Case: A 56 year old man presented with new onset headaches with visual symptoms. Physical examination was normal apart from asymmetrical papilledema and reduced visual acuity 6/9 bilaterally. CSF opening pressure was 26 cm H₂O. CTV showed partially recanalised thrombosis in the superior sagittal sinus and the right sigmoid and transverse sinuses which appeared chronic. His headaches initially improved with propranolol but he continued to complain of visual symptoms; repeat CSF opening pressure was 31 cm H₂O and repeat CTV was reported as, ‘more occlusive’. He was therefore anti-coagulated and treated with acetazolamide.

Six weeks after starting treatment, ophthalmological assessment found worsening visual fields despite reduction in disc swelling on OCT. CSF pressure remained elevated at 30 cm H₂O. Repeat CTV and 4D CTA identified a type IIB occipital dural AV fistula around the thrombosed venous sinuses, causing occipital lobe congestion; the likely cause of the visual field defects.

The patient underwent cerebral angiogram with embolisation of the dural fistula. Following embolization his headaches and papilledema resolved, and visual acuities and fields normalised.

Conclusion Neurologists should be aware of dural AV fistula as a complication of cerebral sinus thrombosis which may cause persistent raised pressure symptoms in treated patients.