High-intensity signals in the basal ganglia from gadolinium-enhanced T1-weighted MRI as an early change in toxoplasma encephalitis in an AIDS patient

Abstract

A 30-year-old Brazilian man hospitalized with AIDS developed a high-grade fever. Neither culture studies nor radiological examinations revealed the cause; small yet highly intense signals in the basal ganglia were detected upon gadolinium (Gd)-enhanced T1-weighted magnetic resonance imaging (MRI) of the head. This finding was equivocal at that time but obviously abnormal for his age. A week later, he developed a movement disorder in his right arm, speech apraxia, and a worsening disturbance of consciousness. Repeated Gd-enhanced T1-weighted MRI demonstrated incredible changes in the brain; enhanced lesions in the basal ganglia deteriorated over time, multiple nodular and ring-enhanced lesions were observed in almost the entire brain. A diagnosis of toxoplasma encephalitis (TE) was confirmed by the detection of Toxoplasma gondii DNA in the cerebrospinal fluid. After initiation of intravenous trimethoprim-sulfamethoxazole (TMP-SMX; 10 mg/kg/day of TMP and 50 mg/kg/day of SMX) treatment, his symptoms and radiological findings improved dramatically. Our case suggests that high-intensity signals seen in the basal ganglia of a Gd-enhanced T1-weighted MRI, even at the preclinical stage, is indicative of TE. Because the use of MRI in general has become more widespread, it is predicted that preclinical lesions of TE will be found in various clinical settings more frequently.