INTRACRANIAL DURAL FISTULAS DRAINING INTO SPINAL VEINS - REPORT ON 2 OBSERVATIONS

The authors report 2 new cases of intracranial dural fistula draining into spinal veins. Comparisons with 19 other published cases showed th at dural fistulae of the spine share common features with intracranial fistulae. The first case concerned a 78-year old woman presenting wit h a thoraco-lumbar myelopathy which proceeded by increasingly severe b outs and ended within 6 months in a flaccid sensorimotor paraplegia wi th urinary incontinence. Paraclinical examinations consisted of MRI, m yelography and spinal as well as cerebral arteriography. MRI and thora co-lumbar myelography displayed marks of dilated retrospinal vessels. Spinal arterioraphy showed no arteriovenous malformation, but the veno us return of Adamkiewicz artery was not visible. Diagnosis was made by cerebral arteriography which demonstrated an intracranial arterioveno us fistula in the occipital region, draining into the posterior spinal vein. Treatment was endovascular and consisted of embolization by mic ro-coils, but clinical improvement was mediocre. Six months later, as the clinical picture was getting worse a second arteriography was perf ormed. It showed recanalization of the fistula which was embolized aga in, using both coils and particles. No improvement in spinal cord defi cit was observed. The second case was that of a 42-year old man presen ting with paraparesis, tetrapyramidal syndrome, sensory deficit at T9, peribuccal dysaesthesias and genito-urinary sphincteral disorders, al l gradually getting worse. The paraclinical exploration was the same a s in the first case. MRI and myelography showed retrospinal vascular i mpressions. Spinal arteriography was normal, except for the lack of ve nous return of Adamkiewicz artery. Cerebral arteriography detected an intracranial dural arteriovenous fistula in the occipital region, drai ning into the anterior and posterior spinal veins. Treatment was surgi cal, consisting of exclusion of the arteriovenous fistula. Partial cli nical improvement was noted. These two cases, compared with those of t he literature, shared a number of features with spinal dural arteriove nous fistulae : they occur in middle-aged and predominantly male patie nts, and the clinical signs of ascending myelopathy are caused by the same physiopathological mechanism of spinal vein hyperpressure. Lesion s of the medulla oblongata or the cervical spinal cord are found only in intracranial arteriovenous fistulae draining into spinal veins. Dia gnosis is based on data provided by myelography (impressions of dilate d and sinuous vessels) and MRI (low-intensity perispinal signals, wide ning of the conus medullaris with high-intensity centrospinal signal) ; spinal cord angiography only shows a lack of venous return of Adamki ewicz artery without any other abnormality, whereas cerebral arteriogr aphy confirms the diagnosis of intracranial dural arteriovenous fistul a draining into spinal veins. Some similitudes are also found with int racranial dural arteriovenous fistulae, including mature age, lack of pain and above all the possibility of cortical venous return, a factor of poor prognosis with potential risk of haemorrhage.Whether surgical or endovascular, treatment of intracranial arteriovenous fistulae dra ining into the spinal veins is sometimes disappointing as regards clin ical recovery, but it is necessary owing to the inescapable aggravatio n on short or long term.