Dermatomal Somatosensory Evoked Potentials Research Articles

Impact of the Order of Movement on the Median Nerve Root Function: A Neurophysiological Study with Implications for Neurodynamic Exercise Sequencing

Background: Neurodynamic exercise is a common clinical practice used to restore neural dynamic balance. The order in which movements are performed during these exercises is believed to play a crucial role in their effectiveness. This study aimed to investigate the impact of different sequences of neurodynamic exercise on nerve root function, with a specific focus on the median nerve. Methods: Participants were assigned randomly to three experimental groups, each undergoing a different test sequence: standard, proximal-to-distal, and distal-to-proximal. Dermatomal somatosensory evoked potentials (DSSEPs) were recorded at key levels (C6, C7, C8, and T1). Results: The findings revealed a significant influence of the movement sequence on DSSEP amplitudes. The execution of neurodynamic exercise in the proximal-to-distal sequence was associated with a notable reduction in amplitudes (p < 0.05). Conversely, the distal-to-proximal sequence resulted in increased amplitudes compared to the standard sequence (p < 0.05). Conclusions: This study underscores the importance of carefully considering the order of movements during neurodynamic exercising, particularly when evaluating nerve roots that lack the protective perineurium. The choice of sequence appears to have a substantial impact on nerve function, with implications for optimizing clinical neurodynamic exercise techniques.

Alterations in Cervical Nerve Root Function during Different Sitting Positions in Adults with and without Forward Head Posture: A Cross-Sectional Study.

The current study aimed to determine whether participants with and without forward head posture (FHP) would respond differently in cervical nerve root function to various sitting positions. We measured peak-to-peak dermatomal somatosensory-evoked potentials (DSSEPs) in 30 participants with FHP and in 30 participants matched for age, sex, and body mass index (BMI) with normal head posture (NHP), defined as having a craniovertebral angle (CVA) >55°. Additional inclusion criteria for recruitment were individuals between the ages of 18 and 28 who were in good health and had no musculoskeletal pain. All 60 participants underwent C6, C7, and C8 DSSEPs evaluation. The measurements were taken in three positions: erect sitting, slouched sitting, and supine. We identified statistically significant differences in the cervical nerve root function in all postures between the NHP and FHP groups (p < 0.001), indicating that the FHP and NHP reacted differently in different positions. No significant differences between groups for the DSSEPs were identified for the supine position (p > 0.05), in contrast to the erect and slouched sitting positions, which showed a significant difference in nerve root function between the NHP and FHP (p < 0.001). The NHP group results were consistent with the prior literature and had the greatest DSSEP peaks when in the upright position. However, the participants in the FHP group demonstrated the largest peak-to-peak amplitude of DSSEPs while in the slouched position as opposed to an erect position. The optimal sitting posture for cervical nerve root function may be dependent upon the underlying CVA of a person, however, further research is needed to corroborate these findings.

The Efficacy of Cervical Lordosis Rehabilitation for Nerve Root Function and Pain in Cervical Spondylotic Radiculopathy: A Randomized Trial with 2-Year Follow-Up.

Sagittal cervical alignment is a clinically related feature in patients suffering from chronic cervical spondylotic radiculopathy (CSR). We designed this randomized trial to explore the effects of cervical lordosis (CL) correction in thirty chronic lower CSR patients with CL &lt; 20°. Patients were assigned randomly into two equal groups, study (SG) and control (CG). Both groups received neck stretching and exercises and infrared radiation; additionally, the SG received cervical extension traction. Treatments were applied 3× per week for 10 weeks after which groups were followed for 3 months and 2 years. The amplitude of dermatomal somatosensory evoked potentials (DSSEPS), CL C2-C7, and pain scales (NRS) were measured. The SG had an increase in CL post-treatment (p &lt; 0.0001), this was maintained at 3 months and 2 years. No statistical improvement in CL was found for the CG. A significant reduction in NRS for SG after 10 weeks of treatment with non-significant loss of change at 3 months and continued improvement at 2 years was found. CG had less significant improvement in post-treatment NRS; the 3-month and 2-year measures revealed significant worsening in NRS. An inverse linear correlation between increased CL and NRS was found (r = -0.49; p = 0.005) for both groups initially and maintained in SG at the final 2-year follow-up (r = -0.6; p = 0.01). At 10 weeks, we found significant improvements in DSSEPS for both groups (p &lt; 0.0001). We identified a linear correlation between initial DSSEPs and CL for both groups (p &lt; 0.0001), maintained only in the SG at the final follow-up for all levels (p &lt; 0.0001). Improved CL in the SG correlated with significant improvements in nerve root function and pain rating in patients with CSR at short and long-term follow-up. These observed effects indicate that clinicians involved in the treatment of patients with symptoms of cervical degenerative disorders should add sagittal curve correction to their armamentarium of rehabilitation procedures for relevant patient populations.

Comparative effects of tensioning and sliding neural mobilization on peripheral and autonomic nervous system function: A randomized controlled trial.

Background:Although different types of neural mobilization (NM) exercises induce different amounts of longitudinal nerve excursion and strain, the question whether the increased longitudinal stress and nerve excursion from sliding or tensioning intervention may subtly affect the neural functions has not been answered yet.Objective:To compare the effects of tensioning NM versus sliding NM of the median nerve on peripheral and autonomic nervous system function.Methods:In this randomized controlled trial, 90 participants were randomly assigned to tensioning NM, sliding NM, or sham NM. The neurophysiological outcome measures included peak-to-peak amplitude of the dermatomal somatosensory evoked potential (DSSEP) for dermatomes C6, C7, C8, and T1. Secondary outcome measures included amplitude and latency of skin sympathetic response. All outcome measures were assessed pretreatment, immediately after the two weeks of treatment and one week after the last session of the treatment.Results:A 2-way repeated measures ANOVA revealed significant differences between the three groups. The post hoc analysis indicated that tensioning NM significantly decreased the dermatomal amplitude for C6, C7, C8, and T1 (). Sympathetic skin responses in the gliding NM group showed lower amplitudes and prolonged latencies post-treatment when compared to tensioning NM group (). In contrast, no significant changes were observed in the DSSEPs and skin sympathetic responses for participants in the sham treatment group ().Conclusions:A tensioning NM on the median nerve had a possible adverse effect on the neurophysiology variables of the nerves involved in the neural mobilization. Thus, tensioning NM with the current parameters that place increased stress and strain on the peripheral nervous system should be avoided.

Dermatomal somatosensory evoked potentials and cortical somatosensory evoked potentials assessment in congenital scoliosis

BackgroundThe aim of this study was to assess the value of dermatomal somatosensory evoked potentials (DSEPs) and cortical somatosensory evoked potentials (SSEPs) in monitoring spinal cord function for patients with congenital scoliosis (CS).MethodsThis retrospective study reviewed the medical records of patients (n = 102) who underwent DSEP (T2-S1 dermatome), of whom 60 were normal subjects and 62 with congenital scoliosis. The study analyzed the latencies and peaks of N1-L, N1-R, P1-L and P1-R recorded by DSEPs of patients’ thoracolumbar dermatomes. To observe the incidence of abnormal DSEPs and SSEPs in CS patients and to analyze the difference in sensitivity and reliability between the two in the examination of scoliosis patients. SPSS 22.0 statistical software package was used to analyze the data, and χ2 test and correlation analysis were used to indicate that the difference was statistically significant, p < 0.05.ResultsSixty two patients with CS were evaluated with total spine magnetic resonance imaging (MRI). Only 23 patients (37.09%) showed spinal cord malformations in the MRI findings. The DSEP recordings showed a relatively high sensitivity (97.8%) compared to the abnormality rate of SSEPs recordings, and the rates of waveform, latency and amplitude abnormalities were much higher in DSEPs recordings (36.6, 36.3, 24.8%) than in SSEPs recordings (3.2, 22.5, 14.5%). The abnormality rate of DSEP records with and without neurological symptoms was higher than the abnormality rate of SSEP records (100% vs 20, 96.2% vs 44.2%, p<0.05). And in 62 patients with CS, the rate of positive MRI (37.1%) was lower than that recorded by DSEP (79.6% / 57.9%). p < 0.05.ConclusionDSEPs are more sensitive to microscopic posterior column dysfunction in patients with CS that cannot be detected by either radiology or routine clinical examination. Preoperative DSEPs assessment is recommended as a baseline examination for intraoperative monitoring and comparison with the postoperative situation. DSEPs recording complements the information obtained from routine clinical and radiological evaluation.

Stimulus artifact removal to detect trigeminal sensory evoked potentials

ObjectiveLarge stimulus and myogenic artifacts usually prevent detection of sensory evoked potentials to electrical stimulation in trigeminal sensory territory (t-SEP). Stimulus Artifact (SA) removal can be obtained by means of two stimulating modes (Dual Mode Stimulation - DMS) having in common a fixed cathode alternatingly referred to opposed anodes, resulting in SAs of opposite polarity. Opposite SAs progressively cancel each other out during averaging, without interaction with the underlying bio-electrical events. MethodsUsing DMS, dermatomal t-SEP were recorded from C5/C6 scalp sites in 24 healthy volunteers after selective, electrical stimulation of five trigeminal nerve areas: supraorbital, infraorbital, superior alveolar, inferior alveolar and auriculotemporal. ResultsReproducible t-SEPs were obtained after stimulation at all sites and showed the classical W shape, without significant differences related to the stimulated area. Cortical responses were formed by a sequence of individual peaks labelled, according to polarity and mean latency, as P8, N13, P19, N27, P38. A later, less stable component followed (N55-P67), poorly defined or absent in about one third of subjects. ConclusionsThe described technique represents a novel approach, within reach of any neurophysiological unit, to record dermatomal SEPs to electrical stimulation of several, discrete areas of significant clinical interest, covering the whole trigeminal sensory territory. SignificanceDMS represents a simple and robust tool to remove SA as the main drawback that has so far prevented recording of t-SEPs in daily clinical practice.

Langerhans Cell Histiocytosis of the Thoracic Spine in an Adult Presenting as Thoracic Radiculopathy

A 35-year-old man complained of right truncal pain around T7-8 dermatomal distribution and on examination, T7-8 spinal tenderness was observed. Magnetic resonance imaging showed osteolytic mass in T8 vertebral body without structural lesions involving spinal nerve roots. Dermatomal somatosensory evoked potentials (DSEP) were helpful in diagnosis with thoracic radiculopathy. Finally, Langerhans cell histiocytosis was confirmed in bone biopsy. Thoracic radiculopathy can be caused by various etiologies including bone tumor and DSEP is useful supplementary tool for diagnosing thoracic radiculopathy.

Diagnostic Implication and Clinical Relevance of Dermatomal Somatosensory Evoked Potentials in Patients with Radiculopathy: A Retrospective Study.

Objective Dermatomal somatosensory evoked potentials (DSEPs) are used to evaluate abnormalities of the somatosensory tract. There have been some studies on the diagnostic value of DSEP in radiculopathy, but it is still controversial. The purpose of our study is to evaluate the diagnostic implication and clinical relevance of DSEPs in patients with radiculopathy by comparing DSEP findings to radiculopathy symptoms and intervertebral foramen (IVF) or spinal canal stenosis in lumbar magnetic resonance imaging (MRI). Methods This retrospective study reviewed the medical records of patients (n = 59) who were examined by DSEP (each L4 and L5 dermatome) and lumbar MRI. Radiculopathy symptoms and DSEPs results were compared. For the evaluation of IVF and spinal canal size, sagittal (each bilateral L4/5 and L5/S1 IVF) and axial MR images were selected at the most stenotic level. The sizes of the IVF and spinal canal were measured by the pixel counts of selected MR images. In addition, stenosis severity was morphologically graded on a 4-point scale. DSEP results were compared with the size and grade of the IVF or spinal canal stenosis. Results DSEPs showed high sensitivity for radiculopathy symptoms. The IVF size at L4/5 and L5/S1 (pixel counts) was significantly related to either L4 or L5 dermatomal somatosensory pathway dysfunction, respectively. However, spinal stenosis (pixel counts and grade) and IVF stenosis grade were not significantly related to DSEPs. Conclusion This paper could be helpful in the electrophysiologic diagnosis of lumbar radiculopathy.

Association Between Latency of Dermatomal Sensory-Evoked Potentials and Quantitative Radiologic Findings of Narrowing in Lumbar Spinal Stenosis.

ObjectiveTo identify the difference of quantitative radiologic stenosis between a normal latency group and an abnormal latency group, and to investigate the association of dermatomal somatosensory-evoked potential (DSEP) with magnetic resonance imaging (MRI) findings of narrowing in patients with lumbar spinal stenosis (LSS).MethodsWe retrospectively reviewed the clinical records and P40 latencies of L5 DSEP of 40 patients with unilateral symptoms of LSS at the L4–5 disc level. Quantitative assessments of stenosis in lumbar spine MRI were performed with measurements of the anteroposterior diameter (APD), cross-sectional area (CSA) of the dural sac, ligamentous interfacet distance (LID), CSA of the neural foramen (CSA-NF), and subarticular zone width. Analyses were conducted through comparisons of radiologic severity between the normal and abnormal latency groups and correlation between radiologic severity of stenosis and latency of DSEP in absolute (APD <10 mm) and relative (APD <13 mm) stenosis.ResultsThe radiologic severities of lumbar stenosis were not significantly different between the normal and abnormal latency groups. In absolute and relative stenosis, latency showed a significant negative correlation with APD (r=-0.539, r=-0.426) and LID (r=-0.459, r=-0.494). In patients with relative stenosis, a weak significant positive correlation was found between latency and CSA-NF (r=0.371, p=0.048). LID was the only significant factor for latency (β=-0.930, p=0.011).ConclusionThe normal and abnormal DSEP groups showed no significant differences inradiologic severity. The latency of DSEP had a negative correlation with the severity of central stenosis, and LID was an influencing factor.

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.

S121. The role of intraoperative dermatomal somatosensory evoked potentials in the absence of changes in standard somatosensory evoked potentials during spine surgeries: A case series

Introduction Intraoperative electrophysiological monitoring is used to potentially avoid permanent injury as a result of surgical manipulation. During spine surgeries, standard monitoring of median or posterior tibial nerve somatosensory evoked potentials (SEPs) can be insensitive and fail to identify useful intraoperative changes in neural function. Dermatomal somatosensory evoked potentials (DSEPs) have previously been shown to be valuable in identifying specific nerve root dysfunction during surgeries involving spinal decompression, fusion, or tumor resections. Methods Between 2012 and 2017, 2785 spine surgeries were performed with intraoperative monitoring at our institution. Of these, 1884 cases utilized DSEP monitoring in addition to standard SEPs of the median and posterior tibial nerves. Results We highlight 7 cases during which intraoperative DSEPs were able to independently identify changes that were not observed through standard mixed nerve SEPs. During these cases, we observed improvements that correlated with adequate neural decompression, real-time changes in individual nerve root function, as well as provided intraoperative monitoring feedback to surgeons when reliable SEP signals were not obtained. Conclusion DSEP monitoring can serve as a useful and sensitive adjunct method for intraoperative monitoring that may provide additional information to surgeons and patients undergoing spine surgeries. The limitation of DSEP monitoring is that it requires coordination between anesthesiologists, surgeons, and skilled monitoring technicians.

Afferent input and sensory function after human spinal cord injury.

Spinal cord injury (SCI) often disrupts the integrity of afferent (sensory) axons projecting through the spinal cord dorsal columns to the brain. Examinations of ascending sensory tracts, therefore, are critical for monitoring the extent of SCI and recovery processes. In this review, we discuss the most common electrophysiological techniques used to assess transmission of afferent inputs to the primary motor cortex (i.e., afferent input-induced facilitation and inhibition) and the somatosensory cortex [i.e., somatosensory evoked potentials (SSEPs), dermatomal SSEPs, and electrical perceptual thresholds] following human SCI. We discuss how afferent input modulates corticospinal excitability by involving cortical and spinal mechanisms depending on the timing of the effects, which need to be considered separately for upper and lower limb muscles. We argue that the time of arrival of afferent input onto the sensory and motor cortex is critical to consider in plasticity-induced protocols in humans with SCI. We also discuss how current sensory exams have been used to detect differences between control and SCI participants but might be less optimal to characterize the level and severity of injury. There is a need to conduct some of these electrophysiological examinations during functionally relevant behaviors to understand the contribution of impaired afferent inputs to the control, or lack of control, of movement. Thus the effects of transmission of afferent inputs to the brain need to be considered on multiple functions following human SCI.

The study and application of intraoperative neurophysiological monitoring in oblique lateral interbody fusion combined with posterior transpedicle internal fixation

Objective To investigate a reliable and practicable model of intraoperative neurophysiological monitoring (IONM) in oblique lateral interbody fusion (OLIF) combined with posterior transpedicle internal fixation. Methods A total of 34 consecutive patients who underwent OLIF combined with posterior transpedicle internal fixation with IONM at the SRRSH from November 2014 to July 2016 were collected and follow-up at least for 3 months postoperative. The intraoperative somatosensory evoked potentials (SEP), motor evoked potentials (MEP), dermatomal somatosensory evoked potential (DSEP) and spontaneous electromyography (sEMG) were used and evaluated, besides, triggered electromyography (tEMG) was used to monitor the implantation of pedicle screws, the possible reasons and treating procedures of monitoring alerts were summarized. Results A total of 34 cases of patients were effectively monitored during OLIF combined with posterior transpedicle internal fixation. SEP monitoring was successful in all patients, and no abnormal SEPs were observed in all cases. DSEP monitoring was successful in 20 cases (58.8%), and no abnormal DSEPs were observed in these patients. MEP was successfully monitored in all cases, eliminating the anesthesia factor, no abnormal MEPs were observed in all cases. The sensitivity and positive predictive value of SEP, MEP, DSEP were 0%. 3 cases had abnormal sEMG reactions during the channel establishment which disappeared after adjustment of channel, and 2 cases which appeared abnormal wave recovered after brief observation. Among the 5 patients with abnormal wave, one case got numbness, one patient felt pain in front of the thigh postoperative. Among the other 29 patients without abnormal wave during channel establishment, one case appeared numbness. These 3 patients with neurologic symptoms recovered in 3 months after conservative treatment. The sensitivity and specificity of sEMG was 66.7% and 90.3% respectively, negative predictive value and positive predictive value were 96.6% and 40% respectively. 6 screws got tEMG response after tapping even the intensity was less than 10mA, which showed broken codex of pedicle according to postoperative CT scan. Conclusion Intraoperative application of sEMG monitoring in OLIF can obviously reduce the incidence of the neurological deficit, which was an effective method. tEMG monitoring during lumbar pedicle screw fixation can detect the mal-positioned screws and protect the nerve roots. SEP, MEP and DSEP did not seem well suited for OLIF. Key words: Lumbar vertebrae; Spinal fusion; Evoked potentials, somatosensory; Evoked potentials, motor; Electromyography

Unilateral suppression of P/N13′ potential amplitude in young patients with persistent numbness due to cervical monoradiculopathy. A case-control study

ObjectiveThe utility of Dermatomal Somatosensory Evoked Potentials (DSEPs) in the diagnostic workup of suspected cervical monoradiculopathy has been limited by significant overlap between measurements obtained from affected versus unaffected roots. In a case-control study, we explored whether, under certain conditions, asymmetry in DSEP parameters may offer significant help in the diagnosis of monoradiculopathy. MethodsDSEPs were obtained bilaterally from patients with persistent (age range 33–55, n=10) or intermittent (age range 31–55, n=7) unilateral sensory symptoms of less than one month duration due to MRI-confirmed cervical monoradiculopathy. DSEPs were also obtained bilaterally from aged-matched asymptomatic volunteers (age range 31–54, n=8) and older asymptomatic volunteers (age range 57–77, n=8). Amplitude and latency of the P/N13′ potential (negative peak at 13ms) were measured. ResultsIn all ten patients with persistent symptoms, the P/N13′ amplitude ratio, defined as P/N13′ amplitude on the symptomatic side divided by P/N13′ amplitude on the contralateral asymptomatic side, ranged between 0.0 and 0.50 (unilateral suppression). In all seven patients with intermittent symptoms, P/N13′ amplitude ratios ranged between 0.60 and 1.00. In all age-matched asymptomatic controls, P/N13′ amplitude ratio (side with lower divided by side with higher amplitude) was always at least 0.80. Among older asymptomatic subjects, DSEPs had inconsistent characteristics. ConclusionsCervical monoradiculopathy with persistent numbness in young patients (aged up to 55years) is very strongly associated with unilateral suppression of P/N13′ DSEP amplitude. No significant asymmetry is observed in cases of monoradiculopathy with intermittent numbness. SignificanceIn young patients with unilateral upper extremity persistent sensory complaints, DSEP amplitude asymmetry, as quantified by the P/N13′ ratio, may offer significant help in the diagnosis of monoradiculopathy.

Addition of a Sagittal Cervical Posture Corrective Orthotic Device to a Multimodal Rehabilitation Program Improves Short- and Long-Term Outcomes in Patients With Discogenic Cervical Radiculopathy

ObjectiveTo investigate the immediate and 1-year effects of a multimodal program, with cervical lordosis and anterior head translation (AHT) rehabilitation, on the intensity of pain, disability, and peripheral and central nervous system function in patients with discogenic cervical radiculopathy (CR). DesignA randomized controlled trial with 1-year and 10-week follow-up. SettingUniversity research laboratory. ParticipantsPatients (N=60; 27 men) with chronic discogenic CR, a defined hypolordotic cervical spine, and AHT posture were randomly assigned to a control group (n=30; mean age, 43.9±6.2y) or an intervention group (n=30; mean age, 41.5±3.7y). InterventionsBoth groups received the multimodal program; in addition, the intervention group received the Denneroll cervical traction device. Main Outcome MeasuresAHT distance, cervical lordosis, arm pain intensity, neck pain intensity, and disability (Neck Disability Index [NDI]), dermatomal somatosensory evoked potentials (DSSEPs), and central somatosensory conduction time (N13–N20). Measures were assessed at 3 time intervals: baseline, 10 weeks, and 1-year follow-up. ResultsAfter 10 weeks of treatment, between-group analysis showed equal improvement in arm pain intensity (P=.40), neck pain intensity (P=.60), and latency of DSSEPs (P=.60) in both intervention and control groups. However, also at 10 weeks, there were significant differences between groups, favoring the intervention group for cervical lordosis (P<.0005), AHT distance (P<.0005), amplitude of DSSEPs (P<.0005), N13 to N20 conduction time (P<.0005), and NDI (P<.0005). Although at 1-year follow-up, between-group analysis identified a regression back to baseline values for the control group. Thus, all variables were significantly different, favoring the intervention group at 1-year follow-up: cervical lordosis (P<.0005), AHT distance (P<.0005), latency and amplitude of DSSEPs (P<.0005), N13 to N20 conduction time (P<.0005), intensity of neck and arm pain, and NDI (P<.0005). ConclusionsThe addition of the Denneroll cervical orthotic device to a multimodal program positively affected discogenic CR outcomes at long-term follow-up. We speculate that improved cervical lordosis and reduced AHT contributed to our findings.

Parameters of dermatomal somatosensory evoked potentials in normal conditions and patients with clinical symptoms of low back pain

Introduction. Dermatomal somatosensory evoked potentials (DSEP) are used to assess the function of afferent pathway following electrical stimulation of the skin around selected dermatomes of single spinal roots. Aim. The aim of the study was to characterize the parameters of DSEP latencies for assessment of L5 and S1 nerve root transmission in healthy people taking into account the important diagnostic difference between the right and left side and the impact of height, age and sex on values of DSEP latencies. Material and methods. DSEP tests were performed in the control group of 30 healthy volunteers and in the patients with low back pain radiating to one of the lower extremities for comparison. Disc‑root conflict was confirmed in MRI studies. Clinical examination included assessment of muscles strength innervated from the L5 and S1 roots and the sensory perception from L5 and S1 dermatomes. In all patients straight leg raising (SLR) and Schober's tests have been performed. To assess the severity of pain, the visual analogue scale (VAS) was used. The clinical and neurophysiological evaluation of patients was performed before and after 4 weeks of the physiotherapeutic exercises selected for this study. Results. Results indicated statistically significant relationship between the DSEP N33, P40, N50 components latencies and the height. The gender and age did not affect DSEP latencies. Values of DSEP latencies in the first and second periods of observations were normal and no sensory and motor disturbances have been observed in patients. DSEP test showed the high conformity with the results of clinical studies. Conclusions. DSEP diagnostic determines well the subjective sensation changes in patients suffering from low back pain. Kinesiotherapy treatment of patients with low back pain without neurological deficits seems to be the appropriate therapeutic method.

Correlation between Dermatomal Somatosensory Evoked Potential, Needle Electromyography and Magnetic Resonance Imaging in Chronic Sensory Lumbosacral Radiculopathies

Objective: To correlate between dermatomal somatosensory evoked potential (DSEP), needle electro myography (EMG) and magnetic resonance imaging (MRI) in patients with clinical picture suggestive of chronic sensory lumbosacral radiculopathy. Design: cross sectional study. Setting: outpatient setting. Participants: 50 patients (29 Males, 21 Females) with chronic sensory lumbosacral radiculopathy. 20 healthy subjects were included as control for DSEP values. Main outcome measures: Medical history, detailed neurological examination, Lumbosacral MRI, lumbosacral DSEP and needle EMG for segment pointing muscles were done for all patients. DSEP were done for lumbosacral roots for control subjects. Results: Mean age of patients 56.36 ± 10.26. Mean disease duration 17.48 ± 6.85 months.Spondylosis constituted 74%, followed by spinal stenosis 14%, lumbar disc prolapse 8%, lastly spondylolithesis 4% In relation to sensory symptoms, DSEP is significantly higher than EMG in detecting lumbosacral radiculopathies (p=0.0001). DSEP sensitivity and accuracy is higher than needle EMG at L4, L5 and S1 In relation to MRI, sensitivity of DSEP at L4 was 93.3%, at L5 and S1 100%. Sensitivity of needle EMG at L4 was 20%, at L5 24.3%, at S1 47.1% . Conclusion: DSEP is highly sensitive than needle EMG in diagnosing and localizing chronic sensory lumbosacral radiculpathies, even if MRI findings are inconclusive.

