M1 Middle Cerebral Artery Occlusion Research Articles

Ischemic stunning of the brain: early recanalization without immediate clinical improvement in acute ischemic stroke.

Early arterial recanalization (ER) with intravenous tissue plasminogen activator (tPA) can lead to dramatic clinical recovery, whereas some patients do not experience immediate clinical improvement. Consecutive patients received tPA 0.9 mg/kg IV within 3 hours after symptom onset. All had M1 or M2 middle cerebral artery occlusions on pretreatment transcranial Doppler. Patients were continuously monitored for 2 hours after bolus. ER was defined as the Thrombolysis in Brain Ischemia intracranial flow increase by >or=1 grade. Stroke severity (National Institutes of Health Stroke Scale [NIHSS]) and recovery (modified Rankin Scale) were assessed independently of transcranial Doppler. One hundred twenty patients (mean age, 68+/-15 years; 63 women; median NIHSS, 17; range, 5 to 29; 90% with >or=10 points) received tPA at a median of 120 minutes, 50% within the first 2 hours. ER was observed in 73 patients (32 complete, 41 partial). No immediate clinical changes (n=23) or worsening (by 1 to 6 points on NIHSS, n=4) was observed in 37% of ERs (nonresponders). Complete ER was found in 8 of these 27 patients. At 24 hours, 22 of 27 patients (82%) had persisting deficits of NIHSS >or=10 points, yet 37% of these nonresponders (10 of 27) still achieved good outcome (modified Rankin score, 0 to 2) at 3 months. Among nonresponders with good outcome, 100% had detectable residual flow signals, and 70% had compensatory flow diversion on prebolus transcranial Doppler compared with 65% and 29% of nonresponders with poor outcome (P<0.05). Compared with responders (n=46), nonresponders had similar prebolus median NIHSS of 16 to 17 points, bolus times of 120 to 132 minutes, median speed of thrombolysis (30 minutes), and ER times of 190 to 193 minutes after onset. Reocclusion occurred in 3 of 4 patients with clinical worsening, 30% of other nonresponders, and 22% of responders. Symptomatic hemorrhage rate was 4% in both groups. At 3 months, mortality was 33% in nonresponders compared with 9% in responders (P=0.001). After successful arterial ER with tPA therapy, lack of early clinical changes or worsening is relatively common (37%) and appears to be independent of time to tPA bolus or reperfusion. However, with tPA alone, at least one third of these nonresponders still achieved good outcomes at 3 months, suggesting the possibility of a "stunned brain" syndrome with delayed recovery. Several different mechanisms may potentially account for this phenomenon.

Deterioration following improvement with tPA therapy: Carotid thrombosis and reocclusion

Clinical improvement of ≥4 points on the NIH Stroke Scale (NIHSS) was seen in 47% of patients 24 hours after treatment with IV tissue plasminogen activator (tPA) for acute ischemic stroke.1 Arterial recanalization can be associated with early recovery;2 following improvement, however, 15% of patients experience clinical deterioration.3 Transcranial Doppler (TCD) ultrasonography has been used to detect arterial occlusion and monitor recanalization during thrombolysis.4 The authors report the clinical and TCD findings in a patient who improved, then subsequently deteriorated, while receiving tPA therapy. A 42-year-old, right-handed woman was seen 80 minutes after the acute onset of right hemiplegia, global aphasia, eye deviation to the left, and a right homonymous hemianopsia (NIHSS score 24). Her medial history included smoking, non–insulin-dependent diabetes mellitus, and peripheral vascular disease requiring bilateral femoral–popliteal bypasses. She had no history of cardiac or cerebral ischemia, and was not taking any antiplatelet treatment. A head CT scan showed a hyperdense left middle cerebral artery (MCA) and no hemorrhage. At 90 minutes from symptom onset, a TCD was performed according to a published protocol,4 using a single-channel, 2-MHz portable unit (Multigon 500M, Yonkers, NY), and head-frame fixation (Marc 500, Spencer Technologies, Seattle, WA). The TCD was consistent with a proximal M1 MCA and A1 anterior cerebral artery (ACA) occlusion ( figure, frame 1) followed by rapid progression to a terminal internal carotid artery (ICA) occlusion (see the figure, frame 2). Within 5 minutes, the …