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Acute effects of smoking on cerebral blood flow velocity evaluated by transcranial doppler
No full textTranscranial doppler examination in the early diagnosis of arteriovenous malformation presenting as migraine with aura
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Effect of smoking on cerebrovascular reactivity.
No full textCurrent smoking is a risk factor for stroke. The aim of this study was to
evaluate the effect of smoking one cigarette on cerebral hemodynamics. Using
transcranial Doppler ultrasound, we studied the changes of flow velocity after
hypercapnia in the middle cerebral arteries (MCAs) of 24 healthy young smokers
and 24 healthy controls matched for age and sex. We obtained hypercapnia with
breath-holding and evaluated cerebrovascular reactivity with the breath-holding
index. In smokers, the evaluation was performed during basal condition,
immediately after smoking one cigarette, and at 10-, 20-, and 30-min intervals
thereafter. In controls, the evaluation was performed at corresponding time
intervals. Breath-holding index (BHI) values at rest were similar for both
controls and smokers. In the former, breathholding index values remained constant
for each of the different evaluations. On the contrary, in smokers,
breath-holding index values were significantly lower immediately (p < 0.0001), at
10 min (p < 0.001), and at 20 min (p < 0.0001) after smoking with respect to
baseline values. Smoking also caused more short-lasting changes, in this case
increases in mean flow velocity (MFV), heart rate (HR), and mean blood pressure
(MBP). These results suggest that a failure of cerebrovascular regulation occurs
after smoking. This phenomenon might contribute to the increased risk of
cerebrovascular disease in current smokers
Cerebrovascular reactivity in migraine with and without aura.
No full textAbnormal cerebrovascular regulation has been implicated in the pathogenesis of
migraine. Our aim in this study was to evaluate cerebrovascular reactivity to
different stimulations in migraine with and without aura. Using bilateral
transcranial Doppler, the changes of flow velocity during hypercapnia and mental
and motor activity were measured in the middle cerebral arteries of 15 controls
and 30 patients with migraine with aura (n = 15) or without aura (n = 15) in an
attack-free period. Vascular response to all tests was similar in controls and
patients. In patients with unilateral headache, no side-to-side difference was
found. These findings suggest that no alteration of cerebrovascular reactivity
exists outside attacks in migraine with and without aura. Further studies with
transcranial Doppler considering all intracranial vessels and the comparison with
other techniques of flow investigation with better regional resolution are needed
to confirm these data
Cerebrovascular reactivity and subcortical infarctions
No full textOBJECTIVES:
To investigate the association between different kinds of ischemic lesions and cerebrovascular reactivity (CR) and to evaluate their relationships with the major risk factors for stroke.
SUBJECTS AND METHODS:
We evaluated CR using the breath-holding index technique during bilateral transcranial Doppler monitoring of flow velocity in the middle cerebral arteries of 41 consecutive patients attending our clinic for a recent, first-ever, ischemic stroke and in 15 control subjects. Based on the location of the lesion determined by computed tomography, the following 3 types of infarctions were identified: cortical (or territorial), single subcortical, and subcortical with multiple silent subcortical infarctions. Patients with a condition of severe carotid artery stenosis or occlusion, which in itself could account for altered CR, were excluded from this study. All physiological and pathologic conditions that could possibly cause an impairment in CR were recorded.
RESULTS:
The breath-holding index was significantly lower in the multiple subcortical infarctions group than in the control subjects (P < .001), single subcortical infarctions group (P < .01), and cortical infarctions group (P < .01). In all of the groups male sex (P < .05) and a history of hypertension (P < .05), regardless of whether hypertension was treated, correlated with low CR. The multiple regression analysis indicated that the only significant factor able to influence the breath-holding index was the type of lesion.
CONCLUSIONS:
Nonstenotic patients with first-ever stroke who had a recent symptomatic subcortical infarction associated with multiple silent infarctions seem to have an impaired cerebrovascular reserve capacity. The strong association of subcortical infarctions with multiple silent infarctions with low CR indicates the role of small vessel vasculopathy and hypoperfusion as possible pathogenetic mechanisms of subcortical infarctions with multiple silent infarctions
Impairment of daytime cerebrovascular reactivity in patients with obstructive sleep apnea syndrome.
No full textSeveral studies have demonstrated a clear association between snoring, sleep
apnoea and increased risk of stroke. However, the possible role of sleep apnoea
in the pathophysiogenetic mechanisms of cerebrovascular disease is still unknown.
Our aim in this study was to investigate cerebral haemodynamic changes during the
waking state in eight patients with sleep apnoea syndrome (OSAS) by means of
transcranial Doppler (TCD). In particular, we studied cerebral vascular
reactivity (CVR) to hypercapnia calculated by means of the breath holding index
(BHI). The investigation was performed in the early morning, soon after
awakening, and in the late afternoon. Data were compared with those of eight
healthy subjects matched for age and vascular risk factors. OSAS patients showed
significantly lower BHI values with respect to controls both in the morning (0.56
vs. 1.36; P < 0.0001) and in the afternoon (1.12 vs. 1.53; P < 0.0001). In
patients, BHI values in the afternoon were significantly higher than in the
morning (P < 0.0001). These data demonstrate a diminished vasodilator reserve in
OSAS patients, particularly evident in the morning. This reduction of the
possibility of cerebral vessels to adapt functionally in response to stimulation
could be linked to hyposensitivity of cerebrovascular chemoreceptors after the
continuous stress caused by nocturnal hypercapnia
Cerebral hemodynamic changes in sleep apnea syndrome and effect of continuous positive airway pressure treatment.
No full textBACKGROUND AND OBJECTIVE: A clear association among snoring, sleep apnea, and
increased risk of stroke has been shown by previous studies. However, the
possible role played by sleep apnea in the pathogenesis of cerebrovascular
disease is subject to debate. To evaluate the influence of hemodynamic changes
caused by obstructive sleep apnea syndrome (OSAS), we investigated
cerebrovascular reactivity to hypercapnia in patients with OSAS.
METHODS: The study was performed at baseline and after 1 night and 1 month of
nasal continuous positive airway pressure (n-CPAP) therapy, with patients in the
waking state (8:00 to 8:30 AM and 5:30 to 6:00 PM) with transcranial Doppler
ultrasonography. Cerebrovascular reactivity was calculated with the
breath-holding index (BHI).
RESULTS: In the baseline condition, compared with normal subjects, patients with
OSAS showed significantly lower BHI values in both the morning (0.57 versus 1.40,
p < 0.0001) and the afternoon (1.0 versus 1.51, p < 0.0001). Cerebrovascular
reactivity was significantly higher in the afternoon than it was in the morning
in both patients (p < 0.0001) and controls (p < 0.05). In patients, the BHI
returned to normal values, comparable with those of control subjects, after both
1 night and 1 month of n-CPAP therapy.
CONCLUSIONS: These findings suggest an association between OSAS and diminished
cerebral vasodilator reserve. This condition may be related to the increased
susceptibility to cerebral ischemia in patients with OSAS, particularly evident
in the early morning
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