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Biomedical subjects

R B Libman

Publications and source records attributed to R B Libman.

13 recordsLinked to original sources
PubMed1997

Stroke associated with cardiac surgery. Determinants, timing, and stroke subtypes.

OBJECTIVE: To determine the nature of strokes complicating cardiac surgery. DESIGN: A medical record review was undertaken of all patients who underwent cardiac surgery (either coronary bypass, valvular surgery, or both) between January 1990 and July 1995. Univariate and multivariate analyses were done using odds ratios (ORs) and logistic regression. RESULTS: A total of 2211 patients underwent cardiac surgery. A total of 44 patients (2%) had postoperative strokes. They were compared with 104 surgical controls. Univariate analysis revealed that the patients with stroke were significantly older and had significantly higher rates of transient ischemic attack, congestive heart failure, and peripheral vascular disease by history. A multivariate logistic regression revealed the significant variables associated with stroke were congestive heart failure (OR, 6.8) and transient ischemic attack (OR, 1.2). Analyses of surgical variables revealed that bypass pump time of more than 120 minutes (OR, 1.40) was the only significant predictor. The majority of strokes (61%) had occurred by postoperative day 2, but 39% occurred between postoperative days 3 to 9. Hemispheric syndromes occurred in 70%, brain stem and cerebellar syndromes in 14%, and lacunar syndromes in 16%. Computed tomographic scans revealed that 29 patients had new infarcts, of which 20 (69%) were territorial, 5 (17%) were small deep, and 4 (14%) were border zone. Hemorrhagic infarction was found in 2 cases (5%). One patient (2.5%) had a cardiorespiratory arrest while undergoing computed tomography. Discharge disposition was good in 88% of patients with stroke (12% with poor outcomes) vs 97% of controls with good outcomes (3% with poor outcomes) (P = .04). CONCLUSIONS: Strokes may be delayed following cardiac surgery perhaps because of ongoing risk of embolism or a hypercoagulable state. A surprisingly high proportion of patients have lacunar syndromes or small-deep infarcts shown on computed tomography. Early computed tomographic imaging may be useful to exclude hemorrhage if anticoagulation is considered, but is not without risk in these potentially unstable patients. Greater understanding of risk factors for stroke, timing, and subtypes may ultimately allow identification of patients at particularly high risk for perioperative stroke.

Aged↗
PubMed1996

Utility of repeat brain imaging in stroke.

PURPOSE: To determine the utility of repeat brain imaging in patients with stroke. METHODS: We reviewed the medical records of 98 consecutive patients in whom stroke was diagnosed between January 1 and December 31, 1991. We noted the number of brain scans performed, the indications cited, and whether repeat imaging changed the therapeutic decisions or final diagnosis. RESULTS: Ninety-eight patients underwent 221 procedures, with 123 repeat imaging studies (98 CT scans and 25 MR images). Sixteen patients had only one scan; 51 had two, and 31 had three or more. Indications for repeat imaging were explicitly documented in 62 (50%) of 123 repeated scans and inferred in another 41 (33%). In 20 (16%), no definite indication could be determined. Indications included lack of acute abnormal imaging findings on the initial scan (n = 48, 39%); compliance with stroke research protocol (n = 11, 9%). In none of the 82 patients did the repeated scan change the diagnosis; therapy was changed in only two (2%) of 82 patients (aspirin was discontinued). CONCLUSIONS: Repeat imaging in patients rarely results in changes in the initial diagnosis or the therapeutic plan; indications for repeat imaging are frequently not clearly stated; in certain groups of patients with stroke, repeat imaging may not be useful.

Aged↗
PubMed1995

Conditions that mimic stroke in the emergency department. Implications for acute stroke trials.

