Transcranial Cortical Stimulation Research Articles

Neuroprotection of Transcranial Cortical and Peripheral Somatosensory Electrical Stimulation by Modulating a Common Neuronal Death Pathway in Mice with Ischemic Stroke.

Therapeutic electrical stimulation, such as transcranial cortical stimulation and peripheral somatosensory stimulation, is used to improve motor function in patients with stroke. We hypothesized that these stimulations exert neuroprotective effects during the subacute phase of ischemic stroke by regulating novel common signaling pathways. Male C57BL/6J mouse models of ischemic stroke were treated with high-definition (HD)-transcranial alternating current stimulation (tACS; 20 Hz, 89.1 A/mm2), HD-transcranial direct current stimulation (tDCS; intensity, 55 A/mm2; charge density, 66,000 C/m2), or electroacupuncture (EA, 2 Hz, 1 mA) in the early stages of stroke. The therapeutic effects were assessed using behavioral motor function tests. The underlying mechanisms were determined using transcriptomic and other biomedical analyses. All therapeutic electrical tools alleviated the motor dysfunction caused by ischemic stroke insults. We focused on electrically stimulating common genes involved in apoptosis and cell death using transcriptome analysis and chose 11 of the most potent targets (Trem2, S100a9, Lgals3, Tlr4, Myd88, NF-kB, STAT1, IL-6, IL-1β, TNF-α, and Iba1). Subsequent investigations revealed that electrical stimulation modulated inflammatory cytokines, including IL-1β and TNF-α, by regulating STAT1 and NF-kB activation, especially in amoeboid microglia; moreover, electrical stimulation enhanced neuronal survival by activating neurotrophic factors, including BDNF and FGF9. Therapeutic electrical stimulation applied to the transcranial cortical- or periphery-nerve level to promote functional recovery may improve neuroprotection by modulating a common neuronal death pathway and upregulating neurotrophic factors. Therefore, combining transcranial cortical and peripheral somatosensory stimulation may exert a synergistic neuroprotective effect, further enhancing the beneficial effects on motor deficits in patients with ischemic stroke.

Evaluation of spinal and cortical magnetic stimulation together with MScan MUNE in the early stages of the disease in the diagnosis of ALS

Electrophysiological methods are still the leading investigations in the diagnosis of ALS. Although needle EMG is the main finding in demonstrating lower motor neuron involvement, the search continues for a method that supports the diagnosis as high as EMG in the electrophysiological evaluation of upper motor neuron involvement. But it would be valuable to try to develop the standards of the classical transcranial cortical stimulation methods.

P32. Improved reliabilty of intraoperative language mapping through preoperative nTMS and baseline linguistic scores

Objective Repetitive navigated transcranial magnetic stimulation (rnTMS) and direct cortical stimulation (DCS) during awake surgery are complementary tools to locate speech functional areas of the brain. However, patients show inter-individual differences in their preoperative linguistic capabilities, which can impact the validity of intraoperative DSC mapping. We developed a standardized approach which utilizes preoperative aphasia scores and rnTMS to screen patients for their capability to perform reliable object naming during awake surgery. Methods We prospectively included 18 patients with language-eloquent brain tumors, scheduled for awake surgery. Aachen Aphasia Score (AAS), Demtect Score (DS) and Berlin Aphasia Score (BAS) were used to evaluate linguistic eloquence of each patient preoperatively. Moreover, all patients underwent 3 runs of naming all objects without rnTMS (baseline run), from which only promptly and correctly named objects were retained for later rnTMS mapping. These selected objects were also used for the intraoperative baseline testing and DCS mapping under level 2 of Ramsay Sedation Score. Results The degree of preoperative language impairment significantly correlated with the incidence of errors during preoperative as well as intraoperative baseline errors (AAT p = 0.01, BAS p = 0.001, DS = 0.001). Patients with significant aphasia (BAS >=2, AAT >=1) and cognitive impairment (DS >=2) committed over 50% of incorrect or delayed namings in the preoperative baseline (p = 0.001). Despite utilizing only the images retained after preoperative baseline naming, these patients still made significantly more mistakes during intraoperative baseline naming than patients with less severe aphasia. Moreover, the dosage of anaesthetic medication significantly correlated with the incidence of errors during intraoperative baseline naming (propofol p = 0.028, remifentanil p = 0.036), despite stopping all systemic analgetic and sedative medication at least 8 min before testing. Conclusion Patients with significant aphasia (BAS >=2, AAT >=2) and cognitive impairment (DS >=2) are not able to perform reliable intraoperative object naming and are therefore not suited for this procedure. In addition, dosages of analgetic and sedative medication during craniotomy should be kept as low as possible to allow for reliable intraoperative cognitive testing.

