Volumetric myelographic magnetic resonance imaging to localize difficult-to-find spinal dural arteriovenous fistulas

Neurologic pathologies of the vertebral spine

At some institutions, musculoskeletal and general radiologists rather than neuroradiologists are responsible for reading magnetic resonance imaging (MRI) of the spine. However, neurological findings, especially intrathecal ones, can be challenging. Intrathecal neurological findings in the spine can be classified by location (epidural, intradural extramedullary, and intramedullary) or etiology (tumor, infection, inflammatory, congenital). In this paper, we provide a succinct review of the intrathecal neurological findings that can be seen on MRI of the spine, primarily by location and secondarily by etiology, in order that this may serve as a helpful guide for musculoskeletal and general radiologists when encountering intrathecal neurological pathologies.

Time-Resolved Magnetic Resonance Angiography for Follow-Up of Treated Dural and Epidural Spinal Arteriovenous Fistula

BACKGROUND

 Spinal arteriovenous fistulas (AVFs) are uncommon vascular malformations of spinal dural and epidural vessels. Actually digital subtraction angiography (DSA) is the gold standard for diagnosis and follow-up. The aim of this study is to demonstrate the validity of the multiphasic magnetic resonance angiography (MRA) to identify recurrent/residual AVFs or their correct surgical and/or endovascular closure.

METHODS

 A retrospective cases series with perimedullary venous plexus congestion due to spinal dural or epidural AVF was performed at our center from April 2014 to September 2019. After 1 month from treatment, the patients were subjected to time-resolved MRA and DSA to demonstrate recurrence or correct closure of AVFs.

RESULTS

 We collected a series of 26 matched time-resolved MRA and DSA in 20 patients who underwent an endovascular and/or surgical procedure. In our series, we reported five cases of recurrence. Time-resolved MRA detected six cases of recurrence, with 100% sensitivity and 95% specificity (p < 0.001). We used DSA as the standard reference.

CONCLUSION

 Time-resolved MRA is a valid tool in posttreatment follow-up to detect recurrent or residual AVFs. It has high sensitivity and specificity and may replace DSA.

Diagnostic accuracy of three-dimensional-rotational angiography and heavily T2-weighted volumetric magnetic resonance fusion imaging for the diagnosis of spinal arteriovenous shunts

BACKGROUND

Spinal arteriovenous shunts (SAVSs) are rare entities occurring in various areas, from the craniocervical junction to the sacral level. Recently, better understanding of SAVS angioarchitecture and elucidation of its pathogenesis have become possible with the advancement of imaging techniques. However, the utility of fusing different image modalities for SAVS diagnostics has not been determined. This study aimed to investigate whether three-dimensional-rotational angiography (3D-RA) and 3D-heavily T2-weighted volumetric MR (3D-MR) fusion imaging would improve the diagnostic accuracy for SAVSs.

METHODS

We retrospectively reviewed 12 SAVSs in 12 patients. Assessment of 3D-RA and 3D-RA/3D-MR fusion images for SAVS was performed by seven blinded reviewers. The final diagnosis was performed by two interventional neuroradiologists with extensive experience, and the interobserver agreement between the reviewers and the final diagnosis was calculated using κ statistics. The comparison of the interobserver agreement between 3D-RA and 3D-RA/3D-MR fusion images was performed for the diagnosis of SAVS subtypes. We also statistically compared the image-quality gradings (on a 4-grade scale) to delineate the 3D relationship between vascular malformations and the surrounding anatomical landmarks.

RESULTS

The interobserver agreement for the 3D-RA/3D-MR fusion images was substantial (κ=0.7071) and higher than that for the 3D-RA images (κ=0.3534). Significantly better image quality grades were assigned to 3D-RA/3D-MR fusion images than to 3D-RA images (p<0.0001) for the evaluation of the examined 3D relationships.

CONCLUSION

The 3D-RA/3D-MR fusion images provided better interobserver agreement of SAVS subtype diagnosis, allowing for detailed evaluation of the SAVS anatomical structures surrounding the shunt.

