Publications by authors named "Vedran Deletis"

58 Publications

Structural changes in brains of patients with disorders of consciousness treated with deep brain stimulation.

Sci Rep 2021 Feb 23;11(1):4401. Epub 2021 Feb 23.

Department of Neurosurgery, Dubrava University Hospital, Avenija Gojka Suska 6, 10000, Zagreb, Croatia.

Disorders of consciousness (DOC) are one of the major consequences after anoxic or traumatic brain injury. So far, several studies have described the regaining of consciousness in DOC patients using deep brain stimulation (DBS). However, these studies often lack detailed data on the structural and functional cerebral changes after such treatment. The aim of this study was to conduct a volumetric analysis of specific cortical and subcortical structures to determine the impact of DBS after functional recovery of DOC patients. Five DOC patients underwent unilateral DBS electrode implantation into the centromedian parafascicular complex of the thalamic intralaminar nuclei. Consciousness recovery was confirmed using the Rappaport Disability Rating and the Coma/Near Coma scale. Brain MRI volumetric measurements were done prior to the procedure, then approximately a year after, and finally 7 years after the implementation of the electrode. The volumetric analysis included changes in regional cortical volumes and thickness, as well as in subcortical structures. Limbic cortices (parahippocampal and cingulate gyrus) and paralimbic cortices (insula) regions showed a significant volume increase and presented a trend of regional cortical thickness increase 1 and 7 years after DBS. The volumes of related subcortical structures, namely the caudate, the hippocampus as well as the amygdala, were significantly increased 1 and 7 years after DBS, while the putamen and nucleus accumbens presented with volume increase. Volume increase after DBS could be a result of direct DBS effects, or a result of functional recovery. Our findings are in accordance with the results of very few human studies connecting DBS and brain volume increase. Which mechanisms are behind the observed brain changes and whether structural changes are caused by consciousness recovery or DBS in patients with DOC is still a matter of debate.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-021-83873-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7902623PMC
February 2021

In Memoriam: Karl Kothbauer, MD (1962-2020).

Clin Neurophysiol 2021 Jan 5;132(1):200-201. Epub 2020 Dec 5.

Head of Intraoperative neurophysiology Department of Neurology, University Hospital de Bellvitge, Barcelona, Spain.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinph.2020.11.006DOI Listing
January 2021

Neurophysiological monitoring of the laryngeal adductor reflex during cerebellar-pontine angle and brainstem surgery.

Clin Neurophysiol 2021 Feb 19;132(2):622-631. Epub 2020 Nov 19.

Department of Intraoperative Neurophysiology. Mount Sinai West Hospital. New York, NY, USA.

Objective: To correlate intraoperative changes of the laryngeal adductor reflex (LAR), alone or in combination with corticobulbar motor evoked potential of vocal muscles (vocal-CoMEPs), with postoperative laryngeal function after posterior fossa and brainstem surgery.

Methods: We monitored 53 patients during cerebellar-pontine angle and brainstem surgeries. Vocal-CoMEPs and LAR were recorded from an endotracheal tube with imbedded electrodes or hook-wires electrodes. A LAR significant change (LAR-SC) defined as ≥ 50% amplitude decrement or loss, was classified as either transient or permanent injury to the vagus or medullary pathways by the end of the surgery.

Results: All patients with permanent LAR loss (n = 5) or LAR-SC (n = 3), developed postoperative laryngeal dysfunction such as aspiration/pneumonia and permanent swallowing deficits (5.6%). Vocal-CoMEP findings refined postoperative vocal motor dysfunction. All seven patients with transient LAR-SC or loss, reverted by changing the surgical approach, did not present permanent deficits.

Conclusions: Permanent LAR-SCs or loss correlated with postoperative laryngeal dysfunction and predicted motor and sensory dysfunction of the vagus nerve and reflexive medullary pathways. In contrast, a LAR-SC or loss, averted by a timely surgical adjustment, prevented irreversible damage.

Significance: Monitoring of the LAR, with vocal-CoMEPs, may enhance safety to resect complex posterior fossa and brainstem lesions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinph.2020.10.021DOI Listing
February 2021

Selective dorsal rhizotomy: functional anatomy of the conus-cauda and essentials of intraoperative neurophysiology.

Childs Nerv Syst 2020 09 7;36(9):1907-1918. Epub 2020 Jul 7.

Section of Neurosurgery, Department of Neurosciences, Biomedicine and Movement Sciences, University Hospital, Verona, Italy.

Introduction: Spasticity is the result of an exaggeration of the monosynaptic muscle stretch reflex due to lesions affecting the central nervous system, in particular an upper motor neuron lesion. Selective dorsal rhizotomy (SDR) is a surgical technique developed to treat spastic diplegia, one of the common forms of cerebral palsy, resulting from the lack of supraspinal inhibitory controls. The aim of SDR is to identify and cut a critical amount of the sensory rootlets, in particular those contributing the most to spasticity, in order to relieve the patient from lower limb spasticity while preserving motor strength and sphincter control. Various surgical techniques to perform SDR have been proposed over time. Similarly, intraoperative neurophysiology (ION)-first introduced by Fasano and colleagues in 1976-is a safe and effective tool to guide the surgeon in the procedure of SDR, but different ION strategies are used by different authors, and the value of ION itself has been questioned.

