A 38-year-old man is brought to the emergency department due to confusion and double vision. His family reports that the patient did not feel well for the past several days due to headaches, nausea, and vomiting. Yesterday, he became progressively confused and experienced double vision. He has a history of HIV and does not take antiretroviral therapy consistently. Temperature is 38.2 C (100.7 F), blood pressure is 122/80 mm Hg, and pulse is 90/min. On physical examination, the patient appears lethargic and disoriented. Pupils are equal and reactive, but the left eye does not move laterally with leftward gaze. The rest of the neurologic examination is unremarkable. Skin examination shows scattered, small, umbilicated papules with surrounding erythema. CT scan of the head reveals mildly enlarged ventricles but no hemorrhage, infarction, or mass lesions. Which of the following is the best next step in evaluation of this patient?

Question

A 38-year-old man is brought to the emergency department due to confusion and double vision.  His family reports that the patient did not feel well for the past several days due to headaches, nausea, and vomiting.  Yesterday, he became progressively confused and experienced double vision.  He has a history of HIV and does not take antiretroviral therapy consistently.  Temperature is 38.2 C (100.7 F), blood pressure is 122/80 mm Hg, and pulse is 90/min.  On physical examination, the patient appears lethargic and disoriented.  Pupils are equal and reactive, but the left eye does not move laterally with leftward gaze.  The rest of the neurologic examination is unremarkable.  Skin examination shows scattered, small, umbilicated papules with surrounding erythema.  CT scan of the head reveals mildly enlarged ventricles but no hemorrhage, infarction, or mass lesions.  Which of the following is the best next step in evaluation of this patient?

Quizplus · Accepted Answer

This patient with untreated HIV (inconsistent antiretroviral use) has headaches, nausea/vomiting, confusion, abducens nerve palsy, and scattered, umbilicated skin papules, raising strong suspicion for infection with Cryptococcus neoformans, an encapsulated yeast. Most cases are seen in patients with AIDS who have CD4 counts <100/mm². ² C neoformans replicates in the central nervous system and clogs the arachnoid villi with yeast components and capsular polysaccharides, leading to CSF outflow obstruction and increased intracranial pressure (ICP). Therefore, patients often develop progressive headaches, nausea/vomiting, and confusion. In approximately 25% of cases, elevated ICP compresses the 6th cranial nerve (abducens nerve), leading to lateral gaze palsy and diplopia. Patients also frequently have fever, malaise, and umbilicated skin lesions that resemble molluscum contagiosum (due to hematogenous dissemination to the skin). Brain imaging is usually normal but may show signs of increased ICP such as enlarged ventricles. The diagnosis is generally made with lumbar puncture (LP), measurement of CSF pressure, analysis of CSF, and capsular polysaccharide antigen testing or India ink stain. Management is with antifungal therapy. In addition, although caution should be exercised when performing an LP in the setting of increased ICP, patients with cryptococcal meningitis often require frequent (eg, daily) LPs and sometimes ventricular drains to decrease ICP. India ink stain (Choices A and B) Toxoplasmic encephalitis is common in patients with untreated AIDS and usually causes progressive headaches, fever, confusion, focal neurologic deficits, and/or seizure. Trimethoprim-sulfamethoxazole is an effective alternate regimen (sulfadiazine and pyrimethamine is first-line). However, brain imaging typically reveals multiple ring-enhancing lesions (not enlarged ventricles). In addition, skin lesions are uncommon. (Choice C) Patients with advanced AIDS are at risk for progressive multifocal leukoencephalopathy, which can manifest with subacute confusion and diplopia. However, headaches, nausea, and vomiting would be atypical, and brain CT scan usually reveals white matter lesions (not ventricular enlargement). Diagnosis is generally made by gadolinium-enhanced MRI of the brain, which reveals multifocal white matter demyelination with no mass effect. (Choice E) Patients with advanced AIDS are at high risk for cytomegalovirus infection in the retina (most common), colon, or lungs. However, neurologic disease is uncommon. When it does occur, cytomegalovirus encephalitis is usually marked by confusion, lethargy, and cranial nerve palsies. Brain imaging usually shows periventricular enhancement. Educational objective: Cryptococcal meningoencephalitis is common in patients with advanced AIDS and generally manifests with signs of elevated intracranial pressure (ICP), including progressive headaches, nausea/vomiting, and confusion. In a minority of patients, elevated ICP compresses the 6th cranial nerve and results in diplopia and lateral gaze palsy. The diagnosis is generally made using lumbar puncture with CSF analysis and India ink stain or capsular polysaccharide antigen testing.

A 38-Year-Old Man Is Brought to the Emergency Department Due