Central Somatosensory Conduction Time Research Articles

Electrophysiological evidence of diabetes' impacts on central conduction recoveries in degenerative cervical myelopathy after surgery.

To assess the impact of diabetes mellitus (DM) on the postoperative motor and somatosensory functional recoveries of degenerative cervical myelopathy (DCM) patients. Motor and somatosensory evoked potentials (MEP and SSEPs) and modified Japanese Orthopedic Association (mJOA) scores were recorded in 27 diabetic (DCM-DM group) and 38 non-diabetic DCM patients (DCM group) before and 1 year after surgery. The central motor (CMCT) and somatosensory (CSCT) conduction time were recorded to evaluate the conductive functions of the spinal cord. The mJOA scores, CMCT and CSCT improved (t test, p < 0.05) in both of the DCM-DM and DCM groups 1year after surgery. The mJOA recovery rate (RR) and CSCT recovery ratio were significantly worse (t test, p < 0.05) in the DCM-DM group compared to the DCM group. DM proved to be a significant independent risk factor for poor CSCT recovery (OR = 4.52, 95% CI 2.32-7.12) after adjusting for possible confounding factors. In DCM-DM group, CSCT recovery ratio was also correlated with preoperative HbA1 level (R = - 0.55, p = 0.003). Furthermore, DM duration longer than 10years and insulin dependence were risk factors for lower mJOA, CMCT and CSCT recoveries among all DCM-DM patients (t test, p < 0.05). DM may directly hinders spinal cord conduction recovery in DCM patients after surgery. Corticospinal tract impairments are similar between DCM and DCM-DM patients, but significantly worsened in chronic or insulin-dependent DM patients. The dorsal column is more sensitively affected in all DCM-DM patients. Deeper investigation into the mechanisms and neural regeneration strategies is needed.

Effect of Biofeedback Corrective Exercise on Reaction Time and Central Somatosensory Conduction Time in Patients With Forward Head Posture and Radiculopathy: A Randomized Controlled Study

ObjectiveThe purpose of this study was to examine the effect of 8 weeks of biofeedback on reaction time and central somatosensory conduction time in patients with forward head posture and cervical radiculopathy. MethodsWe performed a double-blinded randomized controlled trial. Seventy patients with forward head posture and cervical radiculopathy were randomly distributed into study and control groups. The study group received biofeedback forward head posture corrective exercise for 8 weeks, while the control group did not receive any treatment. The main outcome measures were reaction time and central somatosensory conduction time. The secondary outcome measures were the craniovertebral angles, nerve conduction time at N13 and N20, referred arm pain, and neck disability index. ResultsAfter 4 weeks, there were nonsignificant differences between both groups in reaction time and central somatosensory conduction time (P > .05); while there were significant differences between both groups in N13, N20, craniovertebral angle, referred arm pain, and neck disability index scores (P < .05). After 8 weeks, there were significant differences between both groups in all outcome measures (P < .05). ConclusionIn this study, participants receiving biofeedback forward head posture corrective exercise improved both reaction time and central somatosensory conduction time after 8 weeks when compared to a control, nontreatment group.

Demonstration of central conduction time and neuroplastic changes after cervical lordosis rehabilitation in asymptomatic subjects: a randomized, placebo-controlled trial

A randomized controlled study was conducted to evaluate the effect of rehabilitation of the cervical sagittal configuration on sensorimotor integration and central conduction time in an asymptomatic population. Eighty (32 female) participants with radiographic cervical hypolordosis and anterior head translation posture were randomly assigned to either a control or an experimental group. The experimental group received the Denneroll cervical traction while the control group received a placebo treatment. Interventions were applied 3 × per week for 10 weeks. Outcome measures included radiographic measured anterior head translation distance, cervical lordosis (posterior bodies of C2–C7), central somatosensory conduction time (latency) (N13–N20), and amplitudes of potentials for spinal N13, brainstem P14, parietal N20 and P27, and frontal N30. Outcomes were obtained at: baseline, after 10 weeks of intervention, and at 3 months follow up. After 10 weeks and 3-months, between-group analyses revealed statistically significant differences between the groups for the following measured variables: lordosis C2–C7, anterior head translation, amplitudes of spinal N13, brainstem P14, parietal N20 and P27, frontal N30 potentials (P < 0.001), and conduction time N13–N20 (P = 0.004). Significant correlation between the sagittal alignment and measured variables were found (P < 0.005). These findings indicate restoration of cervical sagittal alignment has a direct influence on the central conduction time in an asymptomatic population.

Optimal duration of stretching exercise in patients with chronic myofascial pain syndrome: A randomized controlled trial.

ObjectiveTo explore the effect of variable durations of stretching on neural function, pain, and algometric pressure in patients with chronic myofascial pain syndrome.DesignRandomized controlled trial.PatientsA total of 100 participants diagnosed with chronic myofascial pain syndrome were randomly assigned to a control group or 1 of 3 intervention groups.MethodsThe 3 experimental groups received different durations of cervical spine stretching: 15, 30 or 60 s. The control group did not stretch. Primary outcome measures included peak-to-peak somatosensory-evoked potential for dermatomes C6, C7 and C8. Secondary outcome measures included central somatosensory conduction time (N13–N20), pain intensity, and pressure-pain threshold algometric measurements. All outcome measures were assessed immediately after and 2 h after the treatment session.ResultsPost hoc analysis indicated that stretching for 60 s significantly decreased the dermatomal amplitude for C6, C7 and C8 (p < 0.001) and significantly increased the central conduction time, indicating negative effect (p < 0.001). Stretching for 30 and 60 s resulted in greater improvement in pain intensity and algometric pressure than stretching for 15 s or no stretch (control) p < 0.001.ConclusionStretching cervical muscles involved in chronic myofascial pain syndrome for 30 s was optimal in achieving stretching benefits and minimizing the negative effects on the neural function of the involved nerve roots and central nervous system.LAY ABSTRACTThis study measured the effect of different durations of stretching (15 s, 30 s, 60 s and no stretching) of the muscles around the neck and shoulders in 100 participants with chronic myofascial pain syndrome. The outcome measures assessed the effect on neural function. The results show that stretching for 30 s was the optimal time, for achieving stretching benefits and minimizing the negative effects on the neural function of the involved nerve roots and central nervous system. Stretching for a longer time negatively affected the neural function, but decreased the pain level, while stretching for a shorter time did not achieve the optimal muscle length after stretching.

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.

Central somatosensory conduction time in severely growth-stunted children

To examine the effects of chronic malnutrition on central nervous system function, we used the somatosensory evoked potential to measure the central conduction time of 20 children aged 7-8 y with heights below the third percentile for their age and 20 control children in Honduras. The two groups differed significantly in socioeconomic status, achievement in Bender's neurointegrative test, and hematocrit, but not in birth weight. After median nerve stimulation, the mean central conduction time (interpeak latency between N13 and N20) for the growth-stunted group (6.19 +/- 0.52 ms) did not differ significantly from that of the control subjects (6.30 +/- 0.58 ms), suggesting appropriate myelination and fiber diameter. Somatosensory tracts may escape damage resulting from postnatal dietary deficiencies because myelination in these tracts is almost complete at birth.

Correlation between central somatosensory conduction time, blood flow velocity, and delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage.

In this retrospective study of 67 aneurysmal patients, the predictive role of central conduction time (CCT) on vasospasm occurrence evaluated by means of transcranial Doppler sonography (TCD) and the correlation of CCT to blood flow velocity measured simultaneously in postoperative course were studied. Data about the clinical state of patients at the time of admission (Hunt Hess scale), severity of subarachnoidal hemorrhage on initial CT scan (Fisher grade), timing of surgery (acute or delayed), outcome (Glasgow Outcome Scale), severity of vasospasm graded by highest mean blood flow velocity (BFV) during the entire clinical course and CCT values measured at admission (preoperatively), then postoperatively (one day after surgery) and simultaneously with later TCD investigations were collected from the files. Interhemispheric difference of CCT was also calculated. The results showed that CCT at admission was not predictive for vasospasm. CCT measured either at admission or on the first postoperative day did not differ significantly in the different grades of vasospasm. Similar results were obtained in the acute and in the late operated group of patients. The results also suggest that increased CCT and interhemispheric difference at the time of admission indicate a worse prognosis, but this can be related to higher surgical risk rather than to a higher incidence of late ischemic deterioration. Simultaneous CCT and TCD examinations demonstrated that coincident and statistically significant (p < 0.01) increase of actual CCT (6.7 msec) was found only in the severe grade of vasospasm (BFV 200 cm/s). The authors discuss the role of CCT and TCD monitoring in the management of aneurysmal subarachnoid hemorrhage.

