An exploratory cohort study of sensory extinction in acute stroke: prevalence, risk factors, and time course.

Most studies on sensory extinction have focused on selected patients with subacute and chronic right hemisphere lesions. In studies conducted on acute stroke patients, risk factors and time course were not evaluated. Our aim was to determine the prevalence, risk factors, and time course of sensory extinction in the acute stroke setting. Consecutive patients with acute stroke were tested for tactile, visual, auditory, and auditory-tactile cross-modal extinction, as well as for peripersonal visuospatial neglect (PVN). Tests were repeated at 2, 7, 15, 30, and 90 days after initial examination. A multivariable logistic regression analysis was performed to test the association between sensory extinction and demographic and clinical risk factors. Seventy-three patients (38.4% women) were recruited: 64 with ischemic stroke and nine with haemorrhagic stroke. Mean age was 62.3 years (95% CI 58.8-65.7), mean NIHSS score was 1.6 (95% CI 1.2-2.1), and mean time to first examination was 4.1 days (95% CI 3.5-4.8). The overall prevalence of all subtypes of sensory extinction was 13.7% (95% CI 6.8-23.8). Tactile extinction was the most frequent subtype with a prevalence of 8.2% (95% CI 3.1-17.0). No extinction was found beyond 15 days after the first examination. After adjustment for age, sex, lesion side, type of stroke, time to first examination and stroke severity, a lesion volume ≥2 mL (adjusted OR = 38.88, p = 0.04), and presence of PVN (adjusted OR = 24.27, p = 0.04) were independent predictors of sensory extinction. The insula, the putamen, and the pallidum were the brain regions most frequently involved in patients with sensory extinction. Extinction is a rare and transient phenomenon in patients with minor stroke. The presence of PVN and lesion volume ≥2 mL are independent predictors of sensory extinction in acute stroke.

Incidence, Risk Factors and Anatomy of Peripersonal Visuospatial Neglect in Acute Stroke.

AIM: The study aims to describe the epidemiology and the neural correlates of peripersonal visuospatial neglect (PVN) in patients admitted to the Geneva Stroke Unit for an acute stroke or a transient ischemic attack (TIA). METHODS: Eligible subjects were tested for PVN using both the Ota's discriminative cancellation task and a line bisection task. Brain lesions were identified on diffusion-weighted imaging. A multivariate analysis was performed to identify risk factors of PVN. RESULTS: Ninety-eight consecutive patients (40.8% females) were recruited: 64 cases of ischemic stroke, 9 cases of hemorrhagic stroke and 25 cases of TIAs. The mean age was 61.9 ± 2.86 years. The incidence of PVN was 23.5% (95% CI 15.5-33.1) and was not significantly different between patients with right and left hemisphere stroke. There were 5 cases of ipsilesional neglect. There was no association between PVN and age, sex, stroke severity, handedness, lesion type, lesion volume and time to first examination. Lesions of temporal and parietal lobes were the most frequent in patients with PVN. CONCLUSION: PVN has a low incidence in the acute stroke settings and there is no particular predictor of its presence. It is most often associated with temporo-parietal lesions.

3D fat-saturated T1 SPACE sequence for the diagnosis of cervical artery dissection.

INTRODUCTION: This study aims to demonstrate the added value of a 3D fat-saturated (FS) T1 sampling perfection with application-optimised contrast using different flip angle evolutions (SPACE) sequence compared to 2D FS T1 spin echo (SE) for the diagnosis of cervical artery dissection. METHODS: Thirty-one patients were prospectively evaluated on a 1.5-T MR system for a clinical suspicion of acute or subacute cervical artery dissection with 3D T1 SPACE sequence. In 23 cases, the axial 2D FS T1 SE sequence was also used; only these cases were subsequently analysed. Two neuroradiologists independently and blindly assessed the 2D and 3D T1 sequences. The presence of recent dissection (defined as a T1 hyperintensity in the vessel wall) and the quality of fat suppression were assessed. The final diagnosis was established in consensus, after reviewing all the imaging and clinical data. RESULTS: Overall sensitivity and specificity were 0.929 and 1 for axial T1 SE, and 0.965 and 0.945 for T1 SPACE (P > 0.05), respectively. The two readers had excellent agreement for both sequences (k = 1 and 0.8175 for T1 SE and T1 SPACE, respectively; P > 0.05). The quality of the fat saturation was similar. Very good fat saturation was obtained in the upper neck. Multiplanar reconstructions were very useful in tortuous regions, such as the atlas loop of the vertebral artery or the carotid petrous entry. 3D T1 SPACE sequence has a shorter acquisition time (3 min 25 s versus 5 min 32 s for one T1 SE sequence) and a larger coverage area. CONCLUSION: 3D T1 SPACE sequence offers similar information with its 2D counterpart, in a shorter acquisition time and larger coverage area.

