Self-induced nail disorders

INTRODUCTION

Self-induced dermatoses include body-focused repetitive behaviours (BFRBs), which are defined as undesirable, repetitive motor activities. BFRBs include trichotillomania (TTM), skin-picking disorder (SPD), onychophagia, onychotillomania, dermatitis artefacta and features of other psychiatric disorders.^[1] Self-induced nail disorders (SINDs) are caused due to harmful actions such as biting, sucking, chewing, excessive trimming, pulling off, or filing of nail unit with instruments such as tweezers, files, and razor blades. Onychophagia (and onychotillomania) are categorised as ‘Other Specified Obsessive-Compulsive and Related Disorders (OCRD)’. In the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), SPD, TTM and onychophagia, as a group, are referred to as recurrent BFRBs.^[2-5] No classification divides SINDs into those with psychiatric comorbidity and those without. For example, nail biting can be a part of normal habit in some individuals and can be associated with obsessive-compulsive disorders or tic-disorders in others. It is an area in need of further research . BFRBs are characterised by repetitive behaviours triggered by negative internal states, impaired response inhibition, and negative outcomes such as alopecia and skin lesions. There are clinical similarities between BFRBs and the compulsions seen in obsessive-compulsive disorder (OCD). The symptoms of BFRBs indicate a compulsive nature. Grant and Chamberlain, in their study, concluded that compulsivity was linked to greater psychosocial dysfunction and lower quality of life in individuals with BFRBs.^[6]

SIND’s are very common; hence, the clinical dermatologist needs to be aware, as they can mimic a vast number of cutaneous and nail diseases. It is not yet evident if BFRBs are associated with underlying sensory abnormalities.^[1,7] These clinical conditions are very stressful for the patient. An accurate diagnosis, involving careful history taking and physical examination, is crucial as patients seldom seek professional help for conditions like nail biting or nail picking.

Onychophagia is defined as compulsive nail biting and is classified in DSM-5 under OCRDs.^[5] Onychotillomania, or nail-picking disorder, involves patients repeatedly manipulating various parts of the nail unit^[8] and it falls within the spectrum of onychophagia, lichen simplex chronicus and prurigo nodularis in the skin. Managing SINDs requires a supportive and empathetic approach where the clinician refrains from confronting the patient about the self-inflicted nature of the condition. Currently, there are no United States – Food and Drug Administration (USFDA) approved pharmacotherapies for self-induced dermatosis. The evidence is strongest for habit reversal therapy (HRT).^[1] This review focuses on clinical characteristics, psychiatric comorbidities, diagnosis and management of nail changes that are self-induced, with or without overt psychological abnormalities.

METHODOLOGY

A PubMed search pertaining to published articles using the keywords; Nail tic disorders, ‘Onychophagia’, ‘Onychotillomania’ and ‘Habit tic deformity’ and ‘nail’ were done. The search yielded 35, 9, 58 and 9 indexed English language articles, respectively. The articles related to the ‘Nail Unit’ in ‘dermatology’ were selected for further reading and abstracts were reviewed. These included various kinds of reviews and clinical research. Detailed methodology, clinical features, associated conditions and treatment options were collated and are summarised narratively.

TERMINOLOGY

A variety of terms have been used in literature to describe this group of disorders. Table 1^[2-4,9] summarises the different terminologies in vogue. The term ‘Self-induced nail disorders’ is being used in this article to comprehensively describe these varied clinical entities. Individual defined entities are discussed below.

ONYCHOLYSIS SEMILUNARIS

It is a frequently overlooked factitious nail disorder caused due to the habit of overzealous cleaning of subungual space. It results in the nail detaching from the nail bed, leading to a semilunar area of onycholysis. The condition is commonly seen in women, more rarely in men. Middle-aged women are mainly affected; however, it may be at times seen in teenage or older women.^[4] The patient aims to clean the subungual space with a sharp instrument, leading to damage to the local area. The hyponychium serves as an empty recess beneath the nail plate, where dirt accumulates, prompting the patient to continue cleaning, hence aggravating the onycholysis.

