A previously healthy eleven-year-old girl presented to the emergency room
with pain in the left leg and an inability to walk. The leg had become
increasingly swollen and painful during the two-day period prior to admission,
even though there was no history of trauma. The patient had had fever for
eight days preceding the appearance of symptoms in the leg, and this condition
had been treated by her primary care provider as influenza. She had had no
contact with ill individuals at home, and there was no history of recent
travel. Her immunizations were up to date.
In the emergency room, she was febrile with a temperature as high as
38.5°C. The systolic blood pressure was in the range of 80 to 90 mm Hg.
The left leg was swollen, the leg compartments were tense to palpation, and
the patient had severe calf pain with passive dorsiflexion of the ankle.
Pitting edema was evident in the dorsum of the left foot, which was
erythematous and had a loss of sensation. The active motor examination was
limited due to pain. The patient had a palpable dorsalis pedis pulse, and the
foot was warm to the touch. An erythematous macular rash of the abdomen and
chest was also present.
Radiographs of the left leg revealed extensive soft-tissue swelling with no
evidence of a fracture. A deep venous thrombosis was excluded with use of
Doppler ultrasound.
Laboratory studies demonstrated an elevated C-reactive protein level of
29.4 mg/dL (normal, 0 to 0.3 mg/dL), a Westergren erythrocyte sedimentation
rate of 32 mm/hr (normal, 0 to 20 mm/hr), and the following serum levels:
lactate, 4.3 mmol/L (normal 0.5-1.6 mmol/L); albumin, 2.6 g/dL (26 g/L)
(normal, 3.7 to 5.6 g/dL [37 to 56 g/L]); alanine aminotransferase (ALT), 111
U/L (normal, 10 to 30 U/L); and aspartate aminotransferase (AST), 102 U/L
(normal, 10 to 40 U/L). The activated partial thromboplastin time was 31.7
seconds and the international normalized ratio was 1.3, which were slightly
elevated values. The white blood-cell count was normal (8800/µL [8.8
× 109/L]), but the differential white blood-cell count was
remarkable for the presence of 69% neutrophils and 16% band neutrophils. The
hemoglobin level and platelet count were within normal limits (12.4 g/dL [124
g/L] and 317 × 103/µL [317 × 109/L],
respectively).
The clinical diagnosis of compartment syndrome was made, and the patient
underwent urgent fasciotomy of the left leg. Just before the fasciotomy and
after the patient was anesthetized, the intracompartmental pressure was
measured with use of a Stryker intracompartmental pressure monitor (Stryker
Instruments, Kalamazoo, Michigan) and was noted to be 84 mm Hg in the anterior
compartment, 92 mm Hg in the lateral compartment, 96 mm Hg in the deep
posterior compartment, and 92 mm Hg in the superficial posterior compartment.
A two-incision fasciotomy (medial and lateral) was performed, and extensive
edema was seen in the subcutaneous tissue of both incisions. The fatty tissue
was healthy in appearance, and the deep fascia was white in color and bled
when incised. In the superficial posterior compartment, pus was seen within
the soleus muscle, part of which did not contract with stimulation. The pus
was evacuated and the noncontractile muscle was excised, as was a small dusky
portion of the adjacent flexor digitorum longus muscle. All other muscles in
the other compartments were healthy in appearance and contracted with
electrocautery stimulation. Wound cultures were obtained. The fasciotomy
wounds were copiously irrigated and left open for later inspection and
débridement. The patient was then admitted to the intensive care unit
for monitoring and treatment of hypotension.
Empiric intravenous antibiotic treatment with vancomycin, gentamicin, and
clindamycin was begun. Following surgery, the hypotension was treated with
inotropic pressor support (dopamine, norepinephrine, and epinephrine). The
intraoperative cultures from the soleus muscle as well as from the other three
compartments demonstrated growth of group-A beta-hemolytic Streptococcus
pyogenes. A rapid strep antigen test of throat secretions also detected
the presence of group-A streptococcus. Penicillin was then added to the
antibiotic regimen, and vancomycin was discontinued. The patient continued to
be febrile, and on the second postoperative day, an extensive erythematous
macular rash from the left foot to the groin and lower abdomen developed
(Fig. 1), and necrotic skin
lesions were noted around the medial and lateral aspects of the left ankle
(Fig. 2). The patient promptly
underwent further débridement in the operating room along with random
biopsy and culture of specimens from the thigh and leg as well as from the
necrotic lesions of the ankle. The skin, subcutaneous tissue, and fascia were
excised from each of these samples and sent for analysis to rule out
generalized necrotizing fasciitis. A larger area of noncontractile,
dusky-appearing soleus muscle was removed, and the necrotic skin lesions along
with the underlying subcutaneous tissue and fascia were completely excised.
