[Cerebral vasoreactivity and functional response in stroke: a study with functional MR]
1Department of Clinical Neuroscience; FMRIB Centre. John Radcliffe Hospital., Oxford, OX3 9DU, Reino Unido. rpineiro@sghms.ac.uk
Introduction:
Lacunar infarcts are usually associated with anatomical and possibly functional changes in the walls of small blood vessels (penetrating arteries). The functional effect varies and is accompanied by cerebral adaptive/reorganizational changes. BOLD contrast, originated in the microvasculature (especially with ultra high magnetic fields) depends, in the end, on haemodynamic changes and is useful for exploring patterns of cerebral activation using fMR.
Objectives:
To compare the temporal behaviour of the BOLD signal and the distribution of activation between a group of patients with no functional sequelae following a stroke and a control group, by using fMR at 3T.
Results:
The stroke group showed a smaller number of voxels activated, but this was not statistically significant. The patterns of activation, size of the sensor motor area (SM or ASM) and index of laterality were similar in both groups. In SM the BOLD response was 85% slower (p< 0.01) and 25% less (not statistically significant).
Conclusions:
We found no differences in the patterns of activation of the two groups. This may be explained by the minimal lesions of the stroke group, which were insufficient to produce reorganizational/adaptive changes or by the great variety of responses. The temporal response of the BOLD response was different in the stroke group, probably as a result of the alteration in the haemodynamic response in relation to the underlying processes which damage the functional properties of the vascular wall. This difference in the BOLD response should be interpreted with caution, and borne in mind when interpreting activation in persons with vascular pathology. Further studies are necessary for better understanding of its significance.
