“Compartment” is best described as a group of muscles surrounded by inelastic fascia that does not allow for tissue swelling. Compartment syndrome occurs when there is increased pressure within a confined space. Because the pressure cannot be released by swelling out, it swells in, leading to decreased neurovascular function, which may result in tissue damage and cell death. If not diagnosed immediately, the syndrome can lead to renal failure and death.

Acute compartment syndrome can occur as a result of a crushing injury, muscle tear, injury from overuse of muscles, circumferential burns, or any injury that causes increasing bleeding and swelling within a compartment.

Compartment syndrome is not common and can develop into a chronic condition from muscle overuse in athletes, with slow progression of pain, which is relieved with rest.

Cases of compartment syndrome secondary to a snakebite have been reported,¹ as well as cases secondary to an insect bite.² To our knowledge, however, this case is only the second report of compartment syndrome secondary to a dog bite.³

Case Presentation
A 32-year-old woman postal carrier presented to the emergency department after having been attacked by a pit bull while delivering mail. The dog attacked, then gripped her left lower leg with its teeth, and allegedly continued to shake it for 1 hour. The dog was killed, and his head was removed for rabies investigation.

Physical examination of the patient revealed puncture wounds on the patient’s leg, hand, and thigh; contusion of the right forearm; and a large U-shaped wound on the left anterolateral distal leg 4 inches proximal to the ankle.

The patient was placed on an oxygen monitor and was administered an intravenous (IV) line, while also being given adequate pain control. A radiograph of the left leg did not show any bony involvement.

The wound was irrigated, explored, and debrided before 14 interrupted sutures (Prolene size 4.0) and a posterior splint were placed. The patient was then fitted for crutches and was discharged with instructions to return to the emergency department in 7 to 10 days to have the sutures removed.

During an office visit 13 days after the initial attack, the patient complained of paresthesias involving the lateral 4 toes. She also had pain associated with any movement of the foot. The wound was cyanotic on the skin flap. No drainage, purulent discharge, or cellulitis was evident. Because of the pain and an Achilles contracture, which had started to develop, the patient had decreased range of motion of the left ankle and toes. She was instructed to remove her leg from the posterior splint frequently to perform gentle, active motion exercises; this was the only intervention she received at this point.

Six days later, the patient was referred to a surgeon because of continued swelling of her leg, inability to dorsiflex the foot, and numbness on the dorsum of the foot. A diagnosis of nerve injury or compartment syndrome in the left leg was considered.

Computed tomography (CT) with IV contrast showed inflammatory changes in the soft tissue of the lower left leg. A small amount of gas was seen underneath the skin, suggesting an infection or a skin defect. No masses or fluid collection were noted.

Twenty-three days after the attack, the patient was taken to the operating room because of progressive necrosis of the skin at the site, as well as intermittent edema around the lesion. The inability to dorsiflex the left foot continued, and persistent compartment syndrome or nerve laceration was considered. An arterial and venous Doppler study showed adequate flow in and out of the compartment, and nerve conduction studies showed an intact anterior tibial nerve.

During surgery, partial transection of the anterior tibialis muscle at the tendinomusculocutaneous musculus junction was noted, along with anterior compartment syndrome, with skin and soft-tissue necrosis of the anterior compartment. The anterior compartment was opened and described as “fairly tight.” A moderate amount of bloody fluid was evacuated. The muscle was viable but did not respond well to stimulation. Decompressive fasciotomy was performed. The wound was left open, and the leg was placed in a posterior splint.

Postoperatively, ischemic necrosis of the damaged skin was apparent on the left leg. She was readmitted to the hospital for wound care, including debridement of the wound. Six days later, she underwent a wound closure procedure, in which a 40-cm² full-thickness skin graft from the medial thigh was placed over the wound.

On follow-up visits, the patient was still unable to actively dorsiflex the ankle and toes. Her muscles and tendons were intact, but she continued to have severe pain, especially when standing, because of adhesions over the skin graft.

Discussion
In most cases, neither dog nor human bites are sutured, because they are considered dirty wounds (Figure). However, as a result of the severity of this case, and since the lesion was so extensive, it was thought that suturing was the best option. The wound was well irrigated and debrided before suturing. Nothing other than clinical symptoms pointed toward a diagnosis of compartment syndrome—the CT scan, Doppler studies, and nerve conduction studies did not demonstrate the syndrome. This diagnosis was confirmed only during surgery.

Diagnosis
The clinical presentation is important in determining the diagnosis of compartment syndrome. Results of one study show that the sensitivity of clinical findings for diagnosing compartment syndrome is only 13% to 19%; the positive predictive value of the clinical findings is 11% to 15%; and the specificity and negative predictive value are each 97% to 98%.⁴

The most common presentation of anterior compartment syndrome is diffuse, intense pain that is exacerbated by movement, touch, pressure, stretch, and elevation, or by placing the affected area in a dependent position. Paresthesias are also common because of ischemia along the cutaneous nerve distribution in the affected area.

