Somatosensory Evoked Potentials Studies Research Articles

Neurophysiological evaluation of juvenile systemic lupus erythematosus

BackgroundPeripheral nervous system and the central nervous system involvement in systemic lupus erythematosus (SLE) patients are one of the major causes of morbidity and mortality. The aim of this work was to study the nervous system clinically and electrophysiologically in children with systemic lupus erythematosus.ResultsThe study was carried out on thirty-eight children with SLE. Their age ranged from 5 to 16 years. The most encountered neurologic manifestations were tremors. It was observed in 47.4% of children, followed by headache in 39.5%, sensory manifestation as numbness in 23.7%, cerebrovascular stroke in 5.3%, and chorea in 2.6%, which was unilateral mostly in the upper limb, tics, and convulsion had the same percentage. Around 16% of children had positive findings in MRI, such as cerebrovascular disease, minimal hematoma, pseudotumorcerebri, vasculitis, and ectatic ventricles. Subclinical peripheral neuropathy was reported in nearly 52.6% of children, and clinical peripheral neuropathy was reported in 23.6%. Pure sensory subclinical peripheral neuropathy was detected in 13.1% of children, but mixed subclinical peripheral neuropathy was detected in 39.4%. Nearly 53% of studied children had an abnormal somatosensory-evoked potential study of posterior tibial and median nerves.ConclusionThe current study reported that the clinical neurological manifestations in juvenile SLE is common. Peripheral neuropathy is commonly detected, which could be either clinical or sub-clinical. Somatosensory evoked potential study is of value for early detection of central affection.So, we recommend more studies to determine the guidelines when to order these informative investigations for children with JSLE.

Neuromonitoring in Neurosurgery : An imperative redemption

With the refinement in biomedical gadgetry, it has been a modern day requisite to safeguard the indigenous neuro-architecture and henceforth foretell the postoperative neurological outcome. The intraoperative neuro-physiological monitoring (IONM) comes as no surprise to be the only credible paradigm which can cluethe standing of neural pathway directly during general anesthesia. By engaging with the IONM appliance, the operating surgeon can acknowledge the risk of injury to critical neural structure while dealing with the pathology within its vicinity. Based on the province of the encephalon, a disparate methods of IONM such as MEP, SSEP, ABR, VEP, BCR, AMR etc have unfolded over time. Intraoperative monitoring of motor evoked potentials (MEPs) has been believed to be advantageousin preventing postoperative motor dysfunction while coping up with aneurysmal surgery involving the internal carotid artery (ICA) and middle cerebral artery (MCA) and resection of tumor near sensorimotor areas or corticospinal tract.3–6The fundamental essence of MEP monitoring is based on the detection of a pyramidal tract insult expressed as a decrease of the amplitude of the waveform elicited by electrical stimulation. Conversely, Somatosensory evoked potentials (SSEPs) embraces a series of wave forms that emulate sequential activation of neural structures along the somatosensory pathways.7 The representative stimulation sites classically used for clinical diagnostic in the course of SSEPs studies are the median nerve at the wrist, the common peroneal nerve at the knee, and the posterior tibial nerve at the ankle. Over and above that, SSEPs have been used as an indicator of cerebral ischemia during CEA, although far less commonly and as a surrogate alternative to EEG. SSEPs primarily gauge the integrity of the dorsal (sensory) column of the spinal cord. It furnishes with the real-time examination of spinal tracts at risk during surgical manipulation of the spinal cord such as spinal tumor and pedicle screw instrumentation. Likewise, Auditory brainstem response (ABR) is a test which can assess the brain wave activity and diagnose dysfunctions of the auditory pathways within the auditory nerve and brainstem that occurs in response to an stimuli with clicks or certain tones.8This is notably useful in the surgery of CP angle tumor such as vestibular schwannoma, Microvascular decompression for hemifacial spasm and trigeminal neuralgia. In any neurosurgical endeavour, where a visual field impairment is contemplated during the intraoperative period, the monitoring of flash visual evoked potential (VEP) comes as a rescue to evaluate the state of visual function.9This manoeuvre is explicitly virtuous while performing tumorectomy at the optic chiasm of pituitary adenomas, craniopharyngiomas, tuberculum sellae meningiomas, and other tumors; the removal of brain tumors from the optic pathway and structures in its vicinity such as the optic nerve, optic radiation, and occipital lobe; and clip ligation of aneurysm involving the internal carotid artery, which strike a pose of risking injury and impeding blood flow to the ophthalmic artery.9 Monitoring intraoperative flash visual evoked potentials (VEPs) estimate the functionality of the optic pathway from the retina to the visual cortical area, and hence allows visual impairment to be avoided or minimized. The bulbocavernosus reflex (BCR) is anillustrious somatic reflex that is convenient in gaining information about the state of the sacral spinal cord segments.10 When present, it is indicative of an intact spinal reflex arcs (S2–S4 spinal segments) with afferent and efferent nerves through the pudendal nerve. BCR is of the greatest utility for the monitoring of sacral function in detethering of the tethered cord syndrome.11 A surface electrode is used to electrically stimulate the pudendal afferent fibers at the clitoris or penis and recording of the analogous triggered EMG in external anal sphincter using a subdermal needle electrode. The abnormal muscle response (AMR), which is also known as lateral pread response, is adopted in the microvascular decompression (MVD) for hemifacial spasm.12A complete disappearance of AMR after a convincing MVD from root exit zone implicate a postoperative disappearance of the hemifacial spasm. Nonetheless, the persistence of the AMR does not mean incomplete MVD.