This entity clinically presents as sharp, asymmetric distal onycholysis in the absence of any clinical signs of inflammation. The subungual space gradually extends backward/proximally; even more, dirt accumulates, and a vicious cycle is established. Commonly, 4–6 fingernails are affected, and one-third to one-half of each nail may get detached from the nail bed. True symmetrical half-moon is present less often, as either side is more often involved. At times, there is secondary colonisation by Pseudomonas aeruginosa, forming biofilms.^[3]

Differential diagnosis includes other causes of onycholysis. Nail psoriasis is the most difficult to exclude. Onycholysis in nail psoriasis has a reddish-brown proximal margin^[10], onycholysis semilunaris has a roller coaster transversal onycholysis.

Management involves counselling the patient regarding the patho-mechanism of this condition. This is often not accepted by the patient. They may also feel offended at such an implication. The onycholytic nail needs to be trimmed until its proximal point of attachment. Every month, it is crucial to trim the unattached portion of the nail to maintain proper care.^[4] Finger tips should be kept free of microbes through the application of antimicrobial creams twice daily. The patient needs to avoid sharp instruments and hard brushes. If the patient does not induce further trauma, the nail is expected to regrow normally.

HABIT TIC DEFORMITY

It is a type of nail dystrophy caused by habitual external trauma to the nail matrix, resulting in midline nail changes.^[11] It is typically observed in adults, and arises from a habitual tendency to push back the cuticle [Video 1]. The patient is not aware of this behaviour. The involvement of the thumbnail is classical, though any nail can be affected. Usually, the middle finger is involved in cases with single-nail involvement. Toenail involvement is rare, but reported.^[12] The pathomechanism of the condition is generally not accepted by the patient, who often assume nutritional or vitamin deficiency as the cause.^[2] This disorder is primarily a habit, characterised by an absence of anxiety before nail manipulation, and there is no relief following the act. It is less frequently associated with psychiatric comorbidities, such as OCD.^[3]

The patient presents with a ‘central linear depression surrounded by parallel transverse ridges running from the proximal to the distal end’. The appearance is called ‘washboard nails’ due to its resemblance to a washboard. The cuticle is damaged, detached or absent, resulting in a loss of adhesion between the proximal nail fold and the nail plate. This exposes the distal matrix, giving it the appearance of a pyramidal lunula [Figure 1a and b]. Constant friction on the distal matrix leads to a loss of sheen over the nail plate. The nail’s free margin may curve downward, giving it a claw like appearance. The thumb of the contralateral side pushes the nail fold back, and in one-sided cases, it can be the middle finger of the same hand. Proximal matrix may be exposed, pterygium may occur, or lunulae may become hypertrophic in more severe situations.^[4]

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Figure 1:

(a) Habit tic deformity: Clinical image showing yellow midline furrow, transverse grooves, macro lunula, absent cuticle, lichen simplex chronicus in proximal nail fold, periungual excoriations and haemorrhages. (b) Habit tic deformity: Onychoscopy – non polarised with DermLite 4 magnification ×10: Showing longitudinal midline furrow, transverse furrows, branching grooves, macro lunula covering 1/3^rd of the nail plate, absent cuticle, reddish proximal lunula and periungual scaling.

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Median nail dystrophy of Heller is the primary differential, which presents with similar clinical features, with several oblique ridges extending outward and proximally from the centre of longitudinal nail splitting, giving the appearance of a fir-tree^[13] [Figure 2a and b].

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Figure 2:

(a) Clinical image of median canalicular dystrophy of Heller-Thumb nails show longitudinal fir tree like dystrophy. (b) Non-polarised Dermoscopy with DermLite 4 Magnification ×10 shows multiple transverse furrows arising from the centre of the nail and extending laterally.

