Motor Response Threshold Research Articles

Transcutaneous spinal stimulation in people with and without spinal cord injury: Effect of electrode placement and trains of stimulation on threshold intensity.

Transcutaneous spinal cord stimulation (TSS) is purported to improve motor function in people after spinal cord injury (SCI). However, several methodology aspects are yet to be explored. We investigated whether stimulation configuration affected the intensity needed to elicit spinally evoked motor responses (sEMR) in four lower limb muscles bilaterally. Also, since stimulation intensity for therapeutic TSS (i.e., trains of stimulation, typically delivered at 15-50 Hz) is sometimes based on the single-pulse threshold intensity, we compared these two stimulation types. In non-SCI participants (n = 9) and participants with a SCI (n = 9), three different electrode configurations (cathode-anode); L1-midline (below the umbilicus), T11-midline and L1-ASIS (anterior superior iliac spine; non-SCI only) were compared for the sEMR threshold intensity using single pulses or trains of stimulation which were recorded in the vastus medialis, medial hamstring, tibialis anterior, medial gastrocnemius muscles. In non-SCI participants, the L1-midline configuration showed lower sEMR thresholds compared to T11-midline (p = 0.002) and L1-ASIS (p < 0.001). There was no difference between T11-midline and L1-midline for participants with SCI (p = 0.245). Spinally evoked motor response thresholds were ~13% lower during trains of stimulation compared to single pulses in non-SCI participants (p < 0.001), but not in participants with SCI (p = 0.101). With trains of stimulation, threshold intensities were slightly lower and the incidence of sEMR was considerably lower. Overall, stimulation threshold intensities were generally lower with the L1-midline electrode configuration and is therefore preferred. While single-pulse threshold intensities may overestimate threshold intensities for therapeutic TSS, tolerance to trains of stimulation will be the limiting factor in most cases.

MP62-15 A NOVEL TECHNIQUE OF ADMINISTERING PRECISE PELVIC FLOOR TRIGGER POINT INJECTIONS WITH ELECTRICAL STIMULATION FEEDBACK

You have accessJournal of UrologyCME1 Apr 2023MP62-15 A NOVEL TECHNIQUE OF ADMINISTERING PRECISE PELVIC FLOOR TRIGGER POINT INJECTIONS WITH ELECTRICAL STIMULATION FEEDBACK Claire Burton, Amber Herbert, and Amy Dobberfuhl Claire BurtonClaire Burton More articles by this author , Amber HerbertAmber Herbert More articles by this author , and Amy DobberfuhlAmy Dobberfuhl More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003320.15AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Pelvic floor trigger point injections (PFTPI) are an established therapy in the management of patients with myofascial pain. Commonly, botulinum toxin (BTA) is injected into the pelvic floor using digital palpation of the muscles. This is an imprecise method of delivery, as there is no objective confirmation of drug delivery to the desired location. We propose a technique using a peripheral nerve stimulator (PNS) to precisely isolate the muscles during PFTPI. METHODS: We conducted a retrospective review of patients with myofascial pain who had PFTPI using a PNS (LifeTech NS-2CA DualStim Plus) between 9/1/2020-8/31/2022. 50-100u of BTA reconstituted with 20 mL saline was injected into the levator ani complex at 1, 3, 5, 7, 9, and 11 o'clock. A insulated needle was inserted into the muscle while connected to the PNS. Placement was confirmed when the muscle twitch was palpated. Motor response thresholds were obtained by reducing the PNS amplitude until the muscle twitch was no longer appreciated. We aim to describe the procedure and intraoperative characteristics of patients receiving TPI with PNS. Our secondary objective is to compare patients who did and did not receive subsequent injections. RESULTS: A total of 15 patients underwent 27 injections. 8/15 (53%) received >1 injection. The mean age was 48 yr and 3 patients were male. 67% were non-Hispanic white. This procedure was always combined with another intraoperative procedure (cystoscopy n=3, intradetrusor BTA n=18, urethral sphincter or bladder neck BTA n=6). Mean operative time was 48 minutes (range 29-106). The average interval between injections was 163 days (range 98-364). In comparing those who did or did not undergo a repeat injection procedure, there was no difference in age (48 vs 47 years, p=0.95), BTA units (93.8 vs 71.4, p=0.30), concomitant procedure type, or the average threshold of injection sites (10.7 mA vs 9.8 mA, p=0.57). Among patients who had more than one injection, there was no relationship between average threshold over time (Figure 1). CONCLUSIONS: In this pilot study we demonstrate that pelvic floor TPI with PNS is reliable and reproduceable. Though we lack standardized assessment of benefit, over 50% of patients returned for repeat injections. Further study is needed to compare outcomes of TPI with and without this technique. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e867 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Claire Burton More articles by this author Amber Herbert More articles by this author Amy Dobberfuhl More articles by this author Expand All Advertisement PDF downloadLoading ...

