A 38-year-old woman presented with a 1-week history of progressive headache and acute onset of left-sided hemiparesis. Neurological examination showed bradyphrenia and intermittent left hemiparesis. Brain neuroimaging revealed cavernous sinus thrombosis, subdural empyema, pathological vessel-wall enhancement of the right middle cerebral artery and ischaemia in the right striatum. Cavernous sinus thrombophlebitis with secondary vasculitis and ischaemic stroke was diagnosed. Bacteraemia due to Streptococcus intermedius from a jaw infection was found and she received antibiotic treatment. At six-month follow-up, her symptoms had improved remarkably. Clinical signs such as progressive headache, which does not respond to analgesics, subtle cranial nerve palsy and increased infectious parameters should alert the clinician to conduct appropriate neuroimaging studies. Early initiation of effective antibiotic treatment in these cases is essential and can change the course of the illness and improve prognosis.