Biomedical subjects

Robert J Wityk

Publications and source records attributed to Robert J Wityk.

At least 19 recordsLinked to original sources

PubMed2006

Predicting abnormal coagulation in ischemic stroke: reducing delay in rt-PA use.

Normal prothrombin time (PT) and partial thromboplastin time (PTT) are recommended for administration of recombinant tissue-plasminogen activator (rt-PA) in stroke, but waiting for results can delay use. We examined the charts of 365 stroke patients to assess predetermined risk factors associated with elevated PT/PTT. Elevated PT/PTT can be predicted in patients taking warfarin or heparin/heparinoid or on hemodialysis, according to emergency department triage, with 100% sensitivity and 94.7% specificity. These results could be applied to rt-PA candidates and reduce potential delays.

Adult↗

PubMed2006

Brain injury from cardiac bypass procedures.

Patients who undergo coronary artery bypass grafting (CABG) are at increased risk for brain injury. Surgical techniques have advanced so that the risk of neurological sequelae is decreased, but there remains significant morbidity and mortality related to the postoperative period as well as to the surgery itself. In addition, patients who undergo CABG have comorbidities or demographic factors that may increase their likelihood of developing neurological complications. Pathophysiological mechanisms of cerebral injury after CABG range from hemodynamic compromise to embolization, either intraoperatively or postoperatively. Biochemical markers such as S100 and neuron-specific enolase may play a role in the prediction of outcome after CABG, and because of this may help elucidate other potential risk factors. Specific neurological sequelae are discussed, such as stroke, with summaries of the apparent risk factors, as well as encephalopathy, seizure, and both short- and long-term cognitive deficits. Changes in surgical technique have led to some improvements, but there is no definitive information yet as to the role of some of these, such as the use of off-pump CABG. Other techniques such as the use of an arterial filter are discussed, as are their potential benefits in the prevention of neurological complications.

Biomarkers↗

PubMed2006

Patients with diffusion-perfusion mismatch on magnetic resonance imaging 48 hours or more after stroke symptom onset: clinical and imaging features.

BACKGROUND: Abnormalities in diffusion-weighted (DWI) and perfusion-weighted (PWI) magnetic resonance imaging (MRI) are thought to reflect the presence of brain tissue at risk for ischemic stroke. Many patients with acute ischemic stroke have a mismatch pattern in which the PWI volume is larger than the DWI lesion. This mismatch typically resolves over 24-48 hours. Little is known about the presence of DWI-PWI mismatch in later stages of stroke. METHODS: This is a retrospective study of 122 patients admitted with a diagnosis of acute ischemic stroke who had DWI and PWI abnormalities on studies performed within 7 days of onset of symptoms. Patients were divided into two groups: those with MRI performed <48 hours and those with MRI performed >or=48 hours from onset of symptoms. RESULTS: Among 42 patients with MRI performed >or=48 hours after onset of stroke symptoms, 15 of 42 (36%) showed a mismatch pattern, compared to 45 of 80 (56%) in the <48 hours group (P < 0.05). Most of the patients in the >or=48 hours group with mismatch had large artery occlusive disease and many had neurological fluctuations. A subset of these patients were treated with induced hypertension and showed clinical improvement. CONCLUSIONS: Some patients have persistent DWI-PWI mismatch up to several days after stroke onset. Further studies are needed to determine if these patients should be candidates for reperfusion therapy.

Brain↗

PubMed2006

Safety of induced hypertension therapy in patients with acute ischemic stroke.

INTRODUCTION: The management of blood pressure in acute stroke is controversial. Small pilot studies have suggested that blood pressure augmentation improves short-term neurological function, but the rate of adverse events with induced hypertension (IH) therapy is unknown. METHODS AND RESULTS: We reviewed 100 consecutive patients who underwent perfusion magnetic resonance imaging for acute ischemic stroke. IH therapy was employed in 46 patients and standard therapy (ST) in 54. The two groups had similar baseline characteristics, but more patients in the IH group had significant large-artery stenoses. The IH group achieved significantly higher mean arterial pressure (MAP) than the ST group within 3 days of initiation of therapy with a variety of vasopressor agents. Only 35% of patients in the IH group actually achieved the target MAP augmentation of 10-20% above baseline, however. All patients survived to discharge. Four patients experienced major adverse events in each group. Two patients in the IH group experienced intra cerebral hemorrhage compared to none in the ST group. Two patients in the ST group experienced myocardial ischemia, compared to none in the IH group. The National Institutes of Health Stroke Scale during the hospitalization and place of discharge were similar in both groups. Patients in the IH group were more likely to be admitted to the intensive care unit and had a longer hospital stay by nearly 4 days compared to the ST group. CONCLUSION: These data demonstrate the relative safety of IH therapy in acute stroke patients. Given the greater use of resources, however, the role of IH in improving clinical outcomes requires a prospective, randomized trial.

