Biomedical subjects
Publications and source records attributed to F S Buonanno.
We report three patients with large middle cerebral artery infarctions in the non-dominant hemisphere, with striking recovery of motor function. In each case this excellent functional outcome correlated with selective sparing of the motor cortex in the precentral gyrus. We discuss some of the possible circulatory variants that might underlie this pattern of infarction.
Cardiac right-to-left shunts (RLSs) can be detected by echocardiography and transcranial Doppler ultrasound (TCD). In patients without adequate transtemporal bone windows, results may be obtained by insonating extracranial arteries; however, the sensitivity and practicality of this approach is unknown. In 34 patients evaluated with echocardiography for RLSs, 73 studies were performed with unilateral, simultaneous contrast TCD (cTCD) of the middle cerebral artery (MCA) and anterior cerebral artery (ACA) and submandibular power M-mode Doppler (PMD) ultrasound of the extracranial internal carotid artery (ecICA). The number of microbubble (MB) signals and their times of first appearance were determined. RLS volume was graded on 6 levels (I = trace, II = small, III = medium, IVa = large, IVb = shower, IVc = curtain) and compared between MCA and ecICA recordings. In 2 of 24 cTCD studies in 15 patients without evidence of RLSs on single-gated MCA monitoring, low-volume RLSs (grades I and II) were detected via ecICA insonation; in both, MB signatures were tracked in the ecICA, passing into the ipsilateral ACA. In 40 of 49 studies (26 patients) in which RLSs were demonstrated with single-gated MCA monitoring, more MBs were detected in the ecICA than the MCA, with either single-gated or M-mode images, with increases of 76.9% and 66.1%, respectively (P = .027). Compared to single-gated studies, M-mode technology detected nonsignificant increases in MB number in both the MCA and the ecICA (by 20.2% and 14.0%, respectively). Contrast PMD with cervical ICA recording is at least as sensitive and specific as the traditional MCA method in detecting RLSs; furthermore, this method seems to be more sensitive for low-volume RLSs (grades I-III) because of air MB decay (9.2%) and entry into the ipsilateral ACA (34.2%). This is in concordance with the increase of detected RLS grades observed in 32.7% of patients with echocardiography-documented RLSs. The authors therefore suggest the incorporation of ecICA PMD not only in patients with poor ultrasonic bone windows but also in every patient being evaluated for suspected RLSs.
OBJECTIVE: To investigate the causes of fever in subarachnoid hemorrhage (SAH) and examine its relationship to outcome. BACKGROUND: Fever adversely affects outcome in stroke. Patients with SAH are at risk for cerebral ischemia due to vasospasm (VSP). In these patients, fever may be both caused by, and potentiate, VSP-mediated brain injury. METHODS: The authors prospectively studied patients admitted to a neurologic intensive care unit with nontraumatic SAH, documenting Hunt-Hess grade, Fisher group, Glasgow Coma Score, bacterial culture data, daily transcranial Doppler mean velocities, and maximum daily temperatures. Patients were classified as febrile (temperature above 38.3 degrees C for at least 2 consecutive days) or afebrile (no fever or isolated episodes of temperature above 38.3 degrees C). VSP was verified by either transcranial Doppler or angiographic criteria. Rankin scale scores on discharge were dichotomized into good (0 to 2) or poor (3 to 6) outcomes. RESULTS: Ninety-two consecutive patients were studied. Thirty-eight patients were classified as febrile. No source for infection was found in 10 of 38 (26%) patients. In a multivariate analysis, three variables independently predicted fever occurrence: ventriculostomy (OR, 8.5 [CI, 2.4 to 29.7]), symptomatic VSP (OR, 5.0 [CI, 1.03 to 24.5]), and older age (OR, 1.75 per 10 years [CI, 1.02 to 3.0]). Poor outcome was related to fever (OR, 1.4 per each day febrile [CI, 1.1 to 1.88]), older age (OR, 1.64 per 10 years [CI, 1.04 to 2.58]), and intubation (OR, 21.8 [CI, 5.6 to 84.5]). CONCLUSION: Fever in SAH is associated with vasospasm and poor outcome independently of hemorrhage severity or presence of infection.
