Spontaneous intracranial hypotension due to CSF-venous fistula: Evaluation of renal accumulation of contrast following decubitus myelography and maintained decubitus CT to improve fistula localization.

PURPOSE: Presented here is a strategy of sequential lateral decubitus digital subtraction myelography (LDDSM) followed closely by lateral decubitus CT (LDCT) to facilitate cerebrospinal fluid (CSF)-venous fistula (CVF) localization. MATERIALS AND METHODS: This is a retrospective analysis of patients referred to our institution for evaluation of CSF leak. Patients with Type 1 and Type 2 leaks, and those not displaying MR brain stigmata of intracranial hypotension were excluded. All patients underwent consecutive LDDSM and LDCT. If the CVF was not localized on the first LDDSM-LDCT pair the patient returned for contralateral examinations. Images were reviewed for CVF and for accumulation of contrast within the renal pelvises expressed as a renal pelvis contrast score (RPCS) in Hounsfield units (HU). RESULTS: Twenty-two patients were included in this study. In 21 of 22 patients (95%) a CVF was identified yielding an RPCS for the LDDSM-LDCT pair ipsilateral to the CVF ranging from 71 to 423 with an average of 146 HU. An RPCS of the negative side LDDSM-LDCT pair contralateral to a CVF was available in 8 patients and averaged 51 HU. In 4 patients the initial bilateral LDDSM-LDCT pairs did not reveal the location of the CVF however in 3 of these 4 cases the CVF was revealed on a third LDDSM repeated ipsilateral to the higher RPCS. CONCLUSION: The strategy of sequential LDDSM-LDCT coupled with evaluation of renal accumulation of contrast agent appears to improve the rate of CVF localization and warrants further evaluation.

Thoracolumbar spinal dural arteriovenous fistulae present with longer arteriovenous transit compared to cranial and cervical dural fistulae.

BACKGROUND: Thoraco-lumbar spinal dural arteriovenous fistulae represent a rare subset of central nervous system vascular malformations. One of the unique features of spinal dural arteriovenous fistulae is their extremely low propensity to cause hemorrhage (either parenchymal or subarachnoid), with a distinct clinical presentation of myelopathy secondary to spinal venous congestion. The exact mechanism for this unique presentation is still unclear. METHODS: Following institutional review board approval, we retrospectively analyzed our prospectively maintained database of spinal dural arteriovenous fistulae and cranial (cr) DAVF cases presenting between 2008 and 2021. For all cases, angiograms were reviewed and arteriovenous transit times were calculated. Patient demographics, angiographic features, and clinical and radiological outcomes were assessed. RESULTS: In total, 66 patients presenting with confirmed thoracolumbar spinal dural arteriovenous fistulaes were identified and compared to patients presenting with cervical spinal dural arteriovenous fistulaes (n = 10), ruptured crDAVFs (n = 32) and unruptured crDAVFs (n = 20). Mean age in the target group was 66 ± 13 versus 57-62 in the other groups, p < 0.05 on one-way analysis of variance; with 80% males versus 50%-65% in other groups. Mean arteriovenous transit time in the thoracolumbar group measured 1.98 s ± 0.96 versus 0.25-0.5 s range in other groups (p < 0.0001 on one-way analysis of variance). CONCLUSION: Prolonged arteriovenous transit times may represent a distinct feature of thoracolumbar spinal dural arteriovenous fistulaes. This may, amongst other factors, play a role in the observed lesser likelihood of hemorrhagic complications compared to other dural arteriovenous shunts.

Recognition of the variant type of spinal dural arteriovenous fistula: a rare but important consideration.

OBJECTIVE: Spinal dural arteriovenous fistulas (SDAVFs) typically represent abnormal shunts between a radiculomeningeal artery and radicular vein, with the point of fistulization classically directly underneath the pedicle of the vertebral body, at the dural sleeve of the nerve root. However, SDAVFs can also develop in atypical locations or have more than one arterial feeder, which is a variant of SDAVF. The aim of this study was to describe the incidence and multidisciplinary treatment of variant SDAVFs in a single-center case series. METHODS: Following institutional review board approval, the authors retrospectively analyzed their prospectively maintained database of patients with SDAVFs who presented between 2008 and 2020. For all patients, spinal digital subtraction angiograms were reviewed and variant SDAVFs were identified. Variant types of SDAVFs were defined as cases in which the fistulous point was not located underneath the pedicle. Patient demographics, angiographic features, clinical outcomes, and treatment modalities were assessed. RESULTS: Of 59 patients with SDAVFs treated at the authors' institution, 4 patients (6.8%) were identified as having a variant location of the shunt zone, pinpointed on the dura mater at the intervertebral level, further posteriorly within the spinal canal. In 3 cases (75%), a so-called bimetameric arterial supply was demonstrated. CONCLUSIONS: Recognition of the variant type of SDAVF is crucial for management, as correct localization of the fistulous point and bimetameric supply are critical for successful surgical disconnection, preventing delay in achieving definitive treatment.