Watch brain circulation in unexplained progressive myelopathy: a review of Cognard type V arterio-venous fistulas

Abstract

Background: Intracranial dural arterio-venous fistulas are pathological anastomoses between arteries and veins located within dural sheets and whose clinical manifestations depend on location and hemodynamic features. They can sometimes display perimedullary venous drainage (Cognard type V fistulas-CVFs) and present as a progressive myelopathy. Our review aims at describing CVFs' variety of clinical presentation, investigating a possible association between diagnostic delay and outcome and assessing whether there is a correlation between clinical and/or radiological signs and clinical outcomes.

Methods: We conducted a systematic search on Pubmed, looking for articles describing patients with CVFs complicated with myelopathy.

Results: A total of 72 articles for an overall of 100 patients were selected. The mean age was 56.20 ± 14.07, 72% of patients were man, and 58% received an initial misdiagnosis. CVFs showed a progressive onset in 65% of cases, beginning with motor symptoms in 79% of cases. As for the MRI, 81% presented spinal flow voids. The median time from symptoms' onset to diagnosis was 5 months with longer delays for patients experiencing worse outcomes. Finally, 67.1% of patients showed poor outcomes while the remaining 32.9% obtained a partial-to-full recovery.

Conclusions: We confirmed CVFs' broad clinical spectrum of presentation and found that the outcome is not associated with the severity of the clinical picture at onset, but it has a negative correlation with the length of diagnostic delay. We furthermore underlined the importance of cervico-dorsal perimedullary T1/T2 flow voids as a reliable MRI parameter to orient the diagnosis and distinguish CVFs from most of their mimics.

Keywords: Intracranial dural arterio-venous fistulas (iDAVFs); Intracranial vascular malformations; Myelopathy; Spinal cord disease.

Fig. 1

MRI at the diagnosis. A Axial FLAIR sequence shows hyperintensities in the pons and in the right cerebellar hemisphere (white arrows). B Axial T1-weight image obtained after gadolinium administration reveals enhancement of the same areas (white arrows). C Sagittal T2-weighted image shows intramedullary hyperintensity from the medulla oblongata to D2 vertebra level, with swollen cervical spinal cord (white arrows). D Gd-enhancement of the lesion shown in C (white arrows)

Fig. 2

Cerebral angiography, vertebral artery injections. A The A-V shunt at the fistula site is indicated by the white arrow (LL view). The arterial feeder is the posterior meningeal artery (PMA), arising from the vertebral artery. B Same as in (A) but with digitally subtracted images showing the feeding artery (PMA, a), the fistula site (white arrow), and the precociously enhanced straight sinus (v). Retrograde venous drainage route is indicated by the black arrow. C Parenchimal-phase acquired image showing backward venous drainage route (black arrows) toward the perimedullary venous system. D Late acquisition image showing venous blood direction (black arrows) reaching the perimedullary venous system at cervical level (*)

Fig. 3

Flow chart of the searching strategy

Fig. 4

Misdiagnosis rate. Note. NA, not available

Fig. 5

Symptoms at onset

Fig. 6

Red flags for performing a cerebral angiography