Aged↗

PubMed2006

Blood pressure management during acute ischaemic stroke.

Control of hypertension is a well-established goal of primary stroke prevention. Management of blood pressure in patients during acute ischaemic stroke, however, is complicated by the need to maintain brain perfusion. Lowering blood pressure in the acute setting may avoid the deleterious effects of high blood pressure but may also lead to cerebral hypoperfusion and worsening of the ischaemic stroke. Little information is available from clinical trials concerning optimal blood pressure management in acute stroke. Current protocols of thrombolytic therapy require strict blood pressure control below certain prescribed limits; however, in most acute stroke patients not treated with thrombolysis, blood pressure reduction is not routinely recommended and guidelines for target blood pressures are difficult to justify. Preliminary studies, in fact, suggest that there may be a role for blood pressure elevation in the treatment of some patients with acute ischaemic stroke.

Adrenergic Antagonists↗

PubMed2005

Low-grade carotid stenosis: looking beyond the lumen with MRI.

BACKGROUND AND PURPOSE: The management of carotid atherosclerosis is well-established for symptomatic stenosis above 69%, but the optimal approach for managing lower degrees of narrowing remains uncertain. Because the risk of stroke increases with higher grades of stenosis, we are inclined to consider low-grade disease to be low risk. This approach, however, does not take into account other factors such as plaque size or composition. Plaque may progress to a substantial size before it demonstrates significant stenosis by angiography. We know that low-grade disease can result in cerebrovascular ischemic events, but predicting vulnerable lesions has not been possible by relying on stenosis alone. SUMMARY OF REVIEW: An understanding of the clinical behavior of plaque causing little to no narrowing is now possible with the advent of high-resolution black blood MRI, a modality that does not rely on luminal narrowing for detection. CONCLUSIONS: We present the current understanding of the clinical implications of low-grade carotid stenosis with an example of the MRI assessment of high-risk carotid plaque causing minimal narrowing that highlights the importance of looking beyond the lumen.

Aged↗

PubMed2005

Quantitation of contrast TCD in patients with and without atrial septal aneurysm.

BACKGROUND AND PURPOSE: Patients with a combination of atrial septal aneurysm (ASA) and patent foramen ovale (PFO) have a substantially higher rate of recurrent ischemic events as compared to PFO alone. One possible explanation is a greater degree of right-to-left shunting with the combination. METHODS: Retrospective study using contrast transcranial Doppler ultrasonography (c-TCD) to study the degree of shunting in 46 patients with PFO with either transient ischemic attack or cryptogenic ischemic stroke. Eight patients with PFO+ASA identified on transesophageal echocardiogram were compared to 38 patients with PFO but without ASA. RESULTS: The number of embolic counts was no different with or without an ASA. Valsalva maneuver increased number of emboli, especially in patients with large PFOs. CONCLUSIONS: Patients with ASA in addition to PFO do not appear to have an increased risk of right-to-left shunting as measured by c-TCD as compared to PFO alone.

Case-Control Studies↗

PubMed2005

Etiology of perfusion-diffusion magnetic resonance imaging mismatch patterns.