Transcranial cortical stimulation in the treatment of obsessive-compulsive disorders: efficacy studies.

Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are non-invasive brain stimulation methods that became widely used as therapeutic tools during the past two decades especially in cases of depression and schizophrenia. Low frequency rTMS and cathodal effect of tDCS inhibits cortical functioning while high frequency and anodal effect of tDCS have the opposite effect. Prolonged and repetitive application of either methods leads to changes in excitability of the human cortex that outlast the period of stimulation. Both rTMS and tDCS induce functional changes in the brain-modulating neural activity at cortical level. This paper reviews rTMS and tDCS effects in clinical trials for obsessive-compulsive disorder (OCD). Low frequency rTMS, particularly targeting the supplementary motor area and the orbital frontal cortex, seems to be the most promising in terms of therapeutic efficacy while older studies targeting the prefrontal dorsal cortex were not as successful. tDCS clearly needs to be investigated in large scale and sufficiently powered randomized control studies. From a general point of view, these non-invasive techniques hold promise as novel therapeutic tools for OCD patients.

Soleus MEP-80 response latency in restless legs syndrome

Introduction The purpose of this study was to investigate the latency of soleus MEP-80 response in patients with restless legs syndrome (RLS). We aimed to figure out the etiopathogenesis and to determine an objective diagnostic tool and prognosis indicator. Materials and methods In this study, 40 patients with RLS and 40 controls were included. For all patients and controls routine laboratory investigations, electroneurography (ENG) and transcranial cortical magnetic stimulation (TCCMS) were performed. Finally the MEP-80 response latency of 40 RLS patients and 40 age and gender matched controls were compared. All patients were diagnosed with the 4 criteria defined by ICSD 2 and the severity was classified according to the international restless legs syndrome scaling group (IRLSSG) classification. Results The soleus MEP-80 response latency in RLS patients and controls was 96 ms (SD: ± 12.5) and 81.8 ms (SD: ± 3.4), respectively. The difference between both groups was statistically significant (p ± 8.3 ms n = 24) than in mild-moderate RLS patients (83.2 ms; SD: ± 3.4; n = 16). Conclusion In restless legs syndrome it is known that the corticospinal tract is not directly affected but subcortical inhibition is influenced due to functional spinal neuron impairment. As a result of this study we determined a direct functional impairment of spinal afferent and efferent long reflexes and we recognized that corticospinal late responses are affected in RLS. According to the results of our study we think that Soleus MEP 80 responce can be a new diagnostic modality and a prognostic indicator for RLS patients. Acknowledgements Department of Neurophysiology, Dokuz Eylul University Medical School.

Evoked Potential Monitoring during Spine Surgery

Intraoperative electrophysiological monitoring is used in a variety of procedures. Various techniques are thought to be useful for the detection and prevention of neurological deficits [1,2]. Mechanisms of thoraco-lumbar spinal cord injury during scoliosis surgery include ischemia and over-distraction of vertebral column. This injury can be potentially detected by standard tibial somatosensory evoked potentials (SSEPs) thus reducing the risk of permanent paraplegia [35]. However, SSEPs only detect sensory tracts dysfunction and motor deficits can occur without any SSEP changes [6,7]. Motor evoked potentials (MEP), obtained by transcranial cortical stimulation, can provide an early detection of motor disturbance [8-10]. The combined methods can improve the sensitivity and specificity of the monitoring [11].

Navigated Transcranial Magnetic Stimulation-Guided Resection of a Left Parietal Tumor: Case Report

Operating on tumors with close margins to the primary motor cortex requires a precise preoperative planning. Transcranial magnetic stimulation (TMS) is the only preoperative technique for detecting eloquent cortical regions that is directly comparable to direct cortical stimulation (DCS). Combining this well established method in neurological diagnostics with a non-invasive navigation system using the patient's preoperative MRI scans in the NEXTSTIM system might be a promising tool in preoperative planning. We used preoperative navigated TMS to localize the motor strip in a 75-year-old female patient with a central lesion suspected to be a meningeoma. The elicited data were fused to the navigation MRI in the Brainlab IPLAN system. Following the preoperatively acquired MEP data, a posterior approach to the tumor was planned. After craniotomy, DCS and phase reversal were performed to verify the preoperative results. The motor strip could be located in the same cortical area where the motor response was elicited preoperatively. Navigated transcranial cortical stimulation via the NEXTSTIM system is a helpful tool for preoperative planning.