The aim of this pilot study was to determine whether the use of induced hypertension in acute stroke is feasible and associated with neurologic improvement. Phenylephrine was used to raise the systolic blood pressure in patients with acute stroke by 20%, not to exceed 200 mmHG: Of 13 patients treated, 7 improved by 2 points on the NIH Stroke SCALE: No systemic or neurologic complications were seen. The authors conclude that induced hypertension in acute stroke is feasible and likely safe and can improve the neurologic examination in some patients.
The capsular warning syndrome (CWS) is a subtype of transient ischemic attack characterized by its recurrent nature, absence of cortical signs, and high probability of early capsular stroke. Currently, standard imaging techniques have identified only internal capsule lesions in this entity. The authors present 2 cases with an otherwise typical CWS in whom a brainstem stroke was detected by diffusion-weighted imaging (DWI). DWI's ability to differentiate between acute and chronic infarcts may assist in more accurate localization of clinical syndromes.
Stroke patients with paradoxical embolus mandate a search for deep venous thrombosis (DVT) in the lower extremities. Iliac vein compression, or May-Thumer syndrome, places certain patients at risk for development of DVT. The authors present 3 stroke patients with patient foramen ovale and paradoxical cerebral embolism, with demonstrated iliac vein compression as the presumed source of their embolus. May-Thumer syndrome should be considered a potential source of clot, as definitive therapy of this disorder can be curative.
BACKGROUND AND PURPOSE: Tissue signatures from acute MR imaging of the brain may be able to categorize physiological status and thereby assist clinical decision making. We designed and analyzed statistical algorithms to evaluate the risk of infarction for each voxel of tissue using acute human functional MRI. METHODS: Diffusion-weighted MR images (DWI) and perfusion-weighted MR images (PWI) from acute stroke patients scanned within 12 hours of symptom onset were retrospectively studied and used to develop thresholding and generalized linear model (GLM) algorithms predicting tissue outcome as determined by follow-up MRI. The performances of the algorithms were evaluated for each patient by using receiver operating characteristic curves. RESULTS: At their optimal operating points, thresholding algorithms combining DWI and PWI provided 66% sensitivity and 83% specificity, and GLM algorithms combining DWI and PWI predicted with 66% sensitivity and 84% specificity voxels that proceeded to infarct. Thresholding algorithms that combined DWI and PWI provided significant improvement to algorithms that utilized DWI alone (P=0.02) but no significant improvement over algorithms utilizing PWI alone (P=0.21). GLM algorithms that combined DWI and PWI showed significant improvement over algorithms that used only DWI (P=0.02) or PWI (P=0.04). The performances of thresholding and GLM algorithms were comparable (P>0.2). CONCLUSIONS: Algorithms that combine acute DWI and PWI can assess the risk of infarction with higher specificity and sensitivity than algorithms that use DWI or PWI individually. Methods for quantitatively assessing the risk of infarction on a voxel-by-voxel basis show promise as techniques for investigating the natural spatial evolution of ischemic damage in humans.