Transcranial magnetic stimulation in late-aged people with depressive disorders

IntroductionOne of the most common mental disorders in the elderly is depression.Because of the high frequency of side effects of pharmacotherapy and the comorbid medical illnesses, there are not many ways to treat it.Non-drug therapies, such as repetitive transcranial magnetic stimulation (rTMS), could help overcome the limitations of standard drug therapy for this type of mental disorders.ObjectivesDevelopment of approaches to improving improve the provision of psychiatric care to elderly patients using rTMS.Methods30 patients over the age of 60 with anxiety-depressive spectrum disorders meeting criteria F30-39, F06.3, F06.4 (ICD-10) and a control group with similar criteria that were not treated with rTMS, were recruited from the psychiatric department at a university hospital (Moscow Scientific Research Institute of Psychiatry). Clinical, psychopathological, anamnestic, psychometric (Montgomery-Asberg scale (MADRS), Hamilton scale (HARS), Mini-mental state examination scale (MMSE) instrumental (electroencephalography) research methods were used. Patients of the experimental group underwent 15 sessions of low-frequency rTMS on the right dorsolateral prefrontal cortex (RDLPC). Conditions for the application of 1200 pulses were as follows: frequency - 1 Hz; intensity - 120% of the threshold of motor response (RMT) of the subject; pulse number - 1200; pulse sequence - 300; sequence duration - 300 seconds; sequence interval - 60 seconds; and stimulation time - 23 minutes. Subsequently, the patients were re-examined using the above-mentioned scales to assess their mental state in dynamics.ResultsAnalysis of the collected data shows an increase in the number of respondents and the frequency of achieving remission in the experimental group compared to the control group. No severe side effects of rTMS were observed.ConclusionsrTMS may be a safe method of adjuvant therapy in groups of elderly patients with anxiety-depressive spectrum disorders. Further studies will be needed to clarify the results.Disclosure of InterestNone Declared

MP30-01 “MIXED” MOTOR SACRAL NEUROMODULATION LEAD PLACEMENT RESULTS IN HIGHER IMPLANT RATES

You have accessJournal of UrologyUrodynamics/Lower Urinary Tract Dysfunction/Female Pelvic Medicine: Female Incontinence: Therapy I (MP30)1 Apr 2020MP30-01 “MIXED” MOTOR SACRAL NEUROMODULATION LEAD PLACEMENT RESULTS IN HIGHER IMPLANT RATES Kristen Gurtner, Anastasia Couvaras*, and Colin Goudelocke Kristen GurtnerKristen Gurtner More articles by this author , Anastasia Couvaras*Anastasia Couvaras* More articles by this author , and Colin GoudelockeColin Goudelocke More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000869.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Motor response is recognized as an important guide to sacral neuromodulation (SNM) lead placement as many leads are placed under sedation that alters sensory response. While there is scarce data on optimal characteristics of placement, several publications have explored ideal location, number of electrodes eliciting a response, amplitude of motor threshold and type of motor response associated with successful implantation. Optimized leads have been considered to: provoke response at low amplitudes, utilize all electrodes and prompt a bellows before a toe response. Emerging data may affect what is considered an optimized lead. METHODS: This represents an analysis of a prospective database examining the relationships among motor threshold characteristics, patient reports of sensation and the success and durability of SNM therapy. Leads were placed between November 2017 and August 2019 by a single surgeon with high-volume SNM experience. The amplitude of both toe and bellow motor threshold was recorded for each electrode. This analysis includes patients undergoing staged lead testing for urgency symptoms and voiding dysfunction including non-obstructive urinary retention. Patients having simultaneous pulse generator and lead placement or those undergoing lead revision were excluded. Leads were classified as ″bellows″ or ″toe″ when the lowest motor threshold on all four electrodes was uniform while ″mixed″ leads showed equal or alternating amplitudes across the lead. All leads demonstrated motor response on 4 electrodes. RESULTS: A total of 102 staged leads were placed with 82/102 (80‰) of patients implanted. Distribution of leads were: bellows (22/102; 22‰), toe (8/102; 8‰) and mixed (72/102; 70‰). Implantation rate for mixed leads was 88‰ (63/72) but only 68‰ (15/22; p<0.03) for bellows. Toe-dominant leads were implanted at 50‰ (4/8; p<0.006). Analysis suggests that distal electrode response may be paramount as leads with distal electrodes having equal bellow and toe thresholds had an implant rate of 100‰ (17/17) vs 72‰(31/43; p<0.02) for those with bellows lowest. No differences were seen with proximal electrodes. CONCLUSIONS: While bellows response has traditionally been sought as the ″first″ motor response for SNM lead implantation, our data suggest that a mixed pattern of response appears to result in higher rates of implantation. Source of Funding: N/A © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e438-e438 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Kristen Gurtner More articles by this author Anastasia Couvaras* More articles by this author Colin Goudelocke More articles by this author Expand All Advertisement PDF downloadLoading ...

