Acute confusional state with posterior cerebral artery infarction: a challenge in the diagnosis of acute stroke at bedside.

Acta Neurologica Taiwanica Vol 16 No 3 September 2007 From the Departments of Neurology, Kaohsiung Medical University and Hospital, Kaushung, and Taipei Veterans General Hospital, Yang-Ming Medical University, Taipei, Taiwan. Reprint requests and correspondence to: A-Ching Chao, MD. Department of Neurology, Kaohsiung Medical University and Hospital, Kaohsiung, Taiwan. E-mail: [email protected] Infarctions in the territory of the posterior cerebral arteries (PCA) represent 5-10% of all strokes in the general population. Anatomically, two main territories of vascular supply from the PCA can be differentiated. Proximal and deep PCA territory includes the paramedian mesencephalon, and medial, posterolateral thalamus supplying by the P1 and P2 segments of the PCA; and the superficial PCA territory includes the occipital, temporo-parietal lobes and hippocampus supplying by P3 and P4 segments. According to the report by Cals et al., isolated superficial territory of the PCA infarction, including combinations of the areas supplied by the calcarine, temporo-occipital, parieto-occipital, and temporal arteries, are uncommon, representing less than a third of all PCA infarctions. The most common clinical sign of pure superficial PCA infarction was visual field defect (96%); the second common clinical signs are neuropsychological deficits and higher order visual dysfunction including memory impairment, dysphasia, alexia with or without agraphia, visual neglect, visual agnosia, color anomia and prosopagnosia (58%). Interestingly, agitated confusion was reported in this study, although with a rather low incidence (7%). Acute confusional states and agitated delirium are among the most common psychopathologic disorders in the elderly. However, they are rarely reported as a major symptom in the course of cerebral infarctions. It is known that agitated confusional states can be seen in patients with right middle cerebral artery infarction; also infarction of the PCA can cause agitated delirium, particularly when it involves the dominant or bilateral hemispheres. Destruction or disconnection of dominant hemisphere neocortex from limbic structures, resulting in impairment of focal attention, loss of linguistically organized memory, and/or disruption of temporal sequencing may be responsible for this syndrome . In this issue, Shih et al. present their findings of a hospital based study which aimed to identify the possible anatomic sites and risk factors for the development of confusion or delirium in patients with PCA infarction. They found that confusion or delirium tends to be developed in patients with left or bilateral PCA infarct, and the medial occipito-temporal gyri, especially the left side involvement; is the pivotal factor for the development of confusion or delirium; higher prevalence of diabetes mellitus was also observed. Now, thrombolytic therpy using recombinant tissue plasminogen activator is effective in acute ischemic stroke if administered within 3 hours of onset (Level 1 evidence). So, “time is brain” and any patient who is Acute Confusional State with Posterior Cerebral Artery Infarction: A Challenge in the Diagnosis of Acute Stroke at Bedside