Keywords
subdural empyema - chronic subdural hematoma -
Enterobacter cloacae
Introduction
Infections of the central nervous system include meningitis, ventriculitis, empyema,
and abscesses that can manifest with fever, vomiting, clinical deterioration, hydrocephalus,
brain edema, and seizures requiring medical and surgical treatment to avoid complications.[1]
The diagnosis and treatment of a subdural empyema are sometimes difficult due to the
similar radiological characteristics to chronic subdural hematomas, and the treatment
includes the evacuation of the collection associated with intravenous antibiotics.[2]
Herein, we present the case of a patient with risk factors who developed a subdural
empyema that was treated by surgical and medical means.
Case Description
A 38-year-old male patient with a past medical history of drug consumption and a traumatic
brain injury 1 week prior to admission was referred to the emergency department with
decreased level of consciousness, seizures, and fever. At admission, the vital signs
were: temperature: 38.9°C, a heart rate of 96 beats/min, and blood pressure of 103/66 mm Hg. Neurological examination revealed Glassgow coma scale (GCS) (O2V3M5 =
10), left-sided hemiparesis, and anisocoria. Neuroimaging studies revealed a subdural
collection compatible with a subacute subdural hematoma in the right hemisphere and
associated midline shift and a skull fracture ([Fig. 1]). The decision to evacuate the collection was made. A right-sided craniotomy was
performed, the dura was opened, and a thick membrane was found, which was resected,
and a purulent subdural collection was evacuated; these findings were compatible with
a subdural empyema. A subdural drainage with continuous irrigation was placed and
empiric intravenous antibiotics were initiated. In the immediate postoperative course,
symptoms improved and the computed tomography (CT) scan showed a partial evacuation
of the empyema with a residual collection and midline shift ([Fig. 2]). The subdural drain was removed. Two days after the procedure, the patient presented
fever and lethargy. Analytics showed a white blood cell count of 14500 × 103/mm, accelerate erythrocyte sedimentation rate (65 mm/h), elevated C-reactive protein
(182 mg/L), and an increase in segmented neutrophils (81%). A new CT scan revealed
a right subdural collection with midline shift ([Fig. 3]). The patient underwent an emergent right decompressive craniectomy and a yellowish
purulent material with residual capsule and thick pus attached to the pia mater membrane
were found. The empyema cavity was irrigated with sterile saline solution until the
returning fluid was clear ([Fig. 4]). The brain was noted to be swollen after pus evacuation. Postoperatively, the patient
was transferred to the intensive care unit with slowly favorable recovery with empiric
intravenous antibiotic therapy. A bacterial culture of the purulent specimen identified
Enterobacter cloacae and a specific antibiotic regimen was initiated.
Fig. 1 Brain computed tomography scan showing a subdural collection with hypodense and hyperdense
lesions with midline shift and skull fracture.
Fig. 2 Postoperative computed tomography scan showing evacuation of empyema with the presence
of a subdural drainage and midline shift.
Fig. 3 Computed tomography scan with right subdural collection and midline shift despite
the craniotomy and drainage.
Fig. 4 Intraoperative images of the empyema capsule and purulent content. A yellowish purulent
material with residual capsule and thick pus attached to the pia mater membrane.
Discussion
Subdural empyema is a surgical emergency associated with high mortality and constitutes
15 to 25% of pyogenic intracranial infections, more commonly in men.[3]
[4] This entity can be difficult to diagnose because of its nonspecific presentation.[5]
[6] Overall, this patient could present alterations of consciousness, seizures, meningeal
irritation, and nonspecific symptoms such as fever, headache, and purulent rhinorrhea.[7]
[8]
The treatment of a subdural empyema consists of three points: surgical evacuation
of pus, eradication of the primary foci of infection, and adequate antibiotic therapy.
Craniectomy plus evacuation of the empyema and fibrinoid material were performed in
this patient (it ensures maximal drainage of the loculated pus and allows the total
removal of the infected hematoma capsule). Our patient developed a lesion with considerable
mass effect with a well-defined capsule confirmed by the craniectomy.[3]
[9]
The culture of this patient was positive for Enterobacter cloacae which are facultative anaerobic gram-negative strains belonging to the family of
Enterobacteriaceae and are widely found in nature.[10]
[11] These microorganisms are saprophytic in the environment, as they are found in soil
and sewage, and are also part of the commensal enteric flora of the human gastrointestinal
tract.[10]
[11]
Enterobacter cloacae is an important nosocomial pathogen responsible for bacteremia and lower respiratory
tract, urinary tract and intra-abdominal infections, as well as endocarditis, septic
arthritis, osteomyelitis, and skin and soft tissue infections. The skin and the gastrointestinal
tract are the most common sites through which Enterobacter cloacae can be contracted.[12]
[13]
Our patient had a history of drug addiction; this point was a contributing factor
for the disease. The pathology in this patient could be the result of secondary infection
of a chronic subdural hematoma or hygroma following a traumatic brain injury.[9] The presence of a skull fracture as a mark of head injury in this particular case
was a major predisposing factor for the development of a subdural collection.
Neurological symptoms such as mental status alteration and seizures, as well as fever
and anisocoria were unspecific symptoms of empyema.[2]
[14] On plain CT imaging, a subdural empyema resembles a subdural hematoma in its crescent
shape. In this case, the CT images mimicked a chronic subdural hematoma.[15]
[16]
[17] Despite the first surgery achieved the evacuation of the empyema, a worsening of
the tomographic findings and clinical status were appreciated 2 days after the procedure.
Many causes of subdural empyema have been reported: otitis media, mastoiditis, and
sinusitis were the most frequent primary foci.[1]
[18] Other causes are postcranial surgery and brain traumatic injury with an associated
skull fracture.
Subdural empyema is difficult to diagnose because of its unspecific presentation and
imaging; the neurosurgical management and antibiotic therapy are keys to decrease
the morbidity and mortality.
Conclusion
Subdural empyema is a rare but devastating condition that causes a high mortality
and disability. The diagnosis and treatment should be suspected to evacuate the lesion
and start intravenous antibiotic therapy, which will improve the long-term results
and mortality.
