What does an atypical left vertebral artery waveform signify in a patient with vision changes?

Atypical Left Vertebral Artery Waveform: Significance and Management

The atypical left vertebral artery waveform with 2 peaks and no deflection below baseline likely represents a presteal waveform indicating significant vertebral artery stenosis that requires immediate advanced imaging with MRA or CTA, especially given the associated vision changes which suggest posterior circulation compromise.

Understanding the Waveform Pattern

The described waveform pattern has specific hemodynamic implications:

• Two peaks without deflection below baseline: This pattern is characteristic of a "presteal" waveform in the vertebral artery
• Asymmetry compared to the contralateral side: Indicates pathological flow rather than normal variant
• Association with vision changes: Suggests posterior circulation compromise

Clinical Significance

The vertebral arteries are critical components of the posterior circulation that supply the brainstem, cerebellum, and occipital lobes. Abnormal flow patterns in these vessels can lead to significant clinical consequences:

• Vision changes occur in approximately 20% of posterior circulation strokes 1
• Vertebral artery disease accounts for approximately 20% of all posterior circulation strokes 1
• Presteal waveforms indicate hemodynamically significant stenosis that may progress to complete occlusion

Diagnostic Algorithm

1. Immediate advanced imaging:

   • MRA or CTA of the head and neck is recommended rather than ultrasound for evaluation of vertebral arteries in patients with symptoms suggesting posterior cerebral or cerebellar ischemia (Level of Evidence: C) 1
   • Both MRA and CTA have higher sensitivity (94%) and specificity (95%) compared to ultrasound (sensitivity 70%) for detecting vertebral artery stenosis 1

2. Complete vascular assessment:

   • Evaluate all segments of the vertebral arteries (V1-V4)
   • Assess for atherosclerotic disease, dissection, or extrinsic compression
   • Examine the circle of Willis for completeness and collateral flow

3. Consider catheter angiography:

   • If noninvasive imaging fails to define location or severity of stenosis
   • Particularly useful in patients who may be candidates for revascularization 1

Management Considerations

If vertebral artery stenosis is confirmed:

• Medical therapy:

  • Antiplatelet therapy (aspirin, clopidogrel, or combination therapy)
  • Aggressive risk factor modification (hypertension, diabetes, smoking, hyperlipidemia)
  • Consider anticoagulation if evidence of thrombus formation

• Revascularization:

  • Consider for patients with recurrent symptoms despite medical therapy
  • Options include angioplasty with or without stenting

Potential Pitfalls

1. Misattribution to benign conditions: Vision changes may be incorrectly attributed to migraine or other non-vascular causes, delaying proper diagnosis 2

2. Inadequate imaging: Ultrasound alone is insufficient; MRA or CTA is necessary for proper evaluation 1

3. Overlooking dissection: Vertebral artery dissection can present with similar symptoms and may require different management approaches 2, 3

4. Delayed intervention: Presteal waveforms may progress to complete occlusion and stroke if not addressed promptly

The presence of vision changes in conjunction with an abnormal vertebral artery waveform requires urgent evaluation to prevent potential progression to stroke and permanent visual or neurological deficits.