Cerebral toxoplasmosis complicating the acquired immune deficiency syndrome: clinical and neuropathological findings in 27 patients.

We reviewed the clinical, neuroradiological, and serological findings in 27 patients with cerebral toxoplasmosis complicating the acquired immune deficiency syndrome, 19 of whom were also analyzed neuropathologically. The clinical manifestations of this disorder varied, ranging from headache and fever to coma. However, the characteristic presentation included focal neurological symptoms and signs, usually of subacute onset. In addition, two-thirds of the patients exhibited more generalized cerebral dysfunction with confusion and lethargy. The computed tomographic (CT) scan most commonly revealed ring contrast enhancement, which appeared to correlate best with the histological presence of vascular proliferation and inflammation surrounding the abscesses. However, in 5 patients the CT scan revealed either homogeneous enhancement or no enhancement, and in 3 patients the scans were negative. In general, CT scans underrepresented the number of lesions eventually documented pathologically. Double-dose contrast administration and preliminary experience with magnetic resonance imaging suggested that these techniques were superior to standard CT scanning in detecting Toxoplasma lesions. All patients were seropositive for IgG antibody against Toxoplasma gondii in blood, both before the onset of illness and at the time of presentation, although titers in some patients were as low as 1:8 and most patients did not exhibit rising titers. Prompt therapy resulted in rapid clinical improvement, documented by CT scan, associated with the development of an organizing tissue response in the host and elimination of free organisms. Response to treatment was sufficiently rapid in most patients to allow a trial of therapy as the favored approach to diagnosis.