Functional and Prognostic Assessment in Comatose Patients: A Study Using Somatosensory Evoked Potentials.

AimThe functional prognosis of patients after coma following either cardiac arrest (CA) or acute structural brain injury (ABI) is often uncertain. These patients are associated with high mortality and disability. N20 and N70 somatosensory evoked potentials (SSEP) are used to predict prognosis. We evaluated the utility of SSEP (N20–N70) as an early indicator of long-term prognosis in these patients.MethodsThis was a retrospective cohort study of patients (n = 120) admitted to the intensive care unit (ICU) with a diagnosis of coma after CA (n = 60) or ABI (n = 60). An SSEP study was performed, including N20 and N70 at 24–72 h, after coma onset. Functional recovery was assessed 6–12 months later using the modified Glasgow scale (mGS). The study was approved by our local research ethics committee.ResultsIn the CA and ABI groups, the absence of N20 (36% of CA patients and 41% of ABI patients; specificity = 100%) or N70 (68% of CA patients and 78% of ABI patients) was a strong indicator of poor outcome. Conversely, the presence of N70 was an indicator of a good outcome (AC: specificity = 84.2%, sensitivity = 92.7%; ABI: specificity = 64.2% sensitivity = 91.3%).ConclusionSomatosensory evoked potentials are useful early prognostic markers with high specificity (N20) and sensitivity (N70). Moreover, N70 has additional potential value for improving the prediction of good long-term functional outcomes.Clinical Trial Registration:[https://clinicaltrials.gov/], identifier [2018/01/001].

The Added Value of Somatosensory Potential N70 in Neurological Prognosis After Coma by Acute Brain Structural Injury: A Retrospective Study.

Coma after acute brain structural injury (ABI) are associated with high mortality and disability. Somatosensory evoked potentials (SSEP) N20 and N70 are used to predict prognosis. We assessed the utility of SSEP (N20-N70) as an early indicator of long-term functional prognosis in these patients. We conducted a retrospective cohort study of patients admitted to the intensive care unit (ICU) with a diagnosis of coma after ABI (n=60). An SSEP study including N20 and N70 was performed 24-72 hours after coma onset. Functional recovery was evaluated 6 to 12 months later using the Modified Glasgow Scale (mGS). The study was approved by our local research ethics committee. The absence of N20 (41% specificity=100%) or N70 (78%) was a strong indicator of a poor outcome. In contrast, the presence of N70 was an indicator of a good outcome (specificity=64.2% sensitivity=91.3%). SSEP N20 and N70 are useful early prognostic markers with high specificity (N20) and sensitivity (N70). N70 has potential additional value for improving the prediction of good functional outcomes in the long term.

