Case Presentation: A 27-year-old man with metastatic gastroesophageal junction adenocarcinoma presents with five weeks of progressively worsening bilateral thigh pain. Admission exam is notable for a normal neurological exam. Labs are notable for CSF with malignant cells. Brain and spine MRI reveal diffuse leptomeningeal carcinomatosis. During his hospitalization, the patient develops dizziness and leg weakness requiring him to lower himself to the ground. His friends note that his personality has been different that day, and that the patient endorsed mild blurry vision and worsening chronic headaches earlier. His exam is notable for mild truncal instability. Later that evening, the patient becomes unresponsive and apneic. His exam demonstrates multiple new findings including unresponsiveness to sternal rub, 6 mm pupils bilaterally that are minimally responsive to light, right-sided gaze preference, jerking movements in all extremities, and extensor posturing. He is intubated and transferred to the ICU. A non-contrast head CT scan is urgently obtained and is without evidence of hemorrhage or mass lesion. On repeat neurologic examination, cranial nerve reflexes are newly absent. Neurology and Neurosurgery endorse clinical concern for a basilar artery stroke – specifically, “top of the basilar” syndrome. An urgent head/neck CT angiogram demonstrates absence of intracranial flow and diffuse cerebral edema. He is not deemed to be a tPA or thrombectomy candidate due to severe global anoxic brain injury and an exam consistent with brain death. His family decides to focus on comfort and he ultimately undergoes terminal extubation with his family at bedside.
Discussion: Basilar artery occlusion (BAO) is a subset of posterior circulation strokes occurring in up to 8,000 patients per year and accounting for ~1-4% of all ischemic strokes in the United States. Unlike anterior circulation strokes, BAOs can have variable and stuttering symptoms which last for weeks-months and make them diagnostic challenges. Initial presentations can be highly variable and misleading due to non-specific symptoms such as nausea, vertigo, unilateral or bilateral twitching, jerking or posturing, and confusion. Many clinicians fear the BAO syndrome “locked-in syndrome,” which results from mid-basilar artery occlusion and leads to paralysis with only limited vertical eye movements. However, our patient had a different rare and devastating BAO syndrome called “top of the basilar” syndrome, which results from distal-basilar artery occlusion. “Top of the basilar” syndrome leads to dizziness, vertical gaze and convergence disorders, decreased-absent pupillary light reflex, hypersomnolence, abnormal behavior, ataxia, dysarthria, decreased respiratory drive and coma – many of the symptoms that our patient developed. Finally, BAO has a high mortality of up to 30%, as seen in this case.
Conclusions: Basilar artery occlusions can be challenging to diagnose given their stuttering course comprised of non-specific symptoms. While most clinicians are familiar with “locked-in syndrome,” – this case highlights a different, catastrophic subset of basilar artery strokes called “top of the basilar” syndrome and emphasizes its uncommon presentation including ataxia, abnormal behavior, hypersomnolence, vertical gaze disorder, and decreased-absent pupillary reflex. Given the high associated mortality with basilar artery occlusions, it is important for the hospital medicine clinician to recognize their various presentations.