BACKGROUND AND PURPOSE: Diffusion-and perfusion-weighted magnetic resonance imaging (DWI and PWI) are useful tools for the assessment of brain ischemia. Discrepancies between the extent of DWI and PWI abnormalities are thought to depend pre dominantly on time from symptom onset to magnetic resonance imaging (MRI) examination. However, underlying ischemic stroke etiology can also be important. A mismatch may indicate the presence of tissue at risk for infarction, whereas the relevance of other DWI/PWI patterns is uncertain. The authors therefore investigated the etiology of brain ischemia in patients with different DWI/PWI patterns. METHODS: Retrospective study of 130 patients with acute brain ischemia and detailed stroke workup, including MRI within a week after symptom onset (40 +/- 39 hours). Patients were divided into the following groups: mis-match (PWI > DWI), reverse mismatch (DWI > PWI), and match (<25% difference between PWI and DWI). RESULTS: Mismatch occurred in 49% of patients, whereas 22% had reverse mis-match and 29% matched lesions. Time from symptom onset to MRI examination was similar between the 3 groups. Largeartery atherosclerosis increased by almost 4-fold the odds of mismatch (odds ratio: 3.89, 95% confidence interval: 1.72-8.78; P < .001), whereas patients with reverse mismatch were likely to have cryptogenic stroke. Patients with matched lesions were similarly distributed among different stroke subtypes. CONCLUSIONS: Ischemic stroke etiology appears to influence the development of specific DWI/PWI patterns. Prospective studies are needed to confirm these observations.

Aged↗

PubMed2004

New England Medical Center Posterior Circulation registry.

Among 407 New England Medical Center Posterior Circulation registry patients, 59% had strokes without transient ischemic attacks (TIAs), 24% had TIAs then strokes, and 16% had only TIAs. Embolism was the commonest stroke mechanism (40% of patients including 24% cardiac origin, 14% intraarterial, 2% cardiac and arterial sources). In 32% large artery occlusive lesions caused hemodynamic brain ischemia. Infarcts most often included the distal posterior circulation territory (rostral brainstem, superior cerebellum and occipital and temporal lobes); the proximal (medulla and posterior inferior cerebellum) and middle (pons and anterior inferior cerebellum) territories were equally involved. Severe occlusive lesions (>50% stenosis) involved more than one large artery in 148 patients; 134 had one artery site involved unilaterally or bilaterally. The commonest occlusive sites were: extracranial vertebral artery (52 patients, 15 bilateral) intracranial vertebral artery (40 patients, 12 bilateral), basilar artery (46 patients). Intraarterial embolism was the commonest mechanism of brain infarction in patients with vertebral artery occlusive disease. Thirty-day mortality was 3.6%. Embolic mechanism, distal territory location, and basilar artery occlusive disease carried the poorest prognosis. The best outcome was in patients who had multiple arterial occlusive sites; they had position-sensitive TIAs during months to years.

Academic Medical Centers↗

PubMed2004

Variability in subcortical aphasia is due to variable sites of cortical hypoperfusion.

A variety of fluent and nonfluent aphasias have been reported after left basal ganglia stroke. It has been speculated that this heterogeneity may reflect variations in cortical hypoperfusion resulting from large vessel stenosis. To test this hypothesis, a consecutive series of 24 patients with left caudate infarct identified with diffusion-weighted imaging underwent language testing and perfusion-weighted imaging < 24h from onset of symptoms. Specific regions in perisylvian cortex were rated for the percentage of the region that was hypoperfused. Aphasia type was determined on the basis of speech fluency, comprehension, and repetition performance on the language tests. Association between aphasia type/language impairment and regions of hypoperfusion were identified with Fisher's exact tests. Results demonstrated that in patients with acute left caudate infarct, the presence and type of aphasia reflected regions of hypoperfusion, and generally followed predictions based on chronic lesion studies, regarding anatomical lesions associated with classic aphasia types.

Adult↗

PubMed2003

Acquired immunodeficiency syndrome and the risk of stroke.

BACKGROUND AND PURPOSE: Although acquired immunodeficiency syndrome (AIDS) is thought to increase the risk of stroke, few data exist to quantify this risk. This is the first population-based study to quantify the AIDS-associated risk of stroke. METHODS: We identified all incident ischemic stroke (IS) and intracerebral hemorrhage (ICH) cases among young adults 15 to 44 years of age in central Maryland and Washington, DC, who were discharged from any of the 46 hospitals in the study area in 1988 and 1991. Using data from the medical records, 2 neurologists reviewed each case to confirm the diagnosis. Cases of AIDS among these patients with stroke were defined using Centers for Disease Control and Prevention criteria (1987). The number of cases of AIDS in the central Maryland and Washington population during 1988 and 1991 was determined from regional health departments working with the Centers for Disease Control and Prevention. Poisson regression was used to estimate the age-, race-, and sex-adjusted relative risk of stroke associated with AIDS. RESULTS: There were 385 IS cases (6 with AIDS) and 171 ICH cases (6 with AIDS). The incidences of IS and ICH among persons with AIDS were both 0.2% per year. AIDS conferred an adjusted relative risk of 13.7 (95% confidence interval [CI], 6.1 to 30.8) for IS and 25.5 (95% CI, 11.2 to 58.0) for ICH. After exclusion of 5 cases of stroke in AIDS patients in whom other potential causes were identified, AIDS patients continued to have an increased risk of stroke with an adjusted relative risk of 9.1 (95% CI, 3.4 to 24.6) for IS and 12.7 (95% CI, 4.0 to 40.0) for ICH. CONCLUSIONS: This population-based study found that AIDS is strongly associated with both IS and ICH.

