Onychomycosis

Definition 

 

Fungal infection of the nail

 

Epidemiology

 

Toenail affected 4x more common than fingernail

Prevalence has increased x 4 in last 2 decades

 

Aetiology

 

Dermatophytes most common cause

 

99% T rubrum & T mentagrophytes

- destroy nail by chemical or enzymatic process

 

Pathogenesis

 

First

- keratin of hyponychium is infected by the dermatophyte

 

Second

- involves nail bed & nail plate

- initially invades ventral plate which arises from nail bed

- intermediate plate has soft keratin & can become involved

- dorsal nail plate rarely involved

 

Clinical

 

Usually cosmetic problem only

- may become painful

 

Diagnosis

 

Microscopy of nail scrapings & culture studies

-> hyphae

- can culture if necessary

 

Management

 

Non-operative

 

Debride & remove part or all of nail

 

Topical agents less effective than systemic because don't target matrix

 

Oral antifungals 

- griseofulvin & ketoconazole (need up to 1 year of treatment)

- terbinafine (Lamasil) & itraconazole (Sporanox) 

- more effective with shorter treatment (3-6m)

- remain in the nail for 6 months

 

Operative

 

Zadek's

Terminal Syme amputation