The behavioral significance of coherent resting-state oscillations after stroke.

Stroke lesions induce not only loss of local neural function, but disruptions in spatially distributed areas. However, it is unknown whether they affect the synchrony of electrical oscillations in neural networks and if changes in network coherence are associated with neurological deficits. This study assessed these questions in a population of patients with subacute, unilateral, ischemic stroke. Spontaneous cortical oscillations were reconstructed from high-resolution electroencephalograms (EEG) with adaptive spatial filters. Maps of functional connectivity (FC) between brain areas were created and correlated with patient performance in motor and cognitive scores. In comparison to age matched healthy controls, stroke patients showed a selective disruption of FC in the alpha frequency range. The spatial distribution of alpha band FC reflected the pattern of motor and cognitive deficits of the individual patient: network nodes that participate normally in the affected functions showed local decreases in FC with the rest of the brain. Interregional FC in the alpha band, but not in delta, theta, or beta frequencies, was highly correlated with motor and cognitive performance. In contrast, FC between contralesional areas and the rest of the brain was negatively associated with patient performance. Alpha oscillation synchrony at rest is a unique and specific marker of network function and linearly associated with behavioral performance. Maps of alpha synchrony computed from a single resting-state EEG recording provide a robust and convenient window into the functionality and organization of cortical networks with numerous potential applications.

Accuracy of a novel risk index combining degree of stenosis of the carotid artery and plaque surface echogenicity.

BACKGROUND AND PURPOSE: The purpose of this study was to determine the accuracy of a risk index in symptomatic or asymptomatic carotid stenoses. METHODS: Consecutive patients presenting 50% to 99% carotid stenoses were included. A semiautomated gray scale-based color mapping (red, yellow, and green) of the whole plaque and of its surface was achieved. Surface was defined as the region located between the lumen (Level 0) and, respectively, 0.5, 1, 1.5, and 2 mm. Risk index was based on a combination of degree of stenosis and the proportion of the red color (reflecting low echogenicity) on the surface or on the whole plaque. RESULTS: There were 67 (36%) symptomatic and 117 (64%) asymptomatic carotid stenoses. Risk index values were higher among symptomatic stenoses (0.46 mean versus 0.29; P<0.0001); on receiver operating characteristic curves, risk index presented a stronger predictive power compared with degree of stenosis or surface echogenicity alone. Also, in a regression model including age, gender, degree of stenosis, surface echogenicity, gray median scale of the whole plaque, and risk index, risk index measured within the surface region located at 0.5 mm from the lumen was the only parameter significantly associated with the presence of symptoms (OR, 4.89; 95% CI, 2.7-8.7; P=0.0000002). The best criterion to differentiate between symptomatic and asymptomatic stenoses was a risk index value >0.36 (sensitivity and specificity of 78% and 65%, respectively). CONCLUSIONS: Risk index was significantly higher in the presence of symptoms and could therefore be a valuable tool to assess the clinical risk of a carotid plaque.

Microembolism versus hemodynamic impairment in rosary-like deep watershed infarcts: a combined positron emission tomography and transcranial Doppler study.

