Medical Articles

A tale of Nasty Nails

Presenting complaint

  • 58yo female horse trainer from Namibia
  • Incisional hernia post c/s
  • Repaired without complication
  • No significant medical history
  • Chance finding of severe onychomycosis of all nails
  • Long history – as long as she can remember
  • No treatment as yet but was keen to try and cure the condition

Onychomycosis

  • Onychomycosis (also known as “Dermatophytic onychomycosis,” “Ringworm of the nail,” and “Tinea unguium”) means fungal infection of the nail
  • It is the most common disease of the nails and constitutes about a half of all nail abnormalities.
  • This condition may affect toenails or fingernails, but toenail infections are particularly common. The prevalence of onychomycosis is about 6-8% in the adult population

Symptoms

  • The nail plate can have a thickened, yellow, or cloudy appearance. The nails can become rough and crumbly, or can separate from the nail bed. There is usually no pain or other systemic symptoms
  • Dermatophytids are fungus-free skin lesions that sometimes form as a result of a fungus infection in another part of the body usually in the form of a rash.
  • Patients with onychomycosis may experience significant psychosocial problems due to the appearance of the nail. This is particularly increased when fingernails are affected.

Pathogenisis

  • The causative pathogens of onychomycosis include dermatophytes, Candida, and non-dermatophytic moulds. Dermatophytes are the fungi most commonly responsible in the temperate western countries. Candida and non-dermatophytic moulds are more frequently involved in the tropics and subtropics with a hot and humid climate.
  • Dermatophytes
  • Trichophyton rubrum is the most common dermatophyte involved in onychomycosis.
  • Other
  • Other causative pathogens include Candida and moulds. Candida mainly cause fingernail onychomycosis in people whose hands are often submerged in water.

Types

  • There are four classic types of onychomycosis:
  • Distal subungual onychomycosis
    • The most common form of tinea unguium usually caused by Trichophyton rubrum, which invades the nail bed and the underside of the nail plate.
  • White superficial onychomycosis
    • Caused by fungal invasion of the superficial layers of the nail plate to form “white islands” on the plate. Accounts for only 10 percent of onychomycosis cases.
  • Proximal subungual onychomycosis
    • Fungal penetration of the newly formed nail plate. It is the least common form but found more commonly when the patient is immunocompromised.
  • Candidal onychomycosis
    • Candida species invade fingernails usually occurring in persons who frequently immerse their hands in water. This normally requires the prior damage of the nail by infection or trauma.

Diagnosis

  • Differential:
    • nail psoriasis, lichen planus, contact dermatitis, trauma, nail bed tumour or yellow nail syndrome
  • Diagnosis
    • laboratory confirmation may be necessary. The three main approaches are potassium hydroxide smear, culture and histology. This involves microscopic examination and culture of nail scrapings or clippings.

Treatment

  • Treatment of onychomycosis is challenging because the infection is embedded within the nail and is difficult to reach. As a result symptomatic improvement is very slow and may take a year or more. Recurrence rates remain high. Best practice advises combined topical and systemic therapy.
  • Pharmacological
  • Systemic
    • terbinafine and itraconazole
  • Topical:
    • Nail paints containing ciclopirox or amorolfine.
  • Relative effectiveness of treatments
  • A 2002 study compared the efficacy and safety of terbinafine in comparison with placebo, itraconazole and griseofulvin in treating fungal infections of the nails. The main findings were that for reduced fungus terbinafine was found to be significantly better than itraconazole and griseofulvin, and terbinafine was better tolerated than itraconazole.
  • A meta-analysis of 18 studies on terbinafine, 6 studies on pulse itraconazole, and 3 studies on fluconazole for onychomycosis showed a mycological cure rate of 76%, 63 %, and 48 % respectively
  • Onychomycosis caused by moulds, particularly Fusarium species, are often not responsive to systemic therapy.
  • Recurrence (relapse or reinfection) of onychomycosis is not uncommon, with reported rates ranging from 10-53%
  • Terbinafine (Lamisil)
  • Decreases ergosterol synthesis, causing fungal cell death.
  • Adult
    • Toenails: 250 mg PO dly for 12 wk Fingernails: 250 mg PO dly for 6 wk
    • Pediatric
      • Weight-based dosing 12-20 kg: 62.5 mg/d PO