characterized by abnormal cutaneous sensations such as burning, stinging, itching (pruritus) or even pain of the scalp in the absence of objective dermatological findings ¹. The pathogenesis of scalp dysesthesia is poorly understood and has not been determined ². The pain and pruritus may be related to the chronic tension placed on the occipitofrontalis muscle and scalp aponeurosis secondary to the underlying cervical spine disease ³.

It has been found that 34% of female patients with hair loss complained of scalp dysesthesia ⁴. In a recent survey, Grimalt et al. ⁵ showed that 14% of their diffuse alopecia patients reported scalp dysesthesia. Complaints such as pain and burning of the scalp in patients with diffuse alopecia were described in the earlier dermatology literature ⁶. Both such studies and clinical observations have led to the idea that the diffuse alopecia or telogen effluvium and scalp dysesthesia are related. By definition, telogen effluvium is a nonscarring and diffuse hair loss from the scalp that occurs a few months after a triggering event.

Scalp dysesthesia causes

The underlying mechanisms creating the pain are not clear, though it has been proposed that it is probably multi-etiological. The most accepted hypotheses are increased expression of the neuropeptide substance P, underlying psychiatric disorders, nutritional deficiencies, and perifollicular inflammation ⁷. Substance P is involved in pain perception by the nerve endings, and changes in the production and activity of substance P around the hair follicles may be responsible for the pain and burning sensation ⁸. Hair follicles are innervated by unmyelinated neural plexuses located around the hair follicle stem cells. These nerve fibers contain neuropeptides including substance P and calcitonin gene-related peptide ⁹. These neuropeptides play an important role in the regulation of hair growth and are associated with the neurogenic inflammatory response. Perifollicular substance P is also involved in the regulation of hair growth ¹⁰. An imbalance in the tonic release of neuropeptides may result in inhibition of hair growth. Cutrer et al. ¹¹ hypothesized that chronic activation of the c-fibers, in addition to mediating inflammatory pain and follicular injury, might reduce substance P and calcitonin gene-related peptide concentrations resulting in altered peribulbar antigen presentation and inhibition of further hair growth.

Another explanation may be an underlying psychiatric disorder ⁹. It has been found that 76% of the people who had scalp dysesthesia had psychopathic signs versus 20% in the control group, supporting this idea. Researchers have observed and speculated that there is a connection between psychopathologic findings (such as anxiety) and scalp dysesthesia ¹². In 2006 Gupta and Gupta ¹³ found that numbness and pain are common symptoms of somatoform dissociation or conversion reaction. Kivanç et al. ¹⁴ found that trichodynia was associated with depression in the telogen alopecia group and with obsessive-compulsive personality disorder in the androgenic alopecia group. However, this idea is controversial. Although increased rates of psychiatric problems have been reported in patients with scalp dysesthesia, Ozturk et al. ¹⁵ found no association between scalp dysesthesia and depression or anxiety. In this study the patients with telogen alopecia were consisting the control group, and they could have the opportunity to evaluate only the scalp dysesthesia patients.

Neuropathic pain can also be associated with nutritional deficiencies (iron, vitamin B12, ferritin, zinc, vitamin D, vitamin E). Nutritional factors affect the hair directly, and dietary supplements containing B complex vitamins can influence hair growth ¹⁵. Nutritional deficiencies have been reported in other cutaneous dysesthesia syndromes. For example, glossodynia is characterized by a burning sensation of the tongue and oral mucosa. Menopause, psychogenic disorders, and nutritional factors have also been suggested to cause this phenomenon ¹⁶. However, evidence level is very low to confirm this nutritional hypothesis for scalp dysesthesia patients ¹⁷.

Other dermatological conditions causing scalp pain

Scalp pain can occur with cicatricial alopecia that can be caused by a fungus infection or autoimmune conditions such as cutaneous lupus and lichen planopilaris. Folliculitis decalvans and dissecting cellulitis are forms of primary neutrophilic scarring alopecia that are characterized clinically by chronic suppurative folliculitis and often associated with pruritus or even pain. The inflammatory cells may irritate nerve endings leading to a burning or painful sensation. Hair dye-related dermatitis may also cause burning sensations.

