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Onychomycosis: causes, symptoms, diagnosis, treatment
Last reviewed: 23.04.2024
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What causes onychomycosis?
Approximately 10% of the population suffers from onychomycosis. The risk group includes patients with dermatomycosis of the soles, dystrophy of the nails, circulatory disorders and elderly people. Nails on legs are infected 10 times more often than on hands. Approximately 60-80% of cases are caused by dermatophytes (eg, Trichophyton rubrum). In other cases, the infection is caused by Aspergillus, Scopulariopsis, Fusarium. In patients with chronic skin pigeon candidiasis, candidal onychomycosis may develop (more common on the hands).
Currently, the growing importance in the etiology of onychomycosis is acquired by yeast-like fungi of the genus Candida and mold fungi, as well as mixed fungal infection.
Isolated infection of nail plates with fungi is rare. Usually, the nail lesion occurs secondarily when the fungus spreads from the affected skin of the finger, for example, with mycosis of the feet, brushes. It is also possible hematogenous migration of the fungus to the area of the nail matrix.
This variant of occurrence of onychomycosis occurs in the trauma of the nail phalanx, as well as in patients with endocrine diseases, immunodeficiency states, in particular, with long-term treatment with glucocorticosteroids, cytostatics, HIV infection, etc. In the pathogenesis of onychomycosis, circulatory disturbances in the extremities, especially the lower ones (varicose veins, obliterating endarteritis, heart failure with valvular defects and hypertension). Functional and organic diseases of the nervous system are important, leading to a disruption of tissue trophism. In recent years, the number of young patients with a pathogenetic basis for the development of onychomycosis angiotrophoneurosis, in particular Reynaud's symptom complex, has increased. Given the systemic manifestations of the phenomenon of Raynaud, often occur common fungal nail lesions, usually with lesions of the nail plates of the hands. Endocrine diseases (exogenous and endogenous hypercorticism, diabetes, disorders of the function of the sexual glands), immunodeficiency state (corticosteroids, cytotoxic drugs, immunosuppressants, HIV infection), certain chronic skin diseases characterized by horny disorders and dystrophy of nail plates (ichthyosis, keratoderma, red flat lichen). From an exogenous cause, an important role is played by injuries of nail plates and distal limbs - mechanical, chemical (professional and household), and frostbite and chill. Injury not only promotes the introduction of the fungus into the nail plate, but often provokes onychomycosis in persons already infected with fungi. Thus, the trauma of the peri-oral cusp with manicure and pedicure promotes the appearance of onychomycosis of the hands of persons having mycosis and onychomycosis of the feet.
Symptoms of onychomycosis
With onychomycosis, the nail plates of the feet and, more rarely, the brushes are involved in the process more often. Usually the lesion begins with the I and V toes of the feet. The main clinical signs of onychomycosis are changes in color, nail shape due to subungual hyperkeratosis and destruction of the nail plate. With onychomycosis caused by dermatophytes or mixed microflora, the nail roller is usually not affected.
Depending on the prevailing clinical symptom, three clinical forms of onychomycosis are distinguished: hypertrophic, normotrophic and atrophic.
When the form is hypertrophic, the nail plate thickens due to subungual hyperkeratosis and acquires a yellowish color. The surface of the nail can remain smooth for a long time. In the future, the nail plate can detach from the nail bed, it loses its luster, its edges become serrated.
In the normotrophic form of lesions, there are areas of yellowish and white in the thickness of the nail, while the nail plate does not change its shape, subungual hyperkeratosis is not expressed.
Atrophic form of onychomycosis is characterized by a significant thinning, detachment of the nail plate from the nail bed, the formation of voids or partial destruction of it.
In European and American dermatology, the most common classification of onychomycosis, taking into account not only the clinical features of the affected nail plate, but also the options for the penetration of fungi into it. Distal, distal-lateral, white superficial, proximal subungual and total dystrophic onychomycosis are distinguished.
Distal and distal-lateral subungual onychomycosis is the most common form of onychomycosis, in 85% of cases it is caused by Trichophyton rubrum. With this form, the pathogen usually enters the nail from the affected skin of the feet. The nail plate is infected from the free edge, usually after the defeat of the nail bed, the pathological process slowly spreads towards the matrix in the form of a splinter or yellow oval spot. This form may be accompanied by the appearance of subungual hyperkeratosis.
