Case Notes
History
42 year-old male with right sided numbness and neck pain; history of seizures and hypertension.Exam
Head MR FLAIR Sequence
MR FLAIR can provide information about stroke-age and depth and duration of the oligemic insult. FLAIR becomes positive 2-3 hours after the stroke ictus from cytogenic edema (with minimal conspicuity). If the stroke is completed it becomes more positive (obvious conspicuity after 4-6 hours) with the onset of the proinflammatory response producing vasogenic edema. In essence, the conspicuity of FLAIR can reflect either the time of onset and the amount of ischemic injury. If there is no positive FLAIR the onset is either very early or the ischemic injury is minimal. If minimally positive the onset is either in the hyperacute timeframe or the depth of the stroke is less severe. If clearly positive, the stroke is passed the stroke therapy window and is likely likely to have moderate or greater ischemic injury. FLAIR positivity proceeds over time peaking in the acute phase (3 hours to 3 days). Thus, FLAIR adds useful information about the stroke timeline and/or the stroke depth and duration only during the initial period of stroke stabilization or if there has been a new event with progression of clinical findings. Findings on FLAIR, as used in this discussion, is graded as if on a stroke-age timeline (not positive=very early, somewhat positive=early, clearly positive=outside the treatment window). However, the FLAIR conspicuity could just as well be based on the stroke depth and duration (minimal, moderate, or advanced). Nevertheless, the less obvious the FLAIR the earlier the ischemic event for determining stroke therapy or the lesser the stroke injury (which is always good). It is up to the imager to use FLAIR conspicuity language to best fit the clinical context usually determined by timing of the MR exam relative to the stroke ictus and the interval from the CTA.
Purpose
1. Use FLAIR sequence to confirm recognizable ischemic arterial zone or zones (similar to the DWI scenario).
2. Use FLAIR to estimate the most likely stroke-age and/or depth of the ischemic injury based on the conspicuity of the FLAIR compared to the DWI sequences.
3. Use FLAIR to detect thrombus or prior recanalized thrombus (hyperintensity) in the wall of proximal arteries.
4. Use FLAIR to detect focal mass effect and/or whether there is herniation or impending herniation of brain.
MR FLAIR can provide information about stroke-age and depth and duration of the oligemic insult. FLAIR becomes positive 2-3 hours after the stroke ictus from cytogenic edema (with minimal conspicuity). If the stroke is completed it becomes more positive (obvious conspicuity after 4-6 hours) with the onset of the proinflammatory response producing vasogenic edema. In essence, the conspicuity of FLAIR can reflect either the time of onset and the amount of ischemic injury. If there is no positive FLAIR the onset is either very early or the ischemic injury is minimal. If minimally positive the onset is either in the hyperacute timeframe or the depth of the stroke is less severe. If clearly positive, the stroke is passed the stroke therapy window and is likely likely to have moderate or greater ischemic injury. FLAIR positivity proceeds over time peaking in the acute phase (3 hours to 3 days). Thus, FLAIR adds useful information about the stroke timeline and/or the stroke depth and duration only during the initial period of stroke stabilization or if there has been a new event with progression of clinical findings. Findings on FLAIR, as used in this discussion, is graded as if on a stroke-age timeline (not positive=very early, somewhat positive=early, clearly positive=outside the treatment window). However, the FLAIR conspicuity could just as well be based on the stroke depth and duration (minimal, moderate, or advanced). Nevertheless, the less obvious the FLAIR the earlier the ischemic event for determining stroke therapy or the lesser the stroke injury (which is always good). It is up to the imager to use FLAIR conspicuity language to best fit the clinical context usually determined by timing of the MR exam relative to the stroke ictus and the interval from the CTA.
Purpose
1. Use FLAIR sequence to confirm recognizable ischemic arterial zone or zones (similar to the DWI scenario).
2. Use FLAIR to estimate the most likely stroke-age and/or depth of the ischemic injury based on the conspicuity of the FLAIR compared to the DWI sequences.
3. Use FLAIR to detect thrombus or prior recanalized thrombus (hyperintensity) in the wall of proximal arteries.
4. Use FLAIR to detect focal mass effect and/or whether there is herniation or impending herniation of brain.
Prior Study
CT HeadThere is evidence of a left high-cervical ICA dissection. There is very subtle edema in the left hippocampus.
MRA Head and Neck
There are changes consistent with left high-cervical and vertical intapetrous ICA dissection. There is a short segment with non-filling of the genu segment of the ICA likely representing occlusion. However, the left ICA becomes patent in the horizontal, intrapetrous segment and beyond reflecting patent EC-IC collateralization.
Focal areas of absent MRA signal (consistent with down-stream thromboemboli) were evident in the proximal right ACA, the proximal left PCA, and the left MCA at the M2 trunk division (affecting flow into both the superior and inferior MCA perfusion zones).
MR Diffusion
Positive diffusion in the left hippocampus consistent with post-ictal effects of a recent seizure. A grand mal seizure may have precipitated the left high-cervical ICA dissection.