Neuroimaging of Spinal Cord and Cauda Equina Disorders

PURPOSE OF REVIEW

This article reviews the neuroimaging of disorders of the spinal cord and cauda equina, with a focus on MRI. An anatomic approach is used; diseases of the extradural, intradural-extramedullary, and intramedullary (parenchymal) compartments are considered, and both neoplastic and non-neoplastic conditions are covered. Differentiating imaging features are highlighted.

RECENT FINDINGS

Although T2-hyperintense signal abnormality of the spinal cord can have myriad etiologies, neuroimaging can provide specific diagnoses or considerably narrow the differential diagnosis in many cases. Intradural-extramedullary lesions compressing the spinal cord have a limited differential diagnosis and are usually benign; meningiomas and schwannomas are most common. Extradural lesions can often be specifically diagnosed. Disk herniations are the most commonly encountered mass of the epidural space. Cervical spondylotic myelopathy can cause a characteristic pattern of enhancement, which may be mistaken for an intrinsic myelopathy. A do-not-miss diagnosis of the extradural compartment is idiopathic spinal cord herniation, the appearance of which can overlap with arachnoid cysts and webs. Regarding intrinsic causes of myelopathy, the lesions of multiple sclerosis are characteristically short segment but can be confluent when multiple. Postcontrast MRI can be particularly helpful, including when attempting to differentiate the long-segment myelopathy of neurosarcoidosis and aquaporin-4 (AQP4)-IgG-seropositive neuromyelitis optica spectrum disorder (NMOSD) and when characterizing spinal cord tumors such as primary neoplasms and metastases. Spinal dural arteriovenous fistula is another do-not-miss diagnosis, with characteristic MRI features both precontrast and postcontrast. Tract-specific white matter involvement can be a clue for diseases such as subacute combined degeneration, paraneoplastic myelopathy, and radiation myelitis, whereas gray matter-specific involvement can suggest conditions such as cord infarct, viral myelitis, or myelin oligodendrocyte glycoprotein (MOG)-IgG associated disorder.

SUMMARY

Knowledge of the neuroimaging findings of the many causes of spinal cord and cauda equina dysfunction is critical for both neurologists and neuroradiologists. A structured approach to lesion compartmental location and imaging feature characterization is recommended.

Spinal vascular malformations: Angiographic evaluation and endovascular management

Spinal vascular malformations (SVM) are classified based on their location (intramedullary, perimedullary, radicular, extradural) and flow pattern (high-flow, low-flow, no arteriovenous shunt). High-flow SVMs are generally congenital lesions diagnosed in children and young patients without gender predominance. They present with hemodynamic disturbances, mass effect, or hemorrhages, but may also be discovered incidentally. Low-flow SVMs tend to be acquired lesions presenting in older men with progressive myelopathy caused by spinal venous hypertension. They are rarely associated with vascular syndromes but may accompany prothrombotic conditions. The sensitivity and specificity of conventional MRI are excellent for high-flow SVMs but poor for low-flow lesions, which are frequently diagnosed with extensive delays reducing the potential for favorable outcomes. The sensitivity of advanced MRI techniques remains unclear, notably for the detection of low-flow shunts without flow voids on conventional MRI. Catheter angiography remains the gold standard modality for the evaluation of the spinal vasculature and its disorders. SVMs can be treated by surgical or endovascular means. Initially plagued by high recurrence rates due to inadequate embolization material, endovascular techniques represent nowadays a valid alternative to surgery, thanks notably to the introduction of liquid embolic agents.

Vascular Disorders of the Spinal Cord

PURPOSE OF REVIEW

Prompt recognition and timely management of vascular disorders of the spinal cord can improve patient outcomes. This article provides contemporary and practical knowledge about the most common vascular myelopathies.

