Background and Purpose-Reports of ischemic stroke affecting the hippocampus are rare. In this study we used diffusion-weighted MRI (DWI) to characterize patients with posterior circulation stroke involving the hippocampus. Methods-Fifty-seven consecutive acute stroke patients with hippocampal infarct (HI) on DWI were analyzed with regard to clinical features and ischemic lesion patterns. The last 20 of these underwent additional neuropsychological testing of short-term, working, and episodic long-term memory. Results-We found unilateral HI in 54 and bilateral HI in 3 patients. Visual analysis identified 4 patterns of DWI lesion affecting (1) the complete hippocampus (15/60), (2) the lateral (19/60) or (3) dorsal (22/60) parts of the hippocampal body and tail, and (4) circumscribed lesions in the lateral hippocampus (4/60), corresponding well to hippocampal vascular anatomy. In all cases DWI showed further ischemic lesions in the posterior circulation. Symptoms from lesions outside the hippocampus were the common leading clinical signs. Whereas mnestic deficits were prominent in only 11/57 patients, neuropsychological examination in 20 patients showed deficits of verbal episodic long-term memory in left and of nonverbal episodic long-term memory in right HI. Conclusion-Several phenotypic lesion patterns can be distinguished in HI that usually occur as part of multifocal PCA ischemia. A careful neuropsychological examination is necessary to detect resulting memory deficits.

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This study supports previous observations that migrainous infarction mostly occurs in the posterior circulation, and in younger women with a history of migraine with aura. Acute ischemic lesions were often multiple and located in distinct arterial territories. As there were no overlapping ischemic lesions, hemodynamic compromise during the development of migraine is unlikely the cause of infarction. Differentiation between migrainous infarction and prolonged migraine aura is difficult and associated with delayed admission of patients.

Since decision-making for thrombolysis in acute stroke settings is restricted to a limited time window and based on clinical assessment and CT findings only, thrombolysis is sometimes applied to patients with a final diagnosis other than a stroke. From a prospectively collected stroke/MRI data bank (2004-2010) with 648 suspected ischemic stroke patients treated with rtPA, we identified patients without evidence of acute infarction on follow-up MRI and a final diagnosis other than a stroke or acute cerebrovascular event. We compared demographics, symptoms, complications, and outcome of patients with stroke mimics (SM) to those with acute infarction. In 42 patients, an SM was diagnosed: seizures in 20, conversion disorder in seven, dementia in six, migraine in three, brain tumor in two, and others in four patients. Patients with SM less often had typical stroke symptoms like dysarthria (p < 0.01), facial palsy (p < 0.001), hemiparesis (p < 0.001), horizontal gaze palsy (p < 0.001), and visuospatial neglect (p = 0.03), while aphasia (p = 0.004) and accompanying convulsions (p = 0.01) occurred more often. Independent predictors of SM were known cognitive impairment, aphasia, and accompanying convulsions. Thrombolysis-related complications (orolingual angioedema) occurred in one SM patient and none of the SM patients deteriorated clinically. Stroke mimics comprise neurological/psychiatric disorders and differ from ischemic stroke patients with regard to the clinical presentation at onset. This might be helpful in deciding which patients should undergo acute stroke MRI to rule out SM, facilitate treatment decisions, and reduce the risk of unnecessary therapy.

Background: The human hippocampus can be affected in a large variety of very different neurological diseases, of which acute ischemic stroke, transient global amnesia, epilepsy, and limbic encephalitis are the most common. Less frequent etiologies include various infections and encephalopathy of different origins. Clinical presentation notably comprises confusional state, altered vigilance, memory deficits of various extent and seizures. While in hypoxic or hypoglycemic encephalopathy, clinical presentation and surrounding circumstances provide some clues to reach the correct diagnosis, in the above-listed more common disorders, signs and symptoms might overlap, making the differential diagnosis difficult. This review presents recent studies using the diffusion-weighted imaging (DWI) technique in diseases involving the hippocampus. Methods: References for the review were identified through searches of PubMed from 1965 to January 2011. Only papers published in English were reviewed. Full articles were obtained and references were checked for additional material where appropriate. Results: All pathologies affecting the hippocampus are associated with distinct lesion patterns on magnetic resonance imaging, and especially DWI has the ability to demonstrate even minute and transient hippocampal lesions. In acute ischemic stroke in the posterior cerebral artery territory, involvement of the hippocampal formation occurs in four distinct patterns on DWI that can be easily differentiated and correspond to the known vascular anatomy of the hippocampus. In the subacute phase after transient global amnesia (TGA), dot-like hyperintense lesions are regularly found in the lateral aspect of the hippocampus on DWI. The DWI lesions described after prolonged seizures or status epilepticus include unilateral or bilateral hippocampal, thalamic, and cortical lesions of various extent, not restricted to vascular territories. In limbic encephalitis, DWI lesions are only infrequently found and usually affect the hippocampus, uncus and amygdala. Furthermore, in some rare cases DWI lesions of different etiology may coexist. Conclusion: In patients with diseases affecting the hippocampus, DWI appears to be useful in differentiating between underlying pathologies and may facilitate a definite diagnosis conducive to an optimal treatment. With a careful clinical examination, experience with the interpretation of DWI findings and knowledge of associated phenomena, it is indeed possible to differentiate between ischemic, ictal, metabolic, and TGA-associated findings.