Methods: The purpose of this paper is to review the anatomo-physiological background of SDR, the historical development of the surgical technique, and the essential principles of ION.

Results: While some surgeons privilege a single-level approach and others a multi-level approach, nowadays, there are still neither agreement nor guidelines on the percentage of roots to be cut. Rather, a tailored approach based on both the preoperative functional status as well as intraoperative ION findings seems reasonable. ION is considered not essential to decide the percentage of roots to cut, but it assists to distinguish between ventral and dorsal roots, and to preserve sphincterial function, whenever S2 rootlets are included in SDR.

Conclusions: To optimize the balance between reduction of spasticity and preservation of motor strength while minimizing the neurological damage remains the main goal of SDR.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00381-020-04746-9DOI Listing
September 2020

Letter to the Editor. Intraoperative neuromonitoring in elective aneurysm clipping: methodology matters.

J Neurosurg 2020 Jun 5:1-3. Epub 2020 Jun 5.

6Hospital Universitari de Bellvitge-IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3171/2020.4.JNS201006DOI Listing
June 2020

A New Methodology for Intraoperative Monitoring of the Functional Integrity of the Phrenic Nerve During Cardiothoracic Surgery.

J Clin Neurophysiol 2019 Dec 27. Epub 2019 Dec 27.

Neuromuscular Diseases Unit, Neurosciences Department, University Hospital Germans Trias I Pujol, Barcelona, Spain.

Introduction: The phrenic nerve could be easily injured during cardiothoracic surgeries because of its anatomical relationships. The aim of this study is to describe a new, feasible, and reproducible methodology to achieve a continuous intraoperative neuromonitoring of the phrenic nerve.

Methods: Consecutive patients who underwent open-chest surgery were included. The recording active electrode was placed 5 cm superior to the tip of the xiphoid process, and a hook wire inserted at the motor point of the ipsilateral hemidiaphragm was used as the reference electrode.

Results: We studied 45 patients (92% men, mean age 67 years). Mean height and weight were 167 ± 6.9 cm and 75.6 ± 12.3 kg, respectively. A reproducible compound motor action potential was recorded in 38 (85%) subjects. The mean latency and amplitude values were 9.68 ± 2.40 ms and 1.36 ± 3.83 mV, respectively. No intraoperative events were recorded.

Conclusions: We reported a new methodology which allows the assessment of phrenic nerve functional integrity during surgical procedures.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/WNP.0000000000000677DOI Listing
December 2019

Correction to: Is the new ASNM intraoperative neuromonitoring supervision "guideline" a trustworthy guideline? A commentary.

J Clin Monit Comput 2019 04;33(2):191-192

Section of Neurosurgery, University of Manitoba, Winnipeg, MB, Canada.

The article Is the new ASNM intraoperative neuromonitoring supervision "guideline" a trustworthy guideline? A commentary, written by Stanley A. Skinner, Elif Ilgaz Aydinlar, Lawrence F. Borges, Bob S. Carter, Bradford L. Currier, Vedran Deletis, Charles Dong, John Paul Dormans, Gea Drost, Isabel Fernandez‑Conejero, E. Matthew Hoffman, Robert N. Holdefer, Paulo Andre Teixeira Kimaid, Antoun Koht, Karl F. Kothbauer, David B. MacDonald, John J. McAuliffe III, David E. Morledge, Susan H. Morris, Jonathan Norton, Klaus Novak, Kyung Seok Park, Joseph H. Perra, Julian Prell, David M. Rippe, Francesco Sala, Daniel M. Schwartz, Martín J. Segura, Kathleen Seidel, Christoph Seubert, Mirela V. Simon, Francisco Soto, Jeffrey A. Strommen, Andrea Szelenyi, Armando Tello, Sedat Ulkatan, Javier Urriza and Marshall Wilkinson, was originally published electronically on the publisher's internet portal (currently SpringerLink) on 05 January 2019 without open access. With the author(s)' decision to opt for Open Choice the copyright of the article changed on 30 January 2019 to © The Author(s) 2019 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made. The original article has been corrected.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10877-019-00266-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6420422PMC
April 2019

An improved methodology for intraoperative monitoring of the lateral spreading response during surgery for hemifacial spasm.

Clin Neurophysiol 2018 07 16;129(7):1457. Epub 2018 Apr 16.

New Mount Sinai West Hospital, New York, NY, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinph.2018.03.041DOI Listing
July 2018

Intraoperative identification of the corticospinal tract and dorsal column of the spinal cord by electrical stimulation.

J Neurol Neurosurg Psychiatry 2018 07 7;89(7):754-761. Epub 2018 Feb 7.

