Cerebrospinal Fluid-Venous Fistula

CVFs can arise from various causes, including:

Trauma: Head or spinal injuries can disrupt the normal barriers between the CSF space and venous structures, leading to a fistula.

Iatrogenic: Certain medical procedures, such as lumbar punctures or spinal surgeries, can inadvertently create CSF-venous connections.

Congenital: Some individuals may have anatomical abnormalities or developmental defects that predispose them to CVFs.

Idiopathic: In some cases, the exact cause of the CVF remains unknown.

Patients with CVFs may experience a range of symptoms, which are primarily related to the altered dynamics of CSF circulation and pressure.

Only 1 patients with CVF with cognitive abnormalities was identified. The most common symptom was headache in both reviews. Brain sag was identified in all patients, whereas CSF leak was identified in only 2 patients with SIH with FTD or dementia (4.9%). An epidural blood or fibrin glue patch was used in all patients with CVF and in 33 patients with SIH with FTD or dementia. Fifty-five patients with CVF (79.7%) and 27 patients with SIH with FTD or dementia (65.9%) had surgery.

Conclusions: The 2 cases and literature reviews show the difficulty in diagnosis and treatment of CVF with cognitive decline. Novel imaging techniques should be used in patients with cognitive decline in whom a CSF leak is suspected. Transvenous embolization or surgery should be considered before patching for treatment of CVF-induced brain sag and resulting dementia 2).

To diagnose CVFs, various imaging techniques are used. These may include digital subtraction myelography (DSM), CT myelography (CTM), magnetic resonance imaging (MRI). CSF-venous fistulas (CVFs), first described in 2014, are an important cause of spontaneous intracranial hypotension. CVFs can be challenging to detect on conventional anatomic imaging because, unlike other types of spinal CSF leak, they do not typically result in pooling of fluid in the epidural space, and imaging signs of CVF may be subtle. Specialized myelographic techniques have been developed to help with CVF identification, but these techniques are not yet widely disseminated. This article reviews the current understanding of CVFs, emphasizing correlations between venous anatomy and imaging findings as well as potential mechanisms for pathogenesis, and describes current imaging techniques used for CVF diagnosis and localization. These techniques are broadly classified into fluoroscopy-based methods, including digital subtraction myelography and dynamic myelography, and cross-sectional methods, including decubitus CT myelography and MR myelography with intrathecal injection of gadolinium. Knowledge of these various options, including their relative advantages and disadvantages, is critical in the care of patients with spontaneous intracranial hypotension. Investigation is ongoing, and continued advances in knowledge about CVFs as well as in optimal imaging detection are anticipated 3)

Lateral decubitus digital subtraction myelography (LD-DSM) and CT myelography (LD-CTM) are mainly used for detection, but the most sensitive method is yet unknown.

Patients with spontaneous intracranial hypotension diagnosed with a Cerebrospinal Fluid-Venous Fistula between January 2021 and December 2022 in which the area of CVF(s) was covered by both diagnostic modalities were included. LD-CTM immediately followed LD-DSM without repositioning the spinal needle, and the second half of the contrast agent was injected at the CT scanner. Patients were awake or mildly sedated. Retrospectively, two neuroradiologists evaluated data independently and blinded for the presence of CVF.

Twenty patients underwent a total of 27 combined LD-DSM/LD-CTM examinations (4/20 with follow-up and 3/20 with bilateral examinations). Both raters identified significantly more CVFs with LD-CTM than with LD-DSM (rater 1: 39 vs 9, P<0.001; rater 2: 42 vs 12, P<0.001). Inter-rater agreement was substantial for LD-DSM (κ=0.732) and LD-CTM (κ=0.655). The results remained significant after considering the senior rating for cases of disagreement (39 vs 10; P<0.001), and no CVF detected on LD-DSM was missed on LD-CTM.

In this study, Lateral decubitus CT myelography has a higher diagnostic yield for the detection of CVFs than LD-DSM and should supplement LD-DSM, but further studies are needed. LD-CTM can be easily acquired in awake or mildly sedated patients with the second half of contrast injected just before CT scanning, or it may be considered as a stand-alone investigation 4).