Modification of Electrode in Dermatosensory Evoked Potential

Somatosensory evoked potential (SSEP) usually done using bipolar surface stimulator of peripheral nerve and recorded by cortical surface or subdermal needle electrodes, in this study we modify an adhesive large surface area, surface stimulator using the same montage and method then compare the result between them. We took nineteen patients of median nerve SSEP, locate and identify the shape of dermatom assigned according to text using large square adhesive surface electrode. The same as the shape of dermatom, this is the cathode electrode, for the anode, a strip has the same length of the cathode with a width of two centimetres placed beneath the cathode, the circular ground band between stimulated and recording electrode. The subjects In this study prepared for routine SSEP study the result obtained of both study compared using statistical method and we found there was a significant different between two method and the modified as higher amplitude using lesser stimulated threshold but not significant different between latency. That’s happened because we increased the surface area of stimulation which means more the motor nerve was stimulated.

No Evidence for Dystonia-Like Sensory Overflow of Tongue Representations in Adults Who Stutter.

Persistent developmental stuttering (PDS) disrupts speech fluency in about 1% of adults. Although many models of speech production assume an intact sensory feedback from the speech organs to the brain, very little is actually known about the integrity of their sensory representation in PDS. Here, we studied somatosensory evoked potentials (SEPs) in adults who stutter (AWS), with the aim of probing the integrity of sensory pathways. In addition, we tested the processing of dual sensory input to address a putative link between stuttering and focal dystonia. In 15 AWS (aged 15–55 years; three females) and 14 matched fluent speaking adults (ANS), we recorded SEPs at C5′ and C6′ induced by stimulating separately or simultaneously the tongue or the cheek at the corner of the mouth. We determined latencies (N13, P19, and N27) and peak-to-peak amplitudes (N13-P19, P19-N27). We divided amplitudes from simultaneous stimulation by the sum of those from separate stimulation. Amplitude ratios did not differ between groups, indicating normal processing of dual sensory input. This does not support a clinical analogy between focal dystonia and persistent stuttering. SEP latencies as a measure of transmission speed in sensory pathways were significantly shorter in stuttering subjects than in fluent speaking participants, however, this might have been related to a trend for a height difference between groups, and was not confirmed in a replication dataset. In summary, we did not find evidence for dystonia-like sensory overflow of tongue representations in AWS.

The study of diagnostic capabilities of somatosensory evoked potentials in patients with neurogenic urinary retention

To study diagnostic capabilities of somatosensory evoked potentials (SSEP) in clarifying the mechanisms of formation of urinary disorders. The authors studied the characteristics of nerve impulses during stimulation of the pudendal and tibial nerves in patients with neurogenic urinary retention and cerebral ischemic stroke in the parietal lobes (4 patients), spinal ischemic stroke (10 patients), myelitis at the level of thoracic segments (7 patients), spinal cord cauda equina tumors (3 patients). The study of SSEPs made it possible to determine the localization and nature of damage to the structures of the central nervous system and to establish the neurogenic cause of urinary disorders.

Dermatomal Versus Mixed Somatosensory Evoked Potentials in the Diagnosis of Lumbosacral Spinal Canal Stenosis

The existing literature on the use of dermatomal somatosensory evoked potentials in lumbosacral spinal canal stenosis is limited. The goal of this study was to evaluate the role of dermatomal against mixed tibial somatosensory evoked potential (SEP) as a complementary procedure to imaging studies in the diagnosis of lumbosacral stenosis. Thirty patients with clinically and radiologically diagnosed lumbosacral stenosis and 20 normal individuals were enrolled in the study. The study was ethically approved, and informed consent for participation was provided. All participants underwent bilateral mixed tibial and dermatomal SEP study of the third (L3), fourth (L4), fifth lumbar (L5), and first sacral (S1) dermatomes. N45, N25, N20, and N10 tibial SEP waves were measured from four channels, whereas dermatomal waves were measured from cortical recording. Peak latency and amplitude of each wave were calculated. The cutoff value of the dermatomal S1 latency showed the highest sensitivity and specificity percentages (81.7 and 82.5, respectively), followed by L5 and N25. N25-N45 interpeak latency showed the lowest sensitivity and specificity. All L5, S1, L4, and N25 latency cutoff values presented highly significant differences between affected sides and controls (P < 0.0001), followed by N45 and N20. The amplitude cutoff values of SEP waves showed equivocal sensitivity and specificity percentages. Somatosensory evoked potential studies can be used as a supplementary test for the diagnosis of lumbosacral stenosis, with the dermatomal studies being more valuable expressing multiple root abnormalities. S1 dermatomal wave latency has the highest diagnostic value, followed by L5, N25, and then L4 latencies.