Department of Neurosurgery, Cantonal Hospital of Lucerne, University of Basel, Basel, Switzerland.

Objectives: Anatomical identification of the corticospinal tract (CT) and the dorsal column (DC) of the exposed spinal cord is difficult when anatomical landmarks are distorted by tumour growth. Neurophysiological identification is complicated by the fact that direct stimulation of the DC may result in muscle motor responses due to the centrally activated H-reflex. This study aims to provide a technique for intraoperative neurophysiological differentiation between CT and DC in the exposed spinal cord.

Methods: Recordings were obtained from 32 consecutive patients undergoing spinal cord tumour surgery from July 2015 to March 2017. A double train stimulation paradigm with an intertrain interval of 60 ms was devised with recording of responses from limb muscles.

Results: In non-spastic patients (55% of cohort) an identical second response was noted following the first CT response, but the second response was absent after DC stimulation. In patients with pre-existing spasticity (45%), CT stimulation again resulted in two identical responses, whereas DC stimulation generated a second response that differed substantially from the first one. The recovery times of interneurons in the spinal cord grey matter were much shorter for the CT than those for the DC. Therefore, when a second stimulus train was applied 60 ms after the first, the CT-fibre interneurons had already recovered ready to generate a second response, whereas the DC interneurons were still in the refractory period.

Conclusions: Mapping of the spinal cord using double train stimulation allows neurophysiological distinction of CT from DC pathways during spinal cord surgery in patients with and without pre-existing spasticity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/jnnp-2017-317172DOI Listing
July 2018

Deep brain stimulation for the early treatment of the minimally conscious state and vegetative state: experience in 14 patients.

J Neurosurg 2018 04 16;128(4):1189-1198. Epub 2017 Jun 16.

6Center for Physical Medicine and Rehabilitation, University Hospital Dubrava, Zagreb.

OBJECTIVE An effective treatment of patients in a minimally conscious state (MCS) or vegetative state (VS) caused by hypoxic encephalopathy or traumatic brain injury (TBI) is not yet available. Deep brain stimulation (DBS) of the thalamic reticular nuclei has been attempted as a therapeutic procedure mainly in patients with TBI. The purpose of this study was to investigate the therapeutic use of DBS for patients in VS or MCS. METHODS Fourteen of 49 patients in VS or MCS qualified for inclusion in this study and underwent DBS. Of these 14 patients, 4 were in MCS and 10 were in VS. The etiology of VS or MCS was TBI in 4 cases and hypoxic encephalopathy due to cardiac arrest in 10. The selection criteria for DBS, evaluating the status of the cerebral cortex and thalamocortical reticular formation, included: neurological evaluation, electrophysiological evaluation, and the results of positron emission tomography (PET) and MRI examinations. The target for DBS was the centromedian-parafascicular (CM-pf) complex. The duration of follow-up ranged from 38 to 60 months. RESULTS Two MCS patients regained consciousness and regained their ability to walk, speak fluently, and live independently. One MCS patient reached the level of consciousness, but was still in a wheelchair at the time the article was written. One VS patient (who had suffered a cerebral ischemic lesion) improved to the level of consciousness and currently responds to simple commands. Three VS patients died of respiratory infection, sepsis, or cerebrovascular insult (1 of each). The other 7 patients remained without substantial improvement of consciousness. CONCLUSIONS Spontaneous recovery from MCS/VS to the level of consciousness with no or minimal need for assistance in everyday life is very rare. Therefore, if a patient in VS or MCS fulfills the selection criteria (presence of somatosensory evoked potentials from upper extremities, motor and brainstem auditory evoked potentials, with cerebral glucose metabolism affected not more than the level of hypometabolism, which is judged using PET), DBS could be a treatment option.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3171/2016.10.JNS161071DOI Listing
April 2018

A novel methodology for assessing laryngeal and vagus nerve integrity in patients under general anesthesia.

Clin Neurophysiol 2017 07 14;128(7):1399-1405. Epub 2017 Mar 14.

Department of Intraoperative Neurophysiology, Mount Sinai West Hospital, New York, NY, USA.

Objective: To describe a novel methodology for intraoperative neuro-monitoring of laryngeal and vagus nerves by utilizing the laryngeal adductor reflex (LAR).

Methods: Case series of 15 patients undergoing thyroid and cervical spine surgeries under total intravenous general anesthesia. Vocal fold mucosa was electrically stimulated to elicit a LAR using endotracheal tube based electrodes. Contralateral R1 (cR1) and R2 (cR2) responses were recorded using the endotracheal tube electrode contralateral to the simulating electrode.

Results: The LAR was reliably elicited in 100% of patients for the duration of each surgical procedure. Mean onset latency of cR1 response was 22.4±2.5ms (right) and 22.2±2.4ms (left). cR2 responses were noted in 10 patients (66.7%). No peri-operative complications or adverse outcomes were observed.

Conclusions: The LAR is a novel neuro-monitoring technique for the vagus nerve. Advantages over current monitoring techniques including simplicity, ability to continuously monitor neural function without placement of additional neural probes and ability to assess integrity of both sensory and motor pathways.