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Cautious questioning and proper explanation are helpful in managing such patients. Local application of bland emollients, accompanied by gentle massaging from proximal to distal end, three times a day, has proven to be effective.^[4] In addition, using physical barriers such as bandaging or tape application on the proximal nail fold helps prevent additional trauma and give the nail matrix time to normalise. Ring et al.^[14] employed cyanoacrylate adhesive to restore the barrier between the proximal nail fold and the nail plate. Care should be taken lest contact sensitisation to glue develops. Benzethonium chloride has been successfully used for effective management of habit-tic deformity.^[15] N-acetyl cysteine, administered in a dose of 1800–2400 mg, has been shown to improve the condition.^[16]

ONYCHOPHAGIA

Chronic biting of nail plate, nail folds, nail bed and/or cuticle is defined as onychophagia. The rate of nail-biting reduces as age progresses, even though some patients may have begun or continued the habit into adulthood.^[17] This condition affects up to 20–30% of the general population.^[18] It typically emerges in childhood, usually after the age of 3–4 years.^[19] Populations under stress are more prone to this behaviour. Video 2 demonstrates both onychotillomania and onychophagia in the same patient.

Onychophagia is classified under the subcategory of ‘OCRD’ in the DSM-5, in addition to lip biting and cheek chewing. DSM-5 further classifies onychophagia as a recurrent BFRB disorder.^[16] The association between onychophagia and OCD is inconsistent. Halteh et al.,^[18], found that only 25% of nail biters experienced comorbid OCD or anxiety disorder. Pacan et al.^[20] reported a prevalence of 3.1% for OCD among nail biters, which aligns with the lifetime prevalence in the general population. Onychophagia is more prevalent in individuals with personal or family history of psychiatric disorders. Onychophagia has a worse prognosis in adulthood. The patients may chew one or all nails. Skin picking and TTM are other OCDs that are often associated with onychophagia. There is a familial component, and social problems can aggravate the condition. Etiopathogenesis of onychophagia is discussed in Table 2.^[21,22]

Diagnosing nail biting is more difficult because the patient rarely presents to the physician with this as a primary complaint. Onychophagia is a common condition; however, the patient feels stigmatised, which leads to delays in seeking a medical opinion. The clinician needs to observe nail biting while talking to the patient, a non-judgemental way of taking history and examinations. This aspect is important to identify the disorder in its early stages. Clinically, the patient presents with short, uneven nails; hyponychium is distorted dorsally, forming a distal bulge. Over a period of time, there is a shortening of the nail bed. Presence of melanonychia, brittleness, macrolunula, transverse grooves and pterygium may be seen. The periungual skin shows linear and pinpoint haemorrhages^[23] [Figure 3a].

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Figure 3:

(a) Onychophagia: Clinical image showing brachyonychia, distal ragged edges, patchy rough areas, keratinisation of nail bed, loss of distal nail bed, hyponychial hyperkeratosis, ragged cuticle periungual haemorrhage and excoriations. Excoriations over the distal part of both thumbs. (b): Onychophagia: Non-polarised dermoscopy with DermLite 4 magnification ×10 showing ragged distal edges, periungual scales, red brown streaks, periungual haemorrhage and scaling, traumatic onycholysis.

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Usually, fingernails are involved more often in comparison to toenails. It is physically more difficult to bite toenails; they are harder, and toenail biting may suggest a possible association with psychiatric comorbidity.^[24] Table 3^[23,25-26] summarises nail changes observed by various studies. Table 4^[25-60] shows various studies conducted on onychophagia.

Onychoscopy shows ‘loss of nail plate along with a ragged distal borders,^[23] [Figure 3b]. Histopathology is often not needed; however, it can be done if we need to rule out other differentials. Entrapped red cells and trauma-focal hyperkeratosis are common findings on nail biopsies. Features can mimic other conditions including chronic paronychia, onychotillomania, nail psoriasis and nail lichen planus.^[18]

