Basilar artery occlusion is a life-threatening vascular pathology that can initially present with relatively mild and nonspecific symptoms. Eventually, quadriparesis, dysarthria, altered level of consciousness, and ocular abnormalities may ensue and put the patient at great risk. A presumptive diagnosis can be made during the clinical assessment, but imaging studies are needed in order to confirm that the basilar artery is the site of the occlusion. Catheter angiography and either computed tomography (CT) angiography or magnetic resonance (MR) angiography are recommended modalities.
Signs and symptoms of basilar artery occlusion vary depending on the extent (but also the site) of the occlusion. Unlike the majority of cerebrovascular insults, the clinical course is frequently gradual and starts with relatively mild and nonspecific complaints such as a headache and possibly vertigo, which mimics a transient ischemic attack (TIA) and delays the diagnosis   . Eventually, the typical signs of basilar artery occlusion appear - altered mental state (patients are often in a coma), hemiparesis or quadriparesis, dysphagia, dysarthria, and other neurological deficits    . Additional findings that could be encountered are nausea, vomiting, bulbar dysfunction, locked-in syndrome, ataxia, deficits of the extraocular muscles, and nystagmus, as well as the hearing loss    . Epileptic-like events characterized by bilateral twitching or shaking may be present . Specific symptoms appear in relation to the site of occlusion . For example, occlusion of the middle segment of the basilar artery (which supplies the lateral and medial pons) can result in ipsilateral loss of sensation of the face, dysmetria, and contralateral hemiparesis . Studies that have investigated basilar artery occlusion in both children and adults show a marked predominance of male gender  .
Because of the insidious onset of symptoms, the physician must suspect basilar artery occlusion if any of the abovementioned manifestations are observed. Cardiovascular risk factors, such as hypertension, diabetes mellitus, dyslipidemia, or prior vascular insults are present in a number of patients , meaning that a fully obtained patient history can be of great help in raising clinical suspicion. The neurological exam, however, is the crucial component of the workup, as a detailed assessment of cranial nerve and brainstem functions might reveal the exact site of the lesion . To make a definite diagnosis, imaging studies need to be employed. Computed tomography (CT) is usually the first-line study in patients who exhibit stroke-like symptoms, but the location of the basilar artery is a significant barrier for adequate CT imaging . On the other hand, magnetic resonance imaging (MRI) is a more suitable study that can delineate the soft tissues in more details, particularly through diffusion-weighted imaging (DWI). Importantly, the procedure is time-consuming and is contraindicated for patients with pacemakers or foreign bodies made of metal . Claustrophobia is another important adverse factor when using MRI as an imaging study . Studies recommend conventional catheter cerebral angiography, and either CT and MR angiography, as these procedures provide a precise view of the desired blood vessels  . MR angiography with contrast is particularly useful for evaluation of vertebrobasilar vessels .