Keywords
E. coli
- encephalitis - paranasal sinuses - purulent - subdural empyema
Introduction
The first subdural empyema operation dates back to 1869 when De La Peyronie operated
upon a patient[1] and the terminology of subdural empyema was coined by Kubil and Adams.[2] It constitutes around 13 to 23% of all intracranial infections.[3] The commonest source is the infection from the paranasal sinuses.[4]
[5] The clinical presentation is dramatic and the majority of the cases present with
altered sensorium, features of raised intracranial pressure, headaches, and vomiting.[6]
[7] Subdural empyema developing after surgery trauma or secondarily infected subdural
hemorrhage has a more indolent course. But spontaneous subdural empyema is a very
rare entity.[8]
[9] Aerobic, anaerobic, and microaerophilic organisms are responsible for subdural empyema
in case of spread from paranasal sinuses.[6] The most common organism isolated in post-traumatic cases is Staphylococcus aureus.[7]
Here we present a case of spontaneous subdural empyema presenting with altered sensorium
and being referred to us with a diagnosis of encephalitis.
A 49-year-old female treated elsewhere was referred to our hospital with a diagnosis
of encephalitis with urinary tract infection for further management. She is a known
case of type 2 diabetes mellitus and hypertension for the past 8 years and is on regular
medications. Initially, the patient presented with fever, altered sensorium, and dysuria
for the past 7 days. Following this she received injectable antibiotics at a local
hospital the details of which the patient party could not furnish. Hemogram showed
a total count of 8,170/mm3, 89 neutrophils, and elevated C-reactive protein (116 mg/L). A routine examination
of urine showed the presence of pus cell 2 to 4/high-power field with 3+ glucose and
a urine Culture Sensitivity showed growth of Escherichia coli (E. coli). A previously done unenhanced computed tomography (CT) brain showed a hypodense
left frontotemporoparietal subdural collection. As the patient was referred to us
with a diagnosis of suspected encephalitis, magnetic resonance imaging (MRI) was done.
It showed left frontotemporoparietal subdural empyema with mass effect. The patient
underwent emergency craniotomy and evacuation of the subdural empyema. During the
operation, after the dura was incised, abundant purulent material was drained out.
Pus was sent for culture sensitivity and gene Xpert Plus. Thorough toileting of the
subdural cavity was done and the wound was closed after placement of a subdural drain.
Empirical therapy was started with an injection of meropenem+ sulbactam (1.5 g/8 hour),
metronidazole (100 mL/8 hour), and vancomycin (2 g/8 hour). The patient had multiple
episodes of seizure postoperatively that were managed accordingly. As the sugar was
very high, Actrapid infusion was started as per the endocrinology opinion. The pus
culture report came out to be sterile and the gene Xpert showed no detection of tubercular
bacilli. Urine culture and blood culture sent from the emergency ward also showed
no growth. CT brain after 3 days showed resolution of collection. The patient improved
until complete recovery.
Review of Literature
In an article by Bakker et al, they described a case of an 88-year-old lady having
urinary tract infection with E. coli colony count of more than 105 Colony Count Unit developing subdural empyema. Hematogenous infection of a pre-existing
subdural hematoma, however, is a rare cause of subdural empyema. They concluded that
chronic subdural hematoma, a secondary infection due to hematogenous spread, should
be considered in the differential diagnosis, especially for patients who have recently
had an infection.[8]
Another study by Miedema and Kimpen described a 7-year-old child developing subdural
empyema where E. coli was identified in blood culture and cerebrospinal fluid but her urine was sterile.
They said that a pre-existent subdural hematoma in a child can become infected via
hematogenous seeding of organisms. But most reported cases of infected subdural hematomas
in children are caused by direct extension of the infection from the sinuses or meninges
or occur after surgery.[9]
Another interesting case was reported by Lucas et al where a 68-year-old man presented
with subdural empyema and received surgery for evacuation was found to have a ruptured
mycotic aneurysm (MA) intraoperatively. MAs are rare intracranial pathologies. They
are associated with spontaneous rupture, which is often the first presenting sign.
Subarachnoid hemorrhage and intraparenchymal hemorrhage are the most common sequelae
of ruptured MAs, with subdural hematoma being an atypical presentation. The presentation
of an MA as a subdural empyema has not yet been reported in the literature.[10]
Kaminogo et al in a 76-year-old female patient in a semicomatose state and with left-side
hemiparesis found subdural empyema at operation. Both cultures of subdural fluid and
urine yielded E. coli. Her neurological deficits cleared after the operation and subsequent antibiotic
therapy. They speculated that infection of the urinary tract produced an E. coli bacteremia and subsequently infected subdural hematoma occurred by this microorganism.[11]
In another case report of subdural abscess following chronic subdural hematoma, an
86-year-old male was admitted with drowsiness and left hemiparesis and had spikes
of fever that originated during chronic cholecystitis and cholelithiasis and which
had continued for 2 years prior to admission. Emergency removal of the right hematoma
was carried. Intraoperatively they found that the old hematoma was accompanied by
a yellow-white abscess in the subdural space. Culture revealed growth of E. coli. It was considered that the formation of the subdural abscess might have developed
through the deterioration of the immunological function under the influence of senility.[12]
Nishi et al reported a case of intracranial subdural empyema from renal cyst infection
of a 76-year-old woman was admitted for sudden onset of fever and altered mental status.
The patient had trace amounts of E. coli that were isolated in urine culture. As CT scan revealed an enlargement of the intracranial
fluid collection with mass effect, she underwent urgent surgery, and a brownish-yellow
fluid was drained from the subdural space. The fluid on the culture showed colonies
of gram-negative rods phagocytosed by large amounts of leucocytes, and E. coli were isolated from the drained pus culture. They concluded by saying that the need
for adequate control of urinary tract infections in Autosomal Dominant polycystic
kidney disease patients is very essential to avoid fatal metastatic infection.[13]
Surgical evacuation and adjusting the intravenous antibiotics for a period of 4 to
6 weeks is the treatment opted for by the majority.[14]
[15] But the debate still continues on the most appropriate surgical approach. Some authors
argue that the burr holes are sufficient for evacuation; others suggest craniotomy
is more effective.[16] In cases with multiloculated collections, parafalcine location, and recurrences,
it is better to carry out a wide craniotomy.[14] Whichever technique is used, thorough toileting of the subdural space is to be done
until the fluid is clear and it is wise to keep a subdural drain for a period of 48
to 72 hours.[14]
In our case, the drain was removed after 48 hours, and we converted injectable antibiotics
to oral antibiotics on the 14th day postoperatively and the patient was discharged
with advice for follow-up.
In conclusion, spontaneous subdural empyema should be suspected in patients presenting
with fever, altered sensorium, and hypodense subdural collections in the head CT,
and the use of MRI in such patients increases its sensitivity. In these group of patients,
immediate craniotomy and evacuation of subdural empyema followed by injectable antibiotics,
antiepileptics, and close monitoring help us in achieving a favorable outcome.