Surgical treatment of insular tumours with tractography, functional magnetic resonance imaging, transcranial electrical stimulation and direct subcortical stimulation support

Background and purposeSurgical treatment of insular tumours carries significant risks of limb paresis or speech disturbances due to their localization. The development of intraoperative neuromonitoring techniques that involve evoked motor potentials induced via both direct and transcranial cortical electrical stimulation as well as direct subcortical white matter stimulation, intraoperative application of preoperative tractography and functional magnetic resonanceimaging (fMRI) in conjunction with neuronavigation resulted in significant reduction of postoperative disabilities that enabled widening of indications for surgical treatment. The aim of this study was to present the authors’ own experience with surgical treatment of insular gliomas. Material and methodsOur cohort comprises 30 patients with insular gliomas treated at the Department of Neurosurgery in Sosnowiec. Clinical symptoms included sensorimotor partial seizures in 86.6%; generalized seizures in 23.3%; persistent headaches in 16.6% and hemiparesis in 6.6%. All the patients were operated on with intraoperative neuromonitoring that included transcranial cortical stimulation, direct subcortical white matter stimulation as well as tractography and fMRI concurrently with neuronavigation. The analysis included postoperative neurological evaluation along with the assessment of the radicalism of resection evaluated based on postoperative MRI. ResultsPostoperatively, four patients had permanent hemiparesis (13.3%); importantly, two out of those patients had preoperative deficits (6.6%). Persistent speech disturbances were present in four patients (13.3%). Partial sensorimotor seizures were noted in two patients (6.6%). Seizures in the other patients receded. Intraoperative transcranial electrical stimulation as well as direct subcortical white matter stimulation along with tractography (DTI) and fMRI facilitated gross total resection of insular gliomas in 53.5%, subtotal in 13.3% and partial resection in 33.1%. ConclusionsImplementation of TES, direct subcortical white master stimulation, DTI and fMRI into the management protocol of the surgical treatment of insular tumours resulted in total and subtotal resections in 66% of cases with permanent motor disability in 6.6% of patients. Poor prognosis for independent living after surgery mainly affects patients with WHO grade III or IV.

Neuromodulation for epilepsy

Epilepsy is a common disease. WHO data suggests that 1 in 20 people may have an epileptic seizure in their lifetime and at least 1 in 200 go on to develop epilepsy. Anticonvulsant drug therapy using one or more drugs works as an effective tool to suppress seizures in only 70% of the patients, the remaining 30% are either not responsive or suffer major side effects. Surgical resection then forms the next line of management in selected patients. However in some cases surgical resection may not be possible, hence arises the need for alternative therapies. Neuromodulation of the Central Nervous system is a novel technique under evaluation for Medically Intractable epilepsy. CNS stimulation for epilepsy has been a matter of extensive research. We review the Neurophysiological basis of Neuromodulation in Epilepsy and various modalities viz Vagal nerve stimulation (VNS), Transcranial magnetic stimulation (TMS) and Direct cortical stimulation (DCS). Deep brain stimulation (Hippocampal, Anterior thalamic and STN) and RNS are newer modalities and are also reviewed.

Cortical Brain Stimulation: A Potential Therapeutic Agent for Upper Limb Motor Recovery Following Stroke

There is emerging interest in the use of cortical electrical stimulation as a novel physical agent for the treatment of upper limb motor impairment after stroke. Evidence from animal models suggests that both motor learning and cortical stimulation alter intracortical inhibitory circuits and can facilitate long-term potentiation and cortical remodeling. This article reviews current research on the physiology and use of cortical stimulation animal models and in humans with stroke-related hemiplegia. Both transcranial cortical stimulation techniques and targeted epidural cortical stimulation are discussed in detail.