Significance: The LAR represents a novel method for intraoperatively monitoring laryngeal and vagus nerves. The LAR monitors the entire vagus nerve reflex arc and is thus applicable to all surgeries where vagal nerve integrity may be compromised.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinph.2017.03.002DOI Listing
July 2017

Feasibility of eliciting the H reflex in the masseter muscle in patients under general anesthesia.

Clin Neurophysiol 2017 Jan 5;128(1):123-127. Epub 2016 Nov 5.

Department of Intraoperative Neurophysiology, Mount Sinai West Hospital, New York, NY, USA.

Objective: To explore the feasibility of eliciting the brainstem H reflex in the masseter muscle in patients under general anesthesia.

Methods: We electrically stimulated the masseteric nerve, a branch of the trigeminal nerve, and recorded ipsilateral masseteric and temporalis muscle responses. We tested eight patients who presented with trigeminal neuralgia; one patient had a temporal bone tumor and one patient had a brainstem arteriovenous malformation. All responses were elicited when patients were under general anesthesia and before the initiation of surgery.

Results: The H reflex in the masseter muscle was reliably elicited in 70% of the patients. The reflexes met the usual criteria for the H reflex because they were elicited below the threshold of the direct M response, and their amplitudes decreased when the M response increased with stronger stimuli. The mean onset latencies of the masseter H reflex and the M response were 5.4±1.3ms and 2.6±0.6ms, respectively.

Conclusions: In the present study, we provide evidence of the feasibility of eliciting the H reflex in the masseter muscles of patients under general anesthesia.

Significance: The H reflex of the masseter muscle may represent a new method available for intraoperative monitoring. Specifically, this method may be important for the monitoring of brainstem functional integrity, particularly in the midbrain and mid-pons, in addition to the trigeminal nerve path.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinph.2016.10.092DOI Listing
January 2017

Letter to the Editor: Electrical activity in limb muscles after spinal cord stimulation is not specific for the corticospinal tract.

J Neurosurg Spine 2017 02 30;26(2):267-269. Epub 2016 Sep 30.

Albert Einstein College of Medicine, New York, NY;

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3171/2016.6.SPINE16591DOI Listing
February 2017

Intraoperative Monitoring and Mapping of the Functional Integrity of the Brainstem.

J Clin Neurol 2016 Jul;12(3):262-73

Department of Intraoperative Neurophysiology, University Hospital of Bellvitge, Barcelona, Spain.

The risk of iatrogenic damage is very high in surgical interventions in or around the brainstem. However, surgical techniques and intraoperative neuromonitoring (ION) have evolved sufficiently to increase the likelihood of successful functional outcomes in many patients. We present a critical review of the methodologies available for intraoperative monitoring and mapping of the brainstem. There are three main groups of techniques that can be used to assess the functional integrity of the brainstem: 1) mapping, which provides rapid anatomical identification of neural structures using electrical stimulation with a hand-held probe, 2) monitoring, which provides real-time information about the functional integrity of the nervous tissue, and 3) techniques involving the examination of brainstem reflexes in the operating room, which allows for the evaluation of the reflex responses that are known to be crucial for most brainstem functions. These include the blink reflex, which is already in use, and other brainstem reflexes that are being explored, such as the masseter H-reflex. This is still under development but is likely to have important functional consequences. Today an abundant armory of ION methods is available for the monitoring and mapping of the functional integrity of the brainstem during surgery. ION methods are essential in surgery either in or around the brainstem; they facilitate the removal of lesions and contribute to notable improvements in the functional outcomes of patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3988/jcn.2016.12.3.262DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4960209PMC
July 2016

Letter to the Editor.

J Physiol 2016 07;594(13):3841

Department of Neurosurgery, University Hospital Dubrava, Zagreb, Croatia.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1113/JP272234DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4929324PMC
July 2016

Incidence of intraoperative seizures during motor evoked potential monitoring in a large cohort of patients undergoing different surgical procedures.

J Neurosurg 2017 04 24;126(4):1296-1302. Epub 2016 Jun 24.

Departments of 1 Intraoperative Neurophysiology and.

