What vessel is affected in a bilateral medial temporal lobe stroke, specifically the Posterior Cerebral Artery (PCA)?

From the Guidelines

A bilateral medial temporal lobe stroke typically involves the posterior cerebral arteries (PCAs) [@1@]. These paired vessels supply blood to the medial and inferior temporal lobes, including critical structures such as the hippocampus, parahippocampal gyrus, and portions of the occipital lobe. For a bilateral medial temporal lobe stroke to occur, both the left and right PCAs must be affected simultaneously, which is relatively uncommon. This type of stroke often results from embolic events, cardiac sources, or vertebrobasilar disease since the PCAs originate from the basilar artery bifurcation. The clinical presentation typically includes:

• anterograde amnesia (inability to form new memories) due to bilateral hippocampal damage, while sparing older memories
• visual field defects (cortical blindness or homonymous hemianopia)
• visual agnosia
• prosopagnosia (inability to recognize faces)
• occasionally behavioral changes The bilateral nature of this stroke makes it particularly devastating for memory function, as there is no contralateral hemisphere to compensate for the memory deficits. According to the most recent guidelines [@2@], vascular imaging with duplex ultrasound, CTA, MRA, or digital subtraction angiography has good agreement and can be used to determine treatment eligibility for revascularization procedures. In patients with acute stroke, vascular imaging should be performed to evaluate the mechanism of stroke and assess risk for future stroke [@1@]. Early identification of the stroke etiology or mechanism (carotid atherosclerotic disease or other treatable causes) is critical to treatment decisions and long-term management [@1@]. The primary goal of imaging patients with acute stroke symptoms is to distinguish between hemorrhagic and ischemic stroke [@1@]. In acute stroke patients who are candidates for IV thrombolysis (0-hour to 4.5-hour time window), either noncontrast CT or MRI of the brain is recommended to exclude intracranial hemorrhage and determine the extent of ischemic changes [@1@]. In acute stroke patients who are candidates for endovascular therapy, vascular imaging (CTA, MRA, conventional angiography) is strongly recommended during the initial imaging evaluation [@1@]. In acute stroke patients, vascular imaging of the head and neck should be performed to evaluate the mechanism of stroke and assess risk of future stroke [@1@]. Given the importance of identifying the mechanism of ischemia to prevent subsequent episodes, imaging the cerebral vasculature is a crucial aspect of the workup of patients with stroke, transient ischemic attack (TIA), or suspected cerebrovascular disease [@3@]. The detection of the site of the arterial disease may be crucial to determining the type of acute therapy to institute [@3@]. A variety of imaging modalities are widely available, relatively safe and reliable, and each technique has particular strengths and weaknesses [@3@]. Imagers and clinicians will use their clinical judgment in each case to provide the best possible care [@3@].

From the Research

Bilateral Medial Temporal Lobe Stroke

• The affected vessel in bilateral medial temporal lobe stroke is not directly mentioned in the provided studies 1, 2, 3, 4, 5.
• However, the studies discuss the treatment and outcomes of basilar artery occlusion, which can affect the medial temporal lobe.
• The basilar artery is a vital vessel that supplies blood to the brainstem, cerebellum, and posterior cerebral arteries, which in turn supply the medial temporal lobe 1, 2, 3, 4, 5.
• Occlusion of the basilar artery can lead to ischemic stroke, including bilateral medial temporal lobe stroke.
• The studies suggest that mechanical thrombectomy and intra-arterial thrombolysis can be effective treatments for basilar artery occlusion, but the outcome depends on various factors, including the time to recanalization, age, and neurological status of the patient 1, 2, 3, 4, 5.

Vessel Involved

• The basilar artery is formed by the fusion of the two vertebral arteries, which arise from the subclavian arteries 1, 2, 3, 4, 5.
• The posterior cerebral arteries, which supply the medial temporal lobe, arise from the basilar artery 1, 2, 3, 4, 5.
• Therefore, occlusion of the basilar artery or its branches can lead to bilateral medial temporal lobe stroke.

Treatment and Outcome

• The studies discuss the importance of early recanalization and treatment of basilar artery occlusion to improve outcomes 1, 2, 3, 4, 5.
• Mechanical thrombectomy and intra-arterial thrombolysis are effective treatments for basilar artery occlusion, but the outcome depends on various factors, including the time to recanalization, age, and neurological status of the patient 1, 2, 3, 4, 5.