The second aspect of clinical assessment that is important is the cranial nerve exam, including a focused eye exam. Four of the “Dangerous Ds” to keep in mind as part of the cranial nerve exam are diplopia, dysarthria, dysphagia, and dysphonia. Ptosis may indicate Horner’s Syndrome which, in one study, had the highest predictive value for a diagnosis of PCIS.⁹ Visual fields should be scrutinized for any deficits and extra-ocular movements (EOMs) should be assessed for the possibility of locked-in syndrome. This is a rare presentation of basilar artery occlusion that paralyzes all peripheral motor function except those that control EOMs. In patients who present after a sudden collapse with persistent loss of consciousness and paraplegia with no clear alternative cause, locked-in syndrome should be considered, and EOMs assessed for sparing. Patients with locked-in syndrome may also have hemodynamic instability and cardiac dysrhythmias secondary to massive catecholamine surge associated with massive brain insult. Suffice to say that a focused eye exam may reveal a finding that increases one’s suspicion of PCIS in a patient with an otherwise benign clinical presentation for stroke.

The third aspect of clinical assessment that is important in assessing for PCIS is gait. It is imperative to walk test dizzy patients to assess for truncal ataxia. One clinical pearl is that the vertigo in patients with PCIS tends to be less severe than that in peripheral causes of vertigo, while the ataxia in patients with PCIS tends to be more severe than in patients with a peripheral cause of vertigo. Do not let mild vertigo symptoms sway you away from a diagnosis of PCIS. While much has been written about the bedside head-impulse nystagmus test-of-skew (HINTS) exam for ruling in a central cause of vertigo, observational data suggests that EM physicians are very poor at performing this exam, so that the test is not sufficiently accurate to rule out PCIS and may falsely reassure clinicians that PCIS is not present.¹⁰ Despite a meta-analysis suggesting a 15-fold increased risk for PCIS in patients with a positive HINTS tests, in this author’s opinion the HINTS exam should not be relied on to help make emergency treatment decisions for patients who present with PCIS symptoms.¹¹

Next time you are faced with a patient who presents with the chief complaint of dizziness, consider PCIS in your differential diagnosis and be sure to assess for risk factors, cranial nerve abnormalities (including a focused eye exam), and gait. If there are one or more worrisome features, consider speaking to your local stroke neurologist for consideration of intravenous thrombolysis or endovascular therapy as per your local protocol.