eMedicine Specialties > Emergency Medicine > Infectious Diseases

Hand Infections

Author: Rohini J Haar, MD, Staff Physician, Department of Emergency Medicine, New York University/Bellevue Hospital Center
Coauthor(s): Gregory S Johnston, MD, Assistant Professor, Department of Emergency Medicine, New York University School of Medicine; Chair, Hospital Emergency Preparedness Committee, Bellevue Hospital Center; Consulting Staff, Department of Emergency Medicine, Bellevue Hospital Center, New York University Medical Center, Tisch Hospital, Harbor Veterans Administration Medical Center
Contributor Information and Disclosures

Updated: Dec 4, 2009

Introduction

Background

In 1939, Kanavel, author of the landmark Infections of the Hand, observed, "In almost all cases of serious infection the difficulty is to make a correct diagnosis both as to the nature of the infection and the position of the pus."¹ Specific infections covered in this article include paronychia, felon, herpetic whitlow, tenosynovitis, and deep fascial space infections.

Pathophysiology

Few structures of the body are as complex or as unique as the human hand with the functions of sensation, mobility, and strength in one small area. The hand consists of multiple compartments and planes, the knowledge of which allows one to understand the pathophysiology, diagnosis, and treatment of hand infections.

Paronychia

Infection of the area of the lateral nail fold (paronychium) is typically due to superficial trauma (eg, hangnails, nail biting, manicuring, finger sucking). Artificial nails have also been associated with acute paronychia. Although paronychia typically starts as a cellulitis, its progression to abscess formation is not uncommon. Infection that spreads to the proximal nail edge is termed an eponychia. Occasionally, infection can spread under the nail plate itself, resulting in a subungual abscess.

Chronic paronychia resembles acute paronychia but is usually nonsuppurative. People at risk include those repeatedly exposed to water and/or irritants as well as those who are immunocompromised. Metastatic cancer, subungual melanoma, and squamous cell cancer may rarely present as chronic paronychia.

Felon

The distal palmar phalanx is compartmentalized by tangentially oriented fibrous septa. These septa result in a closed compartment at the distal phalanx, which helps prevent the proximal spread of infection. Infection is typically due to direct inoculation of bacteria by penetrating trauma but may be caused by hematogenous spread and by local spread from an untreated paronychia.

Infection results in edema and increased pressure within the closed compartment. This, in turn, can impair venous outflow and lead to a local compartment syndrome and myonecrosis. Invasion of the bone leads to osteomyelitis.²

Herpetic whitlow

Herpes simplex virus (HSV) infection of the distal finger typically results from direct inoculation of the virus into broken skin. Infection by type 1 or type 2 HSV is clinically indistinguishable. As in herpes infections elsewhere in the body, it is believed that the virus can remain dormant in the neural ganglia, leading to recurrent infections.

Tendon sheaths consist of a visceral layer adherent to the tendon and a parietal layer. Notably, the flexor tendon sheath of the thumb is continuous with the radial bursae, whereas the flexor tendon sheath of the fifth digit is continuous with the ulnar bursae. In 80% of individuals, communication exists between the radial and ulnar bursae. The tenosynovial coverings of the second, third, and fourth digits do not communicate with either the radial bursae or the ulnar bursae in most individuals.

Infection within a flexor tendon sheath, as in other infections of the hand, usually is the result of direct inoculation of bacteria from penetrating trauma.

One common cause of penetrating trauma occurs when one person strikes another person in the mouth, resulting in a fight bite. A tooth may penetrate the metacarpophalangeal (MCP) joint capsule or an extensor tendon. Because the injury occurs while the joint is in flexion, deeper injuries to the extensor tendon or the MCP joint capsule or bone can be easily missed when the hand is examined in extension. For more information, see Bites, Human.

Infection can also occur by hematogenous spread, with Neisseria gonorrhoeae as the offending agent in many cases.

Pyogenic flexor tenosynovitis, an infection of the flexor tendon, is most common in the index, middle, and ring fingers and can form as early as 6 hours after the initial penetration.

Infection typically follows the course of the tendon sheath, which results in the spread of infection into the radial or ulnar bursae, depending on the primary tendon sheath involved. Elevated pressure within the tendon sheath due to infection may impair nutrient flow to the tendon. Tendon necrosis, impaired function, or both are disastrous sequelae of untreated elevated tendon sheath pressure.

Deep fascial space infection

The deep fascial spaces of the hand are potential spaces and consist of the dorsal subaponeurotic space, subfascial web space, midpalmar space, and thenar space. The dorsal subaponeurotic space lies dorsal to the extensor tendons of the hand. The subfascial web space is contiguous with the dorsal subcutaneous space of the digits. The midpalmar space is demarcated by the palmar interosseous muscles dorsally and the flexor tendons of the third, fourth, and fifth digits ventrally. Lastly, the thenar space extends from the long metacarpal bone to the thenar eminence and consists of the area between the adductor pollicis muscle dorsally and the flexor tendon of the second digit ventrally.

These compartments are susceptible to infection by direct penetrating trauma, spread from a neighboring compartment, or hematogenous seeding. Because of the dorsal location of the lymphatics, erythema and swelling commonly appear over the dorsum of the hand, even when the injury is of palmar origin.

