A case of mid-basilar artery thrombosis presenting with a low NIHSS

Introduction: Posterior circulation large vessel occlusions can present with a low National Institutes of Health Stroke Scale (NIHSS) score and cause diagnostic delay. In this report, we aimed to present a case of mid-basilar artery thrombosis who presented to our hospital with a low NIHSS and was treated with successful mechanical thrombectomy.Case: A 75-year-old man with a history of 3 coronary stents presented to the emergency department with speech impairment and weakness of the right arm and leg that began at 13:35. (Door time 13:35.) His neurological examination at presentation showed no pathology, and the NIHSS score was 0; however, the patient, who described difficulty speaking and weakness of the right arm and leg, was noted to have fluctuating symptoms, with the detectable deficit disappearing between examinations. On this clinical suspicion, cranial and carotid computed tomography (CT) angiography was obtained within the stroke protocol (door-to-imaging time 35 minutes). Cranial CT showed no acute pathology, while CT angiography showed a thrombus in the mid-basilar artery permitting flow, and cranial diffusion magnetic resonance imaging showed bilateral acute ischemic lesions at the pontine level. Based on the imaging findings, a decision was made for mechanical thrombectomy (door-to-puncture time 175 minutes). Under general anesthesia, a 6F short sheath was placed via the right femoral artery using the Seldinger technique. Diagnostic angiography showed that the right vertebral artery was occluded distally from its V2 segment (thought possibly consistent with dissection), and the image from the left vertebral artery showed that the basilar artery was occluded from its mid-portion; collateral flow to the bilateral posterior cerebral arteries (PCAs) and the basilar artery was present via the posterior communicating arteries (PCOM). Advancing via the left vertebral artery, complete recanalization (Thrombolysis in Cerebral Infarction [TICI] 3) was achieved at first pass with the direct aspiration (ADAPT) technique; no stent was used. The femoral access site was closed with Angio-Seal. The patient, who developed no new neurological deficit during follow-up, was discharged, and his NIHSS score at the discharge examination was 0.Discussion/Conclusion: In posterior circulation strokes, a low NIHSS or fluctuating neurological findings do not exclude occlusion of a critical large vessel such as the basilar artery. The inability of the NIHSS to adequately reflect some clinical findings of the posterior circulation, and the ability of rich collateral circulation to mask symptoms temporarily, can lead to diagnostic delay. Therefore, when symptoms suggesting brainstem or posterior circulation ischemia are present, even if transient, clinical suspicion should be maintained despite a normal neurological examination, and early vessel imaging should be performed. Our case shows that mechanical thrombectomy can achieve successful recanalization and a good clinical outcome in suitable patients who present with a low NIHSS but have a mid-basilar artery occlusion on imaging. In posterior circulation strokes, the treatment decision should not be based on the NIHSS score alone; the nature and course of symptoms, vessel imaging findings, ischemic lesion burden, and collateral circulation should be evaluated together. This approach may contribute to early recognition of basilar artery occlusions that can potentially lead to severe neurological outcomes and to referring suitable patients for reperfusion therapy without losing time.Keywords: