Presentation
Headache, fever, and confusion.
Patient Data
There are subtle ring-like lesions appreciated in the right frontal lobe, the caudate nucleus bilaterally, and the left parietal lobe. There is a linear hyperdensity in the right parietal lobe, which was appreciated on previous imaging several years prior. This is of undetermined significance; nevertheless, it is potentially vascular in origin.
Mastoid air cells are clear. No mass lesion or mass effect is appreciated. Ventricles and surface CSF spaces are outlined normally.
MRI is recommended for further characterization of the ring-like lesions and linear hyperdensity.
Multiple rim-enhancing lesions with centrally restricted diffusion and surrounding vasogenic edema are interspersed throughout the cortices and cerebellum. Additionally, a single rim-enhancing lesion in the cervical cord was noted.
The left frontal periventricular abscess has subsequent rupture into the left lateral ventricle. Diffusion-restricting material in the occipital horns and bilateral periventricular enhancement are indicative of ventriculitis.
No hydrocephalus. No sinusitis or mastoiditis. No uncal or tonsillar herniation.
Radiological findings demonstrate cerebral abscesses, with recommendations for urgent neurosurgical review.
Case Discussion
This case demonstrates a severe case of cerebral abscesses. The microbiology of cerebral abscesses varies depending on whether the patient is immunosuppressed. Most isolates include Streptococcus species; however, most cases are polymicrobial on cultures. In the immunosuppressed population, such as the HIV-positive patient, organisms typically include toxoplasma, mycobacteria, or fungal.
Specific to this patient, the operative report noted purulent material aspirated and sent for gram stain. Initial cytology of gram-positive cocci and repeat cultures of Strep. intermedius group was obtained. Biopsies and cultures were negative for fungi and toxoplasma. Additionally, the patient was HIV-negative and not immunosuppressed. While an underlying cause of the cerebral abscess was never found, the leading hypothesis was poor dentition, with alcoholism as the likely key contributing factor. The patient survived with prolonged antibiotic treatment.
Ring-enhancing lesions have variable etiology, including but not limited to abscesses, meningioma, leukemia, and metastasis. Cerebral abscesses can have subtle findings on initial CT imaging. Therefore, pre- and post-contrast scans should be obtained in patients with suspected abscesses. MRI is the mainstay of investigation for suspected abscesses, with better sensitivity when compared to CT 1. MRI classical findings include central lower intensity and ring intensity on T1, with T2/FLAIR demonstrating a central high intensity.
Case acknowledgement and courtesy of Dr. Mila Dimitrijevic.
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