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Flow Reversal In Spinal Pial Veins Post Endovascular Occlusion Of Spinal Dural Malformation: Angiographic Demonstration and Prognostic Evaluation 2005

Interventional Spine

Avi I Setton, MD
Rona F Woldenberg , MD, Non ASSR Member
Karen Black , MD, Non ASSR Member
Tanmaya C Shah , MD, Non ASSR Member

Purpose

To report the angiographic observation of flow reversal in pial spinal cord veins draining a spinal dural malformation, immediately post endovascular obliteration of the fistula. Correlation to imaging and clinical parameters may define a prognostic value to this angiographic finding.

Methods & Materials

The angiographic spinal studies of two patients (M45, & M49) treated for symptomatic spinal dural malformations demonstrated immediate reversal of flow in pial spinal veins post endovascular obliteration of the fistula. Selective angiographic studies of the anterior spinal artery (ASA) and calculated circulation time were obtained pre- and post embolization. Neurophysiological recordings, early follow up imaging (MRI) and the clinical course were correlated to evaluate prognostic value of this angiographic finding.

Results

Two patients with rapidly progressive neurological deficits (loss of sphincter control and lower extremity weakness) were studied by MRI, spinal MRA and selective spinal angiography. One spinal dural fistula (Rt. T11) and one epidural fistula (L3) were identified draining to spinal pial veins inducing venous hypertension. Angiographic studies of the dilated pial spinal veins (late venous phase) as well as selective studies in the ASA were obtained. Pre-treatment ASA circulation time was measured. Upon endovascular obliteration of the fistula with acrylic, repeat angiography of the ASA demonstrated immediate improvement in circulation time. Normal sequential filling of pial spinal veins along the conus and lower thoracic cord, including dilated veins previously draining the dural shunt was observed. These findings represent rapid venous pressure normalization in the pial veins. Intra-procedural improvement of motor evoked potentials (MEPs), marked early resolution of MRI findings and dramatic clinical improvement followed.

Conclusion

Angiographic demonstration of reversal of flow in dilated spinal pial veins previously draining dural or epidural fistulas were documented upon obliteration of the lesion. Immediate improvement of ASA circulation time, intra-procedural improvement of MEPs, early regression of myelopathy documented on conventional MRI and rapid clinical improvement followed. This angiographic finding appears to provide prognostic information regarding anticipated clinical recovery and resolution of imaging findings. We recommend reassessment of the ASA including observation of circulation time post embolization as an addition to the angiographic protocol to assess for venous flow reversal and to further evaluate its prognostic value.