RECENT FINDINGS

New studies have provided additional information on the risk factors and impact of neurologic monitoring on perioperative spinal cord infarction. Additionally, recent publications have provided information on the impact of misdiagnosis, corticosteroid treatment, and postoperative prognosis in the treatment of spinal dural arteriovenous fistulas and have discussed the outcome of patients with spinal arteriovenous malformations treated with embolization, surgery, and stereotactic radiosurgery. Finally, recent studies have provided information on the natural history and postoperative prognosis of spinal cavernous malformations and on the risk factors and surgical outcome of patients with spinal epidural hematomas.

SUMMARY

Diagnostic and therapeutic challenges are inherent in managing patients with vascular disorders of the spinal cord, and clinicians should have a thorough understanding of these disorders to facilitate optimal outcomes for patients with these potentially devastating illnesses. This article begins by reviewing functional vascular anatomy and subsequently describes the fundamental characteristics of both ischemic and hemorrhagic vascular myelopathies to equip clinicians with the knowledge to avoid common pitfalls.

Spinal dural fistula and anterior spinal artery supply from the same segmental artery: Case report of volumetric T2 MRI diagnosis and rational endovascular treatment

Spinal dural fistulas (SDAVFs) occasionally arise from the same segmental artery as the radiculomedullary branch to the anterior spinal artery. In such cases, selective fistula embolization that does not endanger the anterior spinal artery is not possible, and surgical fistula disconnection is recommended. We present an exceptional case in which rational embolization strategy of SDAVF was feasible because of separate origins from a common segmental artery pedicle of the ventral radiculomedullary artery and the dorsal radicular artery branch supplying the fistula.

Multidisciplinary approach in the treatment of spinal dural arteriovenous fistula-results of endovascular and surgical treatment

BACKGROUND

The results of treatment for spinal dural arteriovenous fistula (SDAVF) have been controversial. The goal of this study was to compare results of endovascular and surgical treatments to contribute to determining an optimal treatment strategy.

METHODS

A retrospective analysis of the set of 24 SDAVF patients (11 in the endovascular and 13 in the surgical group) was performed. The clinical effect (using the modified Rankin scale [mRS]), the radicality, and the number of clinical recurrences as well as the impact of age, the level of impairment, and the duration of symptoms before the treatment were evaluated.

RESULTS

The average age was 60.1 ± 8.4 years. The median duration of symptoms before establishing a diagnosis was 12 (1-70) months. Clinical improvement was reported in 11 out of 24 (45.8%) patients (36.4% following embolization and 53.8% following surgery, p = 0.444). Radical performance was achieved in 47.4% of endovascular versus 92.9% of surgical procedures (p = 0.009). Clinical recurrence was reported in 35.3% of patients in the endovascular group, whereas no clinical recurrence was reported in the surgical group (p = 0.0133). The graphical residuum after 1 surgery out of 14 (7.1%) was cured early during the control angiography. Clinical improvement was reported 42.1% of patients with mRS ≤ 3 versus 60% of patients with mRS ≥ 4 and, in 57.1% of patients aged ≥ 60 versus in 30% of patients < 60 years (p > 0.05 in both cases). The impact of the duration of symptoms on the clinical results was not statistically significant.

CONCLUSIONS

The surgical treatment of SDAVF appeared to be a more efficient method in terms of the clinical effect, radicality, and lower recurrence rate in comparison with the endovascular treatment. No statistically significant dependence of the clinical result on age, deficit burden, or symptom duration was found.

Dilated Vein of the Filum Terminale on MRI: A Marker for Deep Lumbar and Sacral Dural and Epidural Arteriovenous Fistulas

BACKGROUND AND PURPOSE

Conventional MR imaging can provide important clues regarding the location of a spinal vascular malformation. We hypothesized that a dilated vein of the filum terminale, identified as a curvilinear flow void on T2WI, could be an imaging marker for a lower lumbar (L3-L5) or sacral fistula.

MATERIALS AND METHODS

We retrospectively identified all spinal dural and spinal epidural arteriovenous fistulas from 2 large tertiary referral centers from 2005 to 2018. All patients had a lumbar spinal MR imaging and a conventional spinal angiography. Images were reviewed by 2 neuroradiologists who categorized the level of the arterial feeder to the fistula and the presence or absence of a dilated vein of the filum terminale on T2WI and T1 postcontrast images. We calculated the sensitivity, specificity, positive predictive value, and negative predictive value of the presence of a dilated filum terminale vein for a deep lumbar or sacral fistula.

