Role of Multimodality Intraoperative Neurophysiological Monitoring during Embolisation of a Spinal Cord Arteriovenous Malformation. A Paradigmatic Case

Spinal epidural arteriovenous fistula with improved sphincter impairment detected by intraoperative neurophysiological monitoring

Background:

A spinal epidural arteriovenous fistula (SEAVF) is a rare type of arteriovenous shunt that occurs mainly in the thoracic or lumbar spine. Patients with SEAVF develop motor/sensory disturbances of the lower extremities and sphincter dysfunction. Among these symptoms, sphincter impairments show less improvement than others, and its relevance to neurophysiological monitoring has not been documented.

Case Description:

A 77-year-old woman presented with progressive motor weakness and numbness in the lower extremities and urinary and fecal incontinence. Spinal magnetic resonance imaging showed spinal cord edema in Th5-Th11 and enlarged perimedullary veins. We performed spinal angiography and endovascular treatment under intraoperative neurophysiological monitoring (IOM), including sensory evoked potential (SEP), motor evoked potential (MEP), and bulbocavernosus reflex (BCR) monitoring. Diagnostic angiography revealed a SEAVF with perimedullary venous drainage fed by the left L2 segmental artery. The shunt was completely embolized using N-butyl-2-cyanoacrylate. Although SEP and MEP of the lower legs were recordable during treatment, anal MEP and BCR were not observed. The sphincter symptoms improved 1.5 years after the treatment. Follow-up angiography revealed no shunt recurrence and improved venous congestion. Anal MEP and BCR were detected during angiography, indicating neurophysiological improvement in sphincter function. The prolonged latency of the monitoring suggested a pudendal nerve injury.

Conclusion:

This case report first described improvement of the IOM correlated with the functional recovery of sphincters after embolization of a SEAVF. Follow-up neurophysiological monitoring is important to assess the functional recovery of the sphincter.

The utility of intraoperative neurophysiological monitoring in surgical treatment for spinal arteriovenous malformations: a historical control study

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Postoperative neurological complications are not rare in surgical treatment for spinal arteriovenous malformations (SAVMs).

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An in-group analysis showed that the accuracy of IONM for detecting postoperative neurological complications was relatively high.

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Multimodal IONM may reduce postoperative neurological complications in the surgical treatment for SAVMs.

Objective

Methods

Results

Conclusions

Significance

Percutaneous cryoablation of symptomatic venous malformations as a second-line therapeutic option: a five-year single institution experience

PURPOSE

To report the mid-term outcomes of percutaneous cryoablation (PCA) performed as second-line therapeutic option of venous malformations (VM).

MATERIAL AND METHODS

From 2011 to 2015, PCA was offered in 24 patients (mean age: 31 years, range: 12-64) as second-line treatment for recurrence of symptoms after sclerotherapy and when resection was not possible (due to lesion location or previous failure) or refused by the patient. Adverse effects were recorded, disease-free survival (DFS) and local tissue control (LTC) rates were calculated based on symptoms and volume evolution.

RESULTS

Mean follow-up was 18.7 months (6-48). Nine (37.5%, 9/24) adverse effects occurred and three (12.5%, 3/24) were severe. Mean pain assessed by visual analog scale (VAS) was 41.7 mm (0-80) before treatment and 20.3 mm (0-80) (p=0.01) after. Mean volume decreased significantly after treatment from 22.4 cm³ (0.9-146) to 8.35 cm³ (0-81.3) (p<0.001). Pain recurred in nine patients and size of one lesion increased. The DFS and LTC rates were 54% [95%CI: 22.94-77.27] and 93.33% [61.26-99.03] at 24 months, respectively. Only VM volume >10 cm³ was associated with a higher risk of local recurrence (p=0.05).

CONCLUSION

PCA as second-line treatment appears to be safe and effective for local control of VM according to mid-term results.

KEY POINTS

• Percutaneous cryoablation of venous malformations appeared well tolerated. • Size of venous malformations decreased significantly after percutaneous cryoablation (p<0.001). • Pain decreased significantly after percutaneous cryoablation of venous malformations (p=0.01).

Endovascular treatment of spinal arteriovenous malformations

Spinal arteriovenous malformations (AVMs) are a rare but treatable cause of myelopathy and spinal cord hemorrhage. The clinical presentation and ideal treatment of these lesions vary widely, primarily due to differences in anatomic and angioarchitectural features. Six well-defined types of fistula have been defined: (1) intradural dorsal AVM; (2) intramedullary AVM; (3) extradural-intradural AVM; (4) intradural ventral AVF; (5) extradural/epidural AVF; and (6) conus medullaris AVM. Each of these lesions have unique clinical presentations and variable natural histories and endovascular treatment options. The principles of endovascular treatment include: (1) a complete understanding of the angioarchitecture and anatomic features of the lesion, including identification of radiculomedullary arteries; (2) careful spinal angiography; (3) identification of treatment goals prior to the procedure (i.e., complete occlusion versus partial occlusion aimed at altering natural history); (4) selection of proper embolic agent; and (5) careful follow-up in both the immediate postoperative setting and long term.

