scholarly journals High-resolution direct microstimulation mapping of spinal cord motor pathways during resection of an intramedullary tumor

2015 ◽  
Vol 22 (2) ◽  
pp. 205-210 ◽  
Author(s):  
Ravi Gandhi ◽  
Corinne M. Curtis ◽  
Aaron A. Cohen-Gadol
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Spinal Cord Tumor ◽  
Tumor Resection ◽  
Intramedullary Tumor ◽  
Intramedullary Tumors ◽  
Intramedullary Spinal Cord ◽  
Supratentorial Gliomas ◽  
Microsurgical Techniques

Despite the use of advanced microsurgical techniques, resection of intramedullary tumors may result in significant postoperative deficits because of the vicinity or invasion of important functional tracts. Intraoperative monitoring of somatosensory evoked potentials and transcranial electrical motor evoked potentials has been used previously to limit such complications. Electromyography offers an opportunity for the surgeon to map the eloquent tissue associated with the tumor using intraoperative motor fiber stimulation. Similar to the use of cortical simulation in the resection of supratentorial gliomas, this technique can potentially advance the safety of intramedullary spinal cord tumor resection. The authors describe the use of intraoperative motor fiber tract stimulation to map the corticospinal tracts associated with an intramedullary tumor. This technique led to protection of these tracts during resection of the tumor.

Spinal Cord Monitoring

2016 ◽  
pp. 798-832
Author(s):  
Jeffrey A. Strommen ◽  
Andrea J. Boon
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Spinal Cord Tumor ◽  
Tumor Resection ◽  
Neurophysiological Monitoring ◽  
Spinal Root ◽  
Compound Muscle Action Potentials ◽  
Aneurysm Repair ◽  
Aortic Aneurysm Repair

Intraoperative neurophysiological monitoring is a valuable tool to preserve spinal cord and spinal root integrity during surgical procedures. A monitoring plan may include somatosensory evoked potentials (SEP), motor evoked potentials (MEP), compound muscle action potentials (CMAP), and electromyography (EMG). Such monitoring is individualized depending on the preoperative clinical deficit, the structures most at risk, and the surgical and anesthesia plan. The most common use of these techniques is in primary spine disease, where the spinal cord pathways will typically be monitored with both MEP and SEP. In cervical or lumbar spine surgeries, EMG monitoring will help protect the nerve root either during decompression or during pedicle screw placement. Monitoring during spinal cord tumor resection or vascular procedures (such as aortic aneurysm repair) not only helps prevent deficit, but also allows the surgeon to proceed with confidence and not unnecessarily terminate the procedure.

Dorsal Column Mapping via Phase Reversal Method

Neurosurgery ◽  
2014 ◽  
Vol 74 (4) ◽  
pp. 437-446 ◽  
Author(s):  
Dinesh Nair ◽  
Vishakhadatta M. Kumaraswamy ◽  
Diana Braver ◽  
Ronan D. Kilbride ◽  
Lawrence F. Borges ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Somatosensory Evoked Potentials ◽  
Spinal Cord Tumor ◽  
Tumor Resection ◽  
Dorsal Column ◽  
Neurological Deficits ◽  
Reliable Technique ◽  
Intramedullary Spinal Cord ◽  
Phase Reversal

ABSTRACT BACKGROUND: Safe resection of intramedullary spinal cord tumors can be challenging, because they often alter the cord anatomy. Identification of neurophysiologically viable dorsal columns (DCs) and of neurophysiologically inert tissue, eg, median raphe (MR), as a safe incision site is crucial for avoiding postoperative neurological deficits. We present our experience with and improvements made to our previously described technique of DC mapping, successfully applied in a series of 12 cases. OBJECTIVE: To describe a new, safe, and reliable technique for intraoperative DC mapping. METHODS: The right and left DCs were stimulated by using a bipolar electric stimulator and the triggered somatosensory evoked potentials recorded from the scalp. Phase reversal and amplitude changes of somatosensory evoked potentials were used to neurophysiologically identify the laterality of DCs, the inert MR, as well as other safe incision sites. RESULTS: The MR location was neurophysiologically confirmed in all patients in whom this structure was first visually identified as well as in those in whom it was not, with 1 exception. DCs were identified in all patients, regardless of whether they could be visually identified. In 3 cases, negative mapping with the use of this method enabled the surgeon to reliably identify additional inert tissue for incision. None of the patients had postoperative worsening of the DC function. CONCLUSION: Our revised technique is safe and reliable, and it can be easily incorporated into routine intramedullary spinal cord tumor resection. It provides crucial information to the neurosurgeon to prevent postoperative neurological deficits.