Acquired Immunodeficiency Syndrome↗

PubMed2003

Change in perfusion in acute nondominant hemisphere stroke may be better estimated by tests of hemispatial neglect than by the National Institutes of Health Stroke Scale.

BACKGROUND AND PURPOSE: It has been reported that National Institutes of Health Stroke Scale (NIHSS) scores correlate poorly with hypoperfused tissue measured by perfusion-weighted imaging (PWI) in nondominant hemisphere stroke. We conducted 2 studies to determine whether tests of hemispatial neglect provide a better measure of hypoperfusion and reperfusion than NIHSS in nondominant hemisphere stroke. METHODS: In study 1, 74 patients with acute ischemic, supratentorial stroke were administered the NIHSS, tests of neglect or aphasia, and diffusion-weighted imaging (DWI) and PWI on day 1 (<24 hours from onset) of stroke. Pearson correlations between volumes of PWI/DWI abnormality and functional tests were calculated. In study 2, 10 patients with acute, nondominant hemisphere stroke who were candidates for intervention to restore perfusion underwent PWI, DWI, NIHSS, and a line cancellation test on days 1 and 3. Correlations between change in volumes of PWI/DWI abnormality and change in functional tests were calculated. RESULTS: In study 1, in nondominant hemisphere stroke, volume of PWI abnormality correlated significantly with neglect scores (r=0.71; P<0.002) but not with NIHSS scores (r=0.39; P=NS). In dominant hemisphere stroke, volume of PWI abnormality correlated better with aphasia scores (r=0.50; P=0.0001) than with NIHSS scores (r=0.45; P=0.001). In study 2, change in volume of hypoperfused tissue on PWI correlated with change in line cancellation performance (r=0.83; P=0.003) but not with change in NIHSS score (r=0.26; P=NS). CONCLUSIONS: Tests of hemispatial neglect may better reflect dysfunction and reperfusion than NIHSS for patients with nondominant hemisphere stroke.

Acute Disease↗

PubMed2003

Neural regions essential for writing verbs.

Functional imaging data collected during cognitive tasks show which brain regions are active during those tasks, but do not necessarily indicate which regions are essential for those tasks. Here, in a study of two cases of selectively impaired written naming of verbs after focal brain ischemia, we combined imaging and behavioral testing to unambiguously identify brain regions that are crucial for a specific cognitive process. We used magnetic resonance perfusion imaging to show that the selective impairment in each case was due to hypoperfusion (low blood flow) in left posterior inferior frontal gyrus (PIFG) and precentral gyrus (PrG); the impairment was immediately reversed when blood flow was restored to these regions, indicating that parts of the left frontal lobe are crucial for representing and processing verbs.

Aged↗

PubMed2003

Timing of neurologic deterioration in massive middle cerebral artery infarction: a multicenter review.