BACKGROUND AND PURPOSE: Deep watershed infarcts are frequent in high-grade carotid disease and are thought to result from hemodynamic impairment, particularly when adopting a rosary-like pattern. However, a role for microembolism has also been suggested, though never directly tested. Here, we studied the relationships among microembolic signals (MES) on transcranial Doppler, rosary-like deep watershed infarcts on brain imaging, and cerebral hemodynamic compromise on positron emission tomography (PET), all in severe symptomatic carotid disease. We hypothesized that rosary-like infarcts would be significantly associated with worse hemodynamic status, independent of the presence of MES. METHODS: Sixteen patients with ≥70% carotid disease ipsilateral to recent transient ischemic attack/minor stroke underwent magnetic resonance imaging including diffusion-weighted imaging, (15)O-PET, and transcranial Doppler. Mean transit time, a specific marker for hemodynamic impairment, was obtained in the symptomatic and unaffected hemispheres. RESULTS: Eleven of 16 patients had rosary-like infarcts (Rosary+) and 8 patients had MES. Mean transit time was significantly higher (P=0.008) in Rosary+ patients than in healthy controls (n=10), and prevalence of MES was not different between Rosary+ and Rosary- patients. Contrary to our hypothesis, however, the presence of MES within the Rosary+ subset was associated (P=0.03) with a better hemodynamic status than in their absence, with a significant (P=0.02) negative correlation between mean transit time and rate of MES/h. CONCLUSIONS: Contrary to mainstream understanding, rosary-like infarcts were not independent of presence and rate of MES, suggesting that microembolism plays a role in their pathogenesis, probably in association with hemodynamic impairment. Pending confirmation in a larger sample, these findings have management implications for patients with carotid disease and rosary-like infarcts.

Stroke severity and residual flow determined by transcranial colour-coded ultrasound (TCCD) predict recanalization and clinical outcome during thrombolysis.

OBJECTIVE: To determine clinical, neuroradiological or ultrasonographic parameters associated with early recanalization and clinical outcome in patients treated with intravenous (IVT) or combined intravenous-intra-arterial (IVT-IAT) thrombolysis. METHODS: From 2004 to 2007, all consecutive ischemic stroke patients admitted within a 3-hour window and who underwent thrombolytic therapy were reviewed. Degree of occlusion and recanalization during IVT was assessed by transcranial color-coded ultrasound (TCCD) using Thrombolysis In Brain Ischemia (TIBI) classification. According to our protocol, in case of recanalization (modification of TIBI grade > or = 1) after 30 min of IVT, the procedure was maintained over 1h. When TIBI grade failed to improve after 30 min, IVT was discontinued and IAT performed using the remaining tPA dose. The study endpoints were early recanalization defined as achievement of TIBI > or = 3 grade at 30 min (for this endpoint all patients presenting a TIBI grade 3 at admission were excluded from the model) and clinical outcome at 3 months assessed by the modified Rankin scale. RESULTS: Seventy-one patients underwent either IVT (n=41) or IVT-IAT (n=30). Among all the variables, NIHSS and TIBI grades assessed at baseline were the only independent factors associated with early recanalization and clinical outcome. Furthermore, the combination of these two parameters was superior in predicting early recanalization and outcome to either one of them taken separately. An inverse correlation between NIHSS, TIBI grades and early recanalization was found: the lower the TIBI grade, the lower the probability to recanalize for any given NIHSS. CONCLUSION: Baseline NIHSS and TIBI grades were the only independent factors associated with early recanalization and clinical outcome. The combination of these two parameters was superior to each single variable in predicting the study endpoints and could therefore be used to improve the selection of patients for IVT or more aggressive therapies.

Seeing the phantom: a functional magnetic resonance imaging study of a supernumerary phantom limb.

OBJECTIVE: Supernumerary phantom limb (SPL) is a rare neurological manifestation where patients with a severe stroke-induced sensorimotor deficit experience the illusory presence of an extra limb that duplicates a real one. The illusion is most often experienced as a somesthetic phantom, but rarer SPLs may be intentionally triggered or seen. Here, we report the case of a left visual, tactile, and intentional SPL caused by right subcortical damage in a nondeluded woman. METHODS: Using functional magnetic resonance imaging, we investigated the multimodal nature of this phantom, which the patient claimed to be able see, use, and move intentionally. The patient participated in a series of sensorimotor and motor imagery tasks involving the right, the left plegic, and the SPL's hand. RESULTS: Right premotor and motor regions were engaged when she imagined that she was scratching her left cheek with her left plegic hand, whereas when she performed the same task with the SPL, additional left middle occipital areas were recruited. Moreover, comparison of responses induced by left cheek (subjectively feasible) versus right cheek scratching (reportedly unfeasible movement) with the SPL demonstrated significant activation in right somesthetic areas. INTERPRETATION: These findings demonstrate that intentional movements of a seen and felt SPL activate premotor and motor areas together with visual and sensory cortex, confirming its multimodal dimension and the reliability of the patient's verbal reports. This observation, interpreted for cortical deafferentation/disconnection caused by subcortical brain damage, constitutes a new but theoretically predictable entity among disorders of bodily awareness.