OBJECTIVE The purpose of this study was to investigate the incidence of seizures during the intraoperative monitoring of motor evoked potentials (MEPs) elicited by electrical brain stimulation in a wide spectrum of surgeries such as those of the orthopedic spine, spinal cord, and peripheral nerves, interventional radiology procedures, and craniotomies for supra- and infratentorial tumors and vascular lesions. METHODS The authors retrospectively analyzed data from 4179 consecutive patients who underwent surgery or an interventional radiology procedure with MEP monitoring. RESULTS Of 4179 patients, only 32 (0.8%) had 1 or more intraoperative seizures. The incidence of seizures in cranial procedures, including craniotomies and interventional neuroradiology, was 1.8%. In craniotomies in which transcranial electrical stimulation (TES) was applied to elicit MEPs, the incidence of seizures was 0.7% (6/850). When direct cortical stimulation was additionally applied, the incidence of seizures increased to 5.4% (23/422). Patients undergoing craniotomies for the excision of extraaxial brain tumors, particularly meningiomas (15 patients), exhibited the highest risk of developing an intraoperative seizure (16 patients). The incidence of seizures in orthopedic spine surgeries was 0.2% (3/1664). None of the patients who underwent surgery for conditions of the spinal cord, neck, or peripheral nerves or who underwent cranial or noncranial interventional radiology procedures had intraoperative seizures elicited by TES during MEP monitoring. CONCLUSIONS In this largest such study to date, the authors report the incidence of intraoperative seizures in patients who underwent MEP monitoring during a wide spectrum of surgeries such as those of the orthopedic spine, spinal cord, and peripheral nerves, interventional radiology procedures, and craniotomies for supra- and infratentorial tumors and vascular lesions. The low incidence of seizures induced by electrical brain stimulation, particularly short-train TES, demonstrates that MEP monitoring is a safe technique that should not be avoided due to the risk of inducing seizures.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3171/2016.4.JNS151264DOI Listing
April 2017

ACNS Guideline: Transcranial Electrical Stimulation Motor Evoked Potential Monitoring.

J Clin Neurophysiol 2016 Feb;33(1):42-50

*Departments of Neurology, Neuroscience, and Internal Medicine (Critical Care Medicine), Montefiore Medical Center and the Albert Einstein College of Medicine, Bronx, New York, U.S.A.; †Department of Neurology, Hospital for Special Surgery, New York, New York, U.S.A.; ‡Department of Neurology, Emory University School of Medicine and the Emory Brain Health Center, Atlanta, Georgia, U.S.A.; §Section of Clinical Neurophysiology, Department of Neurosciences, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia; ‖Laboratory for Human Experimental Neurophysiology, School of Medicine, University of Split, Split, Croatia; ¶Neurophysiology Services, Palomar Medical Center, South Gate, California, U.S.A.; and #Departments of Neurology & Neurological Sciences and Neurosurgery, Stanford University School of Medicine, Stanford, California, U.S.A.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/WNP.0000000000000253DOI Listing
February 2016

Cortical activity after stimulation of the corticospinal tract in the spinal cord.

Clin Neurophysiol 2016 Feb 14;127(2):1726-1733. Epub 2015 Nov 14.

Albert Einstein Colleague of Medicine, Institute for Neurology and Neurosurgery, St. Luke's-Roosevelt Hospital New York, NY, USA.

Objective: Intraoperative electrical stimulation of the spinal cord evokes not only high amplitude cortical somatosensory evoked potentials (ScEPs: spinal cord-evoked potentials) recorded from the scalp but also early potentials. It has been postulated that the early potential recorded from the scalp could be generated by antidromic stimulation of the cortico-spinal tract (ACSP: Antidromic Corticospinal tract Potential or "anti D-wave"). In this study, we aimed to investigate the anti D-wave evoked by epidural stimulation in a population of neurologically uncompromised/compromised patients during spine and spinal cord surgery. To better define its origin, we examined its spatial distribution, response to stimulation modification and recording parameters, and finally, we correlated anti D-waves and corresponding epidural recorded D-waves after a transcranial electric stimulation at the same level of spinal cord stimulation.

Methods: Tibial nerve somatosensory evoked potentials (SEPs), transcranially elicited muscle motor evoked potentials (m-MEPs), epidural motor evoked potentials (D-wave), and cortical spinal cord-evoked potentials (ScEPs) as well as Antidromic Cortico Spinal tract Potential (anti D-wave) were intraoperatively recorded in 30 subjects with different degrees of neurological involvement. ScEPs and anti D-wave were evoked by epidural stimulation of the spinal cord, both cranially and caudally to the surgery site and were recorded over the scalp at the midline. The effects of the stimulus rate and high pass filter were also tested.

Results: The anti D-wave was recordable in all neurologically intact patients and was clearly isolated from the ScEPs by its very short latency; recordings of the anti D-wave were limited to the anterior midline, and its amplitude was only slightly reduced by increasing the stimulus rate or by changing the high pass filter, and its latency was slightly longer than that of the D-wave latency. In neurologically compromised patients, the anti D-wave and D-wave exhibit a similar behaviour, both of which were present in neurologically intact or moderately compromised patients and absent in patients with quadri/paraplegia. In a patient with paraplegia due to T8 meningioma and in neurologically intact patients in whom the cauda/conus stimulated the anti D-wave, cortical ScEPs were absent when the stimulation was performed caudally to the surgical site.

Conclusions: We provide evidence that the anti D-wave behaviour and its parameters have a close correlation with the behaviour of the D-wave; specifically, its distribution, response to filtering, stimulus rate, and absence in paraplegic patients.

