Master the board step 3

Master the Boards: USMLE Step 3
Consider HIV status in the context of a brain abscess as follows:
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HIV-negative: Brain biopsy is the next best step.
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HIV-positive: Treat for toxoplasmosis with pyrimethamine and sulfadiazine
for 2 weeks and repeat the head CT.
Progressive Multifocal Leukoencephalopathy (PML)
These brain lesions in HIV-positive patients are not associated with ring
enhancement or mass effect.
There is no specific therapy. Treat the HIV and raise the CD4. When the HIV
is improved, the lesions will disappear.
Neurocysticercosis
Look for a patient from Mexico with a seizure.
Head CT shows multiple 1 cm cystic lesions. Over time, the lesions calcify.
Confirm diagnosis with serology.
When still active and uncalcified, the lesions are treated with albendazole. Use
steroids to prevent a reaction to dying parasites.
Do not use albendazole to treat if there is only calcification. Use only antiepileptic
drugs.
Head Trauma and Intracranial Hemorrhage
Do not use skull x-rays in
head trauma. If the head
trauma is severe, then
diagnosis requires a CT
scan. LOC = CT scan.
Diagnostic Testing
Any head trauma resulting in a loss of consciousness (LOC) or altered mental
status should lead to a CT scan of the head without contrast.
The following table shows possible outcomes of head trauma that can result in
a loss of consciousness and how they vary from one another.
Concussion
Contusion
Subdural
Hematoma
Epidural
Hematoma
Focal deficits Never Rarely Yes or no Yes or no
Head CT Normal Ecchymosis Crescent-shaped
collection
Lens-shaped
collection
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