Fulminant Lewy body disease.

The clinical distinction between Parkinson's disease (PD) with dementia (PDD) and dementia with Lewy bodies (DLB) is challenged by most neuropathological studies showing nearly identical changes in both conditions. We report an unusual case of PD evolving into a rapidly progressive dementia leading to death within 3 months that showed nearly all clinical features of DLB. At autopsy, numerous Lewy bodies and Lewy neurites were found in several areas of the brainstem, the limbic system, and the neocortex, consistent with pure DLB. This case demonstrates that Lewy body disease may exhibit a dramatic course without any coexisting pathology and exemplifies that PD, PDD, and DLB may sometimes represent sequential, yet overlapping, phenotypes of a same clinicopathological entity.

Correlation of cerebrovascular symptoms and microembolic signals with the stratified gray-scale median analysis and color mapping of the carotid plaque.

BACKGROUND AND PURPOSE: To determine whether a stratified gray-scale median (GSM) analysis of the carotid plaque combined with color mapping correlated better with the presence of neurological symptoms and microembolic signals (MES) than a whole plaque measurement. METHODS: A total of 131 patients presenting 167 carotid stenoses between 30% and 99% were analyzed by ultrasound. Emboli detection was performed by transcranial Doppler. For each plaque, the GSM values at depth 0 mm (surface) and at one third (30) and one half (50) of the plaque thickness were compared with the values obtained for the whole plaque. The plaque pixels were mapped into 3 colors: red, yellow and green, depending on their GSM value. RESULTS: Mean GSM values were lower among symptomatic plaques, but a statistically significant difference between values of the whole plaque and those of the surface was obtained only for MES+ stenoses (P<0.01). In a proportional odds logistic regression model based on 4 subgroups with an increasing clinical risk (MES-/symptoms-; MES-/symptoms+; MES+/symptoms-; +; MES+/symptoms+), low mean GSM values and the predominant red color at the surface were independent factors associated with the presence of symptoms or MES (P<0.0005). Furthermore, compared with a whole plaque measurement, analysis of the surface values predicted systematically with a greater sensitivity and specificity (receiver operating characteristic curves) each one of these 4 subgroups. CONCLUSIONS: Low mean GSM values and predominance of the red color at the surface correlated with most of the symptomatic or MES+ stenoses. This combined approach should be further investigated in a longitudinal study.

The pathophysiology of watershed infarction in internal carotid artery disease: review of cerebral perfusion studies.

BACKGROUND AND PURPOSE: In carotid disease, infarcts can occur in the cortical as well as internal watershed (WS), or both. Better understanding the pathophysiology of WS infarcts would guide treatment. Two distinct hypotheses, namely low-flow and micro-embolism, are equally supported by neuropathological and physiological studies. Here we review the evidence regarding the mechanisms for WS stroke in carotid disease and whether they differ between cortical and internal WS infarcts. SUMMARY OF REVIEW: After a brief account of the anatomy of the WS and the cerebrovascular physiology in circumstances of low perfusion pressure, the literature concerning the mechanisms of WS infarction in carotid disease is reviewed and discussed with emphasis on imaging and ultrasound studies of the cerebral hemodynamics. CONCLUSIONS: The evidence strongly favors a hemodynamic mechanism for internal WS infarction, especially regarding the so-called rosary-like pattern in the centrum semiovale. However, the relationships between cortical WS infarction and hemodynamic compromise appear more complicated. Thus, although severe hemodynamic compromise appears to underlie combined cortical and internal WS infarction, artery-to-artery embolism may play an important role in isolated cortical WS infarcts. Based on the high prevalence of microembolic signals documented by ultrasound in symptomatic carotid disease, a recent hypothesis postulates that embolism and hypoperfusion play a synergetic role, according to which small embolic material prone to lodge in distal field arterioles would be more likely to result in cortical micro-infarcts when chronic hypoperfusion prevails. Future studies combining imaging of brain perfusion, diffusion-weighted imaging, and ultrasound detection of microembolic signals should help resolve these issues.