Microangiopathic Occlusion of a Perforating Prepontine Long Circumferential Artery Presenting with Lower Motor Neuron Facial Weakness: Clinical and Radiological Correlation

Abstract

Case Description: A 79-year old male patient with myelodysplastic syndrome associated with severe neutropenia, thrombocytopenia, anemia, hypertension, and hyperlipidemia was admitted for pneumonia secondary to influenza A. Two weeks later he presented with new symptoms of acute dysarthria, and left facial weakness involving his upper and lower face; the following day he developed left arm weakness. Admission computed tomography (CT) and MRI scans revealed an acute ischemic stroke (AIS) in the right posterior frontal cortex. The initial MRI was reported negative for pontine lesions. Anatomically, the cortical infarct could not explain his left lower motor neuron cranial nerve VII (LMN CN VII) facial weakness distribution because in a cortical lesion the upper half of the face would be expected spared due to contralateral cortical innervation. Upon review of the MRI, the initial hyperintensity seen on Fluid-Attenuated Inversion Recovery (FLAIR) was overlooked and later identified as an acute stroke in the vicinity of the perforating prepontine long circumferential artery affecting the CN VII nucleus. Conclusion:In the absence of earache, active infection, and/or inflammation, a sudden onset facial palsy, lower motor neuron distribution, must point to a pontine microangiopathic infarct until proven otherwise. Under these circumstances, maintaining a high level of suspicion is of paramount importance.