Journal of neuroimaging : official journal of the American Society of Neuroimaging
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Parenchymal hypodensity is a proposed risk factor for hemorrhage after recombinant tissue plasminogen activator (TPA) thrombolysis for ischemic stroke. In Buffalo, NY, and Houston, TX, the authors reviewed 70 patients who were treated with intravenous TPA for acute middle cerebral artery (MCA) stroke. Two observers blinded to clinical outcome analyzed initial noncontrast head computed tomography (CT) scans. ⋯ Logistic regression indicated that basal ganglia hypodensity was the best single predictor of hemorrhage. Hypodensity and NIHSS score together predicted all cases of hemorrhage. The authors conclude that basal ganglia hypodensity quantified by CT may be a useful method of risk stratification to select acute MCA stroke patients for thrombolytic therapy.
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Cortical processing involved in seemingly similar tasks may differ in important ways. The authors mapped cortical regions engaged in a commonly performed picture naming task, seeking differences by semantic category. Functional magnetic resonance imaging was used during presentation of standardized line drawings in 18 healthy right-handed female participants, comparing living versus nonliving entities. ⋯ Activation of right inferior temporal cortex (BA19 and BA37) was greater during naming of living versus nonliving category items. No category differences in activation strength in the left temporal lobe were observed. The authors conclude that visual semantic operations may involve visual association cortex in the right temporal lobe in women.
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Case Reports
In vivo 1H magnetic resonance spectroscopic measurement of brain glycine levels in nonketotic hyperglycinemia.
Nonketotic hyperglycinemia (NKH) is an autosomal recessive disorder of glycine metabolism. Defective glycine cleavage causes elevated concentrations of glycine in plasma, urine, and cerebrospinal fluid. A longitudinal study using magnetic resonance imaging (MRI) and single-voxel 1H magnetic resonance spectroscopy (MRS) was performed on an infant with the typical clinical picture of NKH. ⋯ At the age of 10 months, MRI showed normal brain structure, while MRS detected a prominent glycine peak in the brain. Repeat MRS at the age of 13 months showed a small increase in glycine peak and a prominent glutamate/glutamine peak not previously detected. The MRS measurements were consistent with the slight increase in blood glycine level and the elevation in glutamine level, indicating that 1HMRS can be a valuable tool in the diagnosis and monitoring of treatment effects in patients with NKH.
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Intravenous recombinant tissue plasminogen activator (rt-PA) is the only therapy of proven value for patients with acute ischemic stroke (AIS). Controversy exists with regard to the prognostic significance of early computed tomography (CT) changes in patients receiving rt-PA for AIS. The authors retrospectively reviewed all cases of AIS who received intravenous rt-PA for AIS in University of South Alabama hospitals between January 1996 and May 1999. ⋯ The frequency of specific findings were as follows: SE in 13 patients (36%), LGWD in 12 patients (33%), PH in 9 patients (25%), HMCA in 4 patients (11%), and IRS in 3 patients (8%) patients. There was no statistically significant association between the occurrence of these imaging findings and subsequent functional outcome after thrombolysis. The data suggest that the presence of subtle acute CT changes in AIS patients is not predictive of clinical outcome following administration of rt-PA as per National Institute of Neurological Disorders and Stroke protocol.
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There has been limited data on the frequency of microembolic signals in patients with middle cerebral artery (MCA) stenosis, especially during the acute phase of stroke. Using transcranial Doppler, the authors prospectively monitored the MCA segments distal to stenosis in 4 groups of patients for 30 minutes: (1) symptomatic patients with acute ischemic stroke and MCA stenosis, (2) asymptomatic group patients with asymptomatic MCA stenosis, (3) control patients with acute ischemic stroke of undetermined etiology, and (4) normal people. A total of 60 patients completed the study. ⋯ Among 20 patients in the symptomatic group, microembolic signals were detected in 3 patients (15%). The number of emboli ranged from 1 to 6 per 30 minutes. This is the first report of the presence of microembolic signals in acute stroke patients with MCA stenosis.