White surface onychomycosis is most often caused by Trichophyton mentagrophytes (approximately from 90% of cases), less often it is associated with mold fungi of the genus Aspergillus. With white superficial onychomycosis, the nail plates of the first fingers are usually involved in the process. The prerequisite for the development of this form of onychomycosis is the softening of the nail plate in a moist environment, while the pathogen is localized superficially, the matrix and the nail bed are not involved. This clinical form is characterized by superficial foci of white color on the nail plate, reminiscent of the usual leukonichia.
The proximal subungual onychomycosis, like the white surface one, is rare. It occurs as a result of the causative agent from the side of the peri-oral cusp or the surrounding skin, or, which is even rarer, develops against a white surface onychomycosis. This form is characterized by the onset of the disease with the proximal part of the nail plate and the rapid involvement of the nail matrix. Clinically, with maximal onychomycosis, the areas of discoloration of the nail plate first appear, after which onycholysis (separation of the nail of the nail bed) can appear quite quickly.
Total dystrophic onychomycosis develops against the background of distal or distal-lateral, less often proximal onychomycosis. This variety is found both in the defeat of dermatophytes and mold fungi, and yeast of the genus Candida. On examination, the involvement of the entire nail plate is recorded, often with partial or complete destruction.
Diagnosis of onychomycosis
Evaluation of clinical manifestations in diseases of nail plates with onychodystrophy is important both in the diagnosis of various skin diseases and somatic pathology. Correct interpretation of the dermatological status, including the state of the nail plates, determines the direction of the diagnostic search in various fields of medicine. It is this fact that increases the importance of assessing the condition of nails, not only for the purpose of diagnosing a particular disease, but also for the purpose of assessing the state of the macroorganism.
Laboratory diagnostic methods supplement, confirm or exclude a clinical diagnosis. In the practice of a dermatologist, mycological examination (microscopy and sowing) is widely used. There is also a microbiological, histological (with a suspicion of benign and malignant neoplasm of the nail bed) of the study. The choice of diagnostic techniques depends on the clinical manifestations in the affected nail (nail). . Assessment of the state of nails includes an assessment of its shape, surface, thickness, color. An undoubted role in the diagnosis is played by the analysis of clinical manifestations in the area of the nail roller.
The diagnosis is determined by the appearance of the changes, also microscopic analysis and examination of scrapes are also needed. Take the necessary sample is sometimes difficult, since not all affected areas contain fungi. In diagnosis, one should distinguish between psoriasis and lichen planus.
[4], [5], [6], [7], [8], [9], [10]
Differential diagnosis of onychomycosis
Similar clinical manifestations have affected nails with psoriasis, keratoderma, red flat lichen and onychodystrophy.
How to examine?
Treatment of onychomycosis
Treatment of onychomycosis is a very urgent problem in modern dermatology and dermatocosmetology. Often this disease becomes a cosmetic problem for patients, significantly affecting the quality of life, psychological and physical status. Therapy of onychomycosis can be external and systemic. The use of external antifungal agents is justified only with the initial lesion of the distal part of the nail plate, when no more than a third of the nail plate is involved in the process and there is no pronounced subungual hyperkeratosis. In other cases, the use of systemic antifungal agents is indicated. In general, when choosing a method of therapy, the physician is advised to focus on a set of symptoms: the volume of involvement of the nail plate (up to 1/3 or more 1/3), the localization of the lesion (distally or proximally), the presence of onychomycosis on the hands and / or feet, the amount Affected nails, which fingers are affected, the degree of expression of subungual hyperkeratosis.
The introduction of oral antifungal agents from the azole group (itraconazole, fluconazole), as well as terbinafine, which have a stronger, selective effect on the enzyme systems of fungi than ketoconazole, was an important achievement in the treatment of superficial and systemic mycoses in the mid-1980s. Advantages of these drugs is the breadth of the spectrum of action, the ability to selectively accumulate and stay in the nail plate, not getting back into the bloodstream. Itraconazole (Orungal, etc.), whose undoubted advantage is the breadth of the spectrum of action (it acts fungicidally on filamentous, yeast and mold fungi), is prescribed by the pulse-therapy method: 200 mg twice a day during the first week of each month. The duration of treatment with onychomycosis of brushes is 2 months, with onychomycosis of the toes, the drug is recommended to be prescribed for a period of 3 months. The use of pulse therapy in onychomycosis effectively, dramatically reduces the incidence of side effects and reduces the total dose of the drug.