Significance: The presented data demonstrate that the anti D-wave is generated by the antidromic stimulation of fast neurons of the corticospinal tract, and consistent findings have been previously published in animals.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinph.2015.11.004DOI Listing
February 2016

Neurophysiological mechanism of possibly confounding peripheral activation of the facial nerve during corticobulbar tract monitoring.

Clin Neurophysiol 2016 Feb 10;127(2):1710-1716. Epub 2015 Nov 10.

Department of Intraoperative Neurophysiology, Mount Sinai Health System, Roosevelt Hospital, New York, NY, USA.

Objective: To improve the recognition and possibly prevent confounding peripheral activation of the facial nerve caused by leaking transcranial electrical stimulation (TES) current during corticobulbar tract monitoring.

Methods: We applied a single stimulus and a short train of electrical stimuli directly to the extracranial portion of the facial nerve. We compared the peripherally elicited compound muscle action potential (CMAP) of the facial nerve with the responses elicited by TES during intraoperative monitoring of the corticobulbar tract.

Results: A single stimulus applied directly to the facial nerve at subthreshold intensities did not evoke a CMAP, whereas short trains of subthreshold stimuli repeatedly evoked CMAPs. This is due to the phenomenon of sub- or near-threshold super excitability of the cranial nerve. Therefore, the facial responses evoked by short trains TES, when the leaked current reaches the facial nerve at sub- or near-threshold intensity, could lead to false interpretation.

Conclusions: Our results revealed a potential pitfall in the current methodology for facial corticobulbar tract monitoring that is due to the activation of the facial nerve by subthreshold trains of stimuli. This study proposes a new criterion to exclude peripheral activation during corticobulbar tract monitoring.

Significance: The failure to recognize and avoid facial nerve activation due to leaking current in the peripheral portion of the facial nerve during TES decreases the reliability of corticobulbar tract monitoring by increasing the possibility of false interpretation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinph.2015.07.042DOI Listing
February 2016

Shuffle the puzzle: Spinal motor-evoked potentials vs. 50-Hz artifact.

Asian Cardiovasc Thorac Ann 2015 Jul 4;23(6):754-5. Epub 2015 May 4.

Department of Intraoperative Neurophysiology, Mount Sinai Health System-Roosevelt Hospital, New York, NY, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/0218492315585458DOI Listing
July 2015

Intraoperative multimodal evoked potential monitoring during carotid endarterectomy: a retrospective study of 264 patients.

Anesth Analg 2015 Jun;120(6):1352-60

From the *Division of Neuroanesthesia and Intraoperative Neuromonitoring, Department of Anesthesiology, Intensive Care and Pain Therapy, Klinikum St. Georg gGmbH, Leipzig, Saxony, Germany; †Department of Intraoperative Neurophysiology, St. Luke's-Roosevelt Hospital, New York, New York; ‡Department of Anesthesiology, Intensive Care and Pain Therapy, and §Department of Vascular Surgery, Klinikum St. Georg gGmbH, Leipzig, Saxony, Germany; and ‖Department of Anesthesiology, Witten/Herdecke University, Helios Clinic Wuppertal, Nordrhein-Westfalen, Germany.

Background: Methods for detecting intraoperative cerebral ischemia arising from internal carotid artery (ICA) cross-clamping during carotid endarterectomy (CEA) should be sensitive, specific, and rapid to prevent intraoperative stroke. We had 3 objectives pertaining to this: (1) investigation of the rates of success of multimodal evoked potential (mEP) monitoring using a combination of median nerve (m) somatosensory (SS) EPs, tibial nerve SSEPs (tSSEPs), and transcranial electrical stimulated motor EPs (tcMEPs); (2) evaluation of the rates of false-negative mEP results; and (3) analysis of the relationship between different time periods associated with ICA cross-clamping and the postoperative outcome of motor function in patients with significant changes in mEP monitoring.

Methods: Two hundred sixty-four patients undergoing CEA using general anesthesia with monitoring of bilateral mSSEPs, tSSEPs, and tcMEPs were retrospectively reviewed between 2009 and 2012. The rates of successful assessment of mEPs were investigated, and the rate of false-negative mEP results was analyzed. Different time periods (T1--time of clamping, T2--clamping to significant mEP changes, T3--significant mEP change to intervention, and T4--intervention to recovery of EP) were tested using Welch t test for significant association with postoperative motor deficit.

Results: (1) Multimodal EP monitoring was achieved in 241 patients (91.3%, point estimate [PE] 0.91, confidence interval [CI] 0.87 to 0.94), whereas none of the modalities were recordable in one case (PE 0.0038, CI 0.0002 to 0.019). Additionally, tSSEP was not recordable in 21 patients (PE 0.08, CI 0.05 to 0.12), and we found one case of isolated failure of tcMEP recording (PE 0.0038, CI 0.0002 to 0.019). (2) False-negative mEP results were found in 1 patient (0.4%; PE 0.0038, CI 0.0002 to 0.019). Significant mEP changes occurred in 32 patients (12.1%), and thus, arterioarterial shunt was performed in 17 (6.4%) patients. Eleven patients (4.2%) showed transient and 1 showed permanent postoperative motor deficit. (3) There was no significant difference regarding any of the time periods associated with ICA cross-clamping and postoperative alteration of motor function (T1: P = 0.19, CI -30.1 to 6.8 minutes; T2: P = 0.38, CI -23 to 9.5 minutes; T3: P = 0.25, -9.7 to 2.8 minutes; T4: P = 0.42, CI to -15.5 to 7.0 minutes).

