PURPOSE:To investigate the intersubject and intrasubject variability of the activated area in the visual cortex with functional MR imaging. METHODS: Double-section gradient-echo MR images were acquired at 1.5 T in 28 healthy volunteers using the fast low-angle shot (FLASH) technique. Visual stimulation was obtained with light-emitting diode (LED) goggles. Eighteen volunteers were studied twice. The size of the activated areas in the visual cortex and the increase in signal were measured. A reproducibility ratio for size (R size ) and for location (R overlap ) was calculated on a scale of 0.0 to 1.0. RESULTS: Activation was seen in 89% of the subjects. The size of the activated area was widely variable among subjects: mean, 460 Ϯ 284 mm 2 ; range, 0 to 1029 mm 2 in the first study in all volunteers. Signal increases ranged from 3.2% to 10.9%, with a mean of 6.6 Ϯ 1.7%. The mean values of intrasubject variability testing were R size ϭ 0.83 Ϯ 0.16 and R overlap ϭ 0.31 Ϯ 0.11. CONCLUSION: Functional MR imaging with the FLASH technique is useful in identifying certain cortical areas that have quite variable locations among subjects. This study provides reference data for the intrasubject and intersubject variability of the activation pattern of the visual cortex.
It has recently been suggested that most small (<15 mm) subcortical infarcts (SSI) of the centrum ovale (CO) are of lacunar type. We investigated this hypothesis in 255 consecutive patients with a first-ever ischemic stroke who were examined within 24 h after stroke onset and survived on day 10. Fifty-seven patients had CO-SSI: they were older and more likely to have a silent infarct, a lacunar syndrome, arterial hypertension, leuko-araiosis and SSI localized in the basal ganglia or internal capsule and less likely to have a nonlacunar syndrome. On multiple linear regression analysis, independent factors correlated with CO-SSI were the leuko-araiosis score and the presence of a silent infarct, diabetes mellitus and arterial hypertension. However, the presumed cause of the index stroke was large-vessel disease in 7 patients and heart disease in 16. Though we confirm that patients with CO-SSI are more likely to have risk factors for small-vessel disease, a complete diagnostic workup remains necessary in patients with such infarcts because other mechanisms account for one third of them.
Functional MRI (fMRI) of the visual cortex was evaluated in 42 sedated 18-month-old infants (mean corrected age; 31 males, 11 females) with or without periventricular leukomalacia (PVL). Data from 14 infants could not be evaluated because of movement artefacts. Ten of the remaining 28 infants showed no significant fMRI response upon visual stimulation. In 18 infants, a significant signal change upon stimulation was found in the visual cortex: in 17 a signal decrease and in one a signal increase. Functional changes were located mainly in the anterior part of the visual cortex. Seven of the 28 infants had normal MRI and 21 showed variable occipital PVL. An fMRI response was equally frequent in infants without PVL (4 of 7 infants) and with PVL (14 of 21 infants). In conclusion, fMRI was shown to be feasible in sedated infants. No correlation was found between functional activation and the presence or absence of occipital PVL. Type of fMRI response (signal decrease) and localization (anterior part of the visual cortex) are different from those seen in adults, probably reflecting a combination of sedation effects and immaturity of the visual system. At present, fMRI is a highly promising research tool; its clinical relevance still has to be established.
Cholinesterase inhibitors have been shown to improve cognitive
functioning in patients with Alzheimer’s Disease (AD), but are
associated with side effects and only 20-40% of the patients clinically
improve. In this study, we aimed to investigate the acute
pharmacodynamic (PD) effects of a single dose of galantamine on CNS
functioning in mild to moderate AD patients and its potential to predict
long-term treatment response. This study consisted of a challenge phase,
in which a single dose of 16 mg galantamine was administered to 50 mild
to moderate AD patients in a double-blind, placebo-controlled cross-over
fashion. Acute PD effects were monitored with use of a CNS test battery.
In the subsequent treatment phase of the study, patients were treated
with open-label galantamine according to regular care. After 6 months of
galantamine treatment, patients were categorized as either responder or
as non-responder based on their MMSE, NPI and DAD scores. An analysis of
covariance was performed to study the difference in acute PD effects
between responders and non-responders. Acute decreases of absolute
frontal alpha (-20.4; 95%CI=-31.6,-7.47; p=.0046), beta (-15.7; 95%
CI=-28.3,-0.93; p=.0390) and theta (-25.9; 95%CI=-38.4,-10.9; p=.0024)
EEG parameters and of relative frontal theta power (-3.27%;
95%CI=-5.96,-0.58; p=.0187) on EEG after a single dose administration
of galantamine significantly distinguished long-term treatment
responders (n=11) from non-responders (n=32) after 6 months. This study
demonstrates that patients who demonstrate a reduction in EEG power in
the alpha and theta frequency after a single administration of
galantamine 16 mg will most likely respond to treatment.
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