What are the typical clinical features, diagnostic findings, and treatment for toxoplasmosis encephalitis?
Toxoplasmosis encephalitis typically develops in patients with CD4 <200/μL and presents with focal neurologic signs that vary with the location of the protozoal abscess.
However, it may also present with meningismus with fever, headache, and nuchal rigidity.
What are the diagnostic findings of Toxoplasmosis Encephalitis?
Workup usually begins with neuroimaging, with MRI with contrast being more sensitive than CT for detection of multiple lesions.
Characteristic imaging findings are multiple ring-enhancing lesions with mass effect, similar to a variety of other CNS infections and tumors.
Diagnosis can be confirmed with serum antitoxoplasma IgG antibodies as well as PCR of the CSF.
Ancillary imaging such as thallium SPECT (single-photon emission computed tomography), perfusion MRI, or MR spectroscopy may help distinguish toxoplasma encephalitis from PCNSL.
How is Toxoplasmosis Encephalitis treated?
Antimicrobial therapy typically involves induction with sulfadiazine 1500 mg four times daily and pyrimethamine 200 mg load followed by 75 mg daily for 6 weeks.
Patients are then transitioned to maintenance therapy with one-half the dose of sulfadiazine and pyrimethamine until the patient has maintained CD4 >200/μL for at least 6 months.
Leucovorin is coadministered to avoid pyrimethamine-induced hematologic toxicity.
In the proper clinical context with consistent neuroimaging findings, patients should receive empiric treatment for 2 weeks with the antitoxoplasma regimen followed by repeat MRI brain with contrast to look for reduction in lesion size.
If there is no treatment response after 2 weeks, the differential diagnosis should be reconsidered and a brain biopsy considered for definitive diagnosis.