Background and Clinical Significance: Marfan syndrome (MFS) is an autosomal-dominant connective-tissue disorder caused by pathogenic FBN1 variants. Aortic-root dilation and dissection are the canonical complications, whereas spontaneous vertebral artery dissection (VAD) is described only sporadically. Yet, cerebrovascular events are several-fold more common in MFS, and up to 74% of patients exhibit increased vertebral artery tortuosity, a validated predictor of dissection; Case Presentation: A 32-year-old African man with hypertension, type 2 diabetes mellitus, tobacco use, and headaches labelled as migraine presented with acute agitation, visual disturbance, vertigo, dysarthria, and right-sided weakness of two hours’ duration. Examination disclosed previously unrecognised marfanoid stigmata: arachnodactyly with positive wrist and thumb signs, reduced upper-to-lower segment ratio, increased arm-span-to-height ratio, dolichocephaly, pectus excavatum, and a high-arched palate. Non-contrast CT showed left occipital and posterior inferior cerebellar hypodensities. CT angiography demonstrated discontinuous intraluminal filling defects in the left vertebral artery at C4 and C2, and MR angiography confirmed long-segment occlusion/stenosis of the intracranial left vertebral artery. Echocardiography revealed mild aortic-root dilation (4.0 cm; Z-score +2.53) and a small patent foramen ovale (PFO) with a positive bubble study. The patient received intravenous thrombolysis followed by antiplatelet therapy, a high-intensity statin, antihypertensive therapy, and intensified glycaemic control. Because the infarct territory matched the dissected vessel and the small PFO carried no high-risk features (RoPE score 6; PASCAL category “unlikely”), VAD was designated the culprit lesion and the PFO incidental; Conclusions: Spontaneous VAD may be the inaugural manifestation of unrecognised MFS, antedating aortic complications. In young adults with cryptogenic posterior-circulation stroke and marfanoid features, early cervical imaging and Ghent assessment are warranted, and a coexistent PFO should not be assumed causal. Multidisciplinary evaluation supports accurate attribution and surveillance.