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Table of Contents    
LETTERS TO EDITOR
Year : 2019  |  Volume : 67  |  Issue : 4  |  Page : 1156-1158

Changes in Evoked Potentials in a Hybrid Surgery of Spinal Arteriovenous Malformations Associated with Nerve Root AVF


Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), Beijing, China

Date of Web Publication10-Sep-2019

Correspondence Address:
Dr. Hong-Qi Zhang
Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), Beijing - 100053
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.266251

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How to cite this article:
Li XY, Zhang HQ, Ling F, Sun LY, Yu JX, Ren J, He JH. Changes in Evoked Potentials in a Hybrid Surgery of Spinal Arteriovenous Malformations Associated with Nerve Root AVF. Neurol India 2019;67:1156-8

How to cite this URL:
Li XY, Zhang HQ, Ling F, Sun LY, Yu JX, Ren J, He JH. Changes in Evoked Potentials in a Hybrid Surgery of Spinal Arteriovenous Malformations Associated with Nerve Root AVF. Neurol India [serial online] 2019 [cited 2019 Nov 20];67:1156-8. Available from: http://www.neurologyindia.com/text.asp?2019/67/4/1156/266251




Sir,

There are few reports about electrophysiological monitoring changes because of the low incidence of spinal arteriovenous malformation (SAVM).[1],[2],[3],[4] We described a SAVM patient who had experienced the fluctuation of evoked potentials corresponding to the spinal cord blood supply changes during the microsurgical operation.

Institutional approval and informed consent were obtained.

A 35-year-old woman had sudden low-back pain and defecation dysfunction for one week (28-week gestation). The symptoms gradually disappeared after the initial endovascular embolization but reoccurred after 6 months and became worse. The physical examination showed that the muscle strength of both upper and lower extremities was grade 5 and 4, respectively. The hypoesthesia level was below T12. Preoperative catheter angiography [Figure 1] showed that there were three groups of feeding arteries: anterior spinal artery (ASA) arising from left L2 lumbar artery, posterior spinal artery (PSA) from the right/left L1 lumbar arteries and the nerve root artery from left T3 lumbar artery.
Figure 1: Preoperative MRI showed the cone edema and DSA showed that the feeding arteries was ASA arising from left L2 lumbar artery, PSA from the right/left L1 lumbar arteries, and the nerve root artery from left T3 lumbar artery

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We recorded the motor evoked potentials (MEP) and somatosensory-evoked potentials (SEP) of the lower extremities during the operation. No changes were noted during the resection of arteriovenous fistula (AVF) [Figure 2]. Repeated digital subtraction angiography(DSA) suggested the feeding arteries from PSA and nerve root was not opacified any more [Figure 3]. Because the residual lesion was mainly ventrally located, surgical resection was not feasible and endovascular embolization was considered. The MEP of the left lower limb and the anal sphincter decreased significantly [more than 80%; [Figure 4]. Subsequent DSA showed total occlusion of ASA main trunk; the thrombosis was probably due to the absence of intravenous heparin administration [Figure 5]. Microcatheter-directed intra-arterial thrombolysis was immediately performed using urokinase as thrombolytic agent. MEP was restored [Figure 4] after the recovery of conus blood supply [Figure 6]. However, SEP of left limb could not be recovered [Figure 4]. There was no new dysfunction after operation for this patient. This is probably because the recovery of spinal cord function is a gradual process, and fully functional recovery may take a long time.[5] In this case, electrophysiological monitoring signals were rapid and accurate in response to thrombosis and spinal cord blood flow.
Figure 2: After induction of muscle relaxant by anesthesia, we obtained clear waveforms of the lower extremities and anal sphincter MEP. There were no changes in MEP and SEP during the resection of AVF

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Figure 3: DSA suggested that the SAVM supplied by the PSA and the nerve root AVF supplied by the nerve root artery did not develop

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Figure 4: The MEP of the left lower limb and the anal sphincter decreased significantly; immediate catheter-directed intra-arterial thrombolysis was performed. The tcMEP of the lower limb and the anal sphincter was restored immediately after the recovery of the conus blood supply

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Figure 5: DSA showed the occlusion of the main trunk of ASA; the thrombosis was probably due to the lack of administration of the intravenous heparin

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Figure 6: DSA showed the recovery of blood flow at the conus

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We can use this principle to spinal cord vascular surgery. When we need to cut off the spinal blood supply, temporary blocking test can be applied. If the evoked potential does not change, the blood vessel can be sacrificed; if the evoked potential significantly reduced, the blood vessel is not suitable to be cut off.

During a hybrid surgery, blood is in a hypercoagulable state; thrombosis frequently occurs during endovascular procedures. Adequate embolization prior to surgery may be a more reasonable option and requires a high degree of vigilance when intraoperative embolization is necessary.

This is of guiding significance for surgical treatment of SAVM.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

This work was supported by the National Natural Science Foundation of China (81171165, 81671202), the Beijing Municipal Administration of Hospital Clinical Medicine Development Project (ZY201309), and the Beijing Municipal Science and Technology Commission (D161100003816001).

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Chaloupka JC. Future directions in the evaluation and management of spinal cord vascular malformations. Semin Cerebrovasc Dis Stroke 2002;2:245-56.  Back to cited text no. 1
    
2.
Flores BC, Klinger DR, White JA, Batjer HH. Spinal vascular malformations: Treatment strategies and outcome. Neurosurg Rev 2017;40:15-28.  Back to cited text no. 2
    
3.
Kramer CL. Vascular disorders of the spinal cord. Continuum (Minneap Minn). 2018;24. doi: 10.1212/CON.0000000000000595.  Back to cited text no. 3
    
4.
Gobin YP. Classification and endovascular treatment of spinal cord arteriovenous malformations and fistulas. J Stroke Cerebrovasc Dis 1997;6:282-6.  Back to cited text no. 4
    
5.
Li X, Zhang HQ, Ling F, He C, Hu P, Yu J. Intraoperative neurophysiological monitoring during the surgery of spinal arteriovenous malformation: Sensitivity, specificity, and warning criteria. Clin Neurol Neurosur 2018;165:29-37.  Back to cited text no. 5
    


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