Terbinafine (Lamisil, Ekayifin, etc.) is also one of the drugs of choice for the treatment of onychomycosis, especially if they are caused by Dermatophytes. The drug is taken once a day for 250 mg. With onychomycosis of hands and feet, lamizil is prescribed for a period of 6 weeks to 3 months.
Fluconazole (Diflucan, Mycosyst, etc.) is prescribed for onychomycosis of hands and feet caused by dermatophytes or mixed microflora, the dosage of the drug is 150 mg once a week for a period of 6 months - for onychomycosis of brushes and 6-12 months for onychomycosis of the feet.
It should be emphasized that surgical removal of nails in the treatment of onychomycosis is extremely undesirable because of the possibility of irreversible damage to the matrix and the subsequent development of persistent onychomadezis with the formation of the pterygium. The use of modern antimycotics, which have the property of accumulating in the horny appendages of the skin, allows a long time to maintain the fungicidal concentration in the affected area. On the background of systemic therapy, external antifungal therapy can be performed; use special forms designed for the nail plate, - varnish forms with various antifungal agents (amorolfine - loceril, cyclopyroxolamine - Batrafen). In parallel, it is necessary to treat concomitant mycosis with the use of external antifungal agents. Assign the following groups of drugs in the forms of cream, ointment, spray:
- ashes: Clotrimazole (Clotrimazole, Kanesten, Candide, etc.), ketoconazole (Yazoral), miconazole (Dactarin), bifonazole - (Mycospor), econazole (Pevaril et al.), isoconazole (Trtogen);
- allylamines (terbinafine - Lamisil, naphthyfine - Exoderyl);
- morpholine derivatives (amorolfine-loceril);
- derivatives of hydroxypyridone (cyclopyroxolamine-Batrafen)
- other means.
The total duration of external treatment depends on the individual growth rate of nail plates. It is recommended to care for nail plates, their regular filing, and various keratolytic agents (milky salicyl collodion, etc.) can be used.
Treatment of onychomycosis should include not only effective etiological, but also pathogenetic therapy, as well as the identification and correction of the underlying concomitant pathology. In parallel with the appointment of antifungal antibiotics, therapy is needed to improve microcirculation in the distal extremity. Apply pentoxifylline (Trental, Agapurin) 400 mg 2-3 times a day, calcium supplement (Doxychem, Doxium) 250-500 mg 3 times a day, drugs nicotinic acid (xanthinal nicotinate 150-300 mg 3 times a day during meal or 1 ml of 1% solution of nicotinic acid intramuscularly N 10-15 per course). Patients are shown physiotherapeutic procedures aimed at improving blood circulation in the distal extremity. For this purpose, various procedures can be recommended for paravertebral areas in the lumbosacral and cervico-thoracic spine - UHF-therapy, amplipulse therapy, diathermy (N 7-10 daily), etc. Also, supra-vascular laser irradiation of blood in the projection of peripheral arteries. The radiation power at the output is from 15 to 50 mW, the exposure time is 6-10 min for each irradiation zone. Areas of exposure, duration and number of procedures are determined by the variant of vascular pathology and the type of onychomycosis. To increase the efficiency of this technique, a device is used to create a negative pressure (0.1-0.13 atm) in the zone of action of laser radiation.
The effectiveness of therapy for onychomycosis depends largely on the thoroughness of the antifungal treatment of shoes and other household items. For this purpose, 10% formalin solution, 0.5% chlorhexidine bigluconate solution, miconazole spray (Dactarine) can be used.
After the termination of therapy of onychomycosis, preventive treatment of nail plates and feet using modern antifungal cream, varnish and spray are recommended (groups of drugs: azoles, terbinafine, amorolfine, cyclopyroxolamine, etc.).
To prevent relapse, it is necessary to shorten the nails shortly, dry your feet after bathing, use antifungal powders.