Comparison of Motor Outcome in Patients Undergoing Awake vs General Anesthesia Surgery for Brain Tumors Located Within or Adjacent to the Motor Pathways

Surgical removal of intra-axial brain tumors aims at maximal tumor resection while preserving function. The potential benefit of awake craniotomy over craniotomy under general anesthesia (GA) for motor preservation is yet unknown. To compare the clinical outcomes of patients who underwent surgery for perirolandic tumors while either awake or under GA. Between 2004 and 2015, 1126 patients underwent surgical resection of newly diagnosed intra-axial tumors in a single institution. Data from 85 patients (44 awake, 41 GA) with full dataset who underwent resections for perirolandic tumors were retrospectively analyzed. Identification of the motor cortex required significantly higher stimulation thresholds in anesthetized patients (9.1±4 vs 6.2±2.7 mA for awake patients, P=.0008). There was no group difference in the subcortical threshold for motor response used to assess the proximity of the lesion to the corticospinal (pyramidal) tract. High-grade gliomas were the most commonly treated pathology. The extent of resection and residual tumor volume were not different between groups. Postoperative motor deficits were more common in the anesthetized patients at 1 wk (P=.046), but no difference between the groups was detected at 3 mo. Patients in the GA group had a longer mean length of hospitalization (10.3 vs 6.7 d for the awake group, P=.003). Awake craniotomy results in a better early postoperative motor outcome and shorter hospitalization compared with patients who underwent the same surgery under GA. The finding of higher cortical thresholds for the identification of the motor cortex in anesthetized patients may suggest an inhibitory effect of anesthetic agents on motor function.

RHYTHMIC TRANSKRANIAL MAGNETIC STIMULATION IN TREATMENT OF PATIENTS WITH DEPRESSION

23 patients with clinically proven diagnosis of depression were treated with the help of rTMS. The signs of depression were assessed according to the Hospital Anxiety and Depression Scale (HADS) and Zung Self-Rating Depression Scale. The low-frequency (1 Hz) rTMS was conducted on “Neuro-MS/T” with the intensity of 80% from the threshold of motor response to the TMS of the right dorsolateral prefrontal cortex, number of trains – 60, duration – 23 minutes. &#x0D; After 10 sessions of rTMS, the patients noted the improvement of sleep (15), mood improvement (19), a calmer reaction to stressful situations (14). A reduction of depression severity according to assessment scales was also registered (р &lt; 0,05). &#x0D; The therapeutic rTMS method and the chosen protocol of stimulation proved to be effective in treatment of depression and can be used in medical practice under the control of psychotherapist. &#x0D; 23 patients with clinically proven diagnosis of depression were treated with the help of rTMS. The signs of depression were assessed according to the Hospital Anxiety and Depression Scale (HADS) and Zung Self-Rating Depression Scale. The low-frequency (1 Hz) rTMS was conducted on “Neuro-MS/T” with the intensity of 80% from the threshold of motor response to the TMS of the right dorsolateral prefrontal cortex, number of trains – 60, duration – 23 minutes. &#x0D; After 10 sessions of rTMS, the patients noted the improvement of sleep (15), mood improvement (19), a calmer reaction to stressful situations (14). A reduction of depression severity according to assessment scales was also registered (р &lt; 0,05). &#x0D; The therapeutic rTMS method and the chosen protocol of stimulation proved to be effective in treatment of depression and can be used in medical practice under the control of psychotherapist. &#x0D; 23 patients with clinically proven diagnosis of depression were treated with the help of rTMS. The signs of depression were assessed according to the Hospital Anxiety and Depression Scale (HADS) and Zung Self-Rating Depression Scale. The low-frequency (1 Hz) rTMS was conducted on “Neuro-MS/T” with the intensity of 80% from the threshold of motor response to the TMS of the right dorsolateral prefrontal cortex, number of trains – 60, duration – 23 minutes. &#x0D; After 10 sessions of rTMS, the patients noted the improvement of sleep (15), mood improvement (19), a calmer reaction to stressful situations (14). A reduction of depression severity according to assessment scales was also registered (р &lt; 0,05). &#x0D; The therapeutic rTMS method and the chosen protocol of stimulation proved to be effective in treatment of depression and can be used in medical practice under the control of psychotherapist. &#x0D; 23 patients with clinically proven diagnosis of depression were treated with the help of rTMS. The signs of depression were assessed according to the Hospital Anxiety and Depression Scale (HADS) and Zung Self-Rating Depression Scale. The low-frequency (1 Hz) rTMS was conducted on “Neuro-MS/T” with the intensity of 80% from the threshold of motor response to the TMS of the right dorsolateral prefrontal cortex, number of trains – 60, duration – 23 minutes. &#x0D; After 10 sessions of rTMS, the patients noted the improvement of sleep (15), mood improvement (19), a calmer reaction to stressful situations (14). A reduction of depression severity according to assessment scales was also registered (р &lt; 0,05). &#x0D; The therapeutic rTMS method and the chosen protocol of stimulation proved to be effective in treatment of depression and can be used in medical practice under the control of psychotherapist. &#x0D; 23 patients with clinically proven diagnosis of depression were treated with the help of rTMS. The signs of depression were assessed according to the Hospital Anxiety and Depression Scale (HADS) and Zung Self-Rating Depression Scale. The low-frequency (1 Hz) rTMS was conducted on “Neuro-MS/T” with the intensity of 80% from the threshold of motor response to the TMS of the right dorsolateral prefrontal cortex, number of trains – 60, duration – 23 minutes. &#x0D; After 10 sessions of rTMS, the patients noted the improvement of sleep (15), mood improvement (19), a calmer reaction to stressful situations (14). A reduction of depression severity according to assessment scales was also registered (р &lt; 0,05). &#x0D; The therapeutic rTMS method and the chosen protocol of stimulation proved to be effective in treatment of depression and can be used in medical practice under the control of psychotherapist.