Conclusions: Multimodal EP monitoring is applicable during CEA. The 0.4% false-negative rate suggests an advantage of mEP monitoring when compared with isolated mSSEP monitoring. Our data suggest that periods of time during cross-clamping were not significantly associated with postoperative motor deficit. However, the small number of patients limits the conclusiveness of these findings. mEP monitoring could not prevent a postoperative motor deficit in all patients, but our results suggest that it is a useful adjunct to mSSEP monitoring.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1213/ANE.0000000000000337DOI Listing
June 2015

Neurophysiologic markers in laryngeal muscles indicate functional anatomy of laryngeal primary motor cortex and premotor cortex in the caudal opercular part of inferior frontal gyrus.

Clin Neurophysiol 2014 Sep 11;125(9):1912-22. Epub 2014 Feb 11.

Laboratory for Human and Experimental Neurophysiology (LAHEN), School of Medicine, University of Split, Split, Croatia; Department for Research in Biomedicine and Health, School of Medicine, University of Split, Split, Croatia.

Objective: The aim of this study was to identify neurophysiologic markers generated by primary motor and premotor cortex for laryngeal muscles, recorded from laryngeal muscle.

Methods: Ten right-handed healthy subjects underwent navigated transcranial magnetic stimulation (nTMS) and 18 patients underwent direct cortical stimulation (DCS) over the left hemisphere, while recording neurophysiologic markers, short latency response (SLR) and long latency response (LLR) from cricothyroid muscle. Both healthy subjects and patients were engaged in the visual object-naming task. In healthy subjects, the stimulation was time-locked at 10-300 ms after picture presentation while in the patients it was at zero time.

Results: The latency of SLR in healthy subjects was 12.66 ± 1.09 ms and in patients 12.67 ± 1.23 ms. The latency of LLR in healthy subjects was 58.5 ± 5.9 ms, while in patients 54.25 ± 3.69 ms. SLR elicited by the stimulation of M1 for laryngeal muscles corresponded to induced dysarthria, while LLR elicited by stimulation of the premotor cortex in the caudal opercular part of inferior frontal gyrus, recorded from laryngeal muscle, corresponded to speech arrest in patients and speech arrest and/or language disturbances in healthy subjects.

Conclusion: In both groups, SLR indicated location of M1 for laryngeal muscles, and LLR location of premotor cortex in the caudal opercular part of inferior frontal gyrus, recorded from laryngeal muscle, while stimulation of these areas in the dominant hemisphere induced transient speech disruptions.

Significance: Described methodology can be used in preoperative mapping, and it is expected to facilitate surgical planning and intraoperative mapping, preserving these areas from injuries.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinph.2014.01.023DOI Listing
September 2014

Inducing transient language disruptions by mapping of Broca's area with modified patterned repetitive transcranial magnetic stimulation protocol.

J Neurosurg 2014 May 3;120(5):1033-41. Epub 2014 Jan 3.

Laboratory for Human and Experimental Neurophysiology, School of Medicine, University of Split, Croatia;

Object: Until now there has been no reliable stimulation protocol for inducing transient language disruptions while mapping Broca's area. Despite the promising data of only a few studies in which speech arrest and language disturbances have been induced, certain concerns have been raised. The purpose of this study was to map Broca's area by using event-related navigated transcranial magnetic stimulation (nTMS) to generate a modified patterned nTMS protocol.

Methods: Eleven right-handed subjects underwent nTMS to Broca's area while engaged in a visual object-naming task. Navigated TMS was triggered 300 msec after picture presentation. The modified patterned nTMS protocol consists of 4 stimuli with an interstimulus interval of 6 msec; 8 or 16 of those bursts were repeated with a burst repetition rate of 12 Hz. Prior to mapping of Broca's area, the primary motor cortices (M1) for hand and laryngeal muscles were mapped. The Euclidian distance on MRI was measured between cortical points eliciting transient language disruptions and M1 for the laryngeal muscle.

Results: On stimulating Broca's area, transient language disruptions were induced in all subjects. The mean Euclidian distance between cortical spots inducing transient language disruptions and M1 for the laryngeal muscle was 17.23 ± 4.73 mm.

Conclusions: The stimulation paradigm with the modified patterned nTMS protocol was shown to be promising and might gain more widespread use in speech localization in clinical and research applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3171/2013.11.JNS13952DOI Listing
May 2014

Transcranial electrical stimulation and monitoring.

J Neurosurg 2014 Jan 8;120(1):291-2. Epub 2013 Nov 8.