Complications due to onychophagia can affect both the nail unit and the oral cavity. Chronic trauma leads to partial or complete loss of the nail plate that exposes the nail bed and leads to keratinisation of the exposed area, with subsequent irreversible nail shortening. Consequent to chronic trauma and friction, there is activation of melanocytes that clinically present as melanonychia. Multiple nails may be affected by the presence of grey-brown longitudinal bands that vary in width.^[26] Acute and chronic paronychia may occur in patients as cutaneous trauma induced due to onychophagia can provide portal of entry for bacteria [Figure 4]. Chronic paronychia can also occur, presenting with loss of cuticle and erythematous inflamed nail folds due to chronic friction and trauma. Patients can also develop other infections including herpetic whitlow and periungual warts^[48,61,62] [Figure 5]. Oral and dental complications include incisor wear and tear, maloccluded teeth, incisor rotation and apical root absorption. There can be gingival injury causing swelling and abscess. Chronic nail biters may experience pain and dysfunction in the temporomandibular joint.^[48] Enterobacteriaceae family frequently colonises the oral cavity. Enterobacter spp. and Escherichia coli are commonly seen in onychophagia patients, predisposing them to local and systemic infections.^[36,63]

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Figure 4:

Acute paronychia along with damaged proximal nail fold.

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Figure 5:

Shortened nail plate, hyperpigmented proximal nail fold suggestive of chronic handling along with subungual wart.

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The management is multidisciplinary, including pharmacotherapy (either alone or in combination), habit reversal training, counselling, and stimulus control. Most importantly a supportive and empathetic attitude where the clinicians avoid confronting the patient about the self-inflicted nature of the disorder. Pharmacotherapy, whether used alone or in combination, is commonly employed for treatment.^[16] Stimulus control procedures aim to minimise external triggers that make nail biting difficult, along with incorporating aversion therapy. Prevention of nail filing and trimming of splintered cuticles can lead to a reduction in nail-biting temptation. Professional manicures done for the beautification of nails can help motivate patients to preserve their beautiful nails. Application of gel nail helps harden the free edge that cannot be bitten off. Glove bandages, though acting as a physical barrier, can be embarrassing for the patient to use socially. They also lead to a reduced sensation of fingers, hampering daily activity.

Aversion therapy involves repeatedly pairing unwanted behaviour with discomfort to help break the habit. For example, the application of an unpleasant-tasting nail polish interferes with the enjoyable aspect of nail biting. It is often avoided in young children, as it may lead to increased biting behaviour in order to gain attention.^[64] Removable nail polishes are effective alternatives for those who are non-compliant with aversion therapy. They may encourage long-term behavioural change.^[65]

Cognitive behavioural and HRT, have the strongest evidence for the treatment of BFRBs. For HRT to be effective for the patient’s self-injurious behaviour, the technique involves replacing harmful urges with less harmful competing responses. Cognitive behavioural therapy (CBT) encompasses methods such as habit reversal training, the comprehensive behavioural intervention of tic and neurofeedback. Habit reversal training includes five exercises, the first one being awareness training, which helps the patients recognise their feelings, environment, frequency and high-risk situations when they tic. Relaxation training teaches the patients to manage the stress they experience. Competition training involves helping patients to develop a new habit to prevent the onset of tic. Motivation training aims to enhance the patient’s intrinsic motivation, while generalisation training helps the patient mentally rehearse controlling tics before they occur. Three components of HRT include social support, competing for response training and awareness training. Awareness training involves patients saying aloud or writing triggers for nail biting and the negative consequences. When a patient is made conscious of nail biting, competing response training can occur. When the patient has the urge to bite, they clench their fist, clap or sit on their hands to prevent the act.^[66]

Pharmacotherapy is the second-line treatment for onychophagia. As of now, no USFDA approval has been given for pharmacotherapy for BFRB’s however, certain medications are helpful for the management of onychophagia. N-acetylcysteine (NAC), a glutamate modulator, has been used for impulse control disorders including onychophagia.^[16] Excessive levels of glutamate, a key excitatory neurotransmitter in the central nervous system, can lead to neuronal damage and have been linked to various repetitive and compulsive disorders. NAC mitigates glutaminergic hyperactivity by facilitating the release of glutamate into extracellular space. In addition, NAC possesses antioxidant properties through the production of glutathione, a powerful antioxidant. It is typically administered in a dose of 600–3000 mg/day without, any reported side effects.^[9] Selective serotonin reuptake inhibitors (SSRIs), bupropion, and lithium had been reported to be successful in single case reports.^[45,67-69] Clomipramine, lamotrigine, olanzapine, inositol and naltrexone have also been used.^[2] Despite encouraging outcomes, there is limited information regarding the effectiveness of NAC and antidepressants in treating onychophagia. Larger clinical trials are needed to make conclusive statements.