BACKGROUND AND PURPOSE: The goal of this study was to evaluate the utility of perfusion-weighted CT (PWCT) in predicting final infarct volume and clinical outcome in patients with acute middle cerebral artery (MCA) stroke. METHODS: Twenty-two consecutive patients with MCA stem occlusion who underwent intra-arterial thrombolysis within 6 hours of stroke onset had noncontrast CT and CT angiography with whole-brain PWCT imaging before treatment. Infarct volumes were computed from the initial PWCT and follow-up scans; clinical outcome was measured with the modified Rankin scale. RESULTS: Initial PWCT lesion volumes correlated significantly with final infarct volume (P=0.0002) and clinical outcome (P=0.01). For the 10 patients with complete recanalization, the relationship between initial and final lesion volume was especially strong (R(2)=0.94, P<0.0001, slope of regression line=0.92). For those without complete recanalization, there was progression of lesion volume on follow-up imaging (R(2)=0.50, P=0.01, slope of regression line=1.61). All patients with either initial PWCT lesion volumes >100 mL or no recanalization had poor outcomes (Rankin scores, 4 to 6). Mean admission NIH Stroke Scale scores and mean lesion volumes in the poor outcome group were significantly different compared with the good or fair outcome (Rankin scores, 0 to 3) group (21+/-4 versus 17+/-5, P=0.05, and 106+/-79 versus 29+/-37 mL, P=0.01). Patients with initial volumes <100 mL and partial or complete recanalization all had good (Rankin scores, 0 to 2) or fair (Rankin score, 3) outcomes. CONCLUSIONS: Lesion volumes on admission PWCT images approximate final infarct volume for patients with early complete recanalization of MCA stem occlusion. For those without complete recanalization, there is subsequent enlargement of lesion volume on follow-up. Initial PWCT lesion volumes also have predictive value; volumes >100 mL are associated with a poor clinical outcome. In these highly selected patients, initial PWCT lesion volume was a stronger predictor of clinical outcome than was initial NIH Stroke Scale score.
BACKGROUND: Most patients initially seen with a clinical syndrome consistent with a small-penetrator infarct (SPI) also harbor multiple, chronic, hyperintense, white matter lesions on conventional magentic resonance imaging (ie, T2-weighted image [T2WI] and fluid-attenuation inversion recovery [FLAIR] imaging). Diffusion-weighted imaging (DWI) can identify the clinically relevant "index infarction" in such circumstances, since it differentiates between acute and chronic lesions. OBJECTIVE: To determine the clinical and radiological predictors associated with misidentification of an SPI as acute using T2WI and FLAIR images in patients with an acute SPI seen on DWI. PATIENTS: Sixty-seven consecutive patients who had an SPI. METHODS: Two independent examiners, provided with brief clinical information, but blinded to DWI findings, sought a clinically appropriate lesion on T2WI and FLAIR imaging in 67 consecutive patients found to have an SPI seen on DWI. RESULTS: The index infarction based on evaluation of T2WI or FLAIR images was in a different location than the acute lesion as identified by DWI in 9 (13%) and 11 (16%) of 67 patients, respectively. Both T2WI and FLAIR imaging were rated normal in another 9% of the patients. Multivariate analysis showed that small lesion size (<10 mm) was the only predictor of misidentifying the clinically appropriate lesion on conventional magnetic resonance imaging (P<.01). CONCLUSIONS: T2-weighted imaging and FLAIR imaging fail to identify the clinically relevant SPI in almost one quarter of the patients found to have a lesion on DWI. The characteristics of DWI make it well suited for the detection of acute small infarcts. Diffusion-weighted imaging is necessary to consistently define the clinical-anatomical relations in patients initially seen with SPIs.
BACKGROUND: Previous studies have reported a high prevalence of mitral-valve prolapse among patients with embolic stroke (28 to 40 percent), especially among young patients (those < or =45 years old); this finding has practical implications for prophylaxis. However, diagnostic criteria for prolapse have changed and are now based on three-dimensional analysis of the shape of the valve; use of the current criteria reduces markedly the frequency of such a diagnosis and increases its specificity. Previously described complications must therefore be reconsidered. METHODS: In a case-control study, we reviewed data on 213 consecutive patients 45 years old or younger with documented ischemic stroke or transient ischemic attack between 1985 and 1995; they underwent complete neurologic and echocardiographic evaluations. The prevalence of prolapse in these patients was compared with that in 263 control subjects without known heart disease, who were referred to our institution for assessment of ventricular function before receiving chemotherapy. RESULTS: Mitral-valve prolapse was present in 4 of the 213 young patients with stroke (1.9 percent), as compared with 7 of the 263 controls (2.7 percent); prolapse was present in 2 of 71 patients (2.8 percent) with otherwise unexplained stroke. The crude odds ratio for mitral-valve prolapse among the patients who had strokes, as compared with those who did not have strokes, was 0.70 (95 percent confidence interval, 0.15 to 2.80; P=0.80); after adjustment for age and sex, the odds ratio was 0.59 (95 percent confidence interval, 0.12 to 2.50; P=0.62). CONCLUSIONS: Mitral-valve prolapse is considerably less common than previously reported among young patients with stroke or transient ischemic attack, including unexplained stroke, and no more common than among controls. Using more specific and currently accepted echocardiographic criteria, therefore, we could not demonstrate an association between the presence of mitral-valve prolapse and acute ischemic neurologic events in young people.
