Lateral decubitus digital subtraction myelography to identify spinal CSF–venous fistulas in spontaneous intracranial hypotension

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>Spontaneous spinal CSF–venous fistulas are a distinct type of spinal CSF leak recently described in patients with spontaneous intracranial hypotension (SIH). Using digital subtraction myelography (DSM) with the patient in the prone position, the authors have been able to demonstrate such fistulas in about one-fifth of patients with SIH in whom conventional spinal imaging (MRI or CT myelography) showed no evidence for a CSF leak (i.e., the presence of extradural CSF). The authors compared findings of DSM with patients in the lateral decubitus position versus the prone position and now report a significantly increased yield of identifying spinal CSF–venous fistulas with this modification of their imaging protocol.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>The population consisted of 23 patients with SIH who underwent DSM in the lateral decubitus position and 26 patients with SIH who underwent DSM in the prone position. None of the patients had evidence of a CSF leak on conventional spinal imaging.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>A CSF–venous fistula was demonstrated in 17 (74%) of the 23 patients who underwent DSM in the lateral decubitus position compared to 4 (15%) of the 26 patients who underwent DSM in the prone position (p &lt; 0.0001). The mean age of these 16 women and 5 men was 52.5 years (range 36–66 years).</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>Among SIH patients in whom conventional spinal imaging showed no evidence of a CSF leak, DSM in the lateral decubitus position demonstrated a CSF–venous fistula in about three-fourths of patients compared to only 15% of patients when the DSM was performed in the prone position, an approximately five-fold increase in the detection rate. Spinal CSF–venous fistulas are not rare among patients with SIH.</jats:p></jats:sec>

Spontaneous spinal cerebrospinal fluid‐venous fistulas in patients with orthostatic headaches and normal conventional brain and spine imaging

“…The present study confirms prior reports that many patients with spontaneous spinal CSF-venous fistulas do not have low CSF opening pressures. [6][7][8][9][10][11][12][13] This study shows that concerns about a spinal CSF leak should not be dismissed in patients suffering from orthostatic headaches when conventional imaging turns out to be normal, even though the yield of identifying a CSF-venous fistula is low. Among patients with orthostatic headaches and normal conventional imaging, we currently consider DSM to search for CSF-venous fistulas in those with spinal meningeal diverticula but are hesitant to recommend DSM when imaging does not show such diverticula.…”

“…In prior reports from different medical centers, the majority of CSF-venous fistulas were similarly located in the thoracic spine. [6][7][8][9][10][11][12][13] In the presently reported patients, the DSM was generally focused on the region of the spine harboring meningeal diverticula and it was focused on the thoracic spine in those patients who did not have any spinal meningeal diverticula. The present study confirms prior reports that many patients with spontaneous spinal CSF-venous fistulas do not have low CSF opening pressures.…”

“…[6][7][8][9][10][11][12] Using DSM in a lateral decubitus position, we have shown that three-fourths of patients with a brain MRI showing the stigmata of SIH but conventional spinal imaging negative for an extradural CSF collection have a CSF-venous fistula. 13 The occurrence of CSF-venous fistulas in those patients suspected of SIH who have a normal brain MRI has not been formally studied. We hypothesized that, similar to the finding of extradural CSF collections in patients with orthostatic headaches and normal brain MRI, some patients with orthostatic headaches and normal brain MRI may harbor spinal CSF-venous fistulas.…”

“…In all patients, DSM was performed in the lateral decubitus position under general anesthesia, as described previously. 13,14 All radiographic studies were reviewed by at least one board-certified neuroradiologist and one board-certified neurosurgeon, all with special expertise in SIH.…”

Hydrocephalus and CSF Disorders

“…Conversely, patients with more laterally placed CSF leakage beyond the epidural compartment either from a CSF-venous fistula (CVF) or from a distal root sleeve tear do not display SLECs. The presence or absence of a SLEC on MRI is used to proscribe for the prone versus lateral decubitus positioning of the subsequent dynamic myelography [26,27]. Digital subtraction myelography (DSM) and ultrafast CT myelography [28] are techniques of dynamic myelography which allow for imaging of gravity dependent contrast media as it descends within the thecal sac from site of injection within the lumbar spine into the cervical spinal canal.…”