RESULTS

One hundred sixty-two patients were included. An enlarged filum terminale vein was identified in 39 patients. Sensitivity, specificity, positive predictive value, and negative predictive value of the presence of a dilated filum terminale vein for a deep lumbar or sacral fistula were 86%, 98.3%, 94.9%, and 95.1%, respectively.

CONCLUSIONS

The presence of a dilated vein of the filum terminale can accurately localize a spinal dural arteriovenous fistula/spinal epidural arteriovenous fistula to the lower lumbar or sacral spine in patients being evaluated for such lesions. This finding can be used to facilitate both noninvasive and conventional spinal angiography.

Additive Value of 3T 3D CISS Imaging to Conventional MRI for Assessing the Abnormal Vessels of Spinal Dural Arteriovenous Fistulae

Introduction:

We investigated the additive value of the 3T 3D constructive interference in steady state (CISS) sequence to conventional MRI for the evaluation of spinal dural arteriovenous fistulae (SDAVF).

Materials and Methods:

We included 16 consecutive patients (15 men, 1 woman; age range 42–81 years; mean 64 years) with SDAVF who underwent 3T MRI and digital subtraction angiography (DSA) before treatment. Two neuroradiologists independently evaluated the presence of abnormal vessels on 3D CISS-, T₂- and T₁-weighted images (T₁WI, T₂WI), and contrast-enhanced T₁WI using a 3-point grading system. Interobserver agreement was assessed by calculating the κ coefficient.

Results:

The SDAVF site was the cervical region in one patient, the thoracic region in 12 patients, the lumbar region in two, and the sacral region in one. For the visualization of abnormal vessels, the mean score was significantly higher for 3D CISS than the other sequences (P < 0.05). In 12 of 16 cases (75%) both readers made definite positive findings on additional 3D-CISS images. Interobserver agreement was excellent for 3D CISS images (κ = 1.0), good for T₁WI (κ = 0.78; 95% confidence interval [CI] 0.54–1.00) and T₂WI (κ = 0.74; 95% CI 0.48–1.00) and moderate for contrast-enhanced T₁WI (CET₁WI) (κ = 0.50; 95% CI 0.21–0.80).

Conclusion:

For the assessment of abnormal vessels of SDAVF, the 3T 3D CISS sequence adds value to conventional MRI.

Diagnosis of spinal dural arteriovenous fistula using 3D T2-weighted imaging

PURPOSE

To evaluate spinal MRIs without and with 3D T2W imaging among patients without and with spinal dural arteriovenous fistula (SDAVF) confirmed by spinal digital subtraction angiography (DSA).

METHODS

A retrospective case-control study was performed among patients without and with SDAVF who had both spinal MRIs and gold standard spinal DSA. Two neuroradiologists independently reviewed spinal MRIs that were performed with either sagittal T2W turbo spin echo (2D group) or sagittal 3D T2W sampling perfection with application-optimized contrasts using different flip-angle evolutions (SPACE) (3D group) and documented the presence or absence of SDAVF. Using spinal DSA diagnosis as a gold standard, the sensitivity, specificity, and interobserver agreement for the 2D-group and 3D-group MRI diagnosis were calculated.

RESULTS

The 2D group consisted of 21 patients and the 3D group consisted of 16 patients. For both radiologists, the 2D group demonstrated a sensitivity of 100% and specificity of 100%. Interobserver agreement in the 2D group was perfect (k = 1.0). For both radiologists, the 3D group demonstrated sensitivity of 100.0% and specificity of 92.3%. Interobserver agreement in the 3D group was perfect (k = 1.0). While flow voids were considered more conspicuous, spinal cord signal abnormality was considered less conspicuous with 3D T2W SPACE compared with conventional 2D STIR sequence.