ONYCHOTILLOMANIA

It is characterised by ‘recurrent picking or pulling of the nail unit that damages the periungual skin, nail matrix, nail bed and nail plate’. It is a self-induced condition that involves the patient’s fingers and nails, although tools such as scissors, nail files and knives may also be used.^[70] Videos 3-5 demonstrate onychotillomania involving various parts of the nail unit. Onychotillomania is categorised alongside other BFRBs, including onychophagia, TTM and excoriation disorder. It may fall under ‘other specified obsessive-compulsive and related disorders’ specifically within the subsection of BFRBs. It is less recognised and less reported as compared to TTM and excoriation disorder, resulting in less attention in psychiatric literature.^[1] Comorbid psychiatric disorders often include depression, anxiety and psychosis.^[16] Some authorities consider habit tic to be a variant of onychotillomania. Additional related nail behavioural disorders include onychotemnomania (cutting nails excessively short) and onychoteiromania (rubbing nails against a hard piece or with a wooden file to smoothen the nail remnants).

Nail picking is rarely a primary complaint, with patients often diagnosed during routine examinations. A feeling of anxiety before and a sense of relief after nail picking has been reported in patients. In patients of TTM, a thorough examination of all 20 nails as well as skin, scalp and hair is essential along with an assessment for coexisting BFRBs. Given that onychotillomania is associated with depression, anxiety and psychosis, a brief psychiatric examination should be done. Clinical findings are frequently asymmetric and non-specific, with nail plate abnormalities such as transverse ridging, thinning, macrolunula and generalised dystrophy. Repeated trauma to the nail matrix from picking of proximal nail folds can lead to nail plate ridging. Habit tic deformity can be associated with onychotillomania. Periungual skin can be erythematous, inflamed, crusted and erosions can be present^[8] [Figure 6a].

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Figure 6:

(a) Onychotillomania: Clinical image showing transverse wavy lines, periungual/subungual haemorrhages, chromonychia, melanonychia, onychorrhexis, lichen simplex chronicus in proximal nail-fold, anonychia and dystrophy. (b): Onychotillomania: Nonpolarised dermoscopy with DermLite 4 magnification ×10 showing nail plate scaling, wavy lines, periungual haemorrhage and scaling, hang nails, longitudinal melanonychia and chromonychia.

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Onychoscopy can help differentiate onychotillomania from other nail conditions. Maddy et al.^[71] reported ‘wavy lines (uneven longitudinal lines in different planes with a wavy appearance from uneven nail plate growth, obliquely placed nail bed haemorrhages and nail bed grey discoloration)’ [Figure 6b]. A nail biopsy is seldom needed to make a diagnosis. It is indicated in severe cases of nail dystrophy without any other clues in history. The findings include epithelial hyperplasia, acanthosis and hyperkeratosis.^[8]

Differential diagnoses include onychophagia, onychomycosis, and inflammatory disorders of the nail unit, including nail lichen planus and nail psoriasis, trachyonychia and paronychia. Long-term nail picking and manipulation of nail units can lead to complications such as permanent nail dystrophy. Melanocyte activation can occur due to trauma to the proximal nail fold. These changes are permanent even after cessation of the condition.^[25] Superimposed bacterial and viral infections, including acute bacterial paronychia, herpetic whitlow and periungual warts, may also occur, along with chronic paronychia, pterygium and anonychia.^[72] Non-pharmacological treatment options rely on supportive measures. The use of bandages and other occlusives has been found to be useful.^[73,74] If bandages are found unacceptable by the patient socially, cyanoacrylate glue can be used twice a week over the cuticle, to serve as a physical barrier against picking.^[14] Behavioural modification using CBT can help the patient like in other BFRBs.^[75] There are currently no published trials focusing on pharmacologic treatment of onychotillomania. NAC may be tried as it has been found useful in other BFRBs. However, there is no published literature in onychotillomania. In patients with comorbid psychiatric illnesses such as depression, OCD and psychosis, psychotropic drugs including SSRIs, tricyclic anti-depressants and typical antipsychotics have proven useful.^[16]

