Assessment of Blood-Brain Barrier Permeability by Dynamic Contrast-Enhanced MRI in Transient Middle Cerebral Artery Occlusion Model after Localized Brain Cooling in Rats

OBJECTIVE: The purpose of this study was to evaluate the effects of localized brain cooling on blood-brain barrier (BBB) permeability following transient middle cerebral artery occlusion (tMCAO) in rats, by using dynamic contrast-enhanced (DCE)-MRI. MATERIALS AND METHODS: Thirty rats were divided into 3 groups of 10 rats each: control group, localized cold-saline (20℃) infusion group, and localized warm-saline (37℃) infusion group. The left middle cerebral artery (MCA) was occluded for 1 hour in anesthetized rats, followed by 3 hours of reperfusion. In the localized saline infusion group, 6 mL of cold or warm saline was infused through the hollow filament for 10 minutes after MCA occlusion. DCE-MRI investigations were performed after 3 hours and 24 hours of reperfusion. Pharmacokinetic parameters of the extended Tofts-Kety model were calculated for each DCE-MRI. In addition, rotarod testing was performed before tMCAO, and on days 1-9 after tMCAO. Myeloperoxidase (MPO) immunohisto-chemistry was performed to identify infiltrating neutrophils associated with the inflammatory response in the rat brain. RESULTS: Permeability parameters showed no statistical significance between cold and warm saline infusion groups after 3-hour reperfusion 0.09 ± 0.01 min-1 vs. 0.07 ± 0.02 min-1, p = 0.661 for K(trans); 0.30 ± 0.05 min-1 vs. 0.37 ± 0.11 min-1, p = 0.394 for kep, respectively. Behavioral testing revealed no significant difference among the three groups. However, the percentage of MPO-positive cells in the cold-saline group was significantly lower than those in the control and warm-saline groups (p < 0.05). CONCLUSION: Localized brain cooling (20℃) does not confer a benefit to inhibit the increase in BBB permeability that follows transient cerebral ischemia and reperfusion in an animal model, as compared with localized warm-saline (37℃) infusion group.

Clinical features of olivary hypertrophic degeneration in brain magnetic resonance image

Olivary hypertrophic degeneration (OHD) is caused by lesions in dentato-rubro-olivary pathway(myoclonic triangle) and responsible for palatal myoclonus and other involuntary movements. We report the clinical features and magnetic resonance imaging(MRI) findings of 5 patients with OHD. All patients had previous brainstem hemorrhage mainly involving pontine tegmentum in four patients and right superior cerebellar peduncle in one patient T2-weighted MR] revealed round or oval shaped high signal area in the ventral or ventrolateral portion of the medulla. Their clinical presentations were as followings: palatal myoclonus (4 case), ocular myoclonus (3 case), pharyngeal and laryngeal myoclonus (2 case), limb myoclonus (2 case), head shaking (I case) and perioral tremulous movement (1 case). The frequency of myoclonus was 70-170/minute and the median time interval between the insult of the primary lesion and the onset of myoclonic symptoms was 2 months. OHD shown as hyperintense lesions on T2 weighted MRI should be differentiated from ischemic, neoplastic or other pathologic lesions. The characteristic clinical presentations and the location of primary lesions involving myoclonic triangle may be helpful in differential diagnosis from primary medullary lesions.