CONCLUSION

3D T2W SPACE should be used in conjunction with 2D T2W sequences to more accurately detect abnormal cord signal and determine when perimedullary flow voids are pathologically abnormal for the radiologic diagnosis of SDAVF.

Dynamic contrast-enhanced magnetic resonance angiography for the localization of spinal dural arteriovenous fistulas at 3T

OBJECTIVE

This study was undertaken to evaluate the accuracy of dynamic contrast-enhanced magnetic resonance angiography (DCE-MRA) in the precise location and demonstration of fistulous points in spinal dural arteriovenous fistulas (SDAVFs).

METHODS

Fifteen patients (14 men, 1 woman; age range: 40-78 years; mean: 55.5 years) harboring SDAVF who underwent preoperative DCE-MRA and spinal digital subtraction angiography (DSA) between January 2012 and January 2015 were evaluated retrospectively. Two reviewers independently evaluated the level and side of the arteriovenous fistula and feeding artery on 3T DCE-MRA and DSA images. The accuracy of DCE-MRA was assessed by comparing its findings with those from DSA and surgery in each case.

RESULTS

All 15 patients underwent DCE-MRA and DSA. DSA was unsuccessful in two patients due to technical difficulties. All cases were explored surgically, guided by the DCE-MRA. Surgery confirmed that 14 AVF sites were located in the thoracic spine, 5 in the lumbar spine, and 1 in the cervical spine. The origin of the fistulas and feeding arteries was accurately shown by DCE-MRA in 11 of the 15 patients. DCE-MRA also detected dilated perimedullary veins in all 15 patients. Overall, DCE-MRA facilitated DSA catheterization in 10 cases. In six patients, the artery of Adamkiewicz could be observed. In 15 out of 20 fistulas (75%), both readers agreed on the location on DCE-MRA images, and the κ coefficient of the interobserver agreement was 0.67 (95% confidence interval [CI], 0.16-0.87). In 13 of 16 shunts (75%), the DCE-MRA consensus findings and DSA findings coincided. The intermodality agreement was 0.77 (95% CI: 0.35-0.92).

CONCLUSIONS

Our DCE-MRA studies benefited from the use of a high-field 3T MR imaging unit and reliably detected and localized the SDAVF and feeding arteries. As experience with this technique grows, it may be possible to replace DSA with DCE-MRA if surgery is the planned treatment.

Impact of non-contrast enhanced volumetric MRI-based feeder localization in the treatment of spinal dural arteriovenous fistula

BACKGROUND

The preoperative localization of the feeder of spinal dural arteriovenous fistula (SDAVF) could simplify the diagnostic spinal angiographic procedure. Localization by non-contrast-enhanced MRI-based techniques is an attractive option. However, the usefulness of such an approach for evaluation of SDAVF has not yet been reported.

OBJECTIVE

To study the impact of non-contrast MRI-based feeder localization, followed by targeted spinal angiography, in the evaluation of SDAVF before endovascular intervention.

MATERIALS AND METHODS

Prospectively collected data were analyzed and the level of the feeder was localized preoperatively. The procedural time for targeted spinal angiography was calculated and compared with that of a historical cohort, who underwent routine spinal angiographic examination before the study period. Follow-up MRI was carried out to assess the reliability of this model for detection of occasional metachronous lesions that might be missed with this approach.

RESULTS

Seven patients underwent targeted spinal angiography during the study. The feeder level was accurately identified in five patients and was localized to one vertebral level in six patients. The correlation between MRI and DSA was statistically significant. The number of spinal levels assessed was fewer and overall procedure time was significantly shorter compared to historical cohort (58 min vs 162 min, respectively; p<0.001). Intervention was coupled with targeted angiography in two patients. Follow-up MRI demonstrated flow voids in one patient, who had recurrent fistula at one vertebral level below the previously embolized feeder.

CONCLUSIONS

The non-contrast MRI-based localization technique can reliably detect the level of feeder and help in therapeutic planning of SDAVF. The localization techniques potentially shorten the angiographic procedure and may facilitate simultaneous endovascular definitive treatment. Inclusion of follow-up MRI may be useful for detection of synchronous or metachronous lesions if a targeted approach is adopted. Additionally, this helps to identify failed endovascular therapy.

