Human Bites in Emergency Medicine
- Author: Jeffrey Barrett, MD; Chief Editor: Rick Kulkarni, MD more...
Background
Human bite wounds have a notorious reputation, which is mostly based on one injury, the closed-fist injury. Human bites in other areas pose no greater risk than animal bites. Three general types of injuries can lead to complications: (1) closed-fist injury, (2) chomping injury to the finger, and (3) puncture-type wounds about the head caused by clashing with a tooth. Otherwise, the general principles of contaminated wound management apply to human bite wounds.
For more information, see Medscape's Wound Management Resource Center.
Pathophysiology
In a closed-fist injury, forces sufficient to break the skin from striking an opponent's tooth often inoculate the extensor tendon and its sheath. As the hand is flexed at the time of impact, the bacterial load is transferred caudally when the hand is opened and the tendon slides back to its relaxed state. Resulting contamination cannot be removed readily through normal cleansing and irrigation.
When a finger is bitten, such as in a chomping-type injury, tendons and their overlying sheaths are in close proximity to the skin. The wound may appear to be a minor abrasion-type injury, but careful inspection is required to rule out deep injury.
When a tooth strikes the head, even a deep puncture wound may appear innocuous. Deep, subgaleal, bacterial contamination is possible. This is especially true in young children who have relatively thin soft scalp and forehead tissue.
Epidemiology
Frequency
United States
Exact incidence of human bite wounds is unknown, and many cases do not come to medical attention. Institutionalized patients with poor impulse control create a high-risk environment for human bite wounds. Lesch-Nyhan syndrome is an uncommon disorder that includes self-mutilation through biting.
International
In a 4-year retrospective review in the United Kingdom, 421 (13%) human bites were identified out of 3136 case notes. The majority of those bitten were young males, with 44% of the males aged 16-25 years. The male-to-female ratio was 3:1.[1]
Mortality/Morbidity
- The primary concern with human bites of the hand is infection, which can be severe because of spread along tendon sheaths and deep into the hand. Surgical incision and drainage may be needed. Resultant scarring and tissue damage may compromise normal function of the hand.
- Infection also is the major complication of bites in other areas of the body. Most can be treated adequately; however, infections of poorly vascularized structures, such as ear cartilage, may be difficult to treat.
- Other serious infectious complications such as osteomyelitis of the skull vault, necrotizing fasciitis, infectious tenosynovitis, and septic arthritis have been associated with human bites. Transmission of human immunodeficiency virus (HIV) has been reported as a result of a human bite wound.[2]
Sex
- Males generally are at higher risk than females for bite wounds due to their typically more aggressive nature. Closed-fist injuries are encountered almost exclusively in young males.
Age
- Closed-fist injuries occur most often in adolescents and adults younger than 40 years.
- Toddlers frequently bite one another, but injuries usually are superficial and low risk.
- Penetrating tooth injuries of the scalp and forehead pose a higher risk to young patients than to older patients.
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