10.10 Paronychia
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agk's Library of Common Simple Emergencies

Presentation
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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 uncompli- 
    cated 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:
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- Brook I: Aerobic and anaerobic microbiology 
    of paronychia. *Ann Emerg Med* 1990; 
    19:994-996.

Illustration
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img/cse1010.gif

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