Is a brain MRI with or without contrast indicated for a patient presenting with dizziness, migraines, and myoclonic (involuntary muscle) jerks?

Brain MRI for Dizziness, Migraines, and Myoclonic Jerks

MRI head without contrast is the recommended imaging study for patients presenting with dizziness, migraines, and myoclonic jerks, as it provides the highest diagnostic yield compared to CT while avoiding unnecessary contrast administration. 1

Diagnostic Approach Based on Symptoms

For Dizziness:

• MRI without contrast has a diagnostic yield of approximately 4% in isolated dizziness, with ischemic stroke being the most common abnormality (70% of positive findings) 1
• CT head without contrast has a very low diagnostic yield (<1%) and poor sensitivity (20-40%) for detecting causative etiologies in dizziness 2
• The posterior cranial fossa, which is better visualized with MRI than CT, is more likely to contain lesions causing dizziness 2

For Migraines:

• Brain MRI in patients with typical migraine and normal neurological examination has a low yield (approximately 1%) that is equivalent to that of the general asymptomatic population 3
• Routine brain MRI is not recommended for typical migraine presentations without clinical red flags 3

For Myoclonic Jerks:

• Myoclonic jerks can be manifestations of various conditions including epilepsy syndromes, post-hypoxic states, toxic-metabolic disorders, drug reactions, storage diseases, and neurodegenerative disorders 4
• Neuroimaging is important to rule out structural causes, with MRI being the preferred modality due to superior soft tissue resolution 5, 4

Contrast vs. Non-Contrast MRI

• MRI head without IV contrast is generally sufficient for initial evaluation of dizziness, migraines, and myoclonic jerks when there are no specific indications for contrast 1, 6
• Contrast administration (gadolinium) should be reserved for specific clinical scenarios:
  • Suspected intracranial mass lesions 7
  • Evaluation of the internal auditory canal when vestibular schwannoma is suspected 2
  • Suspected inflammatory, infectious, or demyelinating processes 2, 7
  • Known intracranial tumors with suspicion of metastases 7

Clinical Decision Algorithm

1. For patients with isolated dizziness:

   • If no focal neurological deficits are present and HINTS examination (when available) is consistent with peripheral vertigo, imaging may not be necessary 2, 1
   • If imaging is deemed necessary, MRI head without contrast is recommended 1

2. For patients with migraines:

   • If typical migraine features with normal neurological examination, routine imaging is not necessary 3
   • If atypical features, new-onset severe headache, or abnormal neurological examination, MRI head without contrast is preferred 3

3. For patients with myoclonic jerks:

   • MRI head without contrast is recommended to evaluate for structural causes 5, 4
   • Consider contrast if there are signs suggesting inflammatory or neoplastic processes 7

4. When to consider contrast:

   • When evaluating for specific conditions where contrast improves diagnostic yield:
     • Suspected tumors or metastases 7
     • Suspected inflammatory or demyelinating processes 2, 7
     • Evaluation of internal auditory canal for vestibular schwannoma 2

Important Caveats and Pitfalls

• Diagnostic yield of imaging is low in isolated dizziness without other neurological symptoms (<1% for CT, ~4% for MRI) 2, 1
• Risk factors that increase the likelihood of central causes include older age, hypertension, atrial fibrillation, non-whirling type dizziness, and combined neurological symptoms 1
• Specialized MRI protocols (including multiplanar high-resolution DWI) may be more cost-effective than conventional MRI or CT for evaluating dizziness in the emergency department setting 8
• Clinical assessment remains crucial in determining the need for imaging 1, 6

Summary

For a patient presenting with the combination of dizziness, migraines, and myoclonic jerks, MRI head without contrast is the most appropriate initial imaging study. This approach provides the highest diagnostic yield while avoiding unnecessary contrast administration. If the initial MRI reveals findings suggestive of conditions that would benefit from contrast enhancement, a follow-up MRI with contrast can be considered.