OBJECTIVE: To determine the time interval between symptom onset and neurologic deterioration related to cerebral edema in patients with massive middle cerebral artery infarction. The time period between onset and neurologic deterioration represents the window for surgical intervention. DESIGN: Multicenter retrospective chart review. SETTINGS: Five university-affiliated medical centers. PATIENTS: Fifty-three patients with massive middle cerebral artery infarction who experienced neurologic deterioration defined by a decrease in the Glasgow Coma Scale score of two or more points attributable to mass effect. MEASUREMENTS AND MAIN RESULTS: A total of 53 patients (mean age, 62 +/- 18 yrs; 25 [47%] were men) with neurologic deterioration were identified by using International Classification of Diseases (9th revision) codes and local registries. Medical records and neuroimaging studies were reviewed by a stroke neurologist or neurointensivist to identify the time of neurologic deterioration. Thrombolytics were used at presentation in 19 (35%) patients. A total of 19 (36%) patients had neurologic deterioration within 24 hrs of symptom onset. By 48 hrs, 36 (68%) patients had manifested clinical deterioration. A few patients had later neurologic deterioration on day 3 (n = 10), day 4 (n = 2), day 5 (n = 2), and day 6 or after (n = 3). A total of 25 (47%) of the 53 patients died during hospitalization. The highest frequency of deaths occurred on day 3. CONCLUSIONS: Neurologic deteriorations related to cerebral edema after massive middle cerebral artery infarction occur in most patients within 48 hrs of symptom onset.

Brain Edema↗

PubMed2003

Transcranial Doppler markers of diffusion-perfusion mismatch.

BACKGROUND AND PURPOSE: During the evaluation of acute ischemic stroke with diffusion- and perfusion-weighted magnetic resonance imaging (DWI and PWI, respectively), the presence of salvageable brain tissue is suggested by the occurrence of a perfusion-diffusion "mismatch." DWI and PWI, however, are not universally available and have inherent inconveniences, which justify a search for practical diagnostic alternatives. The purpose of this study is to investigate whether there are transcranial Doppler (TCD) markers of mismatch. METHODS: Retrospective analysis of 22 patients with acute ischemic stroke affecting the middle cerebral artery (MCA) territory, who had a TCD performed within 24 hours of magnetic resonance imaging (MRI) with DWI and PWI. RESULTS: MRI and TCD were performed on average 10.8 +/- 9.2 hours apart. Time from symptom onset to MRI and TCD completion were 1.6 +/- 1.6 and 2 +/- 1.9 days, respectively. MCA and intracranial internal carotid artery (ICA) cerebral blood flow velocity (CBFV) asymmetry, together with a large ICA-to-MCA gradient, were associated with the presence of mismatch. The combined use of 2 TCD parameters (MCA CBFV asymmetry of > or = 30% and ICA-to-MCA gradient > or = 20 cm/sec) had a sensitivity of 75%, specificity of 80%, positive predictive value of 82%, and negative predictive value of 73% at detecting mismatch cases. CONCLUSIONS: Diffusion-perfusion mismatch appears to be associated with interhemispheric asymmetry between MCA and ICA CBFVs, and a large CBFV gradient between the ICA and MCA on the affected side. Prospective studies are required to verify these observations and to determine whether TCD can be used to follow patients with mismatch.

Adult↗

PubMed2003

Stroke-free survival and its determinants in patients with symptomatic vertebrobasilar stenosis: a multicenter study.

OBJECTIVE: We sought to determine the long-term stroke-free survival of patients who present with ischemic events related to intracranial vertebrobasilar stenosis. METHODS: A retrospective cohort of patients diagnosed with symptomatic vertebrobasilar stenosis on the basis of magnetic resonance angiography and/or conventional angiography was identified at four academic medical centers. Patients' clinical and follow-up information was obtained through hospitalization records, clinic visits, and telephone interviews. Kaplan-Meier analysis was performed to determine the rate of stroke-free survival for a 5-year period. Cox proportional hazards analysis was performed to determine the effect of demographic and clinical factors on stroke-free survival. RESULTS: A total of 102 patients were included, whose mean age was 64 +/- 12 years. Fifty-five (54%) of the patients were men. The mean follow-up period was 15 +/- 15.9 months (range, 1-60 mo). During the follow-up period, 14 (14%) of the patients experienced recurrent stroke. The overall mortality rate was 21% (n = 21). Stroke-free survival, calculated by using the Kaplan-Meier curve, was 76% at 12 months (95% confidence interval [CI], 66-83%) and 48% at 5 years (95% CI, 27-65%). The risk of recurrent stroke was 10.9 per 100 patient-years, and the rate of recurrent stroke and/or death was 24.2 per 100 patient-years. Cox proportional hazards analysis revealed that increasing age (hazards ratio, 1.05; 95% CI, 1.00-1.09) decreased stroke-free survival. Treatment with either antiplatelet agents or warfarin (hazards ratio, 0.018; 95% CI, 0.003-0.11) had a protective effect on stroke-free survival after adjusting for age, sex, race, hypertension, diabetes mellitus, smoking, hyperlipidemia, and lesion location. CONCLUSION: A low rate of stroke-free survival is observed in patients with symptomatic vertebrobasilar stenosis. Further studies are required to evaluate new medical and endovascular treatment options for this group of patients to improve long-term stroke-free survival.