RHYTHMIC TRANSKRANIAL MAGNETIC STIMULATION IN TREATMENT OF PATIENTS WITH DEPRESSION

23 patients with clinically proven diagnosis of depression were treated with the help of rTMS. The signs of depression were assessed according to the Hospital Anxiety and Depression Scale (HADS) and Zung Self-Rating Depression Scale. The low-frequency (1 Hz) rTMS was conducted on “Neuro-MS/T” with the intensity of 80% from the threshold of motor response to the TMS of the right dorsolateral prefrontal cortex, number of trains – 60, duration – 23 minutes. &#x0D; After 10 sessions of rTMS, the patients noted the improvement of sleep (15), mood improvement (19), a calmer reaction to stressful situations (14). A reduction of depression severity according to assessment scales was also registered (р &lt; 0,05). &#x0D; The therapeutic rTMS method and the chosen protocol of stimulation proved to be effective in treatment of depression and can be used in medical practice under the control of psychotherapist. &#x0D; 23 patients with clinically proven diagnosis of depression were treated with the help of rTMS. The signs of depression were assessed according to the Hospital Anxiety and Depression Scale (HADS) and Zung Self-Rating Depression Scale. The low-frequency (1 Hz) rTMS was conducted on “Neuro-MS/T” with the intensity of 80% from the threshold of motor response to the TMS of the right dorsolateral prefrontal cortex, number of trains – 60, duration – 23 minutes. &#x0D; After 10 sessions of rTMS, the patients noted the improvement of sleep (15), mood improvement (19), a calmer reaction to stressful situations (14). A reduction of depression severity according to assessment scales was also registered (р &lt; 0,05). &#x0D; The therapeutic rTMS method and the chosen protocol of stimulation proved to be effective in treatment of depression and can be used in medical practice under the control of psychotherapist. &#x0D; 23 patients with clinically proven diagnosis of depression were treated with the help of rTMS. The signs of depression were assessed according to the Hospital Anxiety and Depression Scale (HADS) and Zung Self-Rating Depression Scale. The low-frequency (1 Hz) rTMS was conducted on “Neuro-MS/T” with the intensity of 80% from the threshold of motor response to the TMS of the right dorsolateral prefrontal cortex, number of trains – 60, duration – 23 minutes. &#x0D; After 10 sessions of rTMS, the patients noted the improvement of sleep (15), mood improvement (19), a calmer reaction to stressful situations (14). A reduction of depression severity according to assessment scales was also registered (р &lt; 0,05). &#x0D; The therapeutic rTMS method and the chosen protocol of stimulation proved to be effective in treatment of depression and can be used in medical practice under the control of psychotherapist. &#x0D; 23 patients with clinically proven diagnosis of depression were treated with the help of rTMS. The signs of depression were assessed according to the Hospital Anxiety and Depression Scale (HADS) and Zung Self-Rating Depression Scale. The low-frequency (1 Hz) rTMS was conducted on “Neuro-MS/T” with the intensity of 80% from the threshold of motor response to the TMS of the right dorsolateral prefrontal cortex, number of trains – 60, duration – 23 minutes. &#x0D; After 10 sessions of rTMS, the patients noted the improvement of sleep (15), mood improvement (19), a calmer reaction to stressful situations (14). A reduction of depression severity according to assessment scales was also registered (р &lt; 0,05). &#x0D; The therapeutic rTMS method and the chosen protocol of stimulation proved to be effective in treatment of depression and can be used in medical practice under the control of psychotherapist. &#x0D; 23 patients with clinically proven diagnosis of depression were treated with the help of rTMS. The signs of depression were assessed according to the Hospital Anxiety and Depression Scale (HADS) and Zung Self-Rating Depression Scale. The low-frequency (1 Hz) rTMS was conducted on “Neuro-MS/T” with the intensity of 80% from the threshold of motor response to the TMS of the right dorsolateral prefrontal cortex, number of trains – 60, duration – 23 minutes. &#x0D; After 10 sessions of rTMS, the patients noted the improvement of sleep (15), mood improvement (19), a calmer reaction to stressful situations (14). A reduction of depression severity according to assessment scales was also registered (р &lt; 0,05). &#x0D; The therapeutic rTMS method and the chosen protocol of stimulation proved to be effective in treatment of depression and can be used in medical practice under the control of psychotherapist.