T110. Visualization of nerve impulse traveling along the brachial plexus after ulnar nerve stimulation using magnetoneurography system

Introduction In somatosensory evoked potential (SEP) testing, an analysis of Erb’s potentials following median or ulnar nerve stimulation at the wrist may be useful to define a lesion of the lateral cord or the medial cord of the brachial plexus (BP) neuropathy. However, there have been few SEP studies on multiple site recording of Erb’s potentials so that traveling nature of the nerve impulse along BP has not been visualized yet. By analysis of magnetoneurogram with superconducting quantum interference device (SQUID) sensor system, we succeeded in visualizing the nerve impulse traveling along BP and then propagating into the C5–C8 intervertebral foramen after median nerve stimulation. Here we aimed to analyze the nerve impulse traveling along BP following ulnar nerve stimulation at the wrist. Methods Magnetoneurogram over BP of 5 healthy volunteers (Age range, 25–45 years; mean, 32.8 y.o) were measured after ulnar nerve stimulation (supramaximal stimulus; 5 Hz and averaging 2000 responses) using a newly developed 132 channel SQUID biomagnetometer with an X-ray imaging system (RICOH COMPANY, Ltd., Tokyo, Japan). At the same time, SEP was measured at Erb’s point using MEB-2300 (Nihon Kohden Corporation, Tokyo, Japan) for making sure to deliver supramaximal stimulation. After magnetoneurogram recording, evoked action currents were computationally reconstructed by a spatial filter method and the estimated electric currents map was superimposed over X-ray images. Results We were able to record the magnetic fields over the brachial plexus with good signal quality after ulnar nerve stimulation. Distribution of neural activity currents in the brachial plexus were estimated from the measured magnetic fields and visualized over X-ray images in all subjects. The currents distribution showed axonal activity pattern and passed medially to the coracoid process, crossed the clavicle, and reached the C7 - Th1 intervertebral foramen along the nerve path in the period between 8.0 ms and 13.0 ms after the stimulation. The conduction velocity calculated using the peak latency of the estimated current waveform on the nerve path was 67.13 ± 1.96 m/s. Conclusion By analysis of magnetoneurogram with participants’ X-ray image of the upper thorax,we succeeded in visualizing the nerve impulse traveling along (possibly) the medial cord of BP and then propagating into the C7 – Th1 intervertebral foramen after ulnar nerve stimulation at the wrist. Together with our previous study on magnetoneurogram after median nerve stimulation, we consider magnetoneurogram testing as superior to conventional SEP for analyzing the conductive function of BP because the former enables us to evaluate the conductive function of the nerve from the lateral or medial cord of BP to C5 – Th1 intervertebral foramen after median or ulnar nerve stimulation. We propose that the method of magnetoneurograph with the X-ray image can provide useful information for the non-invasive diagnosis of localization of conduction block in BP neuropathy.

S108. Effect of propofol on somatosensorial evoked potentials of long latency, N70