Utility of 3D SPACE T2-weighted volumetric sequence in the localization of spinal dural arteriovenous fistula

OBJECTIVE The aim of this study was to investigate the utility of a heavily T2-weighted volumetric MRI sequence (3D sampling perfection with application-optimized contrasts using different flip-angle evolutions [SPACE]) in the feeder localization of spinal dural arteriovenous fistula (SDAVF). METHODS Patients who were diagnosed with SDAVF and who had 3D SPACE source images available for review were identified from a retrospective review of medical records. A total of 16 patients were identified, and MR images were analyzed separately by 2 blinded observers. The accuracy of the observation and interobserver agreement were measured by Kendall's tau and kappa statistics. RESULTS The site of fistula was accurately predicted by Observers 1 and 2 in 81% and 88% of cases, respectively, which improved to 94% when the level was considered within 1 vertebral level. The observer agreement with gold-standard angiography and interobserver agreement were found to be highly significant (p < 0.0001). CONCLUSIONS The 3D SPACE MRI sequence is valuable in the precise detection of the site of SDAVF. It may help to tailor digital subtraction angiography and thereby reduce the radiation exposure, contrast load, and study time.

Serious myelopathy due to magnetic resonance imaging-occult arteriovenous fistula: Case report of petrous ridge dural arteriovenous fistula

BACKGROUND AND PURPOSE

We present a case of magnetic resonance imaging (MRI)-occult intracranial dural arteriovenous fistula (DAVF) with serious cervical myelopathy and review the pathophysiological background.

SUMMARY OF CASE

A 61-year-old man had suffered from progressive neurological deterioration. He had demonstrated swollen spinal cord with diffuse enhancement and no dilated vascularity on MRI. Finally, digital subtraction angiography revealed DAVF at the petrous ridge and it was successfully treated by embolization.

CONCLUSION

A slow flow DAVF is not readily recognizable on MRI. Whenever a patient presents with unexplainable progressive myelopathy, a possibility of vascular origin has to be considered.

A MRI study of lumbar plexus with respect to the lateral transpsoas approach to the lumbar spine

PURPOSE

To evaluate the relative position between lumbar plexus and access corridor of minimally invasive lateral transpsoas lumbar approach, as well as the approach safety.

METHODS

Three-dimensional fast imaging employing steady-state acquisition (3D FIESTA) sequence images of lumbar spine were obtained from 58 patients with lumbar degenerative diseases for reconstruction to analyze the distribution of lumbar plexus from L1-L2 to L4-L5 level with respect to the transpsoas lumbar approach. The axial image distance (AID) between the anterior edge of lumbar plexus and the sagittal central perpendicular line (SCPL) of disc was measured. SCPL was drawn perpendicularly to the sagittal plane of intervertebral disc and it passed through its central point, which is initial dilator trajectory for transpsoas approach. As related to the SCPL of disc, the distance with a positive value was set to indicate neural tissue posterior to it, while anterior to it was represented by a negative value.

RESULTS

In relation to SCPL of disc, the AID of lumbar plexus was measured 13.01 ± 1.70, 8.61 ± 2.26, 1.12 ± 2.37 and -5.42 ± 3.26 mm from L1-L2 to L4-L5 level, respectively, while the AID of genitofemoral nerve was recorded -1.13 ± 2.87, -5.78 ± 2.33 and -10.53 ± 3.30 mm from L2-L3 to L4-L5 level accordingly.

CONCLUSION

With respect to the SCPL of disc, a trajectory of guide wire or a radiographic reference landmark to place working channel, lumbar plexus lies posteriorly to it from L1-L2 to L3-L4 level and shifts anteriorly to it at L4-L5 level, while genitofemoral nerve locates anteriorly to the SCPL from L2-L3 to L4-L5 level. Neural retraction may take place during sequential dilation of access corridor especially at L4-L5 level.

