Annals of neurology
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Annals of neurology · Oct 1987
Effects of hypothermia on brainstem auditory evoked potentials in humans.
Ten adult patients who underwent open heart surgery under induced hypothermia had brainstem auditory evoked potentials (BAEPs) recorded at 1 degree- to 2 degrees C-steps as body temperature was lowered from 36 degrees C to 20 degrees C to determine temperature-dependent changes. Hypothermia produced increased latencies of BAEP waves I, III, and V; the prolongation was more severe for the later components with the result that interpeak latencies I-III, III-V, and I-V were also prolonged. The temperature-latency relationship was nonlinear and best expressed by exponential curve. ⋯ The amplitude of the BAEP components had a quasiparabolic relationship to temperature; the amplitude rose with hypothermia to 28 degrees or 27 degrees C, but decreased linearly with further cooling. All BAEP components were present at temperatures above 23 degrees C and absent below 20 degrees C. With rewarming, the changes reversed and BAEPs returned to initial prehypothermia status.
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Annals of neurology · Sep 1987
Comparative StudyThe effect of hyperosmotic blood-brain barrier disruption on blood-to-tissue transport in ENU-induced gliomas.
Hyperosmotic blood-brain barrier disruption transiently increases the rate of blood-to-tissue transport of water-soluble compounds to normal brain and has been used in brain tumor patients to increase the delivery of chemotherapeutic drugs. This method remains controversial; debate concerns the extent to which it increases drug delivery to brain tumors. Ethylnitrosourea (ENU)-induced gliomas in rats have the lowest rate of blood-to-tissue transfer of the water-soluble compound alpha-aminoisobutyric acid of all experimental brain tumors studied to date. ⋯ Hyperosmotic blood-brain barrier disruption with 1.6 osmolar mannitol resulted in an averaged whole-tumor transfer constant of 0.013 +/- 0.003 (standard error) mL/(g/min), compared to a transfer constant of 0.007 +/- 0.002 mL/(g/min) for ENU-induced gliomas in the contralateral undisrupted hemisphere, a difference that was not significant. In contrast, hyperosmotic blood-brain barrier disruption produced a large and significant increase in the transfer constant of alpha-aminoisobutyric acid in tumor-free cortex (from 0.002 +/- 0.001 to 0.05 +/- 0.011 mL/[g/min]) and in tumor-free corpus callosum (from 0.001 +/- 0.003 to 0.017 +/- 0.005 mL/[g/min]). Hyperosmotic blood-brain barrier disruption does not appear to be an efficient method with which to increase the rate of delivery of water-soluble drugs to brain tumors but does result in a significant increase in the delivery rate of these drugs to normal brain tissue.
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Annals of neurology · Apr 1987
Cerebrospinal fluid monoaminergic metabolites are elevated in adults with Down's syndrome.
Under conditions of rest and a low monoamine diet, brain monoamine activity was examined in young (less than 35 years) and old (greater than 35 years) adults with Down's syndrome and in control subjects by measuring the cerebrospinal fluid (CSF) and plasma concentrations of the neurotransmitter norepinephrine, and of 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy 4-hydroxyphenylglycol (MHPG), the respective metabolites of the neurotransmitters serotonin, dopamine, and norepinephrine. There were no age-related differences in metabolite concentrations in either the Down's syndrome or control subjects. CSF concentrations of 5-HIAA, HVA, and norepinephrine were significantly higher in young subjects with Down's syndrome as compared with young controls, and CSF concentrations of 5-HIAA and norepinephrine were significantly higher, by twofold or more, in old subjects with Down's syndrome as compared with older controls. The results suggest that monoamine turnover and brain functional activity involving monoamines is elevated in Down's syndrome, and that the early neuropathological changes in the disorder are not associated with a monoamine deficit.
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Annals of neurology · Feb 1987
Irradiation of meningiomas of the intracranial anterior visual pathway.
Twenty patients with progressive visual loss caused by intracranial meningiomas involving the anterior visual pathway were treated with irradiation alone (n = 4) or with irradiation combined with tumor excision (n = 16). Improvement in visual performance occurred in 13 patients; 2 patients experienced temporary improvement; and 5 others maintained stable visual function for up to 9.5 years (mean follow-up, 4.0 years). Radiotherapy seemed to have no effect in 2 patients. ⋯ Only one definite complication of radiotherapy occurred and was related to excessive radiation dose (greater than 7,000 cGy). Irradiation in the range of 5,000 to 5,500 cGy was effective either alone or in combination with surgical excision. Serial assessment of visual acuity and fields allowed us to demonstrate and quantify improvement in our patients following radiotherapy; in contrast, follow-up computed tomographic studies rarely demonstrated reduced tumor size.
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Annals of neurology · Dec 1986
Sickle cell anemia and central nervous system infarction: a neuropathological study.
CNS infarcts were demonstrated in 12 of 24 autopsied patients with sickle cell anemia. The infarcts occurred most extensively in the territory supplied by the distal branches of the internal carotid artery, especially the anterior-middle cerebral artery boundary zone. They were regularly associated with organizing and recanalizing thrombi involving the distal cervical and proximal intracranial divisions of the internal carotid system. On the basis of these findings, we infer that the pathogenesis of the infarction involves perfusion failure or intraarterial embolization in addition to intravascular sickling.