Introduction The aim of the study was to describe the morphological changes of long-latency somatosensory evoked potentials (SEPs) N70 after administration of intravenous propofol in neurologically healthy patients. This allows us to know if the use of this drug is capable of changing its morphology. The knowledge of this fact, will avoid a misinterpretation when using it as a prognostic marker in sedated patients with propofol with postanoxic neurological damage and traumatic brain injury. Methods Observational, descriptive, follow-up study of SEPs of long latency N70 before and after the administration of propofol in neurologically healthy patients in Hospital Espanol from May to October 2017. We used a Cadwell electromyograph equipment, Sierra Wave software version 11.0.116, with registration on C3′ and C4′, reference Fz (SI 10/20), filters 1 Hz and 10 Hz, gain 10 mV, sweep 20 ms, pulse width 100 ms and repetition rate of 1.41 Hz, stimulation on both median nerves. For sedation, we calculated the target plasma concentration of 4 mcg/ml and objectified by the bisespectral index or spectral entropy, anyone available in operating room. We included subjects aged 18–70, indistinct gender, admitted to a surgical procedure that does not involve the central or peripheral nervous system between May and October 2017 with previous complete neurological examination and general laboratories without alterations. We excluded everyone who refused to sign the informed consent.The data was analyzed in the statistical package STATA version 14.1 with Student “t” test was used for related samples. Results We performed SEPs N70 in 11 subjects. The results of this study showed a statistically significant difference in amplitude (p Conclusion Propofol is an agonist of GABA A receptors and blocker of the NMDA receptors reducing glutamatergic activity, that affect the signals of the ascending activating reticular system and the cortico-subcortical association relays, causing statistically significant morphological changes in the replicability of the SEPs of long latency N70 of healthy subjects, mainly in their amplitudes. If we do not considered measurable the replicability of the amplitude, ideally it should be marked as absence of potential.

Objective assessment of cortical activity changes in stroke patients before and after hand rehabilitation with and without botulinum toxin injection

BackgroundUpper limb spasticity is a disabling condition and may result in severe functional limitation. The peripheral action of botulinum toxin (BTX) injection on spasticity is well known, but there are debates around its possible central action.AimThe aim of this study was to assess the clinical, functional, and cortical activation outcome of two antispastic treatments for stroke of the hand and wrist. Thirty patients with upper limb poststroke spasticity were recruited in this study.Patients and methodsThey were randomly allocated to two groups: group A and group B. Both groups received rehabilitation program, whereas group B received additional BTX injection. All patients were assessed at baseline and 8 weeks after treatment using the Modified Ashworth Scale, the Action Research Arm Test and Nine-Hole Peg Test, and somatosensory-evoked potential study of the median nerve.ResultsGroup B showed a higher percentage of change in Modified Ashworth Scale of the wrist flexors and long flexors of fingers and in Action Research Arm Test compared with group A.ConclusionBTX injection in spastic muscles of the wrist and hand, followed by a rehabilitation program led to greater clinical and functional improvement compared with implementing the rehabilitation program alone.

SSEP in Therapeutic Hypothermia Era.

The reliability of somatosensory evoked potentials (SSEPs) in predicting outcome in comatose survivors of cardiac arrest treated with therapeutic hypothermia (TH) has been questioned. We investigated whether the absence of cortical (N20) responses was a reliable predictor of a nonawakening in the setting of TH. A retrospective review was conducted in cardiac arrest survivors treated with TH admitted to a single tertiary care hospital from April, 2010 to March, 2013 who underwent SSEP testing at various time points after cardiac arrest. N20 responses were categorized as normal, present but abnormal, bilaterally absent, or inadequate for interpretation. Neurologic outcome was assessed at discharge by the Cerebral Performance Category Scale (CPC). Ninety-three SSEP studies were performed in 73 patients. Fourteen patients had absent N20 responses; all had poor outcome (CPC 4-5). Eleven patients had absent N20 s during hypothermia, three of whom had follow-up SSEPs after rewarming and cortical responses remained absent. Fifty-seven patients had N20 peaks identified and had variable outcomes. Evaluation of 1 or more N20 peaks was limited or inadequate in 11.4% of SSEPs performed during the cooling because of artifact. Somatosensory evoked potentials remain a reliable prognostic indicator in patients undergoing TH. The limited sample size of patients who had SSEP performed during TH and repeated after normothermia added to the effect of self-fulfilling prophecy limit the interpretation of the reliability of this testing when performed during cooling. Further prospective, multicenter, large scale studies correlating cortical responses in SSEPs during and after TH are warranted. Technical challenges are commonplace during TH and caution is advised in the interpretation of suboptimal recordings.

Somatosensory evoked potentials as a screening tool for diagnosis of spinal pathologies in children with treatment refractory overactive bladder.