BACKGROUND: Diffusion-weighted MRI (DWI) represents a major advance in the early diagnosis of acute ischemic stroke. When abnormal in patients with stroke-like deficit, DWI usually establishes the presence and location of ischemic brain injury. However, this is not always the case. OBJECTIVE: To investigate patients with stroke-like deficits occurring without DWI abnormalities in brain regions clinically suspected to be responsible. METHODS: We identified 27 of 782 consecutive patients scanned when stroke-like neurologic deficits were still present and who had normal DWI in the brain region(s) clinically implicated. Based on all the clinical and radiologic data, we attempted to arrive at a pathophysiologic diagnosis in each. RESULTS: Best final diagnosis was a stroke mimic in 37% and a cerebral ischemic event in 63%. Stroke mimics (10 patients) included migraine, seizures, functional disorder, transient global amnesia, and brain tumor. The remaining patients were considered to have had cerebral ischemic events: lacunar syndrome (7 patients; 3 with infarcts demonstrated subsequently) and hemispheric cortical syndrome (10 patients; 5 with TIA, 2 with prolonged reversible deficits, 3 with infarction on follow-up imaging). In each of the latter three patients, the regions destined to infarct showed decreased perfusion on the initial hemodynamically weighted MRI (HWI). CONCLUSIONS: Normal DWI in patients with stroke-like deficits should stimulate a search for nonischemic cause of symptoms. However, more than one-half of such patients have an ischemic cause as the best clinical diagnosis. Small brainstem lacunar infarctions may escape detection. Concomitant HWI can identify some patients with brain ischemia that is symptomatic but not yet to the stage of causing DWI abnormality.
PURPOSE: To evaluate the diagnostic accuracy of diffusion-weighted magnetic resonance (MR) imaging performed within 6 hours of the onset of stroke symptoms. MATERIALS AND METHODS: The authors reviewed the patient records and images from all patients hospitalized in a 10-month period in whom diffusion-weighted imaging was performed within 6 hours of the onset of strokelike symptoms (n = 22). Analyses included comparison of the initial interpretation of the diffusion-weighted images with the final clinical diagnosis; blinded reviews of computed tomographic (CT) scans and conventional and diffusion-weighted images; and determination of lesion contrast-to-noise ratios (CNRs). RESULTS: Diffusion-weighted images indicated stroke in 14 patients, all of whom had a final diagnosis of acute stroke. Diffusion-weighted images were negative in eight patients, all of whom had a final clinical diagnosis other than stroke (100% sensitivity, 100% specificity, chi 2 = 23.00, P < .0001). Blinded reviews yielded 100% sensitivity and 86% specificity for diffusion-weighted MR imaging (chi 2 = 15.43, P < .0005); 18% sensitivity and 100% specificity for conventional MR imaging (chi 2 = 2.85, P > .2); and 45% sensitivity and 100% specificity for CT (chi 2 = 4.40, P > .10). Lesion percentage CNRs were 77% for diffusion-weighted imaging, 5.5% for CT, 9.8% for T2-weighted MR imaging, and 3.1% for proton-density-weighted MR imaging (P < .002 for diffusion-weighted imaging vs others). CONCLUSION: Diffusion-weighted MR imaging is highly accurate for diagnosing stroke within 6 hours of symptom onset and is superior to CT and conventional MR imaging.