Motor responses of muscles supplied by cranial nerves to subthalamic nucleus deep brain stimuli

The distribution of human corticobulbar motor excitatory and inhibitory output is not fully understood. In particular, it is unclear whether the pattern of innervation is the same for upper and lower facial muscles, and what is the motor cortical area giving rise to such innervation. We used electrodes implanted in the subthalamic nucleus (STN) in patients with Parkinson's disease to activate motor tracts at a subcortical level. We examined the excitatory and inhibitory effects of unilateral single STN deep brain stimulation (sSTN-DBS) in 14 patients by taking recordings from facial, cervical and upper limb muscles on both sides. We measured the latency and amplitude of the motor-evoked potentials (MEPs), and the latency and duration of the silent periods, and compared ipsilateral with contralateral responses and responses obtained in different muscles. Unilateral sSTN-DBS induced strictly contralateral MEPs in the trapezius, deltoid, biceps and thenar muscles. The same stimulus always induced bilateral MEPs in the orbicularis oculi, orbicularis oris, masseter and sternocleidomastoid at a mean latency in the range 6.0-9.1 ms. MEP latencies in the orbicularis oculi and orbicularis oris were significantly longer than in the masseter and sternocleidomastoid (P < 0.01). A short latency small action potential was recorded in the ipsilateral orbicularis oculi that was likely generated by activation of extraocular muscles. During sustained voluntary muscle contraction, a silent period was recorded at similar onset latency on both sides. This period was significantly shorter in orbicularis oculi than in masseter, and in the ipsilateral side for both muscles (P < 0.01). sSTN-DBS is able to activate the descending projecting fibres in the corticobulbar tract eliciting bilateral MEPs and silent periods in facial and cranial muscles. This suggests that fibres to both ipsi- and contralateral motor nuclei descend together at the level of the STN. These findings are relevant in the discussion of the innervation of upper and lower facial muscles in humans and in the interpretation of previous results obtained with transcranial cortical stimulation.

W3 Intraoperative monitoring: Spinal cord

Surgery at and around the spinal cord places the cord at risk from ischemic, thermal or mechanical injury. The most feared injuries cause motor loss, e.g., paraplegia. Somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) are used for spinal cord intraoperative monitoring (IOM). SEPs are easiest to monitor and were first to gain widespread acceptance. SEP IOM reduced postoperative paraplegia by more than 60%. In the SEP technique, spinal cord pyramidal tract integrity is inferred from SEP posterior column monitoring. Correlations were good, yet some discrepancies occurred between posterior column function and motor outcome. SEPs during myelotomy for spinal cord tumors did not predict motor deficits well. In contrast, MEPs monitor pyramidal tracks directly. Transcranial or direct electrical cortical stimulation produces corticospinal (pyramidal) D and I waves recordable directly from the spinal cord. Limb muscle MEPs can and should bemonitored too. These techniquesmore confidently warn surgeons, and predict and prevent intraoperative injury to the spinal motor pathway. Combining D wave spinal recording with muscle MEPs is a reliable technique. D wave without muscle MEPs has shown false positive changes when assessed in scoliosis surgery, possibly due to recording electrode movement during spinal column distraction. Many users now combine SEP and types of MEP, tailored to the particular patient’s condition, surgery and anesthesia regimen. Further development of IOM techniques could map dorsal and lateral columns of the exposed spinal cord, new tools better to prevent intraoperative spinal injury.

Channelopathy: Hypothesis of a common pathophysiologic mechanism in different forms of paroxysmal dyskinesia

Paroxysmal dyskinesias are a rare heterogeneous group of neurologic disorders, characterized by transient sudden choreoathetoid or dystonic attacks without loss of consciousness. This study reports a family with six affected members in three generations, and two sporadic cases of paroxysmal dyskinesia. Familial cases of paroxysmal dyskinesia are affected by idiopathic long-lasting paroxysmal exertion-induced dyskinesia and the sporadic cases by idiopathic short-lasting paroxysmal kinesigenic dyskinesia. Familial cases also suffer from epilepsy, mainly of generalized type, with benign outcome; one sporadic case is affected by migraine. Results presented in this neurophysiologic study include electromyography, somatosensory evoked potentials by median nerve stimulation, somatosensory evoked potentials by posterior tibial nerve stimulation, motor evoked potentials by magnetic transcranial cortical stimulation, visual evoked potentials, brainstem auditory evoked potentials, blink reflex, reflex H, and electroencephalography. The clinical and neurophysiologic findings presented here suggest a condition of hyperexcitability at the muscular and brain level, perhaps as a result of an ion channel disorder, which is in agreement with reports in the literature.