To evaluate the usefulness of somatosensory evoked potential as a screening tool for spinal pathologies in patients with treatment refractory overactive bladder. This prospective study was performed between January 2011 and January 2014. Children >5years old with treatment refractory overactive bladder were enrolled after exclusion of anatomical and neurological causes of incontinence. All patients underwent urodynamic studies, spinal MRI, and somatosensory evoked potential (SEP). Sensitivity, specificity, PPV, and NPV were calculated for SEP. Thirty-one children (average age 8.3±2.9years) were included in the study. SEP was abnormal in 13 (41.9%), and MRI was abnormal in 8 (25.8%) patients. SEP was found to have a sensitivity of 87.5%, a specificity of 73.9%, positive predictive value of 53.85%, and negative predictive value (NPV) of 94.4%. In patients with treatment refractory OAB, SEP is an important tool for the screening of tethered cord/spinal pathologies. Our results suggest that a child with a normal SEP study in this group of patients may not require further investigation with MRI.

Еvaluation data somatosensory evoked potentials and electromyography in patients with multiple sclerosis in the aspect comorbidity

The paper shows the results of electrophysiological methods of investigation in patients with multiple sclerosis (MS) in the aspect of comorbidity. The studies of somatosensory evoked potentials (SSEP) in 216 patients with MS and electroneuromyography in 158 patients with MS, together with the assessment of neurological and psychological status. It is shown that according SSEP increase latency peripheral response in a progressive course of MS compared to remitting associated with older age of patients with progressive MS, and due to involvement in the pathological process of the peripheral nervous system (PNS) and the prevalence of pain syndrome (PS) in patients MS with comorbidity. It is demonstrated, on the basis of electroneuromyographic that MS patients with comorbidity tends to be deeper shock PNS. The data electroneuromyographic clinically appropriate initial stage of sensory or sensorimotor polyneuropathy, which proceeded in 84.8% of patients with MS subclinical and 15.2% had a clear clinical signs.

The cutoff value of ossification of posterior longitudinal ligament (OPLL) for early diagnosis of myelopathy using somatosensory evoked potential in cervical OPLL patients.

Retrospective study. The objective of this study was to find out whether ossification of posterior longitudinal ligament (OPLL) characteristics, including size, shape and subtype, can be used to diagnose myelopathy using somatosensory evoked potential (SEP) in cervical OPLL patients. Yonsei University College of Medicine, Seoul, Korea. We retrospectively reviewed the medical records of 153 cervical OPLL patients who underwent SEP study. OPLL anterior-posterior (AP) diameter, area and involved longitudinal vertebral level were measured. OPLL was classified into subtypes according to longitudinal continuity and shape. Correlation analysis and receiver operating curve were used. Tibial SEP latency was significantly correlated with OPLL AP diameter (P=0.001), diameter occupying ratio (P=0.019), area (P=0.007), area occupying ratio (P=0.008), involved longitudinal vertebral level (P=0.028) and space available for the spinal cord (P=0.019). The cutoff values that were diagnostic for SEP prolongation suggesting myelopathy were 4.91 mm for OPLL AP diameter, 6.02 mm for space available for the spinal cord, 44.5% for diameter occupying ratio, 63.4 mm2 for area, 36.1% for area occupying ratio and level 2 for the involved longitudinal vertebral level. Our results revealed that tibial SEP latency was significantly correlated with OPLL size and suggested cutoff values of OPLL diameter (4.91 mm, 44.5%) and area (63.4 mm2, 36.1%) for early diagnosis of myelopathy. These results can help to establish treatment plans.

A Novel Electrophysiological Method in the Diagnosis of Pudendal Neuropathy: Position-related Changes in Pudendal Sensory Evoked Potentials

To examine the diagnostic value of pudendal somatosensory evoked potentials (SEPs) in pudendal nerve entrapment (PNE) neuropathy by stimulating the 2 sides separately after provocation by a standard sitting position. Routine pudendal SEPs performed in the supine position with bilateral simultaneous stimulation may fail to show the abnormality because the complaints of PNE appear or worsen in the sitting position. Forty-nine patients with PNE and 16 controls were included. SEP recordings were performed by stimulating the dorsal nerve of penis or clitoris on either side. The recordings were performed at the initial supine position, at the beginning and end of the provocation by sitting position, and at the second supine position. Amplitude loss in the SEP responses after prolonged sitting was significantly more pronounced on the symptomatic sides of the patients. Approximately 45% decrease in the SEP amplitude or an amplitude value less than 1.5 µV at the end of sitting are the parameters to be used with high selectivity. The dynamic pudendal SEP study described herein seems to be more helpful in PNE diagnosis than in conventional SEPs.

