As with any origination of ideas meant to counteract the severity of the SARS-CoV-2 virus, so was the goal of the swift and vast production of vaccines made for public use in a short time frame. While vaccines, serving as critical strategies for the ongoing pandemic have always maintained a clinical effectiveness to severe disease and even death, that is not without rudimentary outliers. 

A healthy, atraumatic 40-year-old male with no significant past medical history, presented with a 9-day history of a severe self-limiting headache with progression into the worst headache of his life associated with nuchal rigidity and posterior bilateral leg pain and tightness following the first dose vaccination with Pfizer (EL0142). Vital signs on admission included blood pressure 115/56 mmHg, pulse 67 beats per minute (bpm), respiratory rate 16 breaths per minute, temperature 37.2C and oxygen saturation 100% on room air. Initial CT Head and CTA Head and Neck were unrevealing for visible blood. Nonetheless heightened clinical suspicion prompted a lumbar puncture which showed xanthochromia with elevated red blood cell count at greater than 97,000. MRI Brain revealed evidence of focal areas of subarachnoid hemorrhage along right and left frontal convexities. Laboratory data was essentially non-contributory with a normal platelet count, pro time (PT), international normalized ratio (INR), activated partial thromboplastin time (aPTT), and C-reactive protein (CRP). Two diagnostic cerebral angiograms performed 1 week apart were unrevealing for any specific structural causes to explain the subarachnoid hemorrhages and repeat Transcranial Doppler Ultrasounds remained negative for intracranial vasospasms. The initial meningeal symptoms subsided after a short course of dexamethasone taper and the patient remained neurologically intact from initial presentation through hospital discharge 9 days later. 

Our case depicts the need to portray amplified awareness given the clinical hallmark and presentation of subarachnoid hemorrhages (SAH), with the spontaneous subtype being extremely rare and difficult to disentangle, comprising less than 1% of all SAH (2). Workup to include various etiologies including Reversible Cerebral Vasoconstriction Syndrome, posterior reversible encephalopathy syndrome (PRES), CNS vasculitis, auto-immune meningitis, cerebral aneurysms, and arteriovenous malformations (3) need to be ruled-out before the possibility of vaccine complications can be considered. While the mechanism of action is still unknown, with no reported episodes of Covid-19 vaccine associated subarachnoid hemorrhages, the workup must begin. As such, SAH should be considered critical in order to avoid misdiagnosis in neurologically intact patients so as to ensure an exact therapeutic strategy with good prognosis.