Somatosensory Evoked Potentials In Patients Research Articles

Median Nerve Somatosensory Evoked Potentials in Patients with Chiari Malformation

Median Nerve Somatosensory Evoked Potentials in Patients with Chiari Malformation

Technical Aspects of Motor and Language Mapping in Glioma Patients.

Gliomas are infiltrative primary brain tumors that often invade functional cortical and subcortical regions, and they mandate individualized brain mapping strategies to avoid postoperative neurological deficits. It is well known that maximal safe resection significantly improves survival, while postoperative deficits minimize the benefits associated with aggressive resections and diminish patients' quality of life. Although non-invasive imaging tools serve as useful adjuncts, intraoperative stimulation mapping (ISM) is the gold standard for identifying functional cortical and subcortical regions and minimizing morbidity during these challenging resections. Current mapping methods rely on the use of low-frequency and high-frequency stimulation, delivered with monopolar or bipolar probes either directly to the cortical surface or to the subcortical white matter structures. Stimulation effects can be monitored through patient responses during awake mapping procedures and/or with motor-evoked and somatosensory-evoked potentials in patients who are asleep. Depending on the patient's preoperative status and tumor location and size, neurosurgeons may choose to employ these mapping methods during awake or asleep craniotomies, both of which have their own benefits and challenges. Regardless of which method is used, the goal of intraoperative stimulation is to identify areas of non-functional tissue that can be safely removed to facilitate an approach trajectory to the equator, or center, of the tumor. Recent technological advances have improved ISM's utility in identifying subcortical structures and minimized the seizure risk associated with cortical stimulation. In this review, we summarize the salient technical aspects of which neurosurgeons should be aware in order to implement intraoperative stimulation mapping effectively and safely during glioma surgery.

Effects of Lidocaine on Motor-Evoked Potentials and Somatosensory-Evoked Potentials in Patients Undergoing Intraspinal Tumour Resection: Study Protocol for a Prospective Randomized Controlled Trial.

PurposeAt present, it is believed that intravenous (IV) infusion of lidocaine can inhibit hyperalgesia, relieve postoperative acute and chronic pain, and accelerate the rehabilitation of patients. However, studies of its effects on necessary electrophysiological monitoring during neurosurgery are few, and the results are controversial. This study assumes that the propofol-remifentanil based anaesthesia combined with lidocaine in patients undergoing intraspinal tumour resection will not have adverse effects on motor-evoked potentials (MEPs) or somatosensory-evoked potentials (SEPs).Study Design and MethodsThis is a prospective, randomized, placebo-controlled double-blind trial. A total of 96 patients undergoing intraspinal tumour resection will be randomly allocated to lidocaine and placebo group. The lidocaine group will receive IV lidocaine during anaesthesia, while the placebo group will receive the same dose of normal saline with the same infusion rate and infusion time, and the anaesthesia procedures of the two groups will be the same. All patients will be monitored the MEPs and SEPs of all four limbs during operation. The primary outcome will be the MEP amplitudes of both upper limbs at the end of operation. The secondary outcome measures will be the other electrophysiological parameters at the end of operation, the incidence of alert events for all four limbs, and the incidence of false positive events.DiscussionThe purpose of this study is to evaluate the effects of IV infusion of lidocaine on SEPs and MEPs during intraspinal tumour resection to determine whether electrophysiological monitoring can accurately reflect the integrity of nerve functions while infusing lidocaine and to explore the possibility of lidocaine use during intraspinal tumour resection as an anaesthesia option.

Habituation of Somatosensory Evoked Potentials in Patients with Alzheimer's Disease and Those with Vascular Dementia.

Background and Objectives: The most prevalent dementia are Alzheimer’s disease and vascular dementia. There is evidence that cortical synaptic function may differ in these two conditions. Habituation of cortical responses to repeated stimuli is a well-preserved phenomenon in a normal brain cortex, related to an underlying mechanism of synaptic efficacy regulation. Lack of habituation represents a marker of synaptic dysfunction. The purpose of this study was to assess the habituation of somatosensory evoked potentials (SEPs) in 29 patients affected by mild-to-moderate Alzheimer’s disease (AD-type) or vascular (VD-type) dementia. Materials and Methods: All patients underwent a clinical history interview, neuropsychological evaluation, and neuroimaging examination. SEPs were elicited by electrical stimulation of the right median nerve at the wrist. Six-hundred stimuli were delivered, and cortical responses divided in three blocks of 200. Habituation was calculated by measuring changes of N20 amplitude from block 1 to block 3. SEP variables recorded in patients were compared with those recorded in 15 age- and gender-matched healthy volunteers. Results: SEP recordings showed similar N20 amplitudes in AD-type and VD-type patients in block 1, that were higher than those recorded in controls. N20 amplitude decreased from block 1 to block 3 (habituation) in normal subjects and in VD-type patients, whereas in AD-type patients it remained unchanged (lack of habituation). Conclusions: The findings suggest that neurophysiologic mechanisms of synaptic efficacy that underneath habituation are impaired in patients with AD-type dementia but not in patients with VD-type dementia. SEPs habituation may contribute to early distinction of Alzheimer’s disease vs. vascular dementia.

P-EV003. Origin of giant somatosensory evoked potentials (SEPS) in benign adult familial myoclonus epilepsy (BAFME) using principle component analysis

Introduction. Both benign adult familial myoclonus epilepsy (BAFME) and Unverricht- Lundborg disease (ULD) belong to progressive myoclonus epilepsy with giant somatosensory evoked potentials (SEPs), but their clinical courses are different from each other. We aimed to delineate the generator source of giant SEP P25 and their high frequency oscillations (HFOs) in patients with BAFME and ULD using principal component analysis (PCA). Methods. PCA was performed on giant SEPs and their HFOs obtained by multi-channel scalp recordings of five patients with BAFME and four patients with ULD. To identify HFOs, SEPs were digitally filtered using a 400–1000 Hz band-pass filter. From the peak latencies of the first or second principal component (PC), we identified the corresponding peaks of original P25 and HFOs near P25 (P25-HFOs). Then, from the polarity and distribution of first and second PCs, the P25 and P25-HFOs were estimated as tangential dipole with phase reversal between frontal and parieto-occipital electrodes or as radial dipole without phase reversal. Results. All five patients with BAFME had P25-HFOs, and both P25 and P25-HFOs were estimated as radial dipole, whereas in all four patients with ULD, P25-HFOs was not present and the estimated components of P25 varied among patients. Conclusion. The generator sources of both P25 and P25-HFOs in giant SEPs in patients with BAFME are radial dipole, which suggests crown origin, and P25-HFOs did not occur in patients with ULD. The generator mechanism of giant SEP P25 and P25-HFOs of BAFME may be different from that of ULD.

Impaired pain processing and its association with attention disturbance in patients with amyotrophic lateral sclerosis.

Cognitive dysfunction characterized by executive dysfunction and persistent attention function has been reported in patients with amyotrophic lateral sclerosis (ALS); however, it is unclear if this contributes to the pain processing deficits associated with the disease. We clarified the relationship between pain processing and both cognitive function and sensory symptoms in patients with ALS. We enrolled 23 patients with ALS and 14 healthy control subjects. We examined pain-related somatosensory evoked potentials (SEPs) using an intra-epidermal needle electrode. We evaluated cognitive function and the clinical characteristics of sensation and analyzed their relationships with pain-related SEPs. Pain-related SEP amplitudes were significantly lower, while the rate of amplitude attenuation due to habituation or change in attention was significantly greater in patients with ALS than in control subjects. There were no significant differences in pain-related SEP parameters between patients with or without sensory symptoms. Instead, pain-related SEP amplitude and its rate of attenuation were correlated with cognitive dysfunction, particularly with attention domains. Our results suggest that attention deficit, but not sensory nerve involvement, is a major cause of the alterations in pain-related SEP in patients with ALS.

Surround inhibition in patients with juvenile myoclonic epilepsy

ABSTRACT Objective In healthy subjects, there is a reduction in the amplitudes of somatosensory-evoked potentials (SEPs) after the simultaneous stimulation of two nerves compared to the sum of separate stimulations. This reduction is due to the inhibition of one area in the cortex after stimulation of the neighboring area, which results from the surround inhibition (SI) phenomenon. In this study, we aimed to investigate whether there was a decrease in SI of SEP in patients with juvenile myoclonic epilepsy (JME). Methods We included 17 patients with JME and 18 healthy subjects. Groups were similar in terms of age and gender. We recorded SEPs after stimulating (i) median nerve (mSEP), (ii) ulnar nerve (uSEP), (iii) median and ulnar nerves simultaneously (muSEP) at wrist. The arithmetic sum (aSEP) of amplitudes of mSEP and uSEP was compared with the amplitudes of muSEP. We also calculated SI%. Results The amplitudes of SEPs were significantly higher in the JME group than in the healthy subjects (mSEP, p = 0.005; uSEP, p = 0.032; muSEP, p = 0.014). In healthy subjects and the JME group, the amplitude of muSEP was significantly lower than the aSEP (p = 0.014; p = 0.001, respectively). However, SI% was significantly higher in the JME group (p = 0.010). Significance Although the SI is maintained in JME patients, the higher SI% indicates an impairment relative to healthy subjects.

Acute Effects of Aerobic Exercise on Somatosensory-Evoked Potentials in Patients with Mild Cognitive Impairment

Mild cognitive impairment (MCI) is becoming a serious problem for developing countries as the lifespan of populations increases. Exercise is known to be clinically beneficial for MCI patients. Somatosensory-evoked potentials (SEPs) may be a potential diagnostic and prognostic marker for this population. The objective of this study was to determine the acute effects of aerobic exercise on SEPs in patients with MCI, to test whether SEPs are sensitive enough to detect improvements in early somatosensory processing. The study had a randomized parallel-group design and included 28 MCI subjects (14 in the experimental group and 14 in the control group). The experimental intervention was 20 min of aerobic exercise using a stationary bicycle. The control intervention involved 20 min of movements and stretches. Subjects were assessed before and after a single intervention session. SEPs were recorded by stimulating the median nerve of the dominant hand. Analysis of normalized SEP peak amplitudes showed that a single session of aerobic activity significantly reduced the N30 peak at the F3 channel (p = 0.03). There were no significant effects of aerobic exercise on SEP peak latencies. The results indicate that 20 min of aerobic exercise has a significant effect on the N30 SEP peak amplitude in MCI patients. The results suggest that aerobic exercise is likely to provide sensory-enriching inputs that enhance sensorimotor integration. Future studies should assess the effects of aerobic exercise on somatosensory processing in progressive stages of Alzheimer’s disease, longer exercise durations, and multiple exercise sessions.

The Effect of Xenon-Based Anesthesia on Somatosensory-Evoked Potentials in Patients Undergoing Carotid Endarterectomy

The aim of this study was to investigate the influence of xenon-based anesthesia on somatosensory-evoked potentials. Observational cohort study. University hospital. Twenty subsequent adult patients undergoing elective carotid endarterectomy. Xenon-based anesthesia. Cortical-evoked responses to median nerve stimulation were quantified by measurement of the amplitude and latency of the N20 wave, which are typically assessed during carotid surgery to detect intraoperative cerebral hypoperfusion and ischemia. Primary (N20 amplitude and latency) and secondary (mean arterial pressure, norepinephrine requirements and depth of anesthesia) were assessed during (1) propofol/remifentanil and (2) subsequent xenon/remifentanil anesthesia. Xenon at an inspiratory fraction of 62.5 ± 7% decreased norepinephrine requirement (0.067 ± 0.04 v 0.028 ± 0.02 µg/kg/min, p < 0.001), and mean arterial pressure was unchanged (90.6 ± 15.0 v 93.1 ± 9.6 mmHg, p = 0.40). Somatosensory-evoked potentials were available in all patients during xenon/remifentanil. Despite similar depth of anesthesia (Narcotrend index 38.4 ± 6.2 v 38.5 ± 5.8) during propofol and xenon, N20 amplitude was reduced after xenon wash-in from 3.7 ± 1.7 to 1.4 ± 2.8 µV, p < 0.001 on the surgical and 3.6 ± 1.6 to 1.4 ± 0.6 µV, p < 0.001 on the contralateral side. N20 latency remained unchanged during xenon (22.9 ± 2.1 v 22.5 ± 2.8 ms, p = 0.34 and 22.9 ± 2.0 v 22.9 ± 3.0, p = 0.97). Xenon influences somatosensory-evoked potentials measurement by reducing N20 wave amplitude but not latency. When xenon is considered as an anesthetic for carotid endarterectomy, wash-in needs to be completed before carotid surgery is commenced to provide stable baseline somatosensory-evoked potential measurement.

Early Somatosensory Processing Over Time in Individuals at Risk to Develop Psychosis.

Objective: Somatosensory evoked potentials (SEPs) enable the investigation of thalamocortical and early cortical processing. Previous studies reported alterations of SEPs in patients with schizophrenia as well as in individuals in the prodromal stage. Moreover, cannabis use as an environmental risk factor for the development of schizophrenia has been demonstrated to influence SEP parameters in individuals at risk to develop psychosis. The aim of this study was to explore the course of SEP changes and the impact of concomitant cannabis use in individuals at risk to develop psychosis who sought medical help.Methods: Median nerve SEPs including high-frequency oscillations (HFOs) superimposed on the primary cortical response (N20) were investigated using multichannel EEG in individuals (n = 54 at baseline) remaining at risk to develop psychosis at follow-up after 1 year (high-risk: n = 19; ultra-high-risk: n = 27) vs. subjects with conversion to psychosis (n = 8) and a healthy control group (n = 35). Longitudinal and cross-sectional analyses of SEP components as estimated by dipole source analysis were performed.Results: The longitudinal development of the N20 strength depended on cannabis use. In cannabis non-users, a greater decrease of N20 strengths over time was associated with more negative symptoms at baseline. At baseline, converters did not differ from subjects remaining at risk. At follow-up, converters showed increased low- and high-frequency activity than at-risk subjects and did not differ from controls.Conclusion: The results of this study lead to the suggestion that the deficits in early somatosensory processing in individuals at risk to develop psychosis may not represent a marker for a genetic risk for psychosis but rather reflect state-dependent factors such as negative symptoms. On the other hand, the transition to psychosis seems to represent an interstage between reduced sensory registration from the at-risk state and gating deficits in the chronic state.

Parameters of Somatosensory Evoked Potentials in Patients with Primary Sjӧgren's Syndrome: Preliminary Results.

Primary Sjogren's syndrome (pSS) is a chronic autoimmune disease. The aim of the study was to establish whether in patients with pSS without central nervous system (CNS) involvement, the function of the central portion of the sensory pathway can be challenged. In 33 patients with pSS without clinical features of CNS damage and normal head computed tomography scan, somatosensory evoked potentials (SEP) were studied. The results were compared to other clinical parameters of the disease, particularly to immunological status. The control group consisted of 20 healthy volunteers. Mean latency of all components of SEP was considerably prolonged in patients compared to the control group. Mean interpeak latency N20-N13 (duration of central conduction TT) did not differ significantly between the groups. However, in the study group, mean amplitude of N20P22 and N13P16 was significantly higher compared to healthy individuals. In patients with pSS, significant differences in SEP parameters depending on the duration of the disease and presence of SSA and SSB antibodies were noted. The authors confirmed CNS involvement often observed in patients with pSS. They also showed dysfunction of the central sensory neuron as a difference in the amplitude of cortical response, which indicates subclinical damage to the CNS.

Effects of Dexmedetomidine on motor- and somatosensory-evoked potentials in patients with thoracic spinal cord tumor: a randomized controlled trial.

BackgroundWe hypothesized that the addition of dexmedetomidine in a clinically relevant dose to propofol-remifentanil anesthesia regimen does not exert an adverse effect on motor-evoked potentials (MEP) and somatosensory-evoked potentials (SSEP) in adult patients undergoing thoracic spinal cord tumor resection.MethodsSeventy-one adult patients were randomized into three groups. Propofol group (n = 25): propofol-remifentanil regimenand the dosage was adjusted to maintain the bispectral index (BIS) between 40 and 50. DP adjusted group (n = 23): Dexmedetomidine (0.5 μg/kg loading dose infused over 10 min followed by a constant infusion of 0.5 μg/kg/h) was added to the propofol-remifentanil regimen and propofol was adjusted to maintain BIS between 40 and 50. DP unadjusted group (n = 23): Dexmedetomidine (administer as DP adjusted group) was added to the propofol-remifentanil regimen and propofol was not adjusted. All patients received MEP, SSEP and BIS monitoring.ResultsThere were no significant changes in the amplitude and latency of MEP and SSEP among different groups (P > 0.05). The estimated propofol plasma concentration in DP adjusted group (2.7 ± 0.3 μg/ml) was significantly lower than in propofol group (3.1 ± 0.2 μg/ml) and DP unadjusted group (3.1 ± 0.2 μg/ml) (P = 0.000). BIS in DP unadjusted group (35 ± 5) was significantly lower than in propofol group (44 ± 3) (P = 0.000).ConclusionsThe addition of dexmedetomidine to propofol-remifentanil regimen does not exert an adverse effect on MEP and SSEP monitoring in adult patients undergoing thoracic spinal cord tumor resection.Trial registrationThe study was registered with the Chinese Clinical Trial Registry on January 31st, 2014. The reference number was ChiCTR-TRC-14004229.

Early somatosensory processing in individuals at risk for developing psychoses

Human cortical somatosensory evoked potentials (SEPs) allow an accurate investigation of thalamocortical and early cortical processing. SEPs reveal a burst of superimposed early (N20) high-frequency oscillations around 600 Hz. Previous studies reported alterations of SEPs in patients with schizophrenia. This study addresses the question whether those alterations are also observable in populations at risk for developing schizophrenia or bipolar disorders. To our knowledge to date, this is the first study investigating SEPs in a population at risk for developing psychoses. Median nerve SEPs were investigated using multichannel EEG in individuals at risk for developing bipolar disorders (n = 25), individuals with high-risk status (n = 59) and ultra-high-risk status for schizophrenia (n = 73) and a gender and age-matched control group (n = 45). Strengths and latencies of low- and high-frequency components as estimated by dipole source analysis were compared between groups. Low- and high-frequency source activity was reduced in both groups at risk for schizophrenia, in comparison to the group at risk for bipolar disorders. HFO amplitudes were also significant reduced in subjects with high-risk status for schizophrenia compared to healthy controls. These differences were accentuated among cannabis non-users. Reduced N20 source strengths were related to higher positive symptom load. These results suggest that the risk for schizophrenia, in contrast to bipolar disorders, may involve an impairment of early cerebral somatosensory processing. Neurophysiologic alterations in schizophrenia precede the onset of initial psychotic episode and may serve as indicator of vulnerability for developing schizophrenia.

Somatosensory evoked potentials in chronic inflammatory demyelinating polyradiculoneuropathy.

Somatosensory evoked potentials (SEPs) offer complementary results to those of nerve conduction studies and contribute to the electrodiagnostic criteria of chronic inflammatory demyelinating polyradiculoneuropathy. We performed nerve conduction studies and SEPs in patients with symmetrical motor weakness, areflexia, and/or sensory disturbances lasting for at least 8 weeks. We determined two groups according to the electrodiagnostic criteria of the European Federation of Neurological Societies. Group 1 included patients who met the definite or probable electrodiagnostic criteria, and group 2 included patients who met the possible electrodiagnostic criteria. We also compared SEPs results with those of controls (group of healthy subjects). Sixteen patients (14 men; mean age, 59 ± 17.3 years) were included in the study. The latencies of potentials N9, N13, N7, and N22 and the intervals N9-N13 and N7-N22 were significantly increased in patients compared with controls. The N9/iP14 amplitude ratio was significantly lower in patients. There was no significant difference in the latencies of SEPs between the two groups of patients. We confirm the contribution of SEPs as complementary information to nerve conduction studies in chronic inflammatory demyelinating polyradiculoneuropathy diagnosis. In addition to the usual abnormalities, a decrease in the N9/iP14 amplitude ratio could potentially be used as an electrodiagnostic criterion.

Comparison of somatosensory evoked potentials between adolescent idiopathic scoliosis and congenital scoliosis without neural axis abnormalities

Background contextAbnormal somatosensory evoked potentials (SEPs) have been documented in patients with adolescent idiopathic scoliosis (AIS) with different cure severity. However, few studies investigated whether abnormal SEPs were the cause or effect of idiopathic scoliosis. PurposeThe purpose of this study was to investigate the significance of abnormal SEPs in patients with AIS, and to explore its effect on the etiopathogenesis of AIS. Study design/SettingThis study evaluated SEPs in patients with AIS and congenital scoliosis (CS) with similar curve pattern and severity both in coronal and sagittal planes. Patient sampleFemale patients with AIS and CS in our spine surgery center from 2000 to 2009 were recruited for this study. Outcome measuresRate of abnormal SEPs. MethodsPosterior tibial nerve SEPs (PTN-SEPs) were performed on female patients with AIS and CS. The inclusion criteria were patients with AIS with a Lenke type 1 curve and patients with CS with right thoracic curve (apex between T5 and T12) and normal sagittal profile (kyphosis less than 50° measured from T2 to T12). All patients were evaluated with total spine magnetic resonance imaging, and those with neural axis abnormalities were excluded. The patients with neurological deficits on detailed physical examination were also excluded. Absence of SEPs waveforms or prolongation of peak latency or asymmetrical peak latency were defined as pathological change. The incidence of pathological SEPs and clinical characteristics were compared between patients with AIS and patients with CS. ResultsForty-six patients with AIS and 33 patients with CS were included in this study. There was no significant difference in coronal and sagittal Cobb angle between the two groups. The rate of abnormal SEPs was 32.6% (15/46) and 12.1% (4/33) in AIS and CS groups, respectively, and the difference was statistically significant (p<.05). ConclusionSomatosensory pathway dysfunction could be found in both AIS and CS without neural axis abnormalities, and the patients with AIS tended to have higher rates of somatosensory disorders than patients with CS with similar scoliosis curve, which indicates that both scoliosis curve and primary etiopathogenic factor contribute to the sensory deficit in patients with AIS.

Predictive value of neurological examination for early cortical responses to somatosensory evoked potentials in patients with postanoxic coma

Bilateral absence of cortical N20 responses of median nerve somatosensory evoked potentials (SEP) predicts poor neurological outcome in postanoxic coma after cardiopulmonary resuscitation (CPR). Although SEP is easy to perform and available in most hospitals, it is worthwhile to know how neurological signs are associated with SEP results. The aim of this study was to investigate whether specific clinical neurological signs are associated with either an absent or a present median nerve SEP in patients after CPR. Data from the previously published multicenter prospective cohort study PROPAC (prognosis in postanoxic coma, 2000–2003) were used. Neurological examination, consisting of Glasgow Coma Score (GCS) and brain stem reflexes, and SEP were performed 24, 48, and 72 h after CPR. Positive predictive values for predicting absent and present SEP, as well as diagnostic accuracy were calculated. Data of 407 patients were included. Of the 781 SEPs performed, N20 s were present in 401, bilaterally absent in 299, and 81 SEPs were technically undeterminable. The highest positive predictive values (0.63–0.91) for an absent SEP were found for absent pupillary light responses. The highest positive predictive values (0.71–0.83) for a present SEP were found for motor scores of withdrawal to painful stimuli or better. Multivariate analyses showed a fair diagnostic accuracy (0.78) for neurological examination in predicting an absent or present SEP at 48 or 72 h after CPR. This study shows that neurological examination cannot reliably predict absent or present cortical N20 responses in median nerve SEPs in patients after CPR.

Recordings of long-latency trigeminal somatosensory-evoked potentials in patients under general anaesthesia

Objective The reliability of intra-operative recordings of trigeminal scalp-induced somatosensory-evoked potentials (T-SSEP) is controversial. This investigation aimed to provide evidence that T-SSEP recordings are stable using standardised neurophysiological methodology and anaesthesiological regime. Methods We investigated 99 patients undergoing carotid endarterectomy under total intravenous anaesthesia (propofol/remifentanil infusion). Long-latency T-SSEPs were recorded from the scalp after simultaneously stimulating 2nd and 3rd branches of the trigeminal nerve. The analysis included visual assessments of traces and measurements of latencies and amplitudes of the N13 and P19 peaks of T-SSEP. Furthermore, additional groups of patients were investigated to identify changes in the parameters of T-SSEP that might correspond to different states of anaesthesia and artificial muscle activity. Results We reproducibly recorded T-SSEP responses in 99 patients with a mean latency of 12.4 ms (SD = 0.93) and amplitude of 5.7 μV (SD = 4.7). Collateral investigations concerning changes of T-SSEP caused by neuromuscular blockade improved independence of T-SSEP recordings to muscle relaxation in contrast to facial and cervical muscle activity. Conclusions We demonstrated the reliability of recording stable intra-operative T-SSEP responses with standardised electrophysiological and anaesthesiological regimes. Significance We provided evidence of the non-muscular origin of T-SSEPs recorded from the scalp.

The Role of Research Somatosensory Evoked Potentials in Patients with Premature Ejaculation

The Role of Research Somatosensory Evoked Potentials in Patients with Premature Ejaculation

The value of somatosensory evoked potential in the clinical evaluation of congenital scoliosis with and without intraspinal malformations

To investigate the value of somatosensory evoked potential (SEP) in the diagnosis of congenital scoliosis (CS) with intraspinal malformation. From September 2001 to September 2007 posterior tibial nerve SEP were performed on 187 operatively treated CS patients. There were 85 male and 102 female, and the average age was 13.8 years (range from 30 to 22 years). Patients with intraspinal malformations were diagnosed by MRI. Absence of SEP waveforms, prolongation of peek latency or asymmetrical peek latency were defined as pathological change. The incidence of pathological SEP and clinical characteristics were compared between patients with and without intraspinal malformations. Of 187 patients, intraspinal malformations were diagnosed in 32 patients (17.1%). The incidence of intraspinal malformations was higher in type III (30.8%) than in type I and II CS patients (P < 0.05). The mean Cobb angle of scoliosis in patients with intraspinal malformations was greater than without intraspinal malformations, but there was no difference in kyphosis between the two groups. The ratio of abnormal SEP in patients with intraspinal malformations was 75.0% (24/32), while it was 38.7% (60/155) in patients without intraspinal malformations, and it showed significant difference between the two groups (χ(2) = 4.70, P < 0.05). SEP is a reliable tool for assessment of spinal cord function in patients with congenital scoliosis. It could be helpful for the diagnosis of intraspinal malformations, and also might provide an important reference for assessment and treatment of intraspinal malformations in congenital scoliosis.

Connectivity Analysis of Somatosensory Evoked Potentials in Patients with Major Depression

Connectivity analysis was used to investigate the processing of intracutaneous stimuli and directed interactions within the pain matrix in patients with major depression (MD) and healthy controls (HCs), by means of frequency selective generalized partial directed coherence (gPDC). Eighteen patients with MD and 18 HCs underwent stimulations consisting of moderately painful intracutaneous electrical stimuli to the right and left middle fingers. Connectivity analysis was based on nine selected EEG electrodes. Stimulus-induced changes of the gPDC in a pre/post stimulus comparison and changes in the connectivity pattern in the post-stimulus condition were found. We could identify network changes correlating to the side stimulated, as well as differences between HCs and MD patients. These data support the suggestion that pain processing in response to noxious stimulation in MD patients is different compared to healthy controls, suggesting aberrant functional connectivity. Generalized partial directed coherence is shown to be a promising method to detect changes in connectivity in both within- and between-subject designs.