Severe carotid artery stenosis or occlusion may put patients at risk for ischaemic stroke. Reduced cerebrovascular reserve capacity is a possible indicator of an imminent ischaemic event and can be determined by assessment of cerebrovascular reactivity to a vasodilative stimulus. However, little is known about the distribution of cerebrovascular reactivity in healthy individuals. In 13 healthy volunteers, dynamic T2* MR images, acquired at alternating inspiratory pCO2 levels, showed a high percentage of signal change in grey matter, with a strong linear correlation with end-tidal pCO2. The mean percentages of signal change for grey and white matter were 5.9 +/- 1.2% and 1.9 +/- 0.5%, respectively. The mean time lag between CO2 stimulus and haemodynamic response was 15 +/- 4 s for grey matter and 180 +/- 12 s for white matter. Parameter mapping revealed a hemispherically symmetrical and homogeneous distribution of cerebrovascular reactivity over the entire grey matter. These findings indicate that it may be feasible to detect exhausted cerebrovascular autoregulation in patients with a compromised cerebral vasculature.

No abstract

Two unusual bumps occur on the internal surface of a rib of the marine reptile Prognathodon saturator from the Upper Cretaceous (Maastrichtian) of Maastricht, The Netherlands. These bumps are interpreted as stress fractures, possibly related to agonistic behaviour.

A 68-year-old man presented with a sudden onset of weakness and paresthesia of the left arm. He had a history of myocardial infarction 4 years earlier and a known renal artery stenosis. A nonenhanced computed tomographic scan of the brain showed no signs of hemorrhage or infarction. The patient underwent intravenous thrombolysis with alteplase (0.9 mg/kg body wt, 10% initial bolus dose over 1 minute, followed by infusion of the remaining 90% of the dose over 60 minutes). Soon after, the symptoms completely disappeared except for the persistence of a slight paresthesia of the left arm. Doppler ultrasonography revealed a hypoechoic plaque proximally in the right internal carotid artery causing a 50% to 69% stenosis. ECG showed sinus rhythm with complete right bundle-branch block without ST-segment or T-wave abnormalities. Transcranial Doppler imaging revealed no stenosis of the right middle cerebral artery. Serum lipid profile was within normal limits. In addition to the aspirin (100 mg once per day) and atorvastatin (40 mg once per day) he was already using, the patient was prescribed dipyridamole (200 mg twice per day) for secondary stroke prevention.Fifteen days after the initial onset of symptoms, the patient was enrolled in a clinical study investigating the natural history of carotid artery plaques. Magnetic resonance imaging scans of the brain and right carotid artery plaque were obtained, which revealed a recent discrete infarction of the right sensory region ( Figure 1A and 1B) and a plaque with a large lipid-rich necrotic core with no or little hemorrhage (Figure 2A through 2D), respectively.Three months after the initial event, the patient once more presented with sudden onset of weakness and a numb feeling of the left arm. The patient again underwent intravenous thrombolysis with alteplase. However, the symptoms persisted. A nonenhanced computed tomographic scan, performed 24 hours after thrombolysis, revealed a hypodense area in the right motor region. Repeated Doppler ultrasonography showed no change in carotid plaque echogenicity and degree of luminal narrowing of the right internal carotid artery. Ten days after the onset of the second event, the patient underwent repeated magnetic resonance imaging scans of the brain and right internal carotid artery plaque. These scans confirmed recent infarction in the right motor region ( Figure 1C and 1D) and revealed recent intraplaque hemorrhage ( Figure 2E through 2H).Because of recurrent symptoms, the patient underwent carotid endarterectomy 20 days after the onset of the second event. Histological analysis of the excised plaque demonstrated large intraplaque hemorrhage ( Figure 3A and 3B), confirming the magnetic resonance imaging findings. According to the American Heart Association, it was a type VI plaque (complex plaque with possible surface defect, hemorrhage, or thrombus). 1 To our knowledge, this is the first report showing the in vivo development of carotid intraplaque hemorrhage and the coincidence of ipsilateral ischemic stroke. The findings of ...

No abstract

Bipolar patients in remission have a functional brain disorder that is expressed by a change in physiological response to external stimuli.

No abstract

No abstract