Dermatomal Somatosensory Evoked Potentials: An Indicator of Improvement of Breast Sensibility after Reduction Mammaplasty

Introduction: Many women think about reduction mammaplasty for different reasons. The effect of surgery on the beast sensibility is one of the greatest concerns after reconstructive reductive breast surgery through its affect on patient’s social life and psychological health. The dermatomal somatosensory evoked potential (D-SEP) is a new method to quantitatively evaluate breast sensibility. Patients and Methods: Twenty-five women enrolled in this study presenting with breast enlargement, underwent mammary reduction by using the inferior pyramidal breast reduction technique using the same operative technique described by Robbins with some modifications. All D-SEP amplitudes and latencies were calculated preoperatively and then were reassessed six and twelve months post-surgery in each breast. Result: The results revealed that there is a significant difference in the D-SEP latency pre- and post-operatively. The statistically significant decrease in latency and the breast size demonstrated indicates that the sensibility improved after breast reduction surgery both at six and twelve months. There is also a significant increase in the D-SEP amplitude pre- and post-operatively. The negative and statistically significant increase in amplitude with the decrease in breast size demonstrated indicates that the sensibility improved after breast reduction surgery both at six and twelve months. Conclusion: This study concluded that breast sensibility will improve after breast reduction as indicated by significant reduction of D-SEP latencies and increase of its amplitudes. Our results confirm an inverse relationship between breast size and sensibility, with improvement in sensibility after breast reduction.

Diagnostic use of dermatomal somatosensory-evoked potentials in spinal disorders: Case series

Objective/ContextDermatomal somatosensory-evoked potentials (dSEPs) may be valuable for diagnostic purposes in selected cases with spinal disorders.DesignReports on cases with successful use of dSEPs.FindingsCases 1 and 2 had lesions causing multiple root involvement (upper to middle lumbar region in Case 1 and lower sacral region in Case 2). Cystic lesions in both cases seemed to compress more than one nerve root, and stimulation at the center of the involved dermatomes in dSEPs helped to reveal the functional abnormality. Cases 3 and 4 had lesions involving the spinal cord with or without nerve root impairment. In Case 3, an magnetic resonance imaging (MRI)-verified lesion seemed to occupy a considerable volume of the lower spinal cord, causing only very restricted clinical sensory and motor signs. In Case 4, a cervical MRI showed a small well-circumscribed intramedullary lesion at right C2 level. All neurophysiological investigations were normal in the latter two patients (motor, tibial, and median somatosensory-evoked potentials in Case 3, and electromyography in both) except for the dSEPs.ConclusionsObjectifying the presence and degree of sensory involvement in spinal disorders may be helpful for establishing diagnoses and in therapeutic decision-making. Valuable information could be provided by dSEPs in selected patients with multiple root or spinal cord involvement.

Monitoring superficial peroneal nerve somatosensory evoked potential during L4-5 lumbar root decompression

Background contextPosttibial nerve somatosensory evoked potential (PTN-SSEP) often fails to detect individual nerve root dysfunction, whereas dermatomal somatosensory evoked potential (DSSEP) can be difficult to obtain in anesthetized patients. PurposeThe main aim of this study is to investigate whether the superficial peroneal nerve SSEP (SPN-SSEP), a cutaneous nerve SSEP derived from L4-5 roots, can be relied on as an intraoperative neurophysiological assessment for L4-5 roots. Study design/settingRetrospective review of consecutive case series. Patient sampleThirty-five consecutive patients who underwent lumbar root microdecompression were reviewed. The control group consisted of 11 patients who underwent anterior cervical discectomy and fusion (ACDF). Outcome measuresIntraoperative SSEP measures defined outcome measures. MethodsData from 35 patients undergoing SPN-SSEP, PTN-SSEP, and sural nerve SSEP (SN-SSEP) monitoring during lumbar surgeries were analyzed and compared with the control group of patients underwent ACDF surgery. ResultsCortical SPN-SSEP could be readily recorded in more than 90% patients from both groups. The waveforms of SPN-SSEP were about 30% smaller than PTN-SSEP, but very similar to SN-SSEP. Importantly, SPN-SSEP was capable of detecting intraoperative L4-5 root dysfunction without the corresponding PTN-SSEP or SN-SSEP alterations. Overall, SPN-SSEP displayed twofold greater sensitivity over PTN-SSEP or SN-SSEP. ConclusionsSPN-SSEP was a more sensitive measure for intraoperative L4-5 nerve root dysfunction in comparison with PTN-SSEP and SN-SSEP.