Neurol Med Chir (Tokyo) 50, 482¿484, 2010

Infantile Chronic Subdural Hematoma
Infected by Escherichia Coli
—Case Report—
Yasushi IIMURA, Satoshi TSUTSUMI, Yumiko MITOME, Yasuomi NONAKA,
Yusuke ABE, Yukimasa YASUMOTO, and Masanori ITO
Department of Neurological Surgery, Juntendo University Urayasu Hospital, Urayasu, Chiba

Abstract
A 6-month-old boy presented with a rare case of infected subdural hemorrhage manifesting as sustained
fever and focal seizure. The boy had been well without contributory medical history. Physical examination found no neurological impairment with intact superficial appearance and soft fontanels. The parents denied recent head trauma or shaking injury. Blood examination was normal except for white
blood cell count of 19200/ml and C-reactive protein level of 6.7 mg/dl. Bacterial culture of nasal swab,
urine, stool, and venous blood samples was negative. Cerebrospinal fluid examination showed normal
findings. Cranial computed tomography revealed an expansive subdural fluid collection in the right
frontotemporal region. Magnetic resonance imaging showed the lesion as hypointense on T1- and
hyperintense on T2-weighted images with intense enhancement of the outer membrane. The patient underwent burr-hole drainage, which identified the subdural hematoma encapsulated in a thick outer
membrane and intermingled with pus material. Culture of the pus identified Escherichia coli. The
patient received antibiotic therapy for 8 weeks that resulted in complete resolution of the infection. We
assumed that preexisting subdural hematoma formed after minor head trauma was followed by
hematogenous infection by E. coli. Infected subdural hematoma is possible in infants presenting with
subdural hemorrhage with clinical symptoms of bacteremia.
Key words:

infected subdural hematoma,

Escherichia coli infection,

Introduction

Case Report
A 6-month-old male infant presented with persistent highgrade fever and focal seizure localized in the left upper exSeptember 3, 2009;

Accepted

infant

tremity. The boy was born at full term with normal delivery but had not reached the appropriate developmental
milestones despite the absence of contributory medical
conditions such as otitis media, hemophilia, or congenital
heart disease. The patient was not irritable and showed
good feeding. Physical examination found no neurological
deficit or superficial abnormalities. The abdomen was soft
and he did not suffer persistent diarrhea. His head circumference was 48.8 cm, with soft fontanels, compatible with
his age, and his body weight and height were normal. The
parents denied recent head trauma or non-accidental
shaking injury.
Chest
radiography
showed
no
abnormalities.
Echocardiography revealed intact ventricular functions
without abnormal right-to-left shunting. Blood examination was normal except for white blood cell (WBC) count
of 19200/ml and C-reactive protein (CRP) level of 6.7 mg/dl.
Bacterial culture of nasal swab, urine, stool, and venous
blood samples was negative. Cerebrospinal fluid (CSF) examination by lumbar spinal tap revealed cell count of 1/ml,
and normal CSF glucose and protein levels. Cranial computed tomography revealed a low density subdural fluid
collection in the right frontotemporal region with slight
displacement of the midline structures (Fig. 1). Magnetic
resonance (MR) imaging showed the lesion as hypointense

Infected subdural hematoma is rare in the pediatric population. The mechanism is thought to involve
hematogenous infection of preexisting subdural hematoma, forming a localized infectious focus, not associated
with meningitis. Only a few case series have been reported.5,6,9,10) The causative organisms included Streptococcus
species, Haemophilus influenzae, Escherichia coli,
Salmonella species, and Staphylococcus aureus, indicating
common pathogens with subdural empyema.4) The appropriate management for this peculiar entity has not
been determined, although previous cases had satisfactory
outcomes, in contrast with the meningitis and poor outcome very frequently associated with subdural empyema.
Here we present a case of subdural hematoma associated with E. coli infection that was successfully treated by
burr-hole surgery and intensive antibiotic administration.

Received

treatment,

November 4, 2009

482

Infantile Chronic Subdural Hematoma

483

Fig. 1 Computed tomography scan showing a low density subdural fluid collection in the right frontotemporal region with
slight displacement of the midline structure.
Fig. 3 Intraoperative photograph showing aspirated pinkishred subdural hematoma intermingled with yellowish pus
material.

Fig. 4 Axial T1-weighted magnetic resonance images before
(A) and after (B) administration of contrast medium performed
8 weeks after completion of antibiotic therapy demonstrating
complete resolution of the subdural fluid collection.

