Stroke Case study 1: Woman with aphasia and right-sided numbness




Clinical history

A 70-year-old woman was brought to the emergency room by an ambulance after she developed difficulty communicating, and numbness and weakness of her right arm. Her symptoms fluctuated in severity during a period of more than four hours. Her medical history included hypertension that was not always well controlled and non-insulin-dependent diabetes mellitus.

Examination

Neurological examination upon arrival showed aphasia with impaired naming and reduced verbalfluency, right homonymous hemianopia, and moderate sen-sorimotor hemiparesis. Neurological scores: NIHSS 6, mRS 4.

Special studies

Owing to the time from onset that had been witnessed by the patient’s daughter, the decision was made to perform acute stroke MRI. MRI showed an acute ischemic lesion in the left posterior cerebral artery (PCA) territory involving the hippocampus with a few additional small scattered lesions in the occipital lobe (Figure 1.1). On MRA, the proximal portion of the left PCA was occluded and correspondingly hypoperfusion was detected in nearly the complete territory supplied by this artery. In a similar approach to stroke in the middle cerebral artery (MCA) territory, this woman was treated with intravenous thrombolysis (IVT) in an extended time window based on the diffusion/perfusion mismatch concept. The door-to-needle time wasfive hours.

Follow-up

Her neurological deficit improved significantly within two hours after therapy and at discharge the homonymous hemianopia had resolved completely (NIHSS 1). Follow-up imaging showed only minimal growth of lesion size on DWI with partial recanalization of the P1 and P2 segments of the left PCA. Extensive examination did not identify a source of embolism. The fluctuating course and her risk factors made it likely that she had had a pre-existing stenosis of the PCA that became occluded.
Imaging findings




Diagnosis

MRI-guided IVT in PCA territory brain ischemia.

General remarks

Although posterior circulation territory lesions account for about 15%–20% of all ischemic strokes, patients with infarcts in this territory were underrepresented or even excluded from participation in the large clinical trials investigating acute therapy with thrombolysis. The same holds true for clinical trials examining MRI-guided thrombolysis in the posterior circulation based on the PWI/DWI mis-match concept. A higher onset to treatment time in some studies may reflect the unawareness of typical symptoms of posterior circulation territory lesions in the population. The discrepancy between NIHSS and modified Rankin Scale (mRS) scores is attributable to the known inability of the NIHSS to quantify the specific symptoms of posterior circulation territory lesions adequately, and in turn, phys-icians might hesitate to pursue thrombolysis. In terms of potential benefits and risks of thrombolysis, however, these studies have shown no difference between posterior and anterior circulation territory lesions.

Special remarks

This case supports the approach to treat patients with PCA stro ke with thrombolysis based on the PWI/DW I mismatch concept, as o ne would in the anteri or circulation. Studies have shown that mismatch MRI identifies very comparab le constellations as in MCA stroke. Therapy enhances the chance of a f avorable clinical outcome in these patients. It i s worthwhile to note that this case occurred b ef ore the ECASS-III trial results led to the extension of the three-hour time window to 4.5 hours. To day, faced with a similar patient and given the remaining time of 30 minutes (presentatio n was at four hours) , we might as well have perf ormed“ultrafast”CT-b ased thro mbolysis.

SUG GES TE D R EADING

Breuer L, Huttner HB, Jentsch K, et al. Intravenous thrombolysis in posterior cerebral
artery infarctions.Cerebrovasc Dis2011;31: 448–54.
Förster A, Gass A, Kern R, et al. MR imaging-guided intravenous thrombolysis in posterior
cerebral artery stroke.Am J Neuroradiol2011;32: 419–21.
Pagola J, Ribo M, Alvarez-Sabin J, et al. Thrombolysis in anterior versus posterior
circulation strokes: timing of recanalization, ischemic tolerance, and other differences.
J Neuroimaging2011;21(2): 108–12.
Sato S, Toyoda K, Uehara T, et al. Baseline NIH Stroke Scale score predicting outcome in
anterior and posterior circulation strokes.Neurology2008;70: 2371–7.
Searls DE, Pazdera L, Korbel E, Vysata O, Caplan LR. Symptoms and signs of posterior
circulation ischemia in the New England Medical Center posterior circulation registry.
Arch Neurol2012;69(3): 346–51


Reference Book:
More case studies in stroke common and uncommon presentation
(Edited By: Michael G Hennerici, Rolf Kern, Louis R.Caplan and Kristina szabo)

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