The subcutaneous tissue, muscle, and fascia of the anterior and lateral
compartments were healthy in appearance and were preserved.
The patient had two additional débridement procedures that resulted
in complete resection of the soleus muscle and portions of the gastrocnemius
and flexor digitorum longus muscles. By the fourth postoperative day, the
fever eased and she no longer required inotropic pressor support. On the ninth
postoperative day, antibiotic coverage was reduced to penicillin. The patient
was afebrile by the twelfth postoperative day, at which time the remaining
wounds were closed. She was discharged home on the fifteenth postoperative
day. Figure 3 demonstrates the
findings from the histologic analysis of tissue from the soleus muscle, which
were consistent with the diagnosis of pyomyositis.
Pyomyositis is an infection of the skeletal muscle and is thought to be of
hematogenous origin. It often, although not always, is associated with abscess
formation within the
muscle2. It occurs
in two stages: invasive (or interstitial) and
suppurative2,3.
In the invasive stage, infiltration by neutrophils is present and abscess
formation is not yet seen, while in the suppurative stage an abscess is
present. This is classically a disease of the tropics, where it accounts for
3% to 5% of hospital
admissions4. The
first reported case of pyomyositis occurring in temperate climates was in
19715, and since
then there has been an increase in the numbers reported in the
literature6,7.
In temperate climates, the disease is usually associated with some form of
immune compromise, such as human immunodeficiency virus infection, diabetes,
malignant disease, liver disease, renal disease, rheumatologic disease, or
organ
transplantation8-10.
In the pediatric population, an association with underlying varicella or
atopic dermatitis has been
reported2.
Staphylococcus aureus is the most common pathogen (detected in as
much as 90% of pediatric cases) associated with pyomyositis, whereas
Mycobacterium tuberculosis, Streptococcus pyogenes, and anaerobic
bacteria comprise the rarer
causes6,7,11-14.
However, blood cultures are positive in less than 35% of
patients5,10,15.
Larger muscle groups, such as the thigh and the gluteal muscles, are the most
common areas
affected6,7,
but the pathophysiology is not well understood. Skeletal muscle is normally
resistant to infection, but muscle injury, ranging from blunt trauma to
microtrauma from vigorous exercise, may predispose a muscle to infection in
the setting of
bacteremia6,11,16-18.
Compartment syndrome is rare in pyomyositis. The usual causes of
compartment syndrome include trauma, reperfusion injury, burns, prolonged limb
compression, and
exertion19, with
other rare causes being
hypothyroidism20,
diabetes21,
nephrotic
syndrome22, and
ganglion cyst23.
Cone et al. reported the first association between pyomyositis and compartment
syndrome in cases that occurred in the years 1978 through 1994, in five
patients with
cancer24. Infection
with Staphylococcus aureus, group-A beta-hemolytic streptococcus, and
Vibrio vulnificus has been associated with this combined
entity25-27.
In addition to pyomyositis, other infectious causes, such as necrotizing
fasciitis and streptococcal toxic shock syndrome, have been known to cause
compartment
syndrome28-32.
Although compartment syndrome associated with pyomyositis has been reported to
occur in patients with cancer, liver disease, and rheumatologic
disease24,26,33,
the presence of an underlying comorbid medical condition is not a
requirement25,27.
The mechanism by which pyomyositis leads to a compartment syndrome is
unclear, but it is likely that the inflammatory response in the muscle
initiates a cascade that results in endothelial injury and increased vascular
permeability, which culminates in a compartment syndrome. This is supported by
the case of a patient with immune-mediated myositis, in which muscle
inflammation alone, in the absence of any causative organism, was seen to
result in a compartment
syndrome34.
Moreover, as the presence of an abscess is not a
requirement25,26,
compartment syndrome can occur in both the invasive and the suppurative stages
of pyomyositis.
Our patient also presented with toxic shock syndrome. This is a systemic
illness that is caused by bacterial production of toxin (exotoxin), which
serves as a superantigen, causing potent stimulation of the immune system and
resulting in hypotension, shock, multiorgan failure, and even
death35-37.
