A 28-year-old man comes to the office due to abnormal movements of his arm and face over the last week. The patient has had 1- to 2-minute episodes of jerking and twitching of the left arm and left side of the face. He has also had daily headaches for a few weeks that are often associated with nausea. The patient was recently diagnosed with HIV and started antiretroviral therapy 2 months ago. At that time, his CD4 count was 46/mm³. He has a history of intravenous heroin use but recently started a methadone program. Temperature is 37.8 C (100 F), blood pressure is 124/82 mm Hg, and pulse is 76/min. Cardiopulmonary examination is normal with no murmur. Left arm motor strength is 4/5, and deep tendon reflexes are 3+. An MRI of the brain reveals several ring-enhancing lesions at the gray-white matter junction and basal ganglia. Which of the following is the most appropriate treatment for this patient?

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Quizplus · Accepted Answer

11ec25c8_d470_9f33_bc81_393f4d9e1673_MD0003_00 Toxoplasmosis is caused by the reactivation of Toxoplasma gondii, an intracellular protozoan that lies dormant in infected individuals and rarely reemerges unless there are significant deficits in cell-mediated immunity. Patients with advanced AIDS who have CD4 counts <100/mm³ are at greatest risk (as high as 30%). Although toxoplasmosis may affect multiple organ systems (eg, pulmonary, ocular), encephalitis is by far the most common manifestation. Patients with toxoplasmic encephalitis usually develop headaches, focal neurologic deficits, altered mental status, and fever. Laboratory studies may be normal, but MRI of the brain usually reveals multiple ring-enhancing lesions (with a preference for the basal ganglia). There is no reliable test for toxoplasmic encephalitis. The diagnosis is generally made by the presence of suspicious clinical symptoms, positive T gondii IgG serology, and characteristic CNS findings on MRI. Treatment with several weeks of sulfadiazine and pyrimethamine plus leucovorin (to prevent hematologic side effects) is required. Antiretroviral therapy should be initiated within 2 weeks of toxoplasmosis treatment (once patients are clearly tolerating toxoplasma therapy) for those not already on antiretroviral treatment. (Choice A) Albendazole is used to treat neurocysticercosis, which is associated with consumption of Taenia solium (pork tapeworm) eggs in endemic areas (eg, Central and South America). Neurocysticercosis tends to cause seizures, and an MRI of the brain usually reveals a mixture of enhancing, nonenhancing, and calcified lesions (depending on the stage of the cyst). In this patient with advanced HIV, no history of travel, and multiple ring-enhancing lesions (including on the basal ganglia), toxoplasmosis is more likely. (Choice B) Amphotericin B and flucytosine are used to treat cryptococcal meningitis. Cryptococcal infections tend to present with fever, malaise, and headaches; ring-enhancing lesions on MRI would be atypical. (Choice C) Clarithromycin and ethambutol are used to treat Mycobacterium avium complex (MAC). MAC tends to cause gastrointestinal and pulmonary infections, not CNS infection. (Choice D) Ganciclovir is used to treat cytomegalovirus (CMV). CMV encephalitis is marked by confusion and focal neurologic deficits with evidence of multifocal micronodules or ventricular enhancement on MRI; ring-enhancing lesions are very uncommon. (Choice E) A brain biopsy should be considered only in patients not responding to initial treatment because it is invasive and associated with a high risk for complications. Toxoplasmosis is treated presumptively in patients with characteristic clinical, serologic, and MRI findings. (Choice G) Vancomycin and ceftriaxone are used empirically for bacterial meningitis. Bacterial meningitis typically presents acutely (<1 day) with fever, severe headache, and altered mental status. Nuchal rigidity may also be present. Enhancing lesions are uncommon. Educational objective: Toxoplasmosis causes headache, fever, focal neurologic deficits, and altered mental status in patients with advanced AIDS (CD4 count <100/mm³). An MRI of the brain reveals multiple ring-enhancing lesions. Treatment is with sulfadiazine and pyrimethamine.

A 28-Year-Old Man Comes to the Office Due to Abnormal