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Background and Purpose-Differences between women and men in relation to stroke are increasingly being recognized. Methods-From July 2004 until June 2007, 237 acute ischemic stroke (AIS) patients were treated with recombinant tissue plasminogen activator (rtPA) within 3 hours after onset of symptoms in our stroke unit. Baseline characteristics, etiology, CT/MRI stroke patterns, clinical outcome, and complications of women were compared to those of men. Results-Of 237 AIS patients (mean age 70.7 years), 111 (46.8%) were women and 126 (53.2%) were men. Women were older (Pϭ0.001), but history of hyperlipidemia (Pϭ0.03), smoking (Pϭ0.03), and coronary heart disease (PϽ0.001) was less frequent than in men. Internal carotid artery disease occurred more often in men (Pϭ0.02), whereas atrial fibrillation was observed more often in women (Pϭ0.002). In men borderzone/small embolic and lacunar stroke was found more frequently (39.7 versus 27.2%), whereas women showed a higher percentage of large territorial stroke (72.8 versus 60.3%, Pϭ0.09). Baseline National Institute of Health Stroke Scale scores (12.5 versus 11.3), NIHSS score at discharge (11.0 versus 9.5), 3-month-outcome modified Rankin Scale score, thrombolysis-related (17.1% versus 13.5%) or independent complications (32.4% versus 30.2%), and mortality after 3 months (13.5% versus 9.5%) were similar. Conclusion-Differences of stroke lesion patterns in genders are paralleled by differences in etiology and risk factor profiles (women, cardioembolism; men, large and small vessel disease). Baseline characteristics, rates of rtPA-related and independent complications, as well as clinical outcomes were not different between women and men with AIS.

Background: Patients with posterior circulation stroke (PCS) were underrepresented in or even excluded from the large clinical trials investigating acute therapy with thrombolysis. Therefore, the knowledge about potential benefits and risks of thrombolysis in PCS is sparse. Methods: From July 2004 until June 2007, 237 stroke patients were treated with thrombolysis within 3 h after onset of symptoms in our stroke unit. Baseline characteristics, etiology, CT/MRI stroke patterns, clinical outcome, and complications of patients with PCS were compared to those with anterior circulation stroke (ACS). Results: There were 30 patients in the PCS group; 198 had ACS. In the PCS group, less patients had a history of prior stroke (0/30 vs. 31/198 (15.7%), p = 0.02) and less were treated with platelet inhibitors (6/30 (20.0%) vs. 83/198 (41.9%), p = 0.02). Onset to treatment time was higher in the PCS group (156.2 ± 23.2 vs. 141.1 ± 30.7, p = 0.01). Small vessel disease occurred more often in PCS patients (10/30 (33.3%) vs. 12/198 (6.1%), p < 0.001), whereas stroke of undetermined cause was less frequent (5/30 (16.7%) vs. 75/198 (37.9%), p = 0.02). Correspondingly, PCS patients had more lacunar (13/30 (43.3%) vs. 15/198 (7.3%), p < 0.001) strokes on CT/MRI. Patients with PCS had significantly lower median NIHSS scores after 2 and 24 h, whereas the median NIHSS and mRS scores at discharge as well as the mRS score at the 3-month follow-up, although still lower, did not differ significantly between both groups. Outcome was similar with regard to complications and mortality. Conclusions: Patients with PCS have a higher rate of small vessel disease and lacunar stroke. In terms of potential benefits and risks of thrombolysis, we could demonstrate no significant differences between PCS and ACS. Acute PCS patients should be diagnosed and treated with the same elaborateness as ACS patients.