The study provides valuable insights into the diagnostic yield of LD-DSM and LD-CTM for CVF detection in SIH patients. However, it has limitations related to sample size, study design, and the need for further validation. The findings support the potential role of LD-CTM as a more sensitive diagnostic tool, but its clinical implications and safety considerations should be explored in more detail.

Ultrahigh-Resolution Cone-Beam Computed Tomography 5)

Direct intraoperative visualization of CVF using intrathecal fluorescein. CVF can be identified intraoperatively using fluorescein dye, which can be a valuable adjunct for the surgeon confronted with this disease 6).

DSM had a 90% detection rate of visualizing the exact site of the dural breach in patients with extensive postoperative spinal CSF leaks. The coexistence of a CSF-venous fistula in addition to the primary dural tear was present in about one-fifth of patients. The presence of a CSF-venous fistula should be considered if CSF leak symptoms persist in spite of successful repair of a durotomy 7).

The management of CVFs typically involves interventions aimed at closing or repairing the abnormal communication between the CSF space and the venous system. Treatment options may include:

Blood Patches: In some cases, a targeted epidural or intrathecal blood patch is used to seal the fistula and restore normal CSF pressure.

Embolization: Minimally invasive procedures can be performed to occlude the abnormal connection through the use of embolic materials. Transvenous embolization of CSFVF in SIH patients is safe and effective with a 95% treatment response, significant improvement in imaging outcomes, and a very low rate of complications 8)

Transvenous embolization is independently validated as a highly effective and safe treatment for CVF and is feasible using upper-extremity venous access. Dual-microcatheter and balloon/coil pressure cooker techniques may be used to optimize distribution of embolic material and potentially, treatment efficacy 9).

Surgery: Surgical repair may be necessary in complex cases where other methods are not effective.

Cerebrospinal Fluid-Venous Fistula are increasingly identified as a cause of spontaneous intracranial hypotension (SIH).

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Stuebe C, Jones BA, Syal A, Rahme RJ, Turcotte EL, Toussaint LG 3rd, Ross JS, Bendok BR. Cerebrospinal Venous Fistula Presenting with Cognitive Decline: Systematic Literature Review and Report of Two Cases. World Neurosurg. 2023 Aug;176:74-80. doi: 10.1016/j.wneu.2023.03.056. Epub 2023 Mar 17. PMID: 36934870.
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Häni L, El Rahal A, Fung C, Volz F, Kraus LM, Lützen N, Urbach H, Schnell O, Beck J. Intraoperative Visualization of Flow in Direct Cerebrospinal Fluid-Venous Fistulas Using Intrathecal Fluorescein. Oper Neurosurg (Hagerstown). 2023 May 1;24(5):e336-e341. doi: 10.1227/ons.0000000000000625. Epub 2023 Feb 10. PMID: 37068025.
Schievink WI, Maya MM, Chu RM, Perry TG, Moser FG, Taché RB, Wadhwa VS, Prasad RS. Postoperative Spinal Cerebrospinal Fluid-Venous Fistulas Associated With Dural Tears in Patients With Intracranial Hypotension or Superficial Siderosis-A Digital Subtraction Myelography Study. Neurosurgery. 2023 Aug 1;93(2):473-479. doi: 10.1227/neu.0000000000002444. Epub 2023 Mar 1. PMID: 36856442.
Brinjikji W, Madhavan A, Garza I, Whealy M, Kissoon N, Mark I, Morris PP, Verdoorn J, Benson J, Atkinson JLD, Kobeissi H, Cutsforth-Gregory JK. Clinical and imaging outcomes of 100 patients with cerebrospinal fluid-venous fistulas treated by transvenous embolization. J Neurointerv Surg. 2023 Oct 28:jnis-2023-021012. doi: 10.1136/jnis-2023-021012. Epub ahead of print. PMID: 37898553.
Parizadeh D, Fermo O, Vibhute P, Gupta V, Arturo Larco JL, Grewal SS, Quinones-Hinojosa A, Erben YM, Clendenen S, Rozen TD, Huynh TJ. Transvenous embolization of cerebrospinal fluid-venous fistulas: Independent validation and feasibility of upper-extremity approach and using dual-microcatheter and balloon pressure cooker technique. J Neurointerv Surg. 2023 Jan 23:jnis-2022-019946. doi: 10.1136/jnis-2022-019946. Epub ahead of print. PMID: 36690439.
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