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)
মন্তব্যসমূহ
একটি মন্তব্য পোস্ট করুন