Thalamic abscess caused by a rare pathogen: streptococcus constellatus

Streptococcus constellatus is a microorganism that lives commensally in the oropharyngeal region, urogenital region, and intestinal tract. However, it can cause infection in patients with certain predisposing factors. Rarely, this microorganism can cause a brain abscess. Thalamic localization of brain abscesses is much rarer than abscesses in other locations of the brain. Brain abscess caused by streptococcus constellatus are very rarely been reported in the literature. We present a rare case of a left-sided thalamic abscess caused by streptococcus constellatus in a 25-year-old male patient who was injured by shrapnel pieces in the head and who was malnourished. The patient was successfully treated by stereotactic aspiration and antibiotherapy.


Introduction
Streptococcus constellatus is a member of the Streptococcus family and is part of the normal flora of the oral cavity, urogenital region, and intestinal tract. It can cause purulent infections in patients with cirrhosis, diabetes, malignancy, malnourishment, or conditions that cause immunosuppression [1]. Brain abscesses caused by streptococcus constellatus are reported very rarely in the literature [2,3]. Thalamic abscesses are much rarer than abscesses in other locations of the brain [4,5]. In the literature, there is no single thalamic abscess caused by streptococcus constellatus. We present a rare case of a left-sided thalamic abscess that was caused by streptococcus constellatus in a 25-year-old malnourished male patient who was wounded in the head by shrapnel. The patient was successfully treated with stereotactic aspiration and antibiotherapy.

Patient and observation
A 25-year-old male was brought to the hospital with a chief complaint of headache associated with vomiting, mild fever, and right-sided paresis. He had been found near a small river, lying on the ground in very bad condition. His history revealed that he had been wounded in the head by pieces of shrapnel during a civil war

Discussion
Thalamic localization of brain abscesses is uncommon [6]. In most cases, underlying sources of infection are found, such as congenital heart disease, intrathoracic and abdominal infection-based sepsis, dental caries, otitis media, or sinusitis [6]. However, in some cases no source of sepsis or any predisposing factors are found. The most common organisms in the reported thalamic abscesses are Streptococci and anaerobes. However, the incidence of culturenegative cases accounts for 28 percent of reported thalamic abscesses [6]. streptococcus constellatus is a member of the normal flora of the mouth, gastrointestinal tract, and genitourinary tract and is often associated with purulent infections. Brain abscess caused by streptococcus constellatus is very rare [2,3,6,7]. In all reported cases of streptococcus constellatus abscess, there was either underlying pathology or a history of immunosuppression [2,3,6,7].
Our case is the first reported case in the literature of a single thalamic abscess caused by streptococcus constellatus. In our case, there is a history of malnutrition and a shrapnel wound in the same side of the head as the thalamic abscess. The history of malnutrition and malnutrition-related immunosuppression was the probable underlying condition related to this cerebral abscess; however, we are not sure about the relationship between the shrapnel wound and the thalamic abscess on the same side of the head because the shrapnel pieces were located subcutaneously over the frontal bone and did not enter either the bone or the brain parenchyma.
The best surgical management of thalamic abscesses remains controversial. One of the important goals of thalamic abscess surgery is to prevent intraventricular rupture of the abscess in the operation. Treatment options include stereotactic aspiration, freehand aspiration through a burr hole, stereo-endoscopic aspiration, ultrasound-guided aspiration, surgical transventricular approach, and medical management [5,7,8]. Stereotactic aspiration remains the preferred treatment as it drains the contents of the abscess, reduces mass effect, carries less risk of intraventricular rupture preoperatively, and confirms diagnosis. In our case, the abscess was drained by CT-guided stereotactic technique. After confirmation Page number not for citation purposes 3 of the exact cause, appropriate antibiotic therapy healed the patient with no radiological or neurological sequelae.

Conclusion
Thalamic abscesses are much rarer than abscesses in other locations of the brain. In the literature, there is no single thalamic abscess caused by Streptococcus constellatus. It may be taken into consideration and is critical that pyhsicians include this condition in differential diagnosis.