In anterior compartment syndrome of the leg, the area affected is the first web space of the foot in the deep peroneal distribution. It is important to avoid the pinprick when testing nerve distribution; instead, use the 2-point discrimination test, because a pinprick affects the smallest nerves (which are the last to be affected). Furthermore, when the foot is dorsiflexed, the patient will experience severe pain, as well as palpable tenseness in the affected compartment.

Examining for a pulse, or lack thereof, is least reliable because compartment syndrome is a disorder of the microvasculature; the major vessels are frequently not affected.⁵ Testing of the compartment pressure is required to confirm the diagnosis, but this was not done in our patient because of the urgent need for surgery. Most experts accept a compartment pressure of >30 mm Hg as a positive test.⁶

One study compared near-infrared spectroscopy with compartment pressure in diagnosing lower-extremity compartment syndrome, using electromyography to determine neuromuscular function in volunteers.⁷ However, this continuous, noninvasive monitoring technique has yet to be tested in a controlled patient population. Even more promising is a recent case-control study, which showed that magnetic resonance imaging can help sort out clinically ambiguous cases of compartment syndrome.⁸

Signs and symptoms
Common signs and symptoms of compartment syndrome are listed in the Table.

In a case that involves an animal that grips and shakes its prey, an extensive crush injury is generated—a common cause of compartment syndrome. Anterior compartment syndrome, as in this case, results in a clinical presentation of sharp pain in the muscle on the lateral aspect of the lower leg that gradually gets worse until it is impossible to walk. In addition, the patient experiences weakness when trying to pull the foot upward against resistance, swelling and pain when the foot and toes are bent downward, and tenderness over the anterior tibialis muscle.⁹

Prognosis
The prognosis is excellent to poor, depending on how quickly the compartment syndrome is treated and whether complications develop. Treatment for compartment syndrome is fasciotomy, as was done in this case. In a retrospective study of 40 consecutive cases of fasciotomy for acute lower-leg compartment syndrome, the mortality rate was 15%; a patient’s age was the only significant predictor of outcome.¹⁰ 

Irreversible tissue death can occur within 4 to 12 hours after an acute event, depending on tissue type and compartmental pressure. Amputation may be necessary if the tissue is not viable.

Tissue damage and cell death, in which myoglobin is released into the blood stream, may result in myoglobinuria. The myoglobin may precipitate in the renal tubules, leading to renal failure. Death can also occur from cardiac dysrrhythmias through hyperkalemia secondary to tissue death.¹¹

Conclusion
Compartment syndrome can be prevented by removing the dressing, elevating the affected extremity, and applying a bivalved cast. The prognosis of compartment syndrome directly correlates to the timing of the diagnosis; early diagnosis is essential to prevent permanent tissue damage.  

References
1. Cawrse NH, Inglefield CJ, Hayes C, et al. A snake in the clinical grass: late compartment syndrome in a child bitten by an adder. Br J Plast Surg. 2002;55:434-435.

2. Evans AV, Darvay A, Jenkins IH, et al. Compartment syndrome following an insect bite. Br J Dermatol. 2001;144:636-638.

3. Anderson PJ, Zafar I, Nizam M, et al. Compartment syndrome in victims of dog bites. Injury. 1997;28:717.

4. Ulmer T. The clinical diagnosis of compartment syndrome of the lower leg: are clinical findings predictive of the disorder? J Orthop Trauma. 2002;16:572-577.

5. Matsen FA III, Winquist RA, Krugmire RB Jr. Diagnosis and management of compartmental syndromes. J Bone Joint Surg Am. 1980; 62:286-291.

6. Ehlinger M, Schneider L, Lefebvre Y, et al. Exercise-induced acute bilateral isolated anterolateral compartment syndrome of the leg: a case report of a rare condition [in French]. Rev Chir Orthop Reparatrice Appar Mot. 2004;90:165-170.

7. Gentilello LM, Sanzone A, Wang L, et al. Near-infrared spectroscopy versus compartment pressure for the diagnosis of lower extremity compartmental syndrome using electromyography-determined measurements of neuromuscular function. J Trauma. 2001;51:1-9.

8. Rominger MB, Lukosch CJ, Bachmann GF. MR imaging of compartment syndrome of the lower leg: a case control study. Eur Radiol. 2004;14:1432-1439.

9. McQueen MM, Gaston P, Court-Brown CM. Acute compartment syndrome. Who is at risk? J Bone Joint Surg Br. 2000;82: 200-203.

10. Heemskerk J, Kitslaar P. Acute compartment syndrome of the lower leg: retrospective study on prevalence, technique, and outcome of fasciotomies. World J Surg. 2003;27:744-747.

11. Kennedy TE. Compartment syndrome. In: Aghababian RV, ed. Emergency Medicine: The Core Curriculum. Philadelphia, Pa: Lippincott-Raven; 1998:1359-1360.