Extensive Neurophisyological Evaluation in Primary Premature Ejaculation Patients

Pudendal nerve somatosensory evoked potentials (PN-SEPs), bulbo-cavernosus reflex (BC reflex) and perineal motor evoked potentials (BC MEPs) following transcranial magnetic cortical stimulation (TMS) were performed in patients with primary premature ejaculation (PPE), to investigate the somatic sensory and motor function of the genital area. Methods Fourteen patients with PPE underwent psychological counseling, urologic physical and trasnrectal ultrasound examination, laboratory data and Stamey test. Spinal and cortical PN-SEPs were recorded by dorsal nerve stimulaiton at penile shaft (DN-SEPs) in all patients, and at glans penis (GP-SEPs) in 3 of them. BC reflex was obtained by stimulating the basis of penis. Results Mean sensory thresold did not significantly differ between patients and normal subjects. Cortical DN-SEPs were normal in alla patients. Sensory central conduction was significantly smaller in patients than controls. In 3 patients and in 3 controls undergone both DN-SEPs and GP-SEPs, glans penis sensory threshold was lower than dorsal nerve one, and cortical GP-SEP latency longer than cortical DN-SEP latency. BC reflex was normal in most patients. BC MEPs were normal in all patients, but one. Conclusions We did not confirm either a faster conduction along the pudendal sensory pathway, or a greater cortical representation of the sensory stimuli from the genital area in oue patients. Moreover, we did not confirm an hyperexcitability of BC reflex in them. Our results suggest that the electrophysiological approach is probably not sufficient to clariphy the causes of PPE and more integrated investigation are requested.

Interhemispheric facilitation of the hand motor area in humans.

1. We investigated interhemispheric interactions between the human hand motor areas using transcranial cortical magnetic and electrical stimulation. 2. A magnetic test stimulus was applied over the motor cortex contralateral to the recorded muscle (test motor cortex), and an electrical or magnetic conditioning stimulus was applied over the ipsilateral hemisphere (conditioning motor cortex). We investigated the effects of the conditioning stimulus on responses to the test stimulus. 3. Two effects were elicited at different interstimulus intervals (ISIs): early facilitation (ISI = 4-5 ms) and late inhibition (ISI > or = 11 ms). 4. The early facilitation was evoked by a magnetic or anodal electrical conditioning stimulus over the motor point in the conditioning hemisphere, which suggests that the conditioning stimulus for early facilitation directly activates corticospinal neurones. 5. The ISIs for early facilitation taken together with the time required for activation of corticospinal neurones by I3-waves in the test hemisphere are compatible with the interhemispheric conduction time through the corpus callosum. Early facilitation was observed in responses to I3-waves, but not in responses to D-waves nor to I1-waves. Based on these results, we conclude that early facilitation is mediated through the corpus callosum. 6. If the magnetic conditioning stimulus induced posteriorly directed currents, or if an anodal electrical conditioning stimulus was applied over a point 2 cm anterior to the motor point, then we observed late inhibition with no early facilitation. 7. Late inhibition was evoked in responses to both I1- and I3-waves, but was not evoked in responses to D-waves. The stronger the conditioning stimulus was, the greater was the amount of inhibition. These results are compatible with surround inhibition at the motor cortex.

Age-related changes in muscle fatigue resistance in humans.

The goal of this study was to compare the relative contributions from the muscle and the central nervous system to muscle fatigue resistance in aging. Each subject carried out 90 s of sustained maximal voluntary isometric contraction (MVC) of the thumb using the thenar and forearm thumb muscles. Contractile capacity of the thenar muscles was assessed through tetanic stimulation of the median nerve. Interpolated doublets delivered during an MVC represented the overall voluntary activation level while transcranial cortical stimulation with an electromagnetic stimulator was used to assess motor output upstream from the corticomotoneuronal pathway. Nine elderly subjects [four females and five males, 70+/-9 years old (mean+/-SD)] and 10 younger subjects (five females and five males, 30+/-6 years old) were tested. After the fatiguing exercise, the elderly group's MVC declined by 29% as opposed to 47% in the younger group (p<0.01). The elderly group's greater fatigue resistance was accounted for by increased fatigue resistance at the muscle level as well as in the central nervous system. At least some of the decline in the central motor drive was upstream from the corticomotoneuronal pathway. The higher muscle fatigue resistance in the elderly group was attributable to differences in both the peripheral and central nervous systems.