University Hospital of Bellvitge, Barcelona, Spain; 

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3171/2013.6.JNS131278DOI Listing
January 2014

New methodology for facial nerve monitoring in extracranial surgeries of vascular malformations.

Clin Neurophysiol 2014 Apr 18;125(4):849-855. Epub 2013 Oct 18.

Vascular Birthmark Institute of New York, St Luke's Roosevelt Hospital, Mount Sinai Health System, New York, NY, USA; Department of Interventional Neuroradiology at the Institute for Neurology and Neurosurgery, St Luke's Roosevelt Hospital, Mount Sinai Health System, New York, NY, USA.

Objective: To develop a more reliable methodology for monitoring the facial nerve in surgeries of vascular malformations where the extracranial segment of the nerve is at risk.

Methods: Our methodology comprises: (1) preoperative mapping to identify the anatomical location of the nerve branches, (2) continuous intraoperative monitoring of the compound muscle action potential (CMAP) by stimulating the facial nerve extracranially, in close proximity to where the trunk of the facial nerve exits the skull at the stylomastoid foramen, (3) intraoperative mapping to identify the nerve branches during surgical dissection and quantify the innervating contribution of each branch to the target muscle.

Results: Only three out of 201 surgeries (1.5%) had complete facial nerve trunk injury as a consequence of facial vascular malformation surgery.

Conclusions: We developed a new method to continuously stimulate the facial nerve extracranially eliciting an objective parameter--the CMAP amplitude--to constantly measure changes in the muscle responses throughout surgery, alerting the surgeon before the facial nerve is severely injured. Our methodology notably reduces the complete facial nerve injury during extracranial surgery of facial vascular malformations.

Significance: This comprehensive methodology may also be a valuable tool to prevent facial nerve injury during other types of extracranial surgeries where radical excisions are required.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinph.2013.08.030DOI Listing
April 2014

A comparison of language mapping by preoperative navigated transcranial magnetic stimulation and direct cortical stimulation during awake surgery.

Neurosurgery 2013 May;72(5):808-19

Department of Neurosurgery, Charité Universitätsmedizin, Berlin, Germany.

Background: Navigated transcranial magnetic stimulation (nTMS) is increasingly used in presurgical brain mapping. Preoperative nTMS results correlate well with direct cortical stimulation (DCS) data in the identification of the primary motor cortex. Repetitive nTMS can also be used for mapping of speech-sensitive cortical areas.

Objective: The current cohort study compares the safety and effectiveness of preoperative nTMS with DCS mapping during awake surgery for the identification of language areas in patients with left-sided cerebral lesions.

Methods: Twenty patients with tumors in or close to left-sided language eloquent regions were examined by repetitive nTMS before surgery. During awake surgery, language-eloquent cortex was identified by DCS. nTMS results were compared for accuracy and reliability with regard to DCS by projecting both results into the cortical parcellation system.

Results: Presurgical nTMS maps showed an overall sensitivity of 90.2%, specificity of 23.8%, positive predictive value of 35.6%, and negative predictive value of 83.9% compared with DCS. For the anatomic Broca's area, the corresponding values were a sensitivity of 100%, specificity of 13.0%, positive predictive value of 56.5%, and negative predictive value of 100%, respectively.

Conclusion: Good overall correlation between repetitive nTMS and DCS was observed, particularly with regard to negatively mapped regions. Noninvasive inhibition mapping with nTMS is evolving as a valuable tool for preoperative mapping of language areas. Yet its low specificity in posterior language areas in the current study necessitates further research to refine the methodology.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1227/NEU.0b013e3182889e01DOI Listing
May 2013

A visual object naming task standardized for the Croatian language: a tool for research and clinical practice.

Behav Res Methods 2013 Dec;45(4):1144-58

University of Split, Split, Croatia,

The aim of the present study was to provide normative data for the Croatian language using 346 visually presented objects (Cycowicz, Friedman, Rothstein, & Snodgrass Journal of Experimental Child Psychology 65:171-237, 1997; Roach, Schwartz, Martin, Grewal, & Brecher Clinical Aphasiology 24:121-133, 1996; Snodgrass & Vanderwart Journal of Experimental Psychology: Human Learning and Memory 6:174-215, 1980). Picture naming was standardized according to seven variables: naming latency, name agreement, familiarity, visual complexity, word length, number of syllables, and word frequency. The descriptive statistics and correlation pattern of the variables collected in the present study were consistent with normative studies in other languages. These normative data for pictorial stimuli named by young healthy Croatian native speakers will be useful in studies of perception, language, and memory, as well as for preoperative and intraoperative mapping of speech and language brain areas.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3758/s13428-012-0308-8DOI Listing
December 2013

Intraoperative neurophysiological monitoring in acute paralysis from spinal cord epidural abscess.

Clin Neurol Neurosurg 2013 Mar 1;115(3):346-50. Epub 2012 Jun 1.

Department of Neurosurgery, Warren Alpert Medical School, Brown University, Providence, RI, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clineuro.2012.05.006DOI Listing
March 2013