A rare neurovascular complication of Lemierre syndrome: Skull base pachymeningitis and reversible inflammatory stenosis of the petrous-cavernous internal carotid artery

Lemierre syndrome is a septic thrombophlebitis of the internal jugular vein that follows an oropharyngeal infection, most often caused by Fusobacterium necrophorum . Its intracranial complications are predominantly venous; arterial involvement is uncommon and its nature is rarely characterized on imaging. We report the case of a 22-year-old woman admitted with fever, headache, left cervical pain and vomiting 1 week after an acute pharyngitis treated with azithromycin. Blood cultures grew F necrophorum , and contrast-enhanced cervical computed tomography showed thrombosis of the left internal jugular vein extending to the jugular bulb. Magnetic resonance imaging (MRI) on day 3 showed skull base pachymeningitis with patent dural sinuses. On day 7, the patient developed raised intracranial pressure and diplopia. Time-of-flight angiography showed segmental narrowing of the petrous and cavernous segments of the left internal carotid artery, and contrast-enhanced black-blood 3D T1-weighted fast spin-echo images showed circumferential thickening and enhancement of its wall, absent before contrast and on the contralateral side, consistent with an inflammatory arteritis contiguous to the infected jugular foramen; the dural sinuses remained patent. Treatment combined 21 days of intravenous antibiotic therapy active against anaerobes, therapeutic anticoagulation and acetazolamide. On day 15, MRI with the same sequences showed resolution of the mural enhancement, a normal arterial caliber, regression of the pachymeningitis and partial regression of the jugular thrombosis, and the patient had fully recovered by day 28. This case illustrates how vessel wall MRI, even with a routine sequence interpreted against internal controls, can characterize arterial involvement in Lemierre syndrome and document its reversibility.