10.10 Paronychia

agk’s Library of Common Simple Emergencies

Presentation

The patient will come with finger or toe pain that is either chronic and recurrent in nature or has developed rapidly over the past several hours, accompanied by redness and swelling of the nail fold. There are three distinct varieties:

• The chronic paronychia is most commonly seen with the “ingrown toenail” with chronic inflammation, thickening and purulence of the eponychial fold and loss of the cuticle. There may or may not be granulation tissue. This also occurs with individuals whose hands are frequently exposed to moisture and minor trauma.
• The acute paronychia almost always involves fingers and is much more painful. It is caused by the introduction of pyogenic bacteria by minor trauma and results in acute inflammation and abscess formation within the thin subcutaneous layer between the skin of the eponychial fold and the germinal layer of the eponychial cul- de-sac. In its earliest subacute form there may only be cellulitis with no collection of pus.
• The third variety of paronychia is a subungual abscess, which occurs in the same location as a subungual hematoma, between the nail plate and the nail bed.

What to do:

• Perform a unilateral or bilateral digital block and establish a bloodless field with a rubber tourniquet if a significant surgical procedure is anticipated.
• With a chronic paronychia:
  • You may consider conservative treatment or temporizing the condition by sliding a cotton wedge under the corner of an ingrown nail and placing the patient on antibiotics (e.g., cefadroxil (Duricef) 500mg bid) and warm soaks. Because of the slow growth of nails, this wedging may need to be repeated for weeks or months. When candidiasis is suspected, the area should be kept dry and treated with local applications of nystatin or other topical antifungals. A long course of systemic medication may be required. Followup with a podiatrist is important.
  • A more aggressive approach, and one more likely to be successful, is to sharply excise the entire wedge of affected nail, nailbed and lateral skin fold down to the periosteum of the distal phalynx. Instruct the patient to soak the toe in warm water for 20 min bid and arrange for multiple followup visits. Extensive paronychia requires excision of the entire nail.
  • Instruct the patient to cut toenails straight across to prevent any ingrown nails
• With an acute paronychia:
  • When there is minimal swelling and there appears to be only cellulitis, gently use an 18 gauge needle to separate the cuticle of the lateral nail fold to rule out or drain any collection of pus. Instruct the patient to soak the finger in warm water for ten minutes qid and consider prescribing antibiotics for three or four days.
  • When there is redness and swelling of the nail fold, take an 18 gauge needle or # 15 scalpel blade, separate the cuticle from the nail, open the eponychial cul-de-sac and drain any abscess. Keep the needle or scalpel tip flat against the dorsal surface of the nail. There is no need to make an incision through the skin and thus a digital block is usually not necessary. A tiny wick (1 cm of 1/4" gauze) may be slid into the opening to ensure continued drainage. Debride any periungual pustules. Instruct the patient in warm soaks at least qid. When drainage is complete, antibiotics are not routinely required, but where significant cellulitis was present, a short course of antibiotics may be indicated. Clindamycin (Cleocin) 150mg qid or amoxicillin plus clavulanate (Augmentin) 250mg tid have a wide spectrum of activity against most pathogens isolated from paronychia. The patient should be informed that if the paronychia quickly recurs, excision of a portion of the nail might be required.
  • A more aggressive approach for tha more extensive infection is to excise a portion of the nail. Unlike the more aggressive procedure used with the chronic paronychia, only a portion of the nail need be removed, and no underlying tissue. After establishing a digital block and a bloodless field, simply insert a fine straight hemostat between the nail and the nail bed, along the edge adjacent to the paronychia, and push and spread until you enter the eponychial cul-de-sac. Often it is at this point that pus is discovered. Then using a pair of fine scissors, cut away the quarter or third of the nail bordering the paronychia. Separate the cuticle using the hemostat and pull this unwanted fragment of nail away. A non-adherent dressing is required over the exposed nailbed as well as an early dressing change (within 24 hours).
• With a subungual abscess:
  • You may consider conservative treatment not requiring a digital block. Merely perform a trephination using the same “hot paper clip” technique used for a subungual hematoma. The patient must provide frequent warm soapy soaks over the next 36 hours to prevent recurrence.
  • The more effective but more aggressive technique used when there is a proximal collection of pus requires removal of the proximal 1/3 of the the nail. A straight hemostat is required to separate the cuticle of the eponychium from the underlying nail. Using the hemostat, the proximal portion of the nail is pulled out from under the eponychium and excised. On occasion an incision will have to be made along the lateral border of the eponychium to allow the proximal nail to be excised. The removal of the proximal portion of the nail allows for the complete drainage of the abscess without any risk of recurrence. A non-adherent dressing is also required in this instance. Extensive damage to the germinal matrix by the infection may preclude healthy nail regrowth.
  • When there is a distal collection of pus, a simple excision of an overlying wedge of nail using iris scissors should provide complete drainage.

What not to do:

• Do not order cultures or x rays on uncomplicated cases.
• Do not make an actual skin incision. The cuticle only needs to be separated from the nail in order to release any collection of pus.
• Do not remove an entire fingernail or toenail to drain a simple paronychia.
• Do not confuse a felon (tense tender finger pad) with a paronychia. Felons will require more extensive surgical treatment.

Discussion:

Whenever conservative therapy is instituted, the patient should be advised as to the advantages and disadvantages of that approach. If your patient is not willing or reliable enough to perform the required aftercare or cannot accept the potential treatment failure, then it would seem prudent to begin with the more aggressive treatment modes.

No single antibiotic will provide complete coverage for the array of bacterial and fungal pathogens cultured from paronychias. Theoretically, clincamycin or amoxicilln plus clavulanate should be the most appropriate antibiotics, but because the vast majority of paronychias are easily cured with simple drainage, systemic antibiotics are usually not indicated. In immunocompromised patients and those with peripheral vascular disease, cultures and antibiotics are indeed warranted.

Remain alert to the possible complications of a neglected paronychia such as osteomyelitis, septic tenosynovitis of the flexor tendon or a closed space infection of the distal finger pad (felon). Recurrent infections may be due to a herpes simplex infection (herpetic whitlow) or fungus (onchomycosis). Tumors like squamous cell carcinoma or malignant melanoma, cysts, syphilitic chancres, warts or foreign body granulomas can occasionally mimic a paronychia. Failure to cure a paronychia within four or five days should prompt specialized culture techniques, biopsy or referral.

References:

• Brook I: Aerobic and anaerobic microbiology of paronychia. Ann Emerg Med 1990;19:994-996.

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