Phase Reversal of Somatosensory Evoked Potentials Triggered by Gracilis Tract Stimulation: Case Report of a New Technique for Neurophysiologic Dorsal Column Mapping

Neurosurgery ◽  
2011 ◽  
Vol 70 (3) ◽  
pp. 783-783 ◽  
Author(s):  
Mirela V. Simon ◽  
Keith H. Chiappa ◽  
Lawrence F. Borges ◽  
Marc R. Nuwer ◽  
Vedran Deletis
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Somatosensory Evoked Potentials ◽  
Spinal Cord Tumor ◽  
Tumor Resection ◽  
Dorsal Column ◽  
Intramedullary Spinal Cord ◽  
Phase Reversal ◽  
Dorsal Columns ◽  
A New Technique

Abstract Background and Importance: Reliable visual identification of the median raphae, essential for the preservation of function of the posterior dorsal columns during intramedullary spinal cord tumor resection, is not possible in many cases, because of distorted local anatomy. In such cases, intraoperative neurophysiologic mapping of the dorsal columns offers invaluable information to the surgeon, and guides the myelotomy. We hereby describe such a new technique. Clinical Presentation: A 41 -year-old man with a C3-C4 intramedullary spinal cord tumor underwent successful myelotomy and tumor resection. Dorsal column mapping was performed by use of an 8-contact minielectrode strip placed on the dorsal spinal cord. Direct electrical stimulation was applied via 2 adjacent contacts of the strip at a time, in an attempt to stimulate in succession the left and right dorsal columns. Somatosensory evoked potentials (SSEPs) were recorded after each stimulation, via scalp electrodes. A sharp change in polarity of the recorded scalp SSEPs (phase reversal) indicated when the stimulation of the opposite dorsal column occurred. Myelotomy was performed in between the minielectrode contacts identified as being situated closest to the raphe. The posterior tibial SSEPs were continuously monitored during and after myelotomy and until the dura closure. No changes from premyelotomy SSEPs were present. Postoperatively, the patient had preservation of the posterior column function. Conclusion: SSEP phase-reversal technique is a promising new method to identify the neurophysiologic midline in intramedullary tumor resection. Fast and easy to perform, its final role in neurophysiologic dorsal column mapping awaits confirmation in future applications.

Spinal Cord Mapping as an Adjunct for Resection of Intramedullary Tumors: Surgical Technique with Case Illustrations

Neurosurgery ◽  
2002 ◽  
Vol 51 (5) ◽  
pp. 1199-1207 ◽  
Author(s):  
Alfredo Quinones-Hinojosa ◽  
Mittul Gulati ◽  
Russell Lyon ◽  
Nalin Gupta ◽  
Charles Yingling
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Cervical Spinal Cord ◽  
Tumor Resection ◽  
Neurological Deficits ◽  
Electromyographic Activity ◽  
Intramedullary Spinal Cord ◽  
Motor Tracts ◽  
Stimulation Of

Abstract OBJECTIVE Resection of intramedullary spinal cord tumors may result in transient or permanent neurological deficits. Intraoperative somatosensory evoked potentials (SSEPs) and motor evoked potentials are commonly used to limit complications. We used both antidromically elicited SSEPs for planning the myelotomy site and direct mapping of spinal cord tracts during tumor resection to reduce the risk of neurological deficits and increase the extent of tumor resection. METHODS In two patients, 3 and 12 years of age, with tumors of the thoracic and cervical spinal cord, respectively, antidromically elicited SSEPs were evoked by stimulation of the dorsal columns and were recorded with subdermal electrodes placed at the medial malleoli bilaterally. Intramedullary spinal cord mapping was performed by stimulating the resection cavity with a handheld Ojemann stimulator (Radionics, Burlington, MA). In addition to visual observation, subdermal needle electrodes inserted into the abductor pollicis brevis-flexor digiti minimi manus, tibialis anterior-gastrocnemius, and abductor halluces-abductor digiti minimi pedis muscles bilaterally recorded responses that identified motor pathways. RESULTS The midline of the spinal cord was anatomically identified by visualizing branches of the dorsal medullary vein penetrating the median sulcus. Antidromic responses were obtained by stimulation at 1-mm intervals on either side of the midline, and the region where no response was elicited was selected for the myelotomy. The anatomic and electrical midlines did not precisely overlap. Stimulation of abnormal tissue within the tumor did not elicit electromyographic activity. Approaching the periphery of the tumor, stimulation at 1 mA elicited an electromyographic response before normal spinal cord was visualized. Restimulation at lower currents by use of 0.25-mA increments identified the descending motor tracts adjacent to the tumor. After tumor resection, the tracts were restimulated to confirm functional integrity. Both patients were discharged within 2 weeks of surgery with minimal neurological deficits. CONCLUSION Antidromically elicited SSEPs were important in determining the midline of a distorted cord for placement of the myelotomy incision. Mapping spinal cord motor tracts with direct spinal cord stimulation and electromyographic recording facilitated the extent of surgical resection.

