DWI Negative Large Artery Acute Ischemic Stroke: A Case Report with Review of Literature

Case Report

Austin J Cerebrovasc Dis & Stroke. 2020; 7(1): 1085.

DWI Negative Large Artery Acute Ischemic Stroke: A Case Report with Review of Literature

Raut TP1*, Patil LN1, Munshi M2, Shrivastava M3, Sanghani G3, Shah P3

1Department of Neurosciences, Kokilaben Dhirubhai Ambani Hospital, Mumbai, India

2Department of Neuroradiology, Kokilaben Dhirubhai Ambani Hospital, Mumbai, India

3Department of Interventional Neuroradiology, Kokilaben Dhirubhai Ambani Hospital, Mumbai, India

*Corresponding author: Raut TP, Department of Neurosciences, Kokilaben Dhirubhai Ambani Hospital, Mumbai, India

Received: May 01, 2020; Accepted: October 09, 2020; Published: October 16, 2020


MRI forms an important investigation tool in acute ischemic stroke. Diffusion weighted imaging is a very sensitive sequence to detect ischemia within few minutes. However in certain cases it can be negative especially in lacunar strokes, brainstem strokes and rarely in large artery strokes imaged very early into the onset of stroke. Other tools like MR Angiogram, Perfusion imaging may increase the sensitivity to detect stroke and initiate timely treatment which could prevent devastating consequences. Here authors describe a case of a 57 year old gentleman presenting with right sided weakness of 90 minutes duration with a moderate stroke severity. MRI Diffusion was negative. MR Angiogram didn’t reveal any obvious intracranial occlusion. However MR Perfusion revealed an ischemic penumbra in left anterior cerebral artery territory. Patient didn’t respond to iv thrombolysis and hence subjected to cerebral DSA which revealed thrombus and occlusion of left aca branch. Post mechanical thrombectomy with a stent retriever, he improved clinically and was functionally independent 2 weeks post discharge.

Keywords: Acute ischemic stroke; Diffusion weighted imaging; Magnetic resonance imaging; Perfusion Imaging


MRI: Magnetic Resonance Imaging; CT: Computed Tomography; DWI: Diffusion Weighted Imaging; ADC: Apparent Diffusion Coefficient; FLAIR: Fluid Attenuated Inversion Recovery Sequence; PWI: Perfusion Weighted Imaging; DSA: Digital Subtraction Angiography; IV: Intravenous; AIS: Acute Ischemic Stroke; EVT: Endovascular Treatment


Time is brain. Acute Ischemic Stroke (AIS) if untreated could be a debilitating and life threatening condition hence rapid diagnosis and treatment is necessary for optimizing the outcomes. Traditionally CT Brain has been used in emergency evaluation of patients with AIS to rule out intra-cranial bleed and selects patients for IV thrombolysis. Chalela et.al demonstrated Magnetic Resonance Imaging (MRI) to be more sensitive than CT in detecting acute ischemic stroke [1]. Recently there has been a significant increase in use of MRI in evaluation of patients with AIS [2]. At few centers MRI is used as primary screening tool to select patients eligible for thrombolysis or Endovascular Treatment (EVT). Particularly diffusion weighted magnetic resonance images compared to CT have better sensitivity, accuracy and interrater homogeneity [3]. Sensitivity of Diffusion Weighted Magnetic Resonance Images (DW-MRI) for detecting acute ischemic is stated to be 88-100% [4,5] and specificity 95-100% [4]. MRI-based thrombolysis is safer and potentially more efficacious than standard CT-based thrombolysis [6]. However, DW-MRI has its limitations and false negative DWI images in AIS have been described [7]. We report a case in which DWI-MRI was negative after 90 minutes of symptom onset and perfusion MRI images demonstrated early ischemia. Patient was aggressively treated and had a complete clinical recovery.

Case Presentation

A 57-year-old man, right-handed, businessman by occupation presented to the emergency with sudden onset weakness in right side of body of 90 minutes duration with absolute inability to move right lower limb. There was no history of backpain,radicular pain,fall,seizure or syncope. He had diabetes mellitus and hypertension and was on regular medications. On clinical examination BP was 120/80mmhg, Pulse 82/min, regular. Cranial nerve examination was normal, right upper limb power was MRC (Medical Research Council) grade 3/5 and right leg power MRC grade 0/5 with hypoesthesia on right side. Stroke severity as per NIHSS (National Institutes of Health Stroke Scale) was 7.

MRI Brain stroke protocol done showed negative DWI (Figure 1: A and B) and Fluid attenuated images (FLAIR) (Figure 2A). MRA Angiogram didn’t reveal any obvious extracranial or intracranial occlusion (Figure 2B). MR perfusion study done showed increased time to peak (Tmax) and Mean Transit Time (MTT) in para-sagittal left frontal lobe including paracentral lobule and peri-rolandic region suggestive of tissue at risk of ischemia (Figure 3 A and B). RAPID software showed significant diffusion and perfusion mismatch (Figure 3C). In view of significant deficit with ischemic penumbra despite normal diffusion, patient was considered eligible for IV Thrombolysis with alteplase and 0.9mg/kg tpa was administered. Patient failed to show improvement at the end of 1 hour. Emergent Digital subtraction angiography done showed left distal Anterior Cerebral Artery (ACA) thrombus, thrombotic occlusion of superior internal parietal branch origin and thrombus extending into bifurcation of internal parietal branch with hypoperfusion in parietal territory of ACA (Figure: 4 A and B). Mechanical thrombectomy was done with a 3x40 mm stent retriever following which blood flow to the branches of ACA artery was restored (Figure: 4 C and D). Post- procedure the weakness in right upper limb improved to normal immediately, however the weakness in right leg persisted for 24 hours. Post 24hours the power in right leg improved to MRC grade 4/5 and he could walk with minimal support. MRI brain repeated after 24 hours of the EVT showed few punctate acute infarcts in left frontoparietal cortices (Figure 1: C and D) with FLAIR positivity (Figure: 2C). Patient had transient bladder involvement which improved.At discharge on day 5 patient modified rankin scale was 1 and 0 on 2 weeks of follow up. 2D ECHO and Holter analysis was negative for any cardiac cause and patient was kept on dual antiplatelets,statins and strict glycemia control.