Case Presentation: A 27-year-old man with metastatic gastroesophageal junction adenocarcinoma presents with five weeks of worsening thigh pain. Labs are notable for CSF with malignant cells. Brain and spine MRI reveal diffuse leptomeningeal carcinomatosis. His course is complicated by severe pain that requires increasing doses of opioids. During his hospitalization, the patient develops worsening headaches, dizziness, and leg weakness. His exam demonstrates mild truncal instability. Later that evening, the patient becomes unresponsive and apneic. The patient’s respiratory rate increases with naloxone administration, however he is intubated for persistent altered mental status. A non-contrast head CT scan is without evidence of hemorrhage or mass lesion. In the ICU, his mental status remains poor despite lack of sedation. On repeat neurologic examination, cranial nerve reflexes are newly absent. Head/neck CTA demonstrates absence of intracranial flow and diffuse cerebral edema. Neurology and Neurosurgery endorse concern for a posterior circulation stroke of the basilar artery. He is not deemed to be a tPA or thrombectomy candidate due to his exam being consistent with brain death. His family decides to focus on comfort and he ultimately undergoes terminal extubation with his family at bedside.
Discussion: Every year in the United States, ~200,000 patients have an ischemic posterior circulation stroke. However, posterior circulation strokes are challenging to recognize as they often present with vague symptoms such as dizziness (47%), headache (28%), and nausea and vomiting (27%). Given their non-specific symptoms, they have a significant delay in diagnosis and are 3x more likely to be misdiagnosed compared to anterior circulation strokes. As clinicians, it is imperative to maintain a heightened suspicion for posterior circulation strokes. Signs with the strongest likelihood ratios for posterior circulation strokes include Horner syndrome (72.0), crossed sensory findings (54.7) or motor paresis (24.0), nystagmus (14.0), and ataxia (5.8). Clinicians can also perform a highly sensitive and specific bedside exam, called the HINTS exam, to identify posterior circulation strokes in cases of acute vestibular symptoms. The HINTS exam consists of three components: Head Impulse, Nystagmus, and Test of Skew. A single abnormal HINTS exam component is strongly associated with stroke (sensitivity 100%, specificity 96%, and positive likelihood ratio 25) and an entirely normal HINTS exam is strongly reassuring against stroke (negative likelihood ratio 0.01). In fact, the HINTS exam has been shown to outperform MRI in diagnosing stroke within the first 2 days of acute vertigo syndromes. As such, familiarity with the HINTS exam is an important tool that can be used in the diagnosis of posterior circulation strokes.
Conclusions: Dizziness and lightheadedness are common problems encountered in the hospital setting, and can be challenging to diagnose due to a wide differential diagnosis. Signs with the strongest association for posterior circulation strokes include Horner syndrome, crossed sensory or motor findings, nystagmus, and ataxia. At the bedside, one can utilize the highly sensitive and specific HINTS exam, which consists of Head Impulse, Nystagmus, and Test of Skew, to elucidate whether a patient is having peripheral vertigo or a stroke. Our patient showcases the importance of prompt clinical recognition of posterior circulation strokes – a skill that is imperative for all hospital medicine clinicians.