BS25. Language inhibition and motor response thresholds during extra-operative cortical stimulation mapping

Introduction Electrical cortical stimulation (ECS) is the clinical standard for brain mapping to define the functionally eloquent cortex in patients undergoing pre-surgical evaluation with intracranial electrodes. This study evaluated thresholds for language inhibition and motor response during ECS and their determinants. Methods A retrospective review of clinical information and extra-operative electrocorticography (ECoG) recordings was performed. The thresholds for functional responses were determined and compared with after-discharge (AD) thresholds. Multivariate models were used to evaluate predictors of functional thresholds. Results A total of 122 children were included. The mean language threshold was 7.4 ( ± 3.0) mA. 40/47 (85%) of patients with language response during ECS also had ADs. Language thresholds were found to be equal to or higher than AD thresholds in 34/40 (85%) patients. The mean motor threshold was 5.4 ( ± 2.8) mA. 71/85(83.5%) of patients with motor response during ECS also had ADs. Motor thresholds were found to be equal to or higher than AD thresholds in 47/71 (66%) patients. Minimum AD threshold was a significant determinant of minimum language threshold (regression co-efficient 0.446, 95% CI −0.001 to 0.892, p = 0.050) and minimum motor threshold (regression co-efficient 0.664, 95%CI 0.058 to 1.270, p = 0.034). Conclusion AD threshold was a significant determinant of language and motor thresholds. Most children with functional response during ECS also had ADs, with the functional thresholds being equal to or higher than AD thresholds. These findings underscore a potential pitfall in functional cortex localization with ECS findings and emphasize the need for a functional mapping method with improved neurophysiologic validity, especially in children.

Defining the Construct of Synthetic Androgen Intoxication: An Application of General Brain Arousal.

Synthetic androgens (i. e., anabolic-androgenic steroids) are the primary component to the majority of problematic appearance and performance enhancing drug (APED) use. Despite evidence that these substances are associated with increased risk for aggression, violence, body image disturbances, and polypharmacy and can develop a pattern of chronic use consistent with drug dependence, there are no formal definitions of androgen intoxication. Consequently, the purpose of this paper is to establish a testable theory of androgen intoxication. We present evidence and theorize that synthetic androgen intoxication can be defined by a pattern of poor self-regulation characterized by increased propensity for a range of behaviors (e.g., aggression, sex, drug seeking, exercise, etc.) via androgen mediated effects on general brain arousal. This theory posits that androgens reduce threshold for emotional reactivity, motor response, and alertness to sensory stimuli and disrupt inhibitory control over the behaviors associated with synthetic androgen use. These changes result from alteration to basic neurocircuitry that amplifies limbic activation and reduces top-down cortical control. The implications for this definition are to inform APED specific hypotheses about the behavioral and psychological effects of APED use and provide a basis for establishing clinical, legal, and public health guidelines to address the use and misuse of these substances.

The Lower Limb Joint Pathology Affects the Functional State of the Thigh Muscle Neuromotor Apparatus

Diseases of joints are often associated with the alterations in the function of the associated muscles. The pathophysiological mechanisms underlying these changes in the muscle functions are poorly understood, however. Here, we explored the alterations in the neuromotor status of the hip quadriceps muscles in the coxartrosis and gonartrosis patients using electrostimulation myography. We found elevated motor response and H-reflex thresholds and a decrease of their amplitudes in the coxarthrosis and gonarthrosis patients compared to the healthy subjects. While the alterations in the motor responses may result from the reduced blood supply of the joint and the femoral nerve, changes in H-reflex indicate an involvement of the nociceptive signals from the joint in the central mechanisms of the movement control. We suggest that reduced reflex excitability of the spinal cord motor neurons controlling the quadriceps muscle in the coxartrosis and gonartrosis patients involves the afferents from the flexors and/or presynaptic inhibition of the IA afferents.

Radiofrequency ablation of spinal osteoid osteoma: a prospective study.

OBJECTIVE Surgery has been considered the standard treatment for spinal osteoid osteomas that are refractory to analgesic agents. Radiofrequency ablation (RFA) is a less invasive technique with established efficiency for the treatment of peripheral osteoid osteomas. The main objectives of this study are to evaluate the safety of RFA based on the results of a previous experimental study in rats conducted in the authors' laboratory and to identify its short- and long-term efficiency in the treatment of spinal osteoid osteomas. METHODS Between March 2009 and July 2016, 8 consecutive patients with spinal osteoid osteomas were enrolled in the study and underwent 9 CT-guided RFA procedures. All patients presented with spinal pain (median preoperative visual analog scale [VAS] score 7.55, range 6-8.8) predominantly during the night, and they all had normal neurological examination results before the procedure. Pain (according to the VAS score) and neurological status were reassessed immediately before discharge, with further follow-up at 1, 6, and 12 months after the procedure. At the final follow-up, VAS score, neurological examination, patient satisfaction, and a radiological control (CT scan) were documented (median 48 months, range 12-84 months). VAS scores before and after the procedure were compared during the 3 days before surgery (D0), on the day of the surgery, Day 1 (D1), and at the final follow-up. RESULTS No neurological deficit was documented following the procedure or at the final follow-up. A statistically significant reduction in the VAS score was observed on Day 1 (mean 2.56 ± 0.68, p = 0.005) compared with D0. At the final follow-up, all patients reported a VAS score of 0 and a satisfaction rate of 100%. Only 1 patient had recurrent symptoms (pain, VAS score 8.1) 6 months after the initial RFA. A second procedure was performed, and the patient was subsequently symptom free at the final follow-up. CT scanning performed in all patients (12-84 months post-RFA) showed residual sclerosis in 4 patients and complete resolution of the radiological lesion in the remaining 4 patients. CONCLUSIONS CT-guided RFA appears to be a safe and effective method for the management of spinal osteoid osteoma and can be safely performed for lesions close to the dura or exiting nerve root based on the motor response threshold testing performed during the procedure. It should be considered the treatment of choice for spinal osteoid osteomas refractory to conservative treatment, thus avoiding more aggressive spinal approaches with subsequent potential morbidity.