There are also painful tumoral lesions of the skin and subcutaneous tissue. These lesions can be found anywhere in the peripheral nerve tissue. They have a propensity for developing on the skin and subcutaneous tissue, as well as in oral and pharyngeal locations. An old acronym may help us to remember them. LEND AN EGG tumors (leiomyoma, eccrine spiradenoma, neuroma, dermatofibroma, angiolipoma, neurilemmoma, endometrioma, glomus tumor, and granular cell tumors) must always be considered when there is a tumoral lesion associated with pain ¹⁸.

Scalp dysesthesia symptoms

Scalp dysesthesia also called trichodynia or cutaneous dysesthesia syndrome, is characterized by abnormal cutaneous sensations such as burning, stinging, itching (pruritus) or even pain of the scalp in the absence of objective dermatological findings ¹.

Scalp dysesthesia diagnosis

The diagnosis of scalp dysesthesia is based on clinical suspicion. A comprehensive history and examination are needed to identify any underlying cause. For instance, hyperreflexia, weakness, or autonomic dysfunction can indicate a spinal cord pathology.

Diagnostic tests may include:

• Serology: antinuclear antibody (ANA), antineutrophil cytoplasmic antibodies (ANCA), C-reactive protein (CRP)
• Skin biopsy
• Imaging: plain X-rays, or MRI of the cervical/thoracic spine to eliminate disc herniation, spinal lesions, or fractures.

Serological tests may include testing for the following:

• Glycosylated hemoglobin (HBA1c)
• Complement (C3, C4)
• Antinuclear antibody (ANA)
• Antineutrophil cytoplasmic antibodies (ANCA)
• Antibodies to Borrelia burgdorferi (found in Lyme disease)
• Human immunodeficiency virus (HIV) and viral hepatitis
• C-reactive protein (CRP)
• Iron studies
• Folate
• Vitamin B12
• Vitamin E
• Heavy metal levels
• Angiotensin-converting enzyme (ACE).

Other tests may include:

• Nerve conduction studies to look for demyelinating or axonal neuropathy
• Cerebrospinal fluid (CSF) analysis for oligoclonal bands if demyelination is suspected
• Magnetic resonance imaging (MRI) of the brain and cervical spine if demyelination or ischemia is suspected.

Scalp dysesthesia treatment

Scalp dysesthesia symptoms are of great relevance to patients and place the physician in a challenging diagnostic and therapeutic situation. Although dealing with scalp dysesthesia can be distressing and literature support is weak, there are a number of treatments available. L-Cystine-containing oral preparations, topical corticosteroids (both high potency and low), and anti-inflammatory drugs have been advocated (inflammatory hypothesis). Inhibitors of substance P can also be tried. Cannabinoids, for example, have been demonstrated to inhibit substance P ¹⁹. Capsaicin cream has been used because it blocks substance P when applied to the hair follicles. On the basis of psychiatric origin, the physician also may use low-dose antidepressants (venlafaxine, amitriptyline, and doxepin) and also pregabalin ²⁰.

In 2009, Cutrer et al. ¹¹ have investigated the efficacy of botulinum toxin treatment in cephalalgia alopecia patients and obtained improved pain control and hair regrowth following botulinum toxin A injections. They also observed that botulinum increases substance P and calcitonin gene-related peptide-containing cutaneous nerves in the scalp. Botulinum toxin A injections (BoNT-A) does not block low-level trophic release of neuropeptides such as calcitonin gene-related peptide and allows resumption of substance P and calcitonin gene-related peptide baseline regulation of the hair follicle and hair regrowth ²¹. However, we should keep in mind that botulinum toxin A injections treatment is temporary. The process of painful inflammatory activation, hair follicle regression, and hair loss is repeated after a few months.

Sensory tests revealed that scalp dysesthesia patients were significantly more sensitive to touch and to pressure pain and exhibited cranial mechanical hyperesthesia and cranial hyperalgesia ²². So, gentle scalp maintenance may provide some relief. To support the treatment, it is important to inform the patients about not to use over hot water and harsh shampoos or wear tight pony tail. Other relaxation techniques such as gentle scalp massage may also help in reducing symptoms.

