Late-onset sepsis and encephalopathy after bicycle-spoke injury: a case report
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Bicycle-spoke injuries rarely cause late complications of infection, including sepsis and sepsis-associated encephalopathy, with appropriate treatments.
We experienced a 2-year-old girl who developed the signs of encephalopathy with fever 6 months after a spoke-injury. On admission, the injured skin was inflamed with cellulitis. The blood culture was positive for methicillin-sensitive Staphylococcus aureus. Electroencephalogram showed diffuse slow-wave activity. Diffusion-weighted magnetic resonance imaging detected a high-intensity lesion with decreased diffusivity at the right frontal cortex. She received immunoglobulin and combined antibiotics treatments in the intensive care unit, and successfully overcame the sepsis-associated encephalopathy without neurological impairments.
This is the first report demonstrating that sepsis and its associated encephalopathy occurs in a remote period after the bicycle-spoke injury.
KeywordsSepsis-associated encephalopathy Ankle injury Cellulitis Pathogens And Staphylococcus aureus
Bicycle spoke injury
Diffusion weighted image
Glasgow coma scale
Methicillin-susceptive Staphylococcus aureus
Sepsis associated encephalopathy
Bicycle-spoke injuries (BSI) are caused when the passenger’s foot is caught by the spokes in the rotating wheel of bicycle . The outcome of spoke injuries is generally well with the appropriate treatment, and serious complication rarely occurs in the remote period . However, the internal degloving injury on the skin and soft tissue predisposes patients with BSI to the development of sepsis and other systemic infections.
Sepsis-associated encephalopathy (SAE) is a diffuse cerebral dysfunction that occurs secondary to sepsis in the absence of direct central nervous system (CNS) infection. The diagnosis depends on the exclusion of primary CNS infection and other causes of encephalopathy, because of no specific markers available for SAE. The morbidity and mortality increase with the severity of SAE. Thus, early identification and prompt treatment of underlying infection are important [3, 4].
We herein report a case with cellulitis and SAE that developed 6 months after an accident with bicycle spoke-injury.
Discussion and conclusions
We experienced a case who developed a late-onset staphylococcal infection and encephalopathy after BSI. The soft-tissue injury occurs in all cases with BSI, however, the severity of BSI is often underestimated . The lower extremities are known as the most common site of cellulitis. Notably, the recurrence of cellulitis has been reported to occur in 22 to 49% of affected cases. Among them, 14% of the recurrence was observed in 1 year, while 45% in 3 years. The recurrence typically occurs at the same site as the originally inflamed region [8, 9]. This fact indicates that the recurrence of cellulitis and the following bacteremia may develop several months after the previous injury. Of course, we cannot exclude the possibility that a recent infection was associated with the bacteremia in this case. However, this report provides a better caution that surface injuries could lead to the systemic infection even after 6 months.
SAEs have been reported in children at 4 to 12 years of age. Clinical features of SAE are characterized by the onset with fever and variable levels of brain dysfunction. Altered consciousness could vary from confusion to coma, according to their general conditions . Electrophysiological studies have shown that periodic epileptiform discharges were commonly observed in patients with SAE . Although periodic activity was not clearly demonstrated in our case, synchronized delta activity was observed during the acute phase. Because her consciousness was recovered within 1 week, this intermediate finding might suggest that her brain was less severely damaged by septic condition than those presenting with a complete form of periodic discharges .
Neuroimaging features of SAE include ischemic lesions with hyperintense signals on T2-weighted images . Vasogenic edema is also a common finding in patients with SAE, and it has been also reported to indicate the aberrant function of blood-brain barrier. This mechanism explains well the fact that some patients with SAE presented with posterior reversible encephalopathy syndrome . By contrast, our patient showed the sign of localized cytotoxic edema in the frontal cortex. Because it disappeared without leaving the persistent ischemic lesion, we speculated that hemodynamics of the brain was not severely affected during the acute phase. Neuroimaging features differ among patients according to their ages, severity and the time of evaluation.
The pathophysiology of SAE has not been fully understood. A variety of mechanisms have been proposed, including microscopic brain injury, altered cerebral microcirculation or metabolism, aberrant neurotransmission, and inflammatory mediators . Previous studies suggested that biliary tract or intestinal infections were associated with greater risk of SAE [3, 4]. With regard to pathogens, the most commonly implicated organism is Staphylococcus aureus, as described in this and previous reports . In the present case, proinflammatory cytokines of IL-6 and IL-8 were elevated in CSF. We therefore considered neuroinflammatory signals to be involved in the pathogenic process of SAE.
In summary, this report provides the first evidence that the spoke injury-associated infection causes the recurrent cellulitis after months and raises the risk for the development of SAE in childhood. Cause-and-effect relationship among the pathogens, cytokines in the cerebrospinal fluid, acute-phase brain dysfunctions and long-term outcomes will be worth investigated for SAE patients in future studies.
We thank the patient’s parents for the publication consent.
This work was supported by JSPS Kakenhi grant number 17 K16270 (YM), 17 K12349 (NK), 17 K16271 (YI), 19 K08281 (YS), a Health and Labour Sciences Research Grant on Evidence-based Early Diagnosis and Treatment Strategies for Neuroimmunological Diseases from the Ministry of Health, Labour and Welfare of Japan, and Kawano Masanori Memorial Public Interest Incorporated Foundation for Promotion of Pediatrics (YS) for the analysis of the data.
Availability of data and materials
RT and YM1 wrote the manuscript. NK, YI, MM and SK collected and interpreted the clinical data. TT acquired and analyzed the laboratory data. YS, YM2 and SO revised the manuscript. All authors read and approved the final manuscript.
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Consent for publication
Written informed consent was obtained from the patient’s parents for publication of this case report.
The authors declare that they have no competing interests.
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