Posterior circulation strokes make up 20 percent of all strokes but account for 40 percent of stroke misdiagnoses.¹ Vertigo and dizziness are often the hallmarks, but distinguishing a central (brain) from a peripheral (vestibular) etiology is difficult. Dizziness is especially tricky, with up to 40 percent of strokes presenting with dizziness being missed.² Vertebral artery dissection (VAD) is notoriously elusive, producing anatomically scattered symptoms that may stutter for days.³

Case 1: Posterior Stroke Presenting as Food Poisoning

A 42-year-old man presents to the emergency department (ED) with sudden onset of severe vertigo, headache, nausea, and vomiting after eating Italian food. His blood pressure is 190 over 115. On exam he is in moderate distress, is pressing his eyes shut, and has horizontal nystagmus (not further characterized by the emergency physician). His neurological exam is described as normal, but gait and truncal ataxia are not tested. He is assumed to have benign positional vertigo, is treated with IV Reglan, Benadryl, and Valium, but is not improved two hours later. A neurologist is consulted and a CT shows a large left cerebellar infarct. Craniotomy is ultimately required to relieve brainstem compression.

Case 2: Posterior Stroke Presenting as Intoxication or Malingering

A 62-year-old man awakens from sleep with a headache, trouble speaking, and inability to move his arms or legs, all witnessed by his partner. Symptoms last 10-15 minutes. On arrival in the ED, symptoms have resolved except for the headache. His neurological exam on arrival is documented as normal. Although his ETOH or blood alcohol level is zero, the consulting neurologist concludes that the patient’s symptoms are likely related to drinking wine the night before. At shift change the oncoming emergency physician re-evaluates the patient and notes direction-changing horizontal nystagmus. MRI/MRA reveals a right VAD. The patient is anti-coagulated and does well.

Takeaways

Nystagmus can be complex; its presence in a patient with any neuro symptoms should raise the possibility of a posterior circulation stroke. If nystagmus is the sole finding, we teach that the only potentially “benign” form is horizontal, unidirectional and extinguishable.¹

Gait is key. If unable to test gait, check truncal ataxia by sitting the patient up.

VADs are notoriously difficult to diagnose. Symptoms, it is worth repeating, may be scattered, non-anatomic and stutter for days. Worse, odd symptoms like transient quadriplegia or phonation difficulty may be ascribed to malingering or intoxication. Posterior circulation strokes, especially VADs, may manifest with only a single neurological abnormality, so a thorough neurologic exam is critical.

Bilateral symptoms are more frequent in posterior circulation strokes and can be deceptive.² Vertigo (or “dizziness”) plus any other symptom, e.g., headache, diplopia, numbness or motor weakness raises concern for posterior CVA. While vertigo, headache, neck pain and nausea are common, they are rarely all present.²

Benign positional vertigo or labyrinthitis should only cause vertigo without other neurological signs or symptoms. Speech abnormalities are not limited to anterior circulation strokes. In the setting of vertigo or dizziness, speech must be carefully tested. Accepting basic conversation as normal is inadequate. “Dizziness” as a chief complaint at triage may not find its way into physician notes. Such a vague sensation may get lost in the shuffle of repeated interviews. Always consider dizziness a vertigo equivalent. Think twice before attributing a patient’s symptoms to “Italian food” or “a few drinks.” Humans have usually just eaten something or had “a few beers.”

The gold standard for distinguishing a central versus peripheral etiology is possibly the HINTS exam (Head Impulse, Nystagmus, Test of Skew).¹ Unfortunately, patients who most need this might not be able to tolerate it. For such patients, we adopted a rapid, easily tolerated version of the HINTS exam. Its elements include:

1. Eyes: Nystagmus (if horizontal, is it direction-changing?), pupillary response (Horner syndrome), visual fields and skew.
2. Finger-to-nose/heel-shin tests: (basic tests of cerebellar function)
3. Speech: Cerebellar scanning, aka “staccato speech” e.g., phrases like “British Constitution” will sound like “Brit-tish const-ti-tu-tution.⁴ If in Spanish try, “Todos tenemos talento.”
4. Gait or truncal ataxia: sit up on stretcher or exam table if too uncomfortable to walk.
5. Sensory: Test symmetry of light touch perception. Asymmetry may reveal lateral medullary syndrome (Wallenberg).

Conclusion

We have never reviewed a missed posterior circulation stroke where all elements of neurological exam were documented. Diagnosis of posterior circulation stroke requires an astute clinician who performs and documents an detailed neurologic examination.

Dr. Dajer was ED medical director at NY Presbyterian Lower Manhattan Hospital for 13 years. He has served as a quality and medical malpractice case reviewer for 25 years.

Dr. Pilcher is a retired emergency physician and ED medical director at EvergreenHealth in Kirkland, WA. He has served as a medical-legal consultant in malpractice cases throughout his career and is the editor/publisher of a free opt-in monthly newsletter “Medical Malpractice Insights – Learning from Lawsuits.”

References

1. Kattah JC, Talkad AV, Wang DZ, et al. HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke. 2009;40(11):3504-3510.
2. Tarnutzer AA, Lee SH, Robinson KA, et al. ED misdiagnosis of cerebrovascular events in the era of modern neuroimaging: A meta-analysis. Neurology.2017;88(15):1468-1477.
3. Tarnutzer AA, Lee SH, Robinson KA, et al. ED misdiagnosis of cerebrovascular events in the era of modern neuroimaging: A meta-analysis. Neurology.2017;88(15):1468-1477.
4. Gottesman RF, Sharma P, Robinson KA, et al. Clinical characteristics of symptomatic vertebral artery dissection: a systematic review. Neurologist. 2012;18(5):245-254.

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