Spontaneous intracranial hypotension (SIH) is an important cause of new daily persistent headaches.1 In most patients, the underlying cause is a CSF leak, always at the level of the spine.2 Once escaped into the epidural space, CSF is rapidly absorbed by the spinal epidural venous plexus, which is often maximally dilated in the setting of SIH. With conventional imaging, the presence of contrast in epidural veins has not been demonstrated in SIH, but indirect evidence for rapid venous absorption such as contrast in the renal collection system on CT myelography or early activity of tracer in the bladder on nuclear cisternography is common.1 We report the radiographic demonstration of direct CSF–venous fistulae in patients with SIH using digital subtraction myelography (DSM). DSM allows real-time high-resolution imaging of contrast injected through a lumbar puncture.3,–,5
Case reports.
Case 1.
A 52-year-old woman noted a second half of the day headache, neck stiffness, and interscapular pain. Neurologic examination was normal. MRI showed pachymeningeal enhancement and brain sagging. CT and magnetic resonance (MR) myelography showed multiple thoracic cysts but no CSF leak. CSF examination was normal. Bed rest provided little relief. DSM showed a direct fistula originating from the left T-10 cyst into a spinal epidural vein (figure). Percutaneous fibrin glue injection resulted in resolution of symptoms.
Case 1: Digital subtraction myelography (DSM) images (A–C, frontal projection) show contrast filling spinal vein (arrows). Case 2: DSM images (D–F, frontal projection, and G and H, lateral projection) show contrast filling spinal vein (arrows) and basi-vertebral veins of the vertebral bodies (arrowheads). Case 3: DSM images (I–K, frontal projection, and L and M, lateral projection) show contrast filling spinal vein (arrows) and ventral CSF leak (arrowhead).
Case 2.
A 31-year-old woman noted an orthostatic headache, ringing in the ears, and neck stiffness. Neurologic examination was normal. MRI showed pachymeningeal enhancement, brain sagging, and pituitary enlargement. CT and MR myelography showed an extensive spinal ventral extradural CSF collection. CSF examination was normal. The patient underwent numerous epidural blood patches but symptoms persisted. DSM showed a ventral CSF leak at T-2/3 and she underwent surgical repair resulting in resolution of symptoms. Ten months later, symptoms recurred, but CT myelography did not show any CSF leak. DSM showed a direct fistula originating from the region of the left T-4 nerve root into a spinal epidural vein (figure). The ventral CSF leak was no longer demonstrable. At surgery, epidural venous dilation was significant and a dural tear at the axilla of the left T-4 nerve root was identified and this was sutured, resulting in resolution of symptoms.
Case 3.
A 48-year-old woman noted an orthostatic headache, nausea, emesis, and neck stiffness. Neurologic examination was normal. MRI showed pachymeningeal enhancement and brain sagging. CT and MR myelography showed an extensive spinal ventral extradural CSF collection. CSF examination was normal. She underwent numerous epidural blood patches but symptoms persisted. DSM showed a ventral CSF leak at T-5/6 associated with a direct communication into a spinal epidural vein (figure). At surgery, epidural venous dilation was significant and a ventral dural tear was repaired resulting in resolution of symptoms.
Discussion.
In this report, we demonstrate direct fistulae between the subarachnoid space and spinal epidural veins, a previously unreported finding in SIH. In 2 of the 3 patients, the fistula provided crucial information for localizing the site of the CSF leak. In fact, MRI and CT myelography had not shown any evidence for a CSF leak in these 2 patients. Whether or not DSM should be considered for all patients with refractory SIH but unrevealing conventional spinal imaging remains to be determined. DSM usually is reserved for rapid CSF leaks visible on MRI or CT myelography as extensive longitudinal intraspinal extradural fluid collections.3,–,5 DSM allows visualization of rapid CSF leaks due to its inherent temporal resolution advantage. The procedure differs from conventional myelography in several aspects, although associated risks are similar.4 We have found that the best diagnostic information is obtained when DSM is completed with the patient under anesthesia and complete paralysis with breath hold, although others have reported excellent results without anesthesia.4 DSM technique requires a bolus injection of intrathecal contrast to maximize visualization and allow breath hold imaging. The radiation dose of DSM is slightly higher than that of conventional myelography, but it is less than that of conventional CT myelography because demonstration of a leak is not dependent on post myelography CT imaging.
Iatrogenic CSF venous fistulae following myelography have been reported previously.6 Our cases show that venous injury by a needle is not necessary to create such a direct fistula. The presence of dilated epidural veins (a common spinal imaging characteristic of SIH and documented at surgery in the 2 patients who underwent surgical repair of the CSF leak) and the presence of arachnoid granulations (which have been demonstrated along spinal nerve roots)7 may have contributed to the development of the spontaneous CSF–venous fistulae.
Footnotes
Author contributions: Dr. Schievink: drafting/revising the manuscript, study concept or design, analysis or interpretation of data. Dr. Moser: drafting/revising the manuscript, study concept or design, analysis or interpretation of data. Dr. Maya: drafting/revising the manuscript, study concept or design, analysis or interpretation of data.
Study funding: No targeted funding reported.
Disclosure: The authors report no disclosures relevant to the manuscript. Go to Neurology.org for full disclosures.
- Received October 4, 2013.
- Accepted in final form March 13, 2014.
- © 2014 American Academy of Neurology
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