In an 18‑year‑old HIV‑positive patient with uncertain antiretroviral adherence who presents with altered mental status, a seizure with tooth clenching, and a temperature of 37.9 °C, what is the next step in management: emergent non‑contrast head CT, lumbar puncture, or urine toxicology screen?

Management of HIV-Positive Patient with Seizure and Altered Mental Status

Emergent non-contrast head CT is the next step in management before proceeding with lumbar puncture. 1

Rationale for CT First

This 18-year-old HIV-positive patient with questionable treatment adherence presents with multiple high-risk features that mandate neuroimaging before any invasive procedures:

• Seizure activity with altered mental status creates concern for mass lesions, opportunistic infections (toxoplasmosis, CNS lymphoma), or intracranial hemorrhage 1
• HIV with poor adherence dramatically increases risk of CNS opportunistic infections and mass lesions that could cause elevated intracranial pressure 1
• Recent seizure raises concern for postictal state versus ongoing structural pathology requiring immediate identification 1

Why CT Before Lumbar Puncture

Performing LP without prior imaging in this patient is contraindicated and potentially fatal. 1

The American College of Radiology explicitly states that non-contrast head CT is the initial test of choice when there is clinical suspicion for intracranial infection, mass, or elevated intracranial pressure 1. In HIV patients with poor adherence, the risk of space-occupying lesions (toxoplasmosis, CNS lymphoma, cryptococcoma) is substantially elevated, and LP in the presence of mass effect can precipitate herniation 1.

Key imaging priorities:

• Exclude mass effect, hydrocephalus, or herniation before LP 1
• Identify hemorrhage (seizures can cause falls leading to intracranial bleeding) 1
• Detect ring-enhancing lesions suggestive of toxoplasmosis or abscess 1

Why Not Urine Toxicology First

While alcohol use is mentioned, toxicology screening should not delay neuroimaging in this high-risk patient 1. The American College of Radiology guidelines indicate that for patients with altered mental status and seizures, determining the clinical need for brain imaging takes priority over toxicology screening, particularly when there are risk factors for intracranial pathology 1.

Alcohol intoxication alone does not cause:

• Witnessed seizure with tooth clenching (pathognomonic for tonic-clonic activity) 2
• Prolonged altered consciousness requiring ambulance transport 1
• The combination of HIV, poor adherence, and new neurological symptoms 1

Clinical Algorithm

Step 1: Emergent non-contrast head CT 1

• Fast acquisition (critical in emergency setting) 1
• Excellent for detecting hemorrhage, mass effect, hydrocephalus 1
• Identifies life-threatening emergencies requiring immediate neurosurgical intervention 1

Step 2: If CT shows no mass effect/contraindications → Proceed with LP 1

• Evaluate for meningitis, encephalitis, cryptococcal infection 1
• Opening pressure measurement 1
• CSF analysis including cryptococcal antigen, VDRL, cell counts 1

Step 3: Concurrent management

• Obtain urine toxicology (can be sent simultaneously with CT) 1
• Blood cultures, HIV viral load, CD4 count 1
• Metabolic panel to exclude hypoglycemia, hyponatremia 1

Critical Pitfalls to Avoid

Never perform LP before imaging in HIV patients with altered mental status and seizures. 1 The rate of CNS mass lesions in immunocompromised patients is substantially higher than the general population, and the consequences of herniation are catastrophic 1.

Do not delay CT for toxicology results. 1 The diagnostic yield of CT in this clinical scenario (HIV, seizure, altered mental status) is significantly higher than routine toxicology screening, and CT findings will immediately direct management 1.

Do not assume alcohol explains everything. 1 While alcohol may contribute, the combination of HIV with poor adherence, new-onset seizure, and persistent altered consciousness demands exclusion of life-threatening intracranial pathology 1.

Post-CT Decision Points

If CT reveals:

• Ring-enhancing lesions: Empiric toxoplasmosis treatment, defer LP 1
• Normal CT with persistent symptoms: Proceed to LP for infectious workup 1
• Hemorrhage or mass effect: Neurosurgical consultation, defer LP 1
• Subtle findings: Consider MRI as second-line test for higher sensitivity 1

Answer: C - CT head without contrast is the next step.