Cortical stimulation parameters for functional mapping

PurposeThere is significant variation in how patients respond to cortical electrical stimulation. It has been hypothesized that individual demographic and pathologic factors, such as age, sex, disease duration, and MRI findings, may explain this discrepancy. The purpose of our study is to identify specific patient characteristics and their effect on cortical stimulation, and discover the extent of variation in behavioral responses that exists among patients with epilepsy. MethodWe retrospectively analyzed data from 92 patients with medically intractable epilepsy who had extra-operative cortical electrical stimulation. Mapping records were evaluated and information gathered about demographic data, as well as the thresholds of stimulation for motor, sensory, speech, and other responses; typical seizure behavior; and the induction of afterdischarges. ResultsNinety-two patient cortical stimulation mapping reports were analyzed. The average of the minimum thresholds for motor response was 4.15mA±2.67. The average of the minimum thresholds for sensory response was 3.50mA±2.15. The average of the minimum thresholds for speech response was 4.48mA±2.42. The average of the minimum thresholds for afterdischarge was 4.33mA±2.37. Most striking were the degree of variability and wide range of thresholds seen between patients and within the different regions of the same patient. ConclusionWide ranges of thresholds exist for the different responses between patients and within different regions of the same patient. With multivariate analysis in these series, no clinical or demographic factors predicted physiological response or afterdischarge threshold levels.

Difference in sensory, motor and pain threshold for medium frequency electrical stimuli in different pain conditions-A pilot study

Background: Different current frequencies are considered to produce a different reaction in tissues. But there is still a lack of knowledge about the reactions of tissues on medium frequency electric currents with different frequencies in special groups of diseases or trauma. Objective: The main objective of the study was to find out the difference of physiological response between normal healthy, chronic low back pain and postoperative pain subjects for a medium frequency (4 KHz) electrical stimuli with 20, 50 and 100 Hz base frequencies. Method: Readings were taken for sensory, motor and pain threshold with three different frequencies 20 Hz, 50 Hz & 100 Hz for normal healthy, chronic low back pain and postoperative pain subjects. Electrodes were applied over the dorsal and ventral side of the ankle in all the maneuvers. For the normality of the data, Shapiro-wilk test was done. Statistical analysis was done using IBM SPSS version 20.0 and significance were set at “p Result: A multivariate ANOVA test showed significant difference statistically between groups; sensory and the motor threshold for back pain was less than normal and postoperative subjects, irrespective of the frequencies used for stimulation. The post hoc analysis between groups showed that chronic low back pain subjects differ from normal individuals in pain threshold (difference 1.617mA, p=.041). Conclusion: The sensory and motor response threshold was more in acute pain subjects and in normal individuals than chronic low back pain subjects. Reduced sensory motor threshold and increased pain threshold in chronic back pain subjects may indicate hyperalgesia and perceptual delay in processing of the electrical stimuli by the nerves system.

Alteration of the threshold stimulus for intraoperative brain mapping via use of antiepileptic medications

Abstract Intraoperative seizures during awake craniotomy with cortical and subcortical mapping are a common occurrence. Patients are routinely treated preoperatively with anti-convulsive medications to reduce seizure occurrence. Historically these drugs have not been believed to significantly affect awake craniotomy procedures. We report a patient undergoing intraoperative mapping with differential response and seizure occurrence based upon antiepileptic drug usage. A 43 year old female presented with history of seizures, right sided hemiparesis, electrical sensations, and difficulty with language function. She was determined to have a mass lesion involving the left frontal and temporal lobes and subsequently elected to undergo resection by awake craniotomy with intraoperative mapping. A first attempt at lesion resection was performed after a missed dose of anti-convulsant medication (levetiracetam) and was subsequently aborted because of repeated seizure activity. The threshold for seizure generation (1.75 mA) was observed to be significantly lower than expected. Therapy was begun with both levetiracetam and phenytoin prior to a second attempted resection one week later. Thresholds for cortical motor response in the second operation were significantly higher than expected (> 9.0 mA), and no intraoperative seizure activity was observed. To our knowledge this is the first quantitative example of antiepileptic drugs affecting the current required for intraoperative mapping. This case highlights the potential for higher current requirements in patients preoperatively treated with high doses of antiepileptic drugs, as well as the importance of confirming adequate dosage of antiepileptic drugs in patients at an increased risk of seizure generation.