Interaction of prefrontal cortical and hypothalamic systems in the pathogenesis of depression

Hypothalamo-pituitary adrenal (HPA)-axis hyperactivity leads to increased production of corticotrophin-releasing hormone (CRH) and cortisol; the central effects of these hormones form the final common pathway in the pathogenesis of symptoms of depression. HPAaxis activity may not only be caused by glucocorticoid receptor resistance, developmental sequelae or stress in adulthood, but also by stroke, especially if the left prefrontal cortex is affected. Transcranial cortical stimulation seems to be an effective new treatment for depression. HPA hyperactivity leads, in addition, to a decreased frontal metabolism, probably due to the inhibiting effect of glucocorticoids on the brain metabolism. The hyperactivity of the HPA axis may also explain at least part of the changes in the HPT-axis and contribute to decreased bioavailability of T3 in the brain. Hypofrontality and hyperactivity of the HPA-axis reinforce each other's actions in the development of the signs and symptoms of depression.

Timing and characteristics of perceptual attenuation by transcranial stimulation: a study using magnetic cortical stimulation and somatosensory-evoked potentials.

Transcranial cortical magnetic stimulation (CMS) is a noninvasive, non-noxious procedure to induce perceptual attenuation when applied concomitant to sensory stimuli. To investigate the perceptual timing of simple stimulus features in the somatosensory modality, we applied right hemisphere CMS at different intervals following a stimulus delivered to the left hand. Different intervals between peripheral stimuli and CMS were defined according to the components of the somatosensory-evoked potentials (SEP), previously obtained in response to the same stimulus. Perceptual attenuation was maximal when CMS coincided with the primary cortical response (parietal N20 potential); conversely, perception of stimulus intensity was not modified when CMS was concomitant with the N200 and P300 potentials. Using small CMS intensities, a "perceptual dip" was observed when CMS arrived in coincidence with the N120 potential, a SEP response thought to be originated in part in the second somatic area. Our results support the view that both N200 and P300 are post-perceptual responses. The results also suggest that the cortical processes active during the N20 and N120 potentials may be essential for the conscious perception of somatosensory stimuli delivered to the hand.

Inhibition of muscle sympathetic outflow following transcranial cortical stimulation

The possible contribution of cerebral cortical activity to sympathetic outflow to the muscle vascular bed was assessed in normal human subjects. Muscle sympathetic activity was recorded from motor fascicles of the peroneal nerve in 8 subjects while transcranial magnetic stimulation was applied over the vertex, or unilaterally over the hand area of cortex. By triggering the cortical stimulus from the R-wave of the ECG and introducing delays of 0–600 ms between the trigger and the stimulus, we found that a single cortical stimulus delayed by 200–400 ms caused a pronounced inhibition of one pulse-synchronous sympathetic burst. Stimulation over the vertex was more effective than stimulation over the hand area of cortex. In addition to this inhibition of muscle sympathetic outflow, brain stimulation caused an increase in cutaneous sympathetic activity, both sudomotor (sweating) and vasoconstrictor (decrease in skin blood flow). We suggest that the cerebral cortex may normally suppress muscle sympathetic outflow and speculate that lesions that interrupt this source of inhibition (such as those caused by stroke) may result in an augmented muscle sympathetic outflow.

Intraoperative Monitoring of Spinal Cord Function Using Motor Evoked Potentials via Transcutaneous Epidural Electrode During Anterior Cervical Spinal Surgery

Because false-positive results are not infrequent when monitoring somatosensory evoked potentials during surgery, monitoring of motor evoked potentials (MEPs) has been proposed and successfully used during the removal of spinal cord tumors. However, this often requires direct visual placement of an epidural electrode after a laminectomy. We evaluated the use of MEPs, recorded via a transcutaneously placed epidural electrode, to monitor motor pathway functional integrity during surgery on the anterior cervical spine. Sixteen patients underwent anterior cervical vertebral decompression and fusion for cervical myelopathy and/or radiculopathy. Before surgery, an epidural monitoring electrode was placed transcutaneously at the midthoracic level and was used to record MEPs after transcranial cortical electrical stimulation. Electrode placement was successful in all patients but one, and satisfactory baseline spinal MEPs were obtained except for one patient who had cerebral palsy with significant motor dysfunction. Patients showed no significant changes in spinal MEPs during surgery, and all had baseline or better motor function postoperatively. None had complications from epidural electrode placement or electrical stimulation. We conclude that motor pathways can be monitored safely during anterior cervical spinal surgery using spinal MEPs recorded via a transcutaneously placed epidural electrode, that MEP preservation during surgery correlates with good postoperative motor function, and that cerebral palsy patients may possess too few functional motor fibers to allow MEP recording.