The effects of low pass filtering on central somatosensory conduction time

Central Somatosensory conduction time (CSCT) in the rat was measured by simultaneously recording the cortical somatosensory evoked potential (SEP) and cervical SEP and then subtracting the peak latency of the cervical response from that of the primary cortical response. The low frequency (high pass) filter of the recording system was kept fixed at 3.2 Hz but the high frequency cut-off was progressively raised from 32 to 16 kHz to examine the effects of low pass filtering on the two waveforms from which CSCT is derived. With a bandpass of 3.2–32 Hz, no activity could be reliably identified in either the cortical or cervical traces. With subsequent rises in the high frequency filter, the amplitude of both potentials increased with a concomitant decrease in their latencies. Stable values were obtained with a bandpass of 3.2–3.2 kHz and there was little additional change in waveform configuration. In contrast to the waveforms, low pass filtering had only minimal effects on CSCT and near constant values (in the range 3.6–4.1 ms) were obtained regardless of the setting of the low pass filter. I concluded that low pass filtering has a largely uniform effect on somatosensory activity generated in both primary cortical and cervico-medullary locations.

Age-dependent changes in central somatosensory conduction time.

The effects of aging on central somatosensory conduction time (CSCT) were examined using 125 neurologically healthy subjects aged 10-79 years. There was a mean overall increase in CSCT during the age span studied of 0.5 ms. However, the principal increase in CSCT did not appear to start until the end of the fourth decade, after which there was a steady incremental increase. There was little evidence of an abrupt stepwise increase in CSCT at any age. Age-dependent changes in asymmetry (right-left difference in CSCT) remained approximately constant until the end of the sixth decade. From the age of 60 years onwards, there was a small mean increase in asymmetry of 0.1 ms. Subjects were divided into six age groups and the upper limit of normal for both CSCT and asymmetry was defined for each.

Central auditory conduction time in the rat

Central conduction time is the time for an afferent volley to traverse the central pathways of a sensory system. In the present study, central auditory conduction time (CACT) was calculated for the rat, the first such formal measurement in any animal. Brainstem auditory evoked potentials (BAEPs) were recorded simultaneously with the primary response of the auditory cortex (P1). The latency of wave II of the BAEP, which arises in the cochlear nucleus, was subtracted from that of P1. This yielded a mean CACT of 6.6 ms. The results confirm a previous theoretical estimate that CACT in the rat is at least twice as long as central somatosensory conduction time.

Short latency somatosensory evoked potentials and brain-stem auditory evoked potentials in coma due to CNS depressant drug poisoning. Preliminary observations

In patients in coma due to severe CNS depressant drug overdose the central somatosensory conduction time (CCT) after median nerve stimulation is prolonged and N20 is dispersed. Brain-stem auditory evoked potentials demonstrate delayed interpeak latencies (IPLs) I–III, III–V and I–V. This was observed in 4 out of 5 patients investigated after intake of an overdose of amitriptyline (2 cases), barbiturates, meprobamate and nitrazepam (one case each). Toxic levels of drug overdose were related to prolonged CCT and IPLs, whereas normal CCT and IPLs were found at therapeutic drug plasma levels. CCT, IPLs and dispersion of N20 decreased during the course of coma. All patients were successfully treated. It appeared that SSEP and BAEP investigations could make a distinction between a ‘toxic’ and a ‘therapeutic’ coma level in severe drug overdose. It further appeared that normalization of CCT and IPLs preceded clinical improvement.

Central somatosensory conduction time and acoustic brainstem transmission time in post-traumatic coma.

Short-latency evoked potentials (SEPs) of the scalp and neck after median nerve stimulation and acoustic brainstem evoked potentials (BAEPs) were recorded in 85 patients in post-traumatic coma with clinical signs of brainstem impairment between days 2 and 6 after trauma. The central somatosensory conduction time (CCT), the amplitude ratio (AR) N20:N13, the interpeak latencies (IPL) I-III, III-V, I-V, and the ARs between waves I and V (I:V) and between wave I and the wave IV/V complex (I:IV/V) were calculated and related to the outcome of the patients. In cases of coma due to supratentorial lesions, CCT and ARs of SEPs were close to normal in patients with good outcome: CCT increased and ARs decreased with worsening of outcome. In cases of primary brainstem injury, a significant prolongation of CCT was also seen in patients with good recovery, whereas normal CCTs could be found in patients with severe disability and death outcome. In this case, unilateral absent scalp SEPs were frequently found. The IPLs I-III, III-V, I-V, and the ARs of BAEPs increased with worsening of outcome. Significant differences of IPL I-V and III-V (brainstem transmission time) were seen between patients with good recovery or moderate disability outcome and the patients with severe disability or death outcome. There was no difference in BAEPs between patients with primary brainstem lesion and patients with secondary brainstem lesion. Patients with bilateral absent SEPs and bilateral absent BAEPs not related to traumatic or preexisting hearing disorders died or survived severely disabled. Unilateral absence of scalp SEPs and unilateral absence of BAEPs were frequently found in patients who died or who had severe disability. Asymmetries in scalp SEPs appeared to be distributed equally to all outcome categories, but asymmetries in BAEPs increased with worsening of outcome too. In most of the patients who died or survived disabled, both SEPs and BAEPs were abnormal.