C4-T3 Replacement Laminoplasty and Microsurgical Resection of Ependymoma: 2-Dimensional Operative Video

2021 ◽  
Author(s):  
Vincent N Nguyen ◽  
Mustafa Motiwala ◽  
Larry Ha ◽  
Alan D Boom ◽  
Frederick A Boop
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Sensory Level ◽  
Glial Tumor ◽  
Intramedullary Spinal Cord ◽  
Spinal Ependymoma ◽  
Pin Fixation ◽  
Microsurgical Techniques ◽  
Normal White Matter

Abstract Spinal ependymomas are the most common intramedullary spinal cord tumors in adults.1-4 They are benign histologically, and maximum safe surgical resection should be pursued with the goal of maintaining neurological integrity.4 Spinal ependymoma resections have been described in the operative video literature, including those using techniques of laminoplasty to prevent postlaminectomy kyphosis.1-3,5 Defining the planes between tumor and normal spinal cord is critical to achieving safe maximum resection.3 This video will illustrate the microsurgical techniques used in the resection of a large spinal cord ependymoma in a patient who presented with progressive lower extremity paraparesis and incontinence and was found to have a large intradural, intramedullary C4-T3 lesion with a rostral glial tumor cyst. The patient consented to surgical intervention.  The patient was placed prone in MAYFIELD 3-point pin fixation (Integra LifeSciences, Plainsboro Township, New Jersey). Intraoperative neurophysiological electrodes were placed for somatosensory evoked potentials, motor evoked potentials, and D-wave monitoring of corticospinal tracts.6,7 C3-T4 replacement laminoplasties were performed. A midline dural incision spanning C4-T4 was made. A midline myelotomy preserving the pial venous plexus was performed with a 69 Beaver blade.2 The attachments of the tumor to the normal white matter of the spinal cord were microsurgically defined, coagulated, and divided. Tumor debulking was performed with an ultrasonic aspirator. Once gross total resection was achieved, the pial edges of the spinal cord were reapproximated. The dura was closed in a watertight fashion. The patient recovered from surgery well with preservation of her motor function with a continued T7 sensory level.

scholarly journals Continuous mapping of the corticospinal tracts in intramedullary spinal cord tumor surgery using an electrified ultrasonic aspirator

2017 ◽  
Vol 27 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Ori Barzilai ◽  
Zvi Lidar ◽  
Shlomi Constantini ◽  
Khalil Salame ◽  
Yifat Bitan-Talmor ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Spinal Cord Tumor ◽  
Tumor Resection ◽  
Continuous Mapping ◽  
Intramedullary Spinal Cord ◽  
Ultrasonic Aspirator ◽  
Corticospinal Tracts ◽  
Primary Treatment Modality ◽  
D Wave

Intramedullary spinal cord tumors (IMSCTs) represent a rare entity, accounting for 4%–10% of all central nervous system tumors. Microsurgical resection of IMSCTs is currently considered the primary treatment modality. Intraoperative neurophysiological monitoring (IONM) has been shown to aid in maximizing tumor resection and minimizing neurological morbidity, consequently improving patient outcome. The gold standard for IONM to date is multimodality monitoring, consisting of both somatosensory evoked potentials, as well as muscle-based transcranial electric motor evoked potentials (tcMEPs). Monitoring of tcMEPs is optimal when combining transcranial electrically stimulated muscle tcMEPs with D-wave monitoring. Despite continuous monitoring of these modalities, when classic monitoring techniques are used, there can be an inherent delay in time between actual structural or vascular-based injury to the corticospinal tracts (CSTs) and its revelation. Often, tcMEP stimulation is precluded by the surgeon’s preference that the patient not twitch, especially at the most crucial times during resection. In addition, D-wave monitoring may require a few seconds of averaging until updating, and can be somewhat indiscriminate to laterality. Therefore, a method that will provide immediate information regarding the vulnerability of the CSTs is still needed.The authors performed a retrospective series review of resection of IMSCTs using the tip of an ultrasonic aspirator for continuous proximity mapping of the motor fibers within the spinal cord, along with classic muscle-based tcMEP and D-wave monitoring.The authors present their preliminary experience with 6 patients who underwent resection of an IMSCT using the tip of an ultrasonic aspirator for continuous proximity mapping of the motor fibers within the spinal cord, together with classic muscle-based tcMEP and D-wave monitoring. This fusion of technologies can potentially assist in optimizing resection while preserving neurological function in these challenging surgeries.

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