Vascular diseases of the spinal cord

Vascular disease affecting the spinal can cause substantial neurologic morbidity. Several vascular spinal cord ailments present as neurologic emergencies, and should thus be recognizable to the practicing neurologist. We review the epidemiology, presentation, management strategies, and prognosis of various pathologies, including infarction, dural arteriovenous fistula, arteriovenous malformation, cavernous malformation, compressive epidural hematoma, vasculitis, and genetic abnormalities.

The diagnosis of spinal dural arteriovenous fistulas

STUDY DESIGN

Retrospective consecutive case series.

OBJECTIVE

To review and analyze clinical presentations and radiological imaging of 326 consecutive patients with spinal dural arteriovenous fistula (SDAVF) from 2 institutions.

SUMMARY OF BACKGROUND DATA

The clinical presentations of SDAVF are nonspecific. Patients may be initially diagnosed with other spinal diseases. Magnetic resonance imaging (MRI) can reveal spinal cord changes associated with the disorder, but neurosurgeons often overlook these changes.

METHODS

From 1989 to 2009, 326 patients were diagnosed with SDAVF and treated at Qilu Hospital of Shandong University and the Xuanwu Hospital of the Capital University of Medical Sciences. We retrospectively reviewed the clinical records and radiological images of all patients, and collected and analyzed the related data.

RESULTS

Two hundred eighty-two males and 44 females (male/female ratio 6.4:1; mean age, 53.9 yr; SD, 12.1) were included in the study. Fistulas were located at the T7 spinal segment (41, 12.6%), but were more typically found at T5 to L5 (273, 82.5%). The most common initial symptoms were lower extremity weakness (234, 71.8%), sensory disturbance (229, 70.2%), and sphincter disturbance (87, 26.7%). These percentages increased to, 85.6%, 80.8%, and 52.5%, respectively, until patients were properly diagnosed. The mean diagnostic time to SDAVF was 19.9 months (SD, 25.2). Two major changes noted on magnetic resonance images were intramedullary T2-weighted signal hyperintensity (284, 87.1%) and perimedullary dilated vessels (251, 77%). Fistulas were often located outside of the vertebral segments of T2-weighted signal change (P = 0.005). Magnetic resonance angiography and computed tomography angiography of 33 (71.7%) patients revealed perimedullary dilated vessels and precisely located fistulas in 19 (41.3%) patients. Magnetic resonance angiography and computed tomography angiography studies of the perimedullary vessels also led to identification of a second fistula through angiography. Degenerative disc disease and myelitis were the most common misdiagnoses, and the patients were often treated incorrectly.

CONCLUSION

"Worsening" and "symptoms combination" are progression characteristics of SDAVF. Patients should undergo spinal magnetic resonance imaging when they are first suspected to have SDAVF. Magnetic resonance angiography and computed tomography angiography as noninvasive angiography are helpful for diagnosis.

Clinical presentation and prognostic factors of spinal dural arteriovenous fistulas: an overview

Spinal dural arteriovenous fistulas (AVFs), the most common type of spinal cord vascular malformation, can be a challenge to diagnose and treat promptly. The disorder is rare, and the presenting clinical symptoms and signs are nonspecific and insidious at onset. Spinal dural AVFs preferentially affect middle-aged men, and patients most commonly present with gait abnormality or lower-extremity weakness and sensory disturbances. Symptoms gradually progress or decline in a stepwise manner and are commonly associated with pain and sphincter disturbances. Surgical or endovascular disconnection of the fistula has a high success rate with a low rate of morbidity. Motor symptoms are most likely to improve after treatment, followed by sensory disturbances, and lastly sphincter disturbances. Patients with severe neurological deficits at presentation tend to have worse posttreatment functional outcomes than those with mild or moderate pretreatment disability. However, improvement or stabilization of symptoms is seen in the vast majority of treated patients, and thus treatment is justified even in patients with substantial neurological deficits. The extent of intramedullary spinal cord T2 signal abnormality does not correlate with outcomes and should not be used as a prognostic factor.