Median Nerve Somatosensory Evoked Potential in HTLV-I Associated Myelopathy.

IntroductionHTLV-I Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) is a progressive Myelopathy that mainly involves the corticospinal tract. Despite pronounced involvement of the lower limbs, patients also have abnormalities in their upper limbs. So, we studied somatosensory-evoked potentials (SSEPs) of the median nerve in HAM/TSP patients to determine the extent of the involvement of the pathway of the central nervous system, especially the cervical spinal cord.MethodsIn this cross sectional study, 48 patients with HAM/TSP who were referred to Qaem Hospital in Mashhad from October 2010 to October 2011 were evaluated for various indices, including SSEPs of the median nerve for N9, N11, N13, and N20 waveforms and also N11–13 and N13–20 Inter Peak Latency (IPL), severity of disease (based on Osama criteria), disease duration (less or more than 2 years), age, and gender. SPSS software was used for data analysis. The t-test was used for quantitative data, and the chi-squared test was used for the qualitative variables.ResultsThirty-four patients (70.2%) were females. The mean age was 45.6 ± 14.2 years. About SSEPs indices of the median nerve, N9 and N11 were normal in all patients, but N13 (50%), N20 (16.7%), IPL11–13 (58.3%), and IPL13–20 (22.9%) were abnormal. No significant relationships were found between age, gender, disease duration, and SSEPs indices (p > 0.05), but IPL11–13 and IPL13–20 had significant relationships with disease disability (p = 0.017 and p = 0.01, respectively).ConclusionDespite the lack of obvious complaints of upper limbs, SSEPs indices of the median nerve from the cervical spinal cord to the cortex were abnormal, which indicated extension of the lesion from the thoracic spinal cord up to the cervical spinal cord and thalamocortical pathways. Also, abnormalities in the cervical spinal cord had a direct correlation with the severity of disability in patients with HAM/TSP.

Evaluation of Electrophysiological Effects of Melatonin and Alpha Lipoic Acid in Rats with Streptozotocine Induced Diabetic Neuropathy

Neuropathy is a common complication of diabetes mellitus and is closely related to quality of life. There are many studies in which biological ingredients, such as alpha lipoic acid (ALA), that may inhibit or reduce the generation of diabetic neuropathy were investigated. Another biological agent that may reduce the generation of diabetic neuropathy is melatonin and there are a few studies that investigate the effects of melatonin on diabetic neuropathy. In this study we aimed to examine the effect of melatonin on experimentally induced diabetic neuropathy by comparing it with both ALA and control groups. We included 24 male Wistar rats. Tibial motor nerve conduction and cortical tibial nerve somatosensory evoked potentials (SEP) studies were performed before and after diabetes mellitus (DM) for all rats. Rats were divided into 3 (ALA, melatonin and control) groups. After 2 weeks of treatment period, tibial motor nerve conduction and cortical tibial SEP studies were repeated. Our data showed that ALA significantly increased nerve conduction velocity and amplitude in rats with diabetic neuropathy (p=0,001; p=0,002). Also, melatonin significantly increased nerve conduction velocity and amplitude in rats with diabetic neuropathy (p=0.002; p=0.002). There was no significant difference between the electrophysiological effects of ALA and melatonin. Besides, neither ALA nor melatonin did significantly affect P1 and N1 latency values on cortical tibial nerve SEP studies. Our study is the study in which both tibial nerve conduction and cortical tibial SEP studies were performed to compare effects of ALA and melatonin on experimental diabetic neuropathy. Lack of significant difference on cortical tibial SEP study would be attributed to the involvement of other central nervous system pathways which do not include ALA or melatonin in the pathogenesis. RESULTS of ALA group are important by means of giving objective evidences for results of biochemical studies about the role of ALA in the pathogenesis of diabetic neuropathy. However, there is not enough information about the effect of melatonin in the pathogenesis of diabetic neuropathy. Consequently, results of our study may anticipate further biochemical and clinic studies which investigate the about the role of melatonin in diabetic neuropathy.