An Isolated Posterior Spinal Aneurysm Resection in Which Intraoperative Electrophysiological Monitoring Was Successfully Used to Locate the Lesion and to Detect the Possibility of Ischemic Complications

STUDY DESIGN

A case report.

OBJECTIVE

To report the successful use of electrophysiological monitoring in the surgical resection of a ruptured spinal artery (SA) aneurysm to locate the lesion, and to predict ischemic complications.

SUMMARY OF BACKGROUND DATA

Isolated aneurysm of the posterior SA is an extremely rare event without established treatment and diagnosis procedures. Reports describing the surgical intervention of aneurysm of the posterior SA using electrophysiological monitoring are scant.

METHODS

We performed the surgical resection of a dissected posterior SA aneurysm in an older patient who presented with spinal subarachnoid hemorrhage using intraoperative electrophysiological monitoring.

RESULTS

Intraoperatively, motor evoked potentials decreased over 50% when a distal site of the lesion was clipped, indicating that site was the posterior SA. This lead to further investigation of the vascular anatomy around the lesion, which revealed the descending part of the posterior SA buried deeply in a thick thrombus. Clipping and resection were successful, and ischemia of the posterior SA was avoided. The postoperative clinical course was good, and there was no recurrence or long-term squeal.

CONCLUSION

Electrophysiological monitoring might be useful when intraoperative anatomical findings of the hemodynamic structure are inadequate. Moreover, in our case, intraoperative changes in motor evoked potentials indicated the risk to occlude one of posterior SAs, although it is said that posterior circulation of spinal cord has ischemic tolerance.

Neurophysiologic monitoring and pharmacologic provocative testing for embolization of spinal cord arteriovenous malformations

BACKGROUND AND PURPOSE

Embolization of a spinal cord arteriovenous malformation (SCAVM) is still considered risky. We evaluated the efficacy and reliability of pharmacologic provocative testing with neurophysiologic monitoring in the embolization of SCAVMs.

METHODS

We retrospectively analyzed results of 60 provocative tests during 84 angiographic procedures (in 52 patients) with intended endovascular embolization. Tests included 47 sodium amytal and 56 lidocaine injections. All procedures were performed with general anesthesia and monitoring of cortical somatosensory evoked potentials (SEPs) and transcranial motor evoked potentials (MEPs). For provocative testing, 50 mg of amytal and 40 mg of lidocaine were consecutively injected through a microcatheter placed at the position of intended embolization. If SEPs and MEPs did not change, embolization was performed with N-butyl-cyanoacrylate (NBCA). If SEPs or MEPs changed, NBCA embolization was not performed from that catheter position.

RESULTS

One false-negative result occurred, with an increase in spasticity after embolization. Nineteen positive results occurred: four after amytal injection and 15 after lidocaine injections. Seven injections in a posterior spinal artery feeder resulted in loss of SEPs or MEPs. Eleven injections in the anterior spinal artery feeder and one in the posterior inferior cerebellar artery feeder resulted in loss of MEPs.

CONCLUSION

Provocative testing with amytal and lidocaine combined with neurophysiologic monitoring had a high negative predictive value and was a useful adjunct for SCAVM embolization. Both amytal and lidocaine should be used as provocative agents, and both SEPs and MEPs should be monitored.

Neuroprotective role of neurophysiological monitoring during endovascular procedures in the spinal cord

The endovascular treatment of spinal vascular malformations places the spinal cord at risk for ischemia. When these procedures are performed using general anesthesia, the neurophysiological monitoring methods currently available provide the only means by which to assess the functional integrity of sensory and motor pathways. Neurophysiological monitoring allows a warning for the neuroradiologist of impending irreversible neurological damage so that action may be taken for the prompt restoration of adequate spinal cord perfusion. Muscle motor evoked potentials (mMEPs) better reflect spinal cord perfusion in the anterior spinal artery territory than do somatosensory evoked potentials (SEPs), although their use during spinal endovascular procedures remains anecdotal in the literature. In the study reported here we assessed: (1) the feasibility of intraoperative neurophysiological monitoring, (2) the role of provocative tests with Amytal and Xylocaine, and (3) the specific but complementary role played by SEPs and mMEPs, during endovascular embolization of spinal vascular malformations and tumors. The results suggest that: (1) neurophysiological monitoring is feasible during most endovascular procedures in the spine and spinal cord under general anesthesia, (2) provocative tests enhance the safety of the procedure, (3) mMEPs are more feasible than SEPs and more sensitive than SEPs to provocative tests. We strongly suggest the use of multimodal neurophysiological monitoring and provocative tests during the endovascular treatment of spinal and spinal cord vascular lesions.