OBJECTIVE: To determine if any clinical variables allow early discrimination between stroke and other conditions presenting with a strokelike picture. BACKGROUND: New therapeutic modalities for the treatment of acute ischemic stroke are under active investigation. Many of these treatments have potential adverse effects. It is well known that noncerebrovascular conditions can present with a clinical picture mimicking stroke, so early accurate differentiation of such "mimics" from true stroke is essential. METHODS: Consecutive patients who presented to the emergency department with an initial diagnosis of stroke between January 1990 and January 1992 were evaluated. Chart review allowed these patients to be classified into two final diagnostic groups: stroke mimic and true stroke. Logistic regression was used to estimate the effects of predictor variables measured at initial evaluation on the final diagnosis. RESULTS: There were 411 patients initially diagnosed as having stroke. Of these, 78 patients (19%) were eventually found to have mimics, the majority comprising postictal states, systemic infections, tumors, and toxic-metabolic disturbances. Univariate analysis showed that decreased level of consciousness and normal eye movements increased the odds of mimic, while abnormal visual fields, diastolic blood pressure greater than 90 mm Hg, atrial fibrillation on electrocardiogram, and history of angina decreased the odds of mimic. Multivariate analysis showed that decreased consciousness increased, while history of angina decreased, the odds of mimic. Sensitivity of this model for predicting mimics was only 21% while specificity was 96%. CONCLUSION: For the neurologist faced with an immediate decision as to whether to randomize a patient with probable stroke to an acute treatment protocol, these findings have some usefulness but mandate further research into conditions that mimic stroke in the emergency department.

Aged↗
PubMed1995

Seizures and 'disappearing' brain lesions.

BACKGROUND--Patients with seizures may have abnormal brain imaging. Lesions demonstrated on computerized tomography or magnetic resonance imaging often suggest the underlying cause of the seizures, and may prompt an invasive investigation for diagnosis and treatment. In an increasingly recognized subset of patients however, the imaged lesions spontaneously resolve. While poorly understood, these 'disappearing' lesions may in fact be the consequence of seizures, rather than the cause. Two patients with 'disappearing' lesions are presented: the first patient had a proven cause, the second a probable one. Case 1. A patient with new onset seizures had an abnormal MRI. An angiogram confirmed thrombosis of the straight sinus. On follow-up, she was doing well; repeat imaging was normal with resolution of the lesion. Case 2. A patient with a long seizure history had been well controlled on medications, and had no change in frequency of her seizures. She was found to have a left homonymous hemianopsia. MRI revealed a right parieto-occipital lesion. The patient refused further work-up and was lost to follow-up. She returned almost a year later; repeat imaging was normal. CONCLUSION--Patients with seizures and abnormal imaging suggestive of structural lesions may occasionally have lesions that resolve spontaneously. While some diagnoses remain elusive, an important consideration to exclude in these patients is venous thrombosis.

Adult↗
PubMed1995

When is isolated vertigo a harbinger of stroke?

Isolated vertigo is usually a distressing though benign clinical entity. Recently, however, it has been recognized that in a subset of patients isolated vertigo may be a harbinger of vertebrobasilar stroke. Recognition of this "at risk" subgroup may be difficult. Brainstem auditory evoked potentials (BAEPs) are usually normal in patients with vertigo from labyrinthine disease. We describe a patient with isolated vertigo, in whom BAEPs were abnormal, and who subsequently developed an anterior inferior cerebellar artery territory infarct. BAEP testing might lead to early recognition of those patients at risk for catastrophic stroke, and prompt appropriate investigation and treatment to prevent this outcome.

Cerebral Infarction↗
PubMed1994

Outcome after carotid endarterectomy for asymptomatic carotid stenosis.