Aged↗

PubMed2003

Combined stent placement and thrombolysis in acute vertebrobasilar ischemic stroke.

BACKGROUND AND PURPOSE: Acute vertebrobasilar ischemic stroke is often associated with high morbidity and mortality with limited therapeutic options. Endovascular treatment with thrombolysis has offered some hope for affected patients; however, overall outcomes have been less than satisfactory. In this report, we present the results of our approach in six consecutive cases of acute vertebrobasilar ischemic stroke by combined proximal vessel stent placement and thrombolysis. METHODS: Six consecutive cases were retrospectively reviewed for the clinical outcome of patients presenting to our institution with acute posterior circulation stroke who underwent cerebral revascularization including proximal arterial stent placement by using balloon-expandable coronary stents and intraarterial thrombolysis. All of these patients were initially evaluated by stroke team neurologists and imaged with MR, including diffusion-weighted imaging documenting acute posterior circulation stroke. MR angiography of the circle of Willis was also obtained. Short-term follow-up was conducted to assess National Institutes of Health stroke scores (NIHSS) and modified Rankin scores. RESULTS: In these six cases, a combined approach of proximal arterial stent placement (five cases of vertebral artery origin and one case of carotid and subclavian stent placement plus vertebral artery revascularization) and thrombolysis was performed at variable times after stroke onset (range, 30 hours to 5 days). Four of the six patients had good basilar artery recanalization (Thrombolysis in Myocardial Infarction [TIMI] grade 0-1 before tissue plasminogen activator thrombolysis and TIMI grade 2 after procedure). Four of six patients had excellent immediate recovery and were discharged to an acute rehabilitation unit or their homes with improved neurologic symptoms and functional status. Two patients died: one patient presented with coma at outset with an NIHSS of 38, and the other patient probably had reocclusion of the basilar artery within 24 hours despite initial postprocedural improvement. CONCLUSION: We demonstrate that, in the setting of acute stroke, stent placement in combination with revascularization and thrombolysis is practical and allows quick access to a clot and simultaneously increases perfusion through collaterals during the thrombolytic process. In particular, basilar thrombolysis may be facilitated by proximal vertebral stent placement as concomitant atheromatous vertebrobasilar stenosis is common.

Acute Disease↗

PubMed2002

Intracerebral hemorrhage and postpartum cerebral vasculopathy.

INTRODUCTION: Intracerebral hemorrhage (ICH) associated with pregnancy commonly occurs in the postpartum period in the setting of preeclampsia/eclampsia. We describe the clinical course of two patients with ICH due to postpartum cerebral vasculopathy in the absence of toxemia. METHODS: We reviewed two cases with ICH and postpartum vasculopathy in our hospital (1996-2001) and compared them with seven similar case reports from the literature. RESULTS: Mean age of all patients is 28.7+/-5.6 years (mean+/-S.D.). Toxemia of pregnancy was absent in all cases. ICHs were cortical in eight and putaminal in one patient. Erythrocyte sedimentation rate was elevated in two. Two cases rehemorrhaged during the same admission. No cerebral infarctions were reported. All patients had diffuse vasculopathy on conventional catheter angiography, with no clinical manifestations or laboratory data supportive of extracerebral or systemic vasculitis. Eight patients were treated with corticosteroids, two with additional cytotoxic agents and one with nimodipine alone. Improvement on follow-up cerebral angiography (catheter or MRA) and transcranial Doppler ultrasonography (TCD) was noted in eight cases. One did not have follow-up cerebral imaging but had an excellent clinical outcome. All cases had good to excellent functional recovery. CONCLUSIONS: Postpartum ICH in the absence of toxemia may be associated with isolated cerebral vasculopathy. The clinical course and functional outcome is good to excellent. This entity appears to be distinct from cerebral vasculitis, which is usually associated with poor outcome.

Adrenal Cortex Hormones↗