Sensory and Motor Thresholds of Transcutaneous Electrical Stimulation Are Influenced by Gender and Age

BackgroundTranscutaneous electrical stimulation (ES) is a therapeutic procedure used in rehabilitation. However, the effectiveness of it depends on sensory responses to pain and motor control in neuromuscular recruitment, considering the differences related to gender and age of the subjects treated, as well as the intensity and frequency of ES. ObjectiveTo determine the threshold of sensory perception (TSP) and the threshold of motor response (TMR) in young and elderly individuals of both genders. DesignRandomized controlled clinical trial. SettingGeneral community. ParticipantsEighty volunteers with no history of systemic diseases were selected to participate in the study: 40 men and 40 women were subdivided by convenience sampling and age group into young male and female (age 21.6 ± 2.4 years) groups as well as into elderly female and male groups (age 72.6 ± 6.1 years). InterventionsThe participants received electrical stimulation (ES) at 5 and 50 Hz, with pulse durations of 20, 100, 400, 1000, and 3000 μs applied on the flexor muscle bellies of the wrist and fingers. Main Outcome MeasuresTSP was identified as the first sensation of increased current intensity and TMR as the minimum muscle contraction detected. The results were submitted to analysis of variance, followed by the Tukey's test, with a significance level of 5%. ResultsTSP was lower than TMR for all pulse durations, regardless of gender and age. In women, TSP was lower than that in young and elderly men at both frequencies. However, TSP was higher in elderly subjects than in younger subjects at 50 Hz for both genders. Age also affected the TMR, presenting higher thresholds in elderly subjects of both genders at 50 Hz; however the same occurred only in male subjects at 5 Hz. ConclusionAge and gender interfere directly with ES. These variables should be considered during rehabilitation because they indicate that electrical stimulation in elderly women should be carefully performed, as they have lower thresholds than elderly men when polarized currents are used, and there is a risk of skin lesion because of their high thresholds.

THE EFFECT OF HIGH AND LOW FREQUENCY CORTICAL STIMULATION WITH A FIXED OR A POISSON DISTRIBUTED INTERPULSE INTERVAL ON CORTICAL EXCITABILITY IN RATS

Neurostimulation is a promising treatment for refractory epilepsy. We studied the effect of cortical stimulation with different parameters in the rat motor cortex stimulation model. High intensity simulation (threshold for motor response--100 μA), high frequency (130 Hz) stimulation during 1 h decreased cortical excitability, irrespective of the interpulse interval used (fixed or Poisson distributed). Low intensity (10 μA) and/or low frequency (5 Hz) stimulation had no effect. Cortical stimulation appears promising for the treatment of neocortical epilepsy if frequency and intensity are high enough.

The threshold of cortical electrical stimulation for mapping sensory and motor functional areas

This study aimed to investigate the threshold of cortical electrical stimulation (CES) for functional brain mapping during surgery for the treatment of rolandic epilepsy. A total of 21 patients with rolandic epilepsy who underwent surgical treatment at the Beijing Institute of Functional Neurosurgery between October 2006 and March 2008 were included in this study. Their clinical data were retrospectively collected and analyzed. The thresholds of CES for motor response, sensory response, and after discharge production along with other threshold-related factors were investigated. The thresholds (mean±standard deviation) for motor response, sensory response, and after discharge production were 3.48±0.87, 3.86±1.31, and 4.84±1.38mA, respectively. The threshold for after discharge production was significantly higher than those of both the motor and sensory response (both p<0.05). A negative linear correlation was found between the threshold of after discharge production and disease duration. Using the CES parameters at a stimulation frequency of 50Hz and a pulse width of 0.2ms, the threshold of sensory and motor responses were similar, and the threshold of after discharge production was higher than that of sensory and motor response.

Enhanced propriospinal excitation from hand muscles to wrist flexors during reach-to-grasp in humans

In humans, propriospinal neurons located at midcervical levels receive peripheral and corticospinal inputs and probably participate in the control of grip tasks, but their role in reaching movements, as observed in cats and primates, is still an open question. The effect of ulnar nerve stimulation on flexor carpi radialis (FCR) motor evoked potential (MEP) was tested during reaching tasks and tonic wrist flexion. Significant MEP facilitation was observed at the end of reach during reach-to-grasp but not during grasp, reach-to-point, or tonic contractions. MEP facilitation occurred at a longer interstimulus interval than expected for convergence of corticospinal and afferent volleys at motoneuron level and was not paralleled by a change in the H-reflex. These findings suggest convergence of the two volleys at propriospinal level. Ulnar-induced MEP facilitation was observed when conditioning stimuli were at 0.75 motor response threshold (MT), but not 1 MT. This favors an increased excitability of propriospinal neurons rather than depression of their feedback inhibition, as has been observed during tonic power grip tasks. It is suggested that the ulnar-induced facilitation of FCR MEP during reach may be due to descending activation of propriospinal neurons, assisting the early recruitment of large motoneurons for rapid movement. Because the feedback inhibitory control is still open, this excitation can be truncated by cutaneous inputs from the palmar side of the hand during grasp, thus assisting movement termination. It is concluded that the feedforward activation of propriospinal neurons and their feedback control may be involved in the internal model, motor planning, and online adjustments for reach-to-grasp movements in humans.

