What type of head scan should I order for a patient with auditory and visual hallucinations and daily headaches?

MRI Brain Without Contrast is the Recommended Head Scan for Patients with Auditory and Visual Hallucinations with Daily Headaches

For patients presenting with auditory and visual hallucinations accompanied by daily headaches, MRI brain without contrast is the recommended first-line neuroimaging study. 1

Rationale for MRI Brain Without Contrast

• MRI brain without contrast is superior to CT for detecting subtle structural abnormalities that may be associated with hallucinations and headaches, including small ischemic infarcts, encephalitis, and subtle lesions 1
• MRI offers higher sensitivity for detecting potential causes of hallucinations such as dementia with Lewy bodies (DLB), which may present with visual hallucinations and Parkinsonian symptoms 1
• MRI avoids radiation exposure compared to CT scans, which is particularly important when considering the potential need for follow-up imaging 1
• MRI brain without contrast is specifically recommended by the American College of Radiology (ACR) Appropriateness Criteria for patients with cognitive impairment and visual hallucinations 1

Clinical Considerations

• The combination of auditory hallucinations, visual hallucinations, and daily headaches requires thorough evaluation as it may indicate underlying neurological pathology 1
• Auditory hallucinations have been reported in association with midbrain and brainstem lesions that can be detected on MRI 2
• Case reports have documented auditory hallucinations associated with migraine and structural brain lesions visible on MRI, particularly in the brainstem region 2, 3
• Hallucinations may be associated with various conditions including:
  • Dementia with Lewy bodies 1
  • Migraine with aura (uncommon presentation) 3, 4
  • Structural lesions in the temporal lobe or brainstem 2, 5
  • Psychiatric disorders (which remain a diagnosis of exclusion after ruling out structural causes) 4

When to Consider CT Head Instead

• CT head without contrast may be appropriate as an alternative in specific situations:
  • When MRI is contraindicated (pacemakers, severe claustrophobia, metallic implants) 1
  • In emergency situations where rapid assessment is critical and patient monitoring during scanning is difficult 1
  • When there is suspicion of acute intracranial bleeding, especially in patients on anticoagulants 1
  • In patients with history of trauma or when bony abnormalities of the skull are suspected 1

Additional Imaging Considerations

• For patients with suspected dementia with Lewy bodies (DLB) presenting with visual hallucinations, brain FDG-PET/CT may be considered as a complementary study to MRI 1
• If initial MRI is unrevealing but clinical suspicion for a structural cause remains high, consider:
  • MRI with contrast to evaluate for enhancing lesions such as tumors or inflammatory conditions 1
  • Specialized MRI sequences targeting specific regions (temporal lobes, brainstem) 2, 5

Common Pitfalls to Avoid

• Ordering routine head CT as the initial imaging study, which has lower sensitivity for detecting subtle abnormalities and exposes the patient to unnecessary radiation 1
• Failing to consider that hallucinations may represent a form of migraine aura in some patients, which can be associated with structural abnormalities on MRI 3, 4
• Assuming hallucinations are purely psychiatric in origin without adequate neuroimaging 4
• Overlooking the need for specialized MRI protocols when certain conditions are suspected (e.g., temporal lobe epilepsy, which may require thin-slice coronal images through the hippocampus) 1