Streptococcal toxic shock syndrome usually occurs with an invasive soft-tissue
infection, such as necrotizing fasciitis and pyomyositis, with reported
mortality rates as high as
80%35,38-41.
The currently used diagnostic criteria for streptococcal toxic shock syndrome
are presented in Table
I41.
Our patient met these criteria with the isolation of group-A streptococci from
the muscle, hypotension, elevated liver enzymes, the presence of an
erythematous macular rash, and mild coagulopathy. In addition, blood cultures
that were repeatedly negative supported the presence of exotoxin-mediated
toxic shock in our patient. Streptococcal toxic shock syndrome has also been
associated with compartment
syndrome30,32.
The systemic hypotension that occurs with increased vascular permeability and
alterations in the oncotic pressure of tissue due to decreased synthesis of
albumin may contribute to the development of a compartment syndrome. A
worrisome fact is that the prevalence of streptococcal toxic shock syndrome
has been increasing. A study published in 1993 reported that toxic shock
syndrome occurs in up to 8% of invasive streptococcal
infections40.
Another invasive streptococcal disease, necrotizing fasciitis, deserves
special mention. Differentiating necrotizing fasciitis from other less serious
soft-tissue infections, such as cellulitis, is difficult because the early
clinical signs are
nonspecific42-44.
A three-stage system based on skin changes has been proposed by Wong and
Wang45. The first
stage includes erythema, swelling, and tenderness to palpation extending
beyond the areas of skin involvement. The second stage includes blisters or
bullae, skin fluctuance, and skin induration. The third and final stage
involves hemorrhagic bullae, skin anesthesia, crepitus, and skin
necrosis45. On
visual examination, necrotizing fasciitis can manifest as grayish necrotic
fascia, an absence of fascial bleeding, and a foul-smelling
"dishwater"
pus45,46.
Necrosis of the superficial fascia, thrombosis of fascial vasculature with
angiitis and fibrinoid necrosis of vessel walls, and the presence of organisms
and neutrophilic infiltration in the fascia are seen
histologically47.
In the case of our patient, the random biopsy areas of the posterior part
of the leg, away from the fasciotomy sites, revealed normal subcutaneous
tissue, fascia, and overlying skin. The biopsy results of the erythematous
thigh were consistent with cellulitis, although the subcutaneous tissue
underlying the necrotic skin lesion of the ankle showed many focal areas of
necrosis and acute inflammation (Fig.
4). Taken in isolation, the histologic findings of the ankle
lesion are consistent with necrotizing fasciitis. However, grossly, no grayish
necrotic fascia or pus was seen. The results of frozen-section analysis of the
specimens were available to us intraoperatively, and the decision was made to
resect only the necrotic skin lesions along with underlying tissues down to
and including the deep fascia and to delay the more aggressive fasciotomy and
débridement of the surrounding tissues (as would be indicated for
necrotizing fasciitis) in hopes of limb salvage. Fortunately, the ankle
lesions did not recur, and the patient proceeded to recover without the need
for more extensive débridement.
In summary, this is a case of atraumatic compartment syndrome occurring in
the setting of streptococcal pyomyositis and toxic shock syndrome in a
previously healthy child. Compartment syndrome has been associated with both
pyomyositis and streptococcal toxic shock syndrome, both of which are being
reported more frequently in the literature. The positive rapid strep test from
the throat swab suggests—but does not prove—the mode of bacterial
entry in our patient. Subclinical microtrauma of the leg in the setting of
transient streptococcal bacteremia may have seeded the muscles, and subsequent
uncontrolled bacterial proliferation with exotoxin production may have
contributed to the development of toxic shock syndrome. Retrospectively,
several clues point to an infectious cause of illness: unexplained fevers at
home, hypotension on arrival, the presence of a rash, and a painful swollen
leg without a history of injury. The urgent need to treat the compartment
syndrome in this patient precluded magnetic resonance imaging of the leg with
gadolinium
enhancement48. Such
imaging studies might have aided us in finding the cause of the compartment
syndrome in our patient, but they also would have further delayed the
fasciotomy that proved to be both diagnostic and therapeutic. The onset of the
necrotic skin lesions of the ankle prompted us to re-explore the leg to remove
suspected additional necrotic tissue beneath the skin lesions. Appropriate
antibiotic selection and a low threshold for repeat débridement are
essential for the purpose of achieving limb salvage and eradication of
infection in a patient with compartment syndrome and toxic shock. ?