The progression of subclavian arterial stenosis and the subsequent formation of collateral pathways serve to alter the pressure gradients in subclavian steal syndrome, altering ipsilateral vertebral artery flow from its normal state to "latent," "transient," and "continuous" steals. A similar altered flow in the carotid arteries can be observed with stenosis of the proximal common or innominate artery. A 59-year-old man was seen in the vascular laboratory for evaluation of symptomatic peripheral arterial disease. An incidental asymptomatic stenosis of the right innominate and left proximal subclavian artery was found. Further cerebral vascular evaluation displayed a continuous right subclavian steal and a latent steal in the right internal carotid artery. Transcranial Doppler examination displayed "transient" steal in the terminal right internal carotid artery. Combining duplex and transcranial Doppler evaluations allows sequential evaluation of the progression of arterial disease and its effect on the flow patterns in the cerebral vasculature.
20 patients with hyperthyroidism were observed with repeated EEG measurements before and during treatment (ObsidanR; MethimazolR). 17 patients, before starting antithyroid therapy, had slight to moderate EEG abnormalities. A prevalence for moderate disturbances occurred for patients with a higher degree of hyperthyroidism. The dominant EEG frequency was higher than in euthyroid controls, but no exact correlation to T3-values could be observed. 16 patients showed abnormal reactivity to photic stimulation. One-week therapy by propranolol produced only a slight synchronizing effect in EEG's, where T3-values decreased. After 4 weeks selective therapy by MethimazolR all patients were euthyroid, but some EEG abnormalities persisted in 12 patients in a lower degree. The dominant EEG frequency decreased to control-group ranges and abnormal photic reactivity was reduced. After 6 months some EEG disturbances re-increased tentiatively, in 3 relapses excessively. These observations confirm the prognostic value of EEG measurements for the recognition of occurrence and persistence of cerebral disturbances in severe metabolic dysfunctions.
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