Etude des potentiels evoques multimodalitaires dans les epilepsies partielles de l'enfant

A multimodal evoked potential study was realised in three groups of children or adolescents 5 to 15 years old. The first group included 25 normal non-epileptic subjects; the second group was composed of 27 subjects with partial idiopathic epilepsy (PIE) (benign childhood epilepsy with centro-temporal spike; childhood epilepsy with occipital paroxysms); the third group was formed of 20 subjects with partial symptomatic epilepsy (PSE) without patent anatomical lesion or with anatomical lesion. Recording for each subject included: flash visual evoked potentials, pattern visual evoked potentials, brainstem auditory evoked potentials and somatosensory evoked potentials. Each curve obtained was studied for the response morphology, the measure of the different wave latencies, the inter-peak latencies (conduction time) and the amplitudes. A statistical treatment of the data was performed to evaluate the significance of variation of the different parameter values obtained for the various groups. Among the significantly modified parameters, we found: an increase of the amplitudes in the PIE and a decrease in the PSE, specially when an anatomical lesion exists; an asymmetrical amplitude of the somatosensory responses in the PIE with centro-temporal spike; an increase of the central somatosensory conduction time in the PSE with anatomical lesion.

Short latency somatosensory-evoked potentials in children —part 3. Findings following head injury

Fourteen children aged 3 to 11 years who suffered from coma for at least 6 hours had somatosensory-evoked potential studies performed within 24 hours of neurotrauma. The upper cervical (Cv2) and bilateral cortical somatosensory-evoked potentials were recorded for calculation of the central somatosensory conduction time. Despite the fact that the SEP recordings were performed in the intensive care unit and the patients were receiving opiate and barbiturate therapy, satisfactory somatosensory-evoked potentials were recorded in all patients. Symmetrical short latency cortical somatosensory-evoked potentials were recorded bilaterally in 10 patients. Two patients with hemorrhagic cerebral contusions and unilateral cerebral edema had ipsilateral abnormalties of the cortical somatosensoryevoked potential. These patients all had normal central somatosensory conduction times and all had satisfactory neurological recoveries, although the two patients with abnormal cortical somatosensory-evoked potentials had focal neurological deficits. Two patients whose head injuries were complicated by hypoxia and refractory intracranial hypertension had bilaterally abnormal cortical somatosensory-evoked potentials, and both had vegetative outcomes. There was no correlation between the Glasgow Coma Score and central somatosensory conduction time; however, the number of components to the cortical somatosensory-evoked potential was related to the Glasgow Coma Score. The results suggest that the recording of somatosensory-evoked potentials can provide useful information about the functional status of central and cortical somatosensory pathways in children following major head injury.

Short latency somatosensory-evoked potentials in children —part 1 normative data

Spinal, subcortical, and short latency cortical somatosensory-evoked potentials (SEPs) following electrical stimulation of the median or tibial nerve were studied in 100 children aged 4 weeks to 13 years. Standard neurophysiological methods of recording surface SEPs were used in sedated and nonsedated children. The morphology of the SEPs was similar to that obtained in adults; however, the initial components of the cortical SEP following median nerve stimulation did show maturational changes in both interpeak latencies and morphology. The negative peak latencies recorded over Erb's point (N9 equivalent) and the second cervical vertebra (N13 equivalent) following median nerve stimulation, and over the lumbothoracic junction (N14 equivalent) following tibial nerve stimulation were directly related to patient age and limb length. There was no correlation between age and the latencies of either the initial negativity (N18 equivalent) or the initial positivity (P28 equivalent) of the cortical SEPs following respective median and tibial nerve stimulation. The central somatosensory conduction time decreased slowly during the first decade and attained adult values after 8 years of age. The lumbar spine to scalp transit time showed no direct relationship to age. Comparisons of SEPs recorded in the same subject when awake and under general anesthesia showed that the latencies of the subcortical, spinal, and Nl-Pl complex of the cortical SEP are identical; however, the later components of the cortical SEP vary both in latency and amplitude with anesthesia. This study represents normative data against which SEP in children with disorders of the central nervous system may be compared.