OBJECTIVE: To compare the long-term outcome in patients with asymptomatic carotid stenosis (ACS) among those treated with carotid endarterectomy (CE) or medical therapy. BACKGROUND: Until randomized trials are completed, treatment of ACS will depend on identification of subgroups likely to benefit from CE. METHODS: A retrospective cohort study was done on 215 patients with ACS: 107 underwent CE, and 108 were treated medically (MED). A neurologist reviewed medical records and performed a telephone interview to detect outcome (stroke and death). Mean follow-up was 3.8 years; only 4% were lost to follow-up. RESULTS: Among CE patients, there was a 4.7% risk of postoperative ipsilateral stroke within 30 days. Four of five postoperative strokes occurred among patients with prior contralateral symptoms. There was no significant difference between CE and MED in the cumulative life-table 5-year risk of ipsilateral stroke, any stroke, or survival free of any stroke. Among diabetics, however, there were no ipsilateral strokes at 5 years after CE compared to 20% in MED (p = 0.03). Excluding postoperative complications, the 5-year risk of ipsilateral stroke was reduced among CE patients who "ever smoked" (CE 1%, MED 8%, p = 0.03) and the 5-year risk of any stroke was reduced among CE patients who had no prior myocardial infarction (CE 6%, MED 16%, p = 0.02). Among those with prior contralateral carotid territory symptoms, the 5-year risk of any stroke was worse in the MED patients (CE 5% MED 32%, p = 0.004). Among CE patients, a Cox proportional hazards model determined that the independent predictors of worse long-term outcome were: a history of myocardial infarction; admission systolic blood pressure greater than 160 mm Hg; and age greater than 65. CONCLUSION: The approach to patients with ACS will await completion of large, randomized clinical trials, now in progress. Even if these studies are negative, there may remain specific subgroups of patients who show clear benefit from carotid endarterectomy.

Adult↗
PubMed1994

Central retinal artery occlusion from carotid dissection diagnosed by cervical computed tomography.

BACKGROUND: Carotid dissection may lead to many different types of neurological deficits, both transient and permanent. CASE DESCRIPTION: We present a patient with an isolated central retinal artery occlusion who was found to have an ipsilateral carotid dissection by neck computed tomographic scan, later confirmed by angiography. CONCLUSIONS: This is the first reported case of carotid dissection causing central retinal artery occlusion without any other neurological deficits. It demonstrates the diagnostic usefulness of computed tomographic imaging in such cases.

Adult↗
PubMed1992

Neurologic improvement in pure motor hemiparesis: implications for clinical trials.

Knowledge of the natural history of certain stroke subtypes is essential for the proper analysis and interpretation of clinical trials of stroke therapy. We evaluated the degree of weakness on admission and again 7 to 10 days later in 62 patients with pure motor hemiparesis (PMH) and 280 patients with motor deficits from other stroke syndromes (OSS). During the 7-to-10-day study interval, we found that the OSS group worsened slightly in motor function, whereas the PMH group improved (p = 0.01). Among those who improved in both groups, those in the PMH group improved to a greater extent than did those in the OSS group (p = 0.02). This occurred despite a greater frequency of worsening during the first 12 hours after stroke onset in the PMH group. By the fourth day following PMH onset, a majority of patients had improved, and this improvement was sustained until day 10. The two groups did not differ significantly in age, race, sex, history of cardiac disease, hematocrit, anticoagulation treatment, blood glucose, or medical complications in hospital. Lacunar infarcts occurred in 84% of PMH and 23% of OSS. Patients with PMH show significant spontaneous improvement in weakness within 7 to 10 days of admission, compared with patients with OSS. Stratification by admission stroke syndrome in clinical trials may be necessary before judging the efficacy, or lack thereof, of a therapeutic agent.

Aged↗
PubMed1986

A dose-ratio comparison of mu and kappa agonists in formalin and thermal pain.

The effects of putative mu and kappa agonists, with and without naloxone, were compared in the formalin and tail flick tests in rats. The mu agonist sufentanil was more potent in the tail flick test than the formalin test while the opposite was true for the kappa agonist ethylketocyclazocine (EKC). MR2034 was equipotent in the two tests and in the tail flick test, analgesia decreased at high doses. The naloxone (0.1 mg/kg) dose-ratios (DR) for sufentanil and EKC were 3 to 7 times larger for the tail flick test than the formalin test. From this and other DR studies it is argued that in thermal pain tests, opioid analgesia is mediated primarily by mu receptors while in non thermal tests kappa effects predominate.

Analgesia↗
PubMedDate not supplied

Basilar artery migraine and reversible imaging abnormalities.

We report a case of a basilar artery migraine in a 17-year-old boy with transient CT and MR abnormalities after each of two migraine episodes. A repeat MR study 6 months after the last event showed complete resolution of the lesion. Transient abnormalities on brain images similar to those shown in our case have been reported in patients with migraine and other neurologic conditions and are most likely related to cerebral vasogenic edema.

Adolescent↗