Are evoked potentials clinically useful in the study of patients with Chiari malformation Type 1?

OBJECTIVE In this study, the authors describe the brainstem auditory evoked potential (BAEP) and somatosensory evoked potential (SSEP) alterations found in a large cohort of patients with Chiari malformation Type 1 (CM-1), the relationship between the BAEPs/SSEPs and the clinical findings, the abnormalities in patients with associated syringomyelia, and the clinical and neuroradiological risk factors that are associated with abnormal evoked potentials (EPs). METHODS A prospectively collected database containing 545 patients with CM-1 was queried to search for patients satisfying the following criteria: 1) an age of at least 14 years, 2) neuroradiological criteria of CM-1, 3) no prior Chiari-related surgeries, and 4) preoperative EP studies conducted at the authors' institution. The 200 patients included in this cohort were classified into CM-0, CM-1, and CM-1.5 subtypes. Linear, planimetric, and angular measurements of the posterior fossa were conducted, as well as syringomyelia measurements. Two separate multiple logistic regression models were used, one to predict the covariates associated with abnormal BAEPs, and a second model to explore the variables associated with an abnormal SSEP. In these models, the BAEPs and SSEPs were dichotomized as being normal or abnormal. RESULTS Headaches were the main symptom in 70.5% of the patients, and Valsalva-induced headaches were most frequent in patients with CM-1 and CM-1.5 compared with patients with CM-0 (p = 0.031). BAEPs were abnormal in 38.5% of patients, and abnormal SSEPs were found in 43.5% of the entire cohort. Syringomyelia was most frequent in patients with CM-0 (64.3%) and CM-1 (51.1%) compared with those with CM-1.5 (34.7%; p = 0.03). Age (OR 1.03, 95% CI 1.00-1.06), the degree of tonsillar herniation (OR 1.08, 95% CI 1.01-1.16), and lower cranial nerve dysfunction (OR 3.99, 95% CI 1.29-14.01) had a statistically significant correlation with abnormal BAEPs. Only age (OR 1.07, 95% CI 1.04-1.10) and the degree of tonsillar herniation (OR 1.11, 95% CI 1.04-1.19) had a statistically significant correlation with abnormal SSEPs. CONCLUSIONS A high percentage of patients with CM-1 exhibited EP alterations regardless of their clinical or radiological findings. These findings suggest that EPs do not add any clinically relevant information nor are they helpful in establishing which symptomatic patients with CM should undergo surgical treatment. However, BAEP and SSEP studies clearly play an important role in incidentally detected patients with CM and may help to establish objective evidence of subclinical dysfunctions. In addition, neurophysiological studies may help to define subgroups of patients who require further testing and follow-up to personalize strategies for the management of incidental and oligosymptomatic patients.

ID 10 – A novel electrophysiological method in the diagnosis of pudendal neuropathy: Position related changes in pudendal sensory evoked potentials

Pudendal nerve entrapment (PNE) is a common cause of resistant and disabling perineal pain. Although it is diagnosed clinically, neurophysiological tests are used for the diagnosis. Since the complaints worsen in the sitting position, routine pudendal somatosensory evoked potentials (SEP) performed in the supine position with midline stimulation may fail to show the PNE. We hypothesized that diagnostic value of SEP can be increased by stimulating the right and left sides separately along with provocation by maintained sitting position (dynamic SEP). Forty-nine patients with PNE and 16 healthy controls were included. SEP recordings were performed by stimulating the dorsal nerve of penis/clitoris on either side. The recordings were performed at the first supine position, at the beginning and end of a standardized sitting posture and at the second supine position. Regarding the patients with recordable responses, we might suggest that approximately 45% decrease in SEP amplitude or an amplitude value less than 1.5 mV at the termination of the sitting position (and their reversal with switching to the supine position again) are the parameters to be used with high selectivity. The dynamic pudendal SEP study described herein seems to be more valuable in PNE diagnosis than conventional SEPs.