The assessment of severe head injury by short-latency somatosensory and brain-stem auditory evoked potentials

The relative prognostic value of short-latency somatosensory evoked potentials (SEPs) and brain-stem auditory evoked potentials (BAEPs) was assessed in 35 patients with post-traumatic coma. Analysis of the evoked potentials was restricted to those recorded within the first 4 days following head injury. Abnormal SEPs were defined as an increase in central somatosensory conduction time or an absence of the initial cortical potential following stimulation of either median nerve. Abnormal BAEPs were classified as an increase in the wave I–V interval or the loss of any or all of its 3 most stable components (waves I, III and V) following stimulation of either ear. SEPs reliably both good and bad outcomes. All 17 patients in whom SEPs were graded as normal had a favourable outcome and 15 of 18 patients in whom SEPs were abnormal had an unfavourable outcome. Although abnormal BAEPs were associated with an unfavourable outcome in almost all patients (6 of 7), only 19 of 28 patients with normal BAEPs had a favourable outcome. The finding of normal BAEPs was therefore of little prognostic significance. These results confirm the superiority and greater sensitivity of the SEP in detecting abnormalities of brain function shortly after severe head trauma.

Maturation of central somatosensory conduction time in infancy and childhood.

To investigate the age-dependency of central conduction time somatosensible evoked potentials to median nerve stimulation were recorded in 80 infants and children from the age of one week to 20 years. It is shown that the central conduction time starts at about 14 ms in the neonatal period and then gradually declines until the 7th or 8th year of life to the normal adult value with an upper limit of 7 ms. By dividing the data into several groups with age delimiters at 0.5, 1, 3, 5 and 7 years it shows significant differences of the mean values for the central conduction times according to the Student's t-test. The graph itself can well be approximated by the exponential regression y = 6.099 + 7.55 X e-0.686 X x where y represents the CCT and x the age in years. This slow maturation kinetic is presumably due to the ongoing central myelinisation.

Somatosensory evoked potentials after head injury: The significance of the double peak

The calculation of central somatosensory conduction time by subtracting the peak latency of the cervical potential from that of the initial cortical response in patients in posttraumatic coma provides both a reliable indication of outcome plus an assessment of brain damage. The interpretation of such recordings is confounded in a minority of patients by the presence in the cortical SEP of a biphasic cortical negativity, giving the impression that the initial cortical response (N20) has bifurcated into two subcomponents. Depending upon which subcomponent is assumed to be N20, an individual recording may ambiguously appear to have a central conduction time either within normal limits or very abnormally prolonged. The aetiology and significance of this double peak phenomenon was studied in 30 patients with severe head trauma. It is concluded that the first of the subcomponents invariably represents the genuine N20 potential irrespective of its relative amplitude. The second subcomponent is assumed to be N25, a minor cortical potential which can be recorded in only a limited number of normal subjects. The double peak effect appears to be created by a distortion in the early cortical waveform probably due to the characteristic reduction in its amplitude following head injury.

Central and spinal somatosensory conduction times during hypothermic cardiopulmonary bypass and some observations on the effects of fentanyl and isoflurane anesthesia

Somatosensory evoked potentials (SEPs) following median nerve stimulation were recorded over Erb's point (N10), neck (N13) and scalp (N20) of 17 neurologically normal patients during hypothermic cardiopulmonary bypass. Anesthesia was induced with fentanyl and 100% oxyge, and supplemented with isoflurane as necessary. All 3 SEPs were recorded at esophageal temperatures (T e) of down to 19.5°C. The central conduction time (CCT, defined as N20-N13 interpeak interval) increased exponentially with decreasing temperature (CCT T e = 1.066 37−T e·CCT 37 ; r = −0.96). The spinal conduction time (SCT, defined as N13-N10 interpeak interval) also increased exponentially but less steeply than the CCT (SCT T e = 1.047 37−T e·SCT 37 