A 26-year-old man with type 1 diabetes of 20 years' duration had acute onychocryptosis (Fig. 2.6a) which had not
responded to palliative care and underwent total nail avulsion. His toe healed in 5 weeks (Fig. 2.6b-d).
' For acute onychocryptosis which does not respond to palliative care, surgery can be a permanent solution
• A partial or total nail avulsion with phenolization can take several weeks to heal.
Involuted toe nail
This is excessive lateral curvature of the nail plate. If epithelial cells become trapped as they are shed in the
sulcus they can accumulate, causing pain and pressure. The nail sulcus is gently cleared with a Black's file. In severe cases, nail avulsion with phenolization of the nail bed, as shown in Fig. 2.6 can provide a permanent solution.
Onychomycosis (fungal nail). When fungal infection invades the nail plate it first causes white or yellowish discolouration of a patch of nail, which subsequently becomes thickened and friable. The majority of infections are caused by moulds called dermatophytes, or by yeasts, notably Candida albicans. There are four distinct types of onychomycosis:
• Distal and lateral subungual onychomycosis, which affects toe nails twice as commonly as finger nails. This is commonly caused by dermatophyte infection. The nail becomes detached from the bed (onycholysis) changing to a creamy white opaque colour (Fig. 2.7)
• Proximal subungual onychomycosis which is secondary to chronic paronychia caused by infection with yeasts of Candida species and is often associated with interdigital candidiasis
• Superficial white onychomycosis which is caused by Trichophyton mentagrophytes and is relatively uncommon
• Total dystrophic onychomycosis where the whole of the nail plate is destroyed is a consequence of any of the first three types.
Onychomycosis can cause chronic pain, physical disability and secondary bacterial infection. Eradication of the fungal infection is not easy, and some patients will opt for palliative care if they are not concerned by the cosmetic effect and the infection is not spreading.
Diagnosis can be confirmed by culture of nail clippings taken from the most proximal part of the affected nail to obtain crumbly material: however, many infections are treated without laboratory confirmation. Treatment can be palliative or active. Active treatment involves topical or systemic agents.
Palliative care involves regular debulking and thinning of the nail which can be done with a scalpel by a podiatrist. This approach is usually sufficient for most fungal nail infections and active treatment should only be considered when the infection is causing unpleasant symptoms or distress.
For topical treatment the thickness of the nail is reduced with a scalpel and an antifungal agent applied directly to the remnants. Agents available include topical amorolfine nail lacquer and strong iodine BP. Treatment should continue until a new nail has formed, which may take up to 12 months.
If systemic treatment is undertaken it is important to be aware of the possible side-effects of therapy.
• Terbinafine 250 mg daily for 3 months is the drug of choice for fungal nail infections. Rarely, it can cause liver toxicity
• Itraconazole 200 mg daily for 3 months or as Sporanox Pulse 200 mg bd for 7 days and subsequent courses repeated after a 21-day interval. Itraconazole has been associated with liver damage and should not be given to patients with a history of liver disease.
Inflammation of the nail fold. Inflammation of the nail fold, or paronychia, can be acute or chronic.
Acute paronychia is due to bacterial infection, is painful, points and discharges pus. If the margin of the nail plate is pressing on the inflamed area it should be cut back. Collections of pus should be drained. A swab is sent for microscopy and culture, and appropriate systemic antibiotics prescribed.
Chronic paronychia results in the periungual tissues appearing erythematous and oedematous. The infection extends to the nail plate which may develop yellowish-green or yellowish-brown pigmentation.
Chronic paronychia is frequently caused by infection with Candida albicans and the treatment is with terbinafine or itraconazole, as described above. The feet should be kept dry.
Lesions under the nail These can be due to:
Subungual haematoma. This follows a trauma to the nail, when blood collects under the nail plate causing red, purple or black discolouration. Pain can be agonizing. The patient should be reassured that drainage will relieve pain and reduce damage to the nail bed. The blood is evacuated through a small hole made in the nail plate by paring with a scalpel or with a chiropodist's nail drill. If the nail plate is loose it should be cut back as far as possible to prevent the loose area from catching on the hose and causing further injury, and also to assist inspection of the nail bed.
Subungual necrosis. This can be due to trauma, infection or hydrostatic pressure from a haematoma under the nail bed which is not evacuated in time to prevent local ischaemia and tissue death.
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