For more on hand anatomy, see Hand, Anatomy.

Mortality/Morbidity

Infections of the hand (especially dominant-hand infections) can be devastating and frequently require admission for antibiotic therapy and/or surgical intervention. Possible complications are outlined below (see Complications).

Clinical

History

• Paronychia
  • Recent trauma to the lateral nail fold
  • In acute paronychia, history of nail biting or manicuring
  • In chronic paronychia, history of repeated exposure to water and/or irritants (Those at risk may include people that frequently wash dishes or perform housekeeping duties.)
  • In children, history of finger sucking
  • Erythema and pain in early stages, followed by frank abscess formation with increased pain
  • History of diabetes (One study found that pediatric and adolescent patients with type 1 diabetes mellitus had an increased frequency of paronychia over the control group [34.4% vs 23%, respectively].)³
• Felon
  • Recent trauma to finger pad
  • Pain, typically throbbing in nature
  • Swelling, pressure, and erythema
  • Presence and/or progression from paronychia
• Herpetic whitlow
  • Genital herpes in self or partner
  • Health care worker (not as common as once believed, likely secondary to increased protection with standard body-substance precautions)
  • Children with gingivostomatitis
  • Most commonly on tip of finger rather than on shaft
  • Localized pain, pruritus, and swelling followed by the appearance of clear vesicles
  • Typically localized to 1 finger only (symptoms involving more than 1 finger are more typical of coxsackievirus infection)
• Infectious tenosynovitis
  • Recent penetrating trauma to the hand
  • Gonococcal infection, particularly disseminated infection
  • Pain, especially with passive extension of the finger
  • Edema of the entire finger
  • Variable history of fever
• Deep fascial space infection
  • Recent penetrating trauma to the hand
  • Recent or untreated tenosynovitis
  • Palmar blister (may result in subfascial web space abscess)
  • Pain and edema of the hand
  • Pain with movement of the fingers
  • Variable history of fever

Physical

• Paronychia
  • Edema, erythema, and pain along lateral edge of the nail fold
  • May have extension to the proximal nail edge (eponychium)
  • Presence of frank abscess formation and fluctuance, although less common in chronic cases
  • Subungual abscess (floating nail) if pus has extended under the nail plate
• Felon
  • Painful, tense, and erythematous finger pad
  • Pointing of abscess possibly present
  • Signs typically limited to area distal to the distal interphalangeal joint because of anatomic constraints
  • Evidence of penetrating trauma
• Herpetic whitlow
  • Clear vesicles on an erythematous border localized to one finger
  • Pain, typically out of proportion to findings
  • Edema
  • Turbid or cloudy fluid in vesicles, possibly suggesting a superimposed pyogenic infection
  • In later stages, coalescence of vesicles to form an ulcer
  • Distal finger pulp that remains soft, which may help distinguish herpes simplex virus (HSV) infections from bacterial felons
• Infectious tenosynovitis
  • The 4 cardinal signs, first described by Kanavel, include the following:
    • Tenderness along the course of the flexor tendon
    • Symmetric edema of the involved finger
    • Pain on passive extension (believed by some authors to be the most important sign)
    • Flexed resting posture of finger
  • All 4 signs possibly not present early in the course of infection
  • May have associated lymphangitis, lymphadenopathy, and fever
• Deep fascial space infections - All possibly presenting with lymphangitis (identified dorsally), lymphadenopathy, and fever
  • Dorsal subaponeurotic abscesses - Result in swelling and pain on the dorsum of the hand and pain with passive movement of the extensor tendons (difficult to distinguish from dorsal subcutaneous infection)
  • Subfascial web space infections - Present with pain and swelling on the dorsum and palmar surfaces of the hand (Because the subfascial space is contiguous with the dorsal subcutaneous space, tracking of infection from the former to the latter results in a collar button abscess named for its hourglass shape.)
  • Midpalmar space infections - Present with pain, swelling, loss of palmar concavity, pain with movement of the third and fourth digits, and dorsal swelling secondary to the tracking of infection dorsally along the lymphatics
  • Thenar space infections - Result in marked swelling of the thumb-index web space, flexed and abducted resting posture of the thumb, and pain with passive adduction

Causes

• Paronychia
  • Staphylococcus aureus and Streptococcus species are most common in acute cases.
  • Candida albicans (95%) and atypical mycobacteria are causes in chronic cases and in patients who are immunocompromised.
  • Anaerobes may be involved in the pediatric population secondary to finger sucking and children's playing in unhygienic spaces.
• Felon: S aureus is the most common causative organism, but gram-negative organisms have been identified.
• Herpetic whitlow: HSV-1 or HSV-2 is responsible.
• Infectious tenosynovitis
  • S aureus and Streptococcus species are commonly isolated; however, some authors believe that N gonorrhoeae should be considered a possible pathogen until excluded by culture data.
  • Eikenella corrodens is observed in infections caused by human bites.
  • Pasteurella multocida and Capnocytophaga infections caused by cat and dog bites can progress rapidly to septic shock and death.
• Deep fascial space infections
  • S aureus and Streptococcus species are most commonly isolated.
  • Organisms mentioned for infectious tenosynovitis also apply to deep space infections. This may be the result of local spread from infected neighboring tendon sheaths.

• Search for CME/CE on This Topic »

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