Pathological effects and motor response threshold changes following radiofrequency application at various distances from the L-5 nerve root: an experimental study

Radiofrequency (RF) ablation is a minimally invasive technique often used percutaneously in the treatment of many conditions such as spasticity, pain, and osteoid osteoma. The purpose of this study was to assess the value of motor response threshold (MRT) as an indirect indicator of the RF generator's electrode to nerve distance, and to evaluate the effects of RF at various distances from a nervous structure. The L-5 nerve root was studied in 102 Sprague-Dawley rats (sham contralateral side). Motor response thresholds at 0, 2, 4, 5, and 6 mm from the nerve root were assessed before and after RF application for 2 minutes at 80° C on Days 0 and 7. Radiofrequency was applied 0, 2, 4, 5, and 6 mm away from L-5 and with the addition of interposed cortical bone. The effects of RF application on MRT were studied, and subsequent nerve injury was evaluated using light microscopy pathological examination. There is a significant correlation between MRT and the distance between the electrode tip and L-5, with MRT less than 0.5 V when the electrode was in direct contact with the root. Electrical and pathological changes following RF application were more pronounced at 0 mm, with worsening seen on Day 7. Radiofrequency at 2 and 4 mm produced fewer electrical and histological deleterious effects on the nerve on Days 0 and 7, with an obvious improvement on Day 7. At 5 mm, electrical and histological abnormalities were minimal on Day 0 and were fully reversible on Day 7. At 6 mm and with interposed cortical bone, MRT and pathological findings were unchanged on Days 0 and 7. The MRT proved to be a useful and reliable tool in decreasing nerve morbidity following RF ablation in animals and may be used in humans for the same purpose. It serves as an indirect indicator of the proximity of the RF generator's electrode tip to any adjacent motor nervous structure. A minimum safe distance of 5 mm between the electrode tip and the nerve is required to avoid irreversible nerve injury, unless a bony wall is interposed between them, thus serving as a nerve shield. In medical conditions that require RF ablation of the nerve, such as spasticity and pain, the MRT must be lower than 0.5 V. When a nerve lesion is to be avoided such as in cases of osteoid osteoma, an MRT higher than 2.5 V is considered safe, reflecting a distance greater than 5 mm.

The threshold elicited motor response via an in situ femoral nerve catheter predicts analgesia following total knee replacement

BackgroundContinuous femoral nerve blocks are a part of the multimodal perioperative anesthetic regimen following total knee replacement. Elicitation of a quadriceps muscle contraction (QC) at placement is desirable. We prospectively evaluated the relationship between elicited motor response and threshold current with block success in situ femoral nerve catheters after total knee replacement.MethodsAfter Institutional Review Board approval and written informed consent, 100 adults aged ≥18 years, undergoing total knee replacement were studied. The threshold current for an elicited motor response (QC or sartorius muscle contraction [SC]) was recorded during needle insertion, after femoral nerve catheter advancement, and prior to local anesthetic administration on the first postoperative day. Patients were assessed for pinprick sensory anesthesia of the femoral nerve distribution by an observer unaware of the current threshold or evoked motor response at 5-minute intervals for 30 minutes. A successful block was considered a lack of pinprick sensation within 30 minutes.ResultsNinety patients completed the study. A QC was obtained at needle insertion in 89 and maintained following catheter advancement in 77 subjects. Prior to drug administration a QC was obtained in 66 patients, 13 demonstrated an SC, and 11 had no motor response. QC prior to drug administration had a sensitivity of 0.85 (95% confidence intervals [CI]: 0.75 to 0.92) and a specificity of 0.55 (95% CI: 0.37 to 0.72) for complete femoral nerve block. The specificity of a QC prior to drug administration was greater than at catheter placement (P = 0.006). Compared to the threshold current at catheter placement, 27 patients had a decrease, 60 had an increase, and 3 exhibited no change in the threshold current prior to drug administration (P < 0.01). The median interquartile range (IQR) threshold current in patients that achieved a complete block was 0.56 (0.29 to 0.80) mA compared with 1.1 mA (0.41 to 2.75) mA for incomplete blocks (P < 0.01). The area under the receiver operator characteristics curve for current threshold prior to local anesthetic administration (0.74) was greater than at catheter placement (0.45) (P < 0.001). The intersection of sensitivity and specificity for the minimal threshold current prior to local anesthetic injection was 0.84 mA.ConclusionThe elicited motor response and current threshold from a stimulating femoral catheter measured prior to local anesthetic injection is an important determinant of the success of femoral nerve block following bolus administration.