Fig. 2 Axial magnetic resonance (MR) images showing the
subdural accumulation as hypointense on T1- (A) and hyperintense on T2-weighted (B) images with intense enhancement of
the outer membrane (arrows) (C).

on T1- and hyperintense on T2-weighted images with intense enhancement of the outer membrane (Fig. 2). The
preoperative diagnoses were isolated subdural empyema
not associated with meningitis and chronic subdural
hematoma concurrent with bacteremia.
Burr-hole surgery revealed the thick and expansive
pinkish-red outer membrane of the hematoma, intermingled with yellowish pus material (Fig. 3). Following aspiration of the capsulated fluid, the hematoma cavity was carefully irrigated with a copious amount of physiological saline solution. Then a silastic tube was placed in the hema-

Neurol Med Chir (Tokyo) 50, June, 2010

toma cavity, and withdrawn on postoperative day 3. Culture of the purulent specimen identified E. coli as the
causative organism. Postoperatively the patient was treated with antibiotic therapy with intravenous administration of third-generation cephalosporin (ceftriaxone sodium hydrate, 125 mg/day in 2 divided doses) for 8 weeks,
resulting in resolution of the fever and seizure, and normalization of the blood WBC count and CRP level. MR imaging performed following completion of antibiotic therapy revealed complete resolution of the subdural fluid accumulation (Fig. 4). The patient was discharged without
neurological sequelae and has been doing well as an outpatient without remission or recurrence of infection.

Discussion
E. coli is the most common cause of bloodstream infection,
but the epidemiology has not well been defined in the nonselected population. A cohort study showed that infants
and the elderly were at highest risk for E. coli infection.7)

484

Y. Iimura et al.

Hematogenous transmissions of E. coli usually occur as a
complication of focal infections of the urinary or gastrointestinal tracts, but occasionally also occur as primary bacteremia without a definite source. The predisposing factors were not identified in 70% of patients, which reflects
the limited understanding of E. coli infection.3) In the
present case, the predisposing factors were not identified.
We assumed that asymptomatic urinary tract infection or
gastroenteritis was the probable origin of the E. coli infection, although no extracranial focal infection was identified.
Subdural empyema is estimated to account for 10–20%
of all childhood intracranial bacterial infections. Subdural
empyema usually develops as a complication of bacterial
meningitis resulting in significant morbidity and mortality, despite recent advances in neuroimaging, surgical techniques, and antibiotic therapy.1,2,11) A large series found
that 30 of 80 patients with infantile meningitis had concomitant subdural empyema.3) The prevalent pathogens of
infantile meningitis are Streptococcus species, Haemophilus influenzae, E. coli, and Salmonella species.3,13) In past
large series, E. coli was responsible for 9.7% to 27% of
cases.3,8,13)
Subdural hemorrhage in an infant has been considered
to result from rupture of the cortical bridging veins, but recent investigation suggested a dural origin, as the intradural vessels, thin-walled and adapted for fluid resorption, may be the most likely to leak, resulting in bleeding
into the dura and simultaneously forming a subdural
hematoma either spontaneously or after an otherwise innocuous event.12) Our patient had no apparent history of
traumatic episodes. Therefore, we assumed that the preexisting subdural hematoma had formed after unrecognized
minor head trauma, and hematogenous infection by E. coli
had occurred via the outer membrane resulting in empyema. The significantly thickened outer membrane of the
hematoma found intraoperatively may support this
mechanism.
The appropriate surgical option, and correct dose and
period of antibiotic administration to treat infected subdural hematoma have not been determined because of its
rarity. The reported infant cases were successfully
managed by burr-hole drainage and empirical administration of antibiotic agents.5,6,9,10) All patients had only localized subdural infection with minimal signs of meningitis,
in contrast to subdural empyema commonly associated
with meningitis, which may be the reason for the more
satisfactory outcome of patients with infected subdural
hematoma. A thick membrane formed in the chronic subdural hematoma may act as a barrier to the dissemination
of localized infection within the capsulated hematoma
resulting in meningitis. In the present case, we selected
burr-hole drainage as a less invasive surgery because the
patient did not have any neurological deficits caused by
the lesion except for persistent focal seizure in the contralateral upper extremity. Burr-hole drainage and ade-

quate subdural irrigation followed by intensive antibiotic
therapy successfully resolved the infection without remission or recurrence. Experience with more cases is needed
to better understand and standardize the treatment
strategy for infantile infected subdural hematoma.
Pediatric subdural empyema can be successfully treated
with early surgical intervention, eradication of the infectious agent, and administration of appropriate antibiotic
agents. We should be aware of the possibility of infected
subdural hematoma in infants who present with subdural
hemorrhage with clinical symptoms of bacteremia.

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Address reprint requests to: Satoshi Tsutsumi, M.D., Ph.D.,
Department of Neurological Surgery, Juntendo University
Urayasu Hospital, 2–1–1 Tomioka, Urayasu, Chiba
279–0021, Japan.
e-mail: shotaro＠juntendo-urayasu.jp

Neurol Med Chir (Tokyo) 50, June, 2010