ONYCHOTEMNOMANIA

This involves cutting nails too short, leading to secondary trauma. Patients may use scissors, blades or knives to go till the far proximal end of nails. Clinically, the patient has extremely small nail plates with exposed distal edges [Figure 7a and b].

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Figure 7:

(a) Onychotemnomania: Clinical image showing wedge-shaped subungual haemorrhages, pus points, traumatic onycholysis, shiny nail plate, periungual haemorrhage and excoriations. (b) Onychotemnomania: Non-polarised dermoscopy with DermLite 4 magnification ×10 showing Subungual and periungual haemorrhage, subungual puspoint, onycholysis, splinter haemorrhages, ragged nail folds and absent cuticle.

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ONYCHOTEIROMANIA

This condition refers to the presence of very thin nails that crack easily due to excessive filing or rubbing of the nail surface. Patients can file the nail folds and in extreme cases, they may reach the nail bed epithelium^[4] [Figure 8a and b]. Video 6 demonstrates onychoteiromania.

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Figure 8:

(a) Onychoteiromania: Clinical image showing thinned out nail plate, nail plate scaling, dystrophy, lichen simplex chronicus (LSC) in proximal nail fold, nail plate and periungual haemorrhages. (b): Onychoteiromania: Non-polarised dermoscopy with DermLite 4 magnification ×10 showing melanonychia, red streaks, wavy lines, scaling, periungual haemorrhage and scaling.

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Bidet nails are a variant of onychoteiromania.^[76] The free margin of the nail is rubbed against a surface leading to a distal triangular defect of the nail plate. The nail defect is reportedly acquired secondary to rubbing against the glazed earthenware of the bidet. There is involvement of the 2^nd, 3^rd, and 4^th fingers of the dominant hand. Onychoscopy shows the presence of dilated capillaries and pinpoint haemorrhages. Majority of the patients have been reported to have obsession with excessive cleanliness.^[77]

ONYCHODAKNOMANIA

It is a rare entity where the patient bites their fingernails between their teeth, typically using premolars and canines. This self-mutilating behaviour is extremely painful^[78] and is often associated with an underlying psychiatric disorder. As a result, it can lead to the formation of irregular and deep depressions and surface irregularities. Patients may respond to a multidisciplinary approach and pharmacotherapy with combination therapy of anti-psychotics and anti-depressants.^[40]

Various non-pharmacological and pharmacological treatment options used in the management of SINDs are summarised in Table 5^{[14,52,60,65,79-81]} and Table 6,^{[45,68,82-89]}, respectively.

FUTURE DIRECTIONS

Dermatologists need to be aware regarding SIND’s so that they can identify the condition and offer appropriate diagnosis and management. Standard protocols need to be developed with regard to the referral of a patient to a psychiatrist or psychologist. These disorders lead to significant psychological and physical morbidity; hence, larger clinical trials are needed to develop effective therapy.

CONCLUSION

Self-inflicted nail damage is more common than generally reported or anticipated. SIND’s are auto-aggressive disorders, mimicking various nail disorders. Most patients do not acknowledge the fact that they suffer from any such disorder. They deny the diagnosis and aetiology and most often do not even present with the primary complaint of these conditions. It is important for the clinician to be aware of these entities to make a correct diagnosis, suspect underlying psychiatric comorbidity and thereby offer appropriate treatment options. Psychotherapy can be beneficial for mild-to-moderate conditions, whereas medication can be used in severe cases.