References

1. Laidler NK, Chan J. Treatment of scalp dysesthesia utilising simple exercises and stretches: A pilot study. Australas J Dermatol. 2018;59(4):318–321. doi:10.1111/ajd.12807
2. Rakowska, A., Olszewska, M., & Rudnicka, L. (2017). Trichoscopy of scalp dysesthesia. Postepy dermatologii i alergologii. https://pdfs.semanticscholar.org/9d58/c82189af301e45cbc386f722c53c9522eb52.pdf
3. Thornsberry LA, English JC 3rd. Scalp dysesthesia related to cervical spine disease. JAMA Dermatol 2013; 149: 200-3.
4. Rebora A, Semino MT, Guarrera M. Trichodynia. Dermatology. 1996;192:292–3.
5. Grimalt R, Ferrando J, Grimalt F. Trichodynia. Dermatology. 1998;196(3):374.
6. Hoss D, Segal S. Scalp dysesthesia. Arch Dermatol. 1998;134:327–30.
7. Baldari M, Montinari M, Guarrera M, Rebora A. Trichodynia is a distinguishing symptom of telogen effluvium. J Eur Acad Dermatol Venereol. 2009;23:733–4.
8. Ericson M, Gabrielson A, Worel S, Lee WS, Hordinsky MK. Substance P (SP) in innervated and non-innervated blood vessels in the skin of patients with symptomatic scalp. Exp Dermatol. 1999;8:344–5.
9. Trichodynia (Scalp Dysesthesia). https://www.intechopen.com/books/current-perspectives-on-less-known-aspects-of-headache/trichodynia-scalp-dysesthesia
10. Paus R, Heinzelmann T, Schultz KD, Furkert J, Fechner K, Czarnetzki BM. Hair growth induction by substance P. Lab Investig. 1994;71:134–40.
11. Cutrer FM, Sandroni P and Wendelschafer-Crabb G. Botulinum toxin treatment of cephalalgia alopecia increases substance P and calcitonin gene-related peptide-containing cutaneous nerves in scalp. Cephalalgia. 2010;30(8):1000–6.
12. Durusoy C, Ozenli Y, Adiguzel A, Budakoglu IY, Tugal O, Arikan S, et al. The role of psychological factors and serum zinc, folate and vitamin B12 levels in the aetiology of trichodynia: A case-control study. Clin Exp Dermatol. 2009;34:789–92.
13. Gupta MA, Gupta AK. Stressful major life events are associated with a higher frequency of cutaneous sensory symptoms: An empirical study of non-clinical subjects. J Eur Acad Dermatol Venereol. 2004;18:560–5.
14. Kivanç-Altunay I, Savaş C, Gökdemir G, Köşlü A, Ayaydin EB. The presence of trichodynia in patients with telogen effluvium and androgenetic alopecia. Int J Dermatol. 2003;42:691–3.
15. Ozturk P, Orhan FO, Ozer A, Akman Y, Kurutas E. Evaluation of anxiety and levels of serum B12, folate, TSH, ferritin, and zinc in telogen alopecia patients with trichodynia. Int J Trichol. 2012;4(4):251–4.
16. Moore PA, Guggenheimer J, Orchard T. Burning mouth syndrome and peripheral neuropathy in patients with type 1 diabetes mellitus. J Diabet Complicat. 2007;21:397–402.
17. Durusoy, Ozturk P, Orhan FO, Ozer A, Akman Y, Kurutas E. Evaluation of anxiety and levels of serum B12, folate, TSH, ferritin, and zinc in telogen alopecia patients with trichodynia. Int J Trichol. 2012;4(4):251–4.
18. Naversen DN, Trask DM, Watson FH, Burket JM. Painful tumors of the skin: “LEND AN EGG”. J Am Acad Dermatol. 1993;28(2):298–300.
19. OConnor TM, OConnell J, Obrien DJ, et al. The role of substance P in inflammatory disease. J Cell Physiol. 2004;201:167–180.
20. Sarifakioğlu E, Onur O. Women with scalp dysesthesia treated with pregabalin. Int J Dermatol. 2013;52:1398–1461.
21. Durham PL, Cady R, Cady R. Regulation of calcitonin gene-related peptide secretion from trigeminal nerve cells by botulinum toxin type A: Implications for migraine therapy. Headache. 2004;44:35–43.
22. Defrin R, Lurie R. Indications for peripheral and central sensitization in patients with chronic scalp pain (trichodynia). Clin J Pain. 2001;29(5):417–424.