PURPOSE: To investigate additional information provided by maps of relative cerebral blood flow in functional magnetic resonance (MR) imaging of human hyperacute cerebral ischemic stroke. MATERIALS AND METHODS: Diffusion-weighted and hemodynamic MR imaging were performed in 23 patients less than 12 hours after the onset of symptoms. Maps of relative cerebral blood flow and tracer mean tissue transit time were computed, as were maps of apparent diffusion and relative cerebral blood volume. Acute lesion volumes on the maps were compared with follow-up imaging findings. RESULTS: In 15 of 23 subjects (65%), blood flow maps revealed hemodynamic abnormalities not visible on blood volume maps. A mismatch between initial blood flow and diffusion findings predicted growth of infarct more often (12 of 15 subjects with infarcts that grew) than did a mismatch between initial blood volume and diffusion findings (eight of 15). However, lesion volumes on blood volume and diffusion maps correlated better with eventual infarct volumes (r > 0.90) than did those on blood flow and tracer mean transit time maps (r approximately 0.6), likely as a result of threshold effects. In eight patients, blood volume was elevated around the diffusion abnormality, suggesting a compensatory hemodynamic response. CONCLUSION: MR imaging can delineate areas of altered blood flow, blood volume, and water mobility in hyperacute human stroke. Predictive models of tissue outcome may benefit by including computation of both relative cerebral blood flow and blood volume.
BACKGROUND AND PURPOSE: Small infarcts in the territory of penetrator arteries were described as causing a number of distinct clinical syndromes. The vascular pathophysiology underlying such infarcts is difficult to ascertain without careful pathological study. However, the occurrence of multiple, small infarcts, linked closely in time but dispersed widely in the brain, raises the possibility of an embolic mechanism. The current study determines the frequency and clinical characteristics of patients with well-defined lacunar syndromes and the diffusion-weighted imaging (DWI) evidence of multiple acute lesions. METHODS: Sixty-two consecutive patients who presented to the emergency room with a clinically well-defined lacunar syndrome were studied by DWI within the first 3 days of admission. RESULTS: DWI showed multiple regions of increased signal intensity in 10 patients (16%). A hemispheric or brain stem lesion in a penetrator territory that accounted for the clinical syndrome ("index lesion") was found in all. DWI-hyperintense lesions other than the index lesion ("subsidiary infarctions") were punctate and lay within leptomeningeal artery territories in the majority. As opposed to patients with a single lacunar infarction, patients with a subsidiary infarction more frequently (P<0.05) harbored an identifiable cause of stroke. CONCLUSIONS: Almost 1 of every 6 patients presenting with a classic lacunar syndrome has multiple infarctions demonstrated on DWI. This DWI finding usually indicates an identifiable cause of stroke and therefore may influence clinical decisions regarding the extent of etiologic investigations and treatment for secondary prevention.
An 81 year old right handed woman developed a left alien hand syndrome characterised by involuntary movements of choking and hitting the face, neck, and shoulder. The patient showed multiple disorders of primary sensation, sensory processing, hemispatial attention, and visual association, as well as a combination of sensory, optic, and cerebellar ataxia (triple ataxia) of the left arm in the absence of motor neglect or hemiparesis. Imaging studies disclosed subacute infarction in the right thalamus, hippocampus, inferior temporal lobes, splenium of corpus callosum, and occipital lobe due to right posterior cerebral artery occlusion. This rare syndrome should be considered as a "sensory" or "posterior" form of the alien hand syndrome, to be distinguished from the "motor" or "anterior" form described more commonly.
BACKGROUND AND PURPOSE: We sought to characterize the evolution of acute ischemic stroke by MRI and its relationship to patients' neurological outcome. METHODS: Fourteen patients with acute ischemic stroke underwent MRI within 13 hours of symptom onset (mean, 7.4+/-3 hours) and underwent repeated imaging and concurrent neurological examination at 8, 24, 36, and 48 hours and 7 days and >42 days after first imaging. RESULTS: Diffusion-weighted imaging (DWI) lesion volumes increased between the first and second scans in 10 of 14 patients; scans with maximum DWI lesion volume occurred at a mean of 70.4 hours. Initial DWI lesion volume correlated with the largest T2 lesion volume (r=0.97; P<0.001). Final lesion volume was smaller than maximum lesion volume in 12 of 14 patients. There was positive correlation between the follow-up National Institutes of Health Stroke Scale score and the initial DWI lesion volume (r=0.67; P=0. 01) and maximum T2 lesion volume (r=0.77; P<0.01) and negative correlation with initial mean apparent diffusion coefficient ratio (ADCr) (r=-0.64; P<0.05). The ADCr was 0.73 at initial imaging and fell between the initial and second scans in 10 of 14 patients. Mean ADCr did not rise above normal until 42 days after stroke onset (P<0. 001). CONCLUSIONS: Serial MRI demonstrates the dynamic nature of progressive ischemic injury in acute stroke patients developing over hours to days, and it suggests that both primary and secondary pathophysiological processes can be valuable targets for neuroprotective interventions.
BACKGROUND AND PURPOSE: An M-shaped bifid notch on the ascending branch, or on the zenith, of the R wave in inferior ECG leads (II, III, aVF), so called "crochetage," is an indicator of ostium secundum atrial septal defects. The pathophysiology underlying this finding remains unknown. A crochetage pattern has not been previously reported in patients with patent foramen ovale (PFO); however, the location of this defect and the secundum atrial septum are similar. The purpose of this study was to determine the prevalence of crochetage in cryptogenic stroke patients with or without PFO. METHODS: A conservative selection scheme was used to identify patients likely to have had PFO-associated strokes (ie, cryptogenic) and to exclude any structural, functional, or vascular heart disease responsible for ECG changes. All patients had a standard 12-lead ECG. The prevalence of crochetage in each group was determined. RESULTS: Sixty consecutive patients were studied (28 with echo-documented PFO and 32 echo-negative control subjects). The crochetage pattern was present in at least 1 inferior limb lead in 10 of 28 PFO patients (36%) and 3 of 32 control subjects (9%) (P<0.05). The sensitivity and specificity of the crochetage pattern for diagnosis of PFO in cryptogenic stroke cases were 36% and 91%, respectively; positive predictive value was 77%. CONCLUSIONS: The finding of an ECG crochetage pattern may help to identify stroke patients with PFO, may help to streamline their diagnostic workup, and may warrant future studies to determine its value in stratifying stroke risk in patients with PFO.
OBJECTIVE: Standard MRI confirms the diagnosis of posterior leukoencephalopathy syndrome (PLES), recently associated with an increasing number of medical conditions. In PLES, T2-weighted MRI demonstrates hyperintensity spreading out from posterior brain regions; the pathophysiology remains mysterious. In the acute setting, diffusion-weighted imaging (DWI), but not standard MR imaging, can distinguish ischemic injury from those conditions known to cause vasogenic brain edema. DWI is potentially valuable in understanding the pathophysiology of PLES and in diagnosing patients who do not have previously known risk factors. METHODS: Serial CT and MRI studies (including DWI, apparent diffusion coefficient [ADC] maps, and, in one instance, perfusion-weighted imaging) were performed in three female patients with a neurologic syndrome consistent with PLES while hospitalized for treatment of other conditions. RESULTS: None of the patients had previously described risk factors for PLES; all had only mild elevations in blood pressure. MRI showed large, abnormal, T2 hyperintense regions in the posterior cerebrum with corresponding hyperintensity on ADC maps-signal characteristics predominantly consistent with vasogenic edema. There were also smaller patchy posterior cortical regions with decreased ADC and bright DWI consistent with infarction in one, and dramatic conversion of a large region to an ischemic pattern in another. CONCLUSIONS: ADC maps and DWI can successfully differentiate PLES from early cerebral ischemia, thus playing a pivotal role in treatment decisions. PLES is associated with a wider variety of conditions than has been previously reported and is not always reversible. Hyperintense DWI signal in patients with the syndrome likely marks a tissue stage of permanent brain injury.