N8) Altered mental status, photophobia, and phonophobia

Review the Learning Outcomes, Hx, PE and Labs, and begin the module with your Provisional Diagnosis. Keep hitting "Next" to move through the module.

Learning Outcomes

  1. Articulate your relationship with the consulting diagnostic radiologists in the evaluation of a patient with altered mental status.
  2. Review the DDx considerations in a patient with altered mental status.
  3. Identify the spectrum of imaging findings in appropriate modalities for evaluating a patient with altered mental status.


Physical Exam


Provisional Diagnosis

Select the Dx you believe is most appropriate
This patient with a known HSV-1 infection presenting with fever, photophobia, phonophobia, and vomiting without meningeal signs likely has HSV encephalitis. The patient’s hyperorality or pica suggests Klüver-Bucy syndrome, suggesting resultant damage to the bilateral temporal lobes.
Well done. You were correct

Potential Acuity

What is your assessment of the likely acuity for this patient?

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The patient requires urgent workup for their condition.

First Imaging Study

What is the first imaging study you will order?

A head MRI with and without contrast should be performed to evaluate for findings suggestive of encephalitis. It can also rule out an abscess.
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Pertinent Imaging Observations

Click on the links below to view images from the study, and assess these key findings as best you can.

Watch our video

View the full study if you'd like to take a look yourself.

Second Imaging Study

What is the next imaging study you will order?

The diagnosis is strongly suggested with the MRI.
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What is your Diagnosis now that you have seen the imaging results?

The patient is presenting with neurological deficits secondary to HSV encephalitis.

Current Acuity

Initially, you selected and we suggested acuity.

Has your concern for this patient changed?

The patient requires urgent workup and management.

Assessment and Plan

Please provide your assessment and plan for this patient

This is a 28-year-old patient whose clinical presentation and imaging findings are concerning for HSV encephalitis. As a space occupying mass was not seen on MRI, the patient should undergo a lumbar puncture to confirm the diagnosis. If confirmed, the patient should be treated with IV acyclovir and seizure prophylaxis drugs.

Lessons Learned:
- Herpes Encephalitis is the most common cause of fatal sporadic encephalitis in USA in all age groups. The most common cause is viral reactivation from HSV-1. Patients classically do not present with meningeal signs. 
- CSF analysis with PCR is the gold standard for establishing diagnosis. It should be performed after a space occupying lesion is ruled out to prevent iatrogenic brain herniation. MRI will show bilateral temporal lobe hyperintensities on T2 and diffusion-weighted images.

Socioeconomic Factors: HSV-1 is common and affects up to half of the general population.

That's the end of the module! Once you've reviewed the video(s), you can click here for another case challenge.

Abeer Dagra, MS3 - Content Contributor
Kevin Pierre, MD - Editor
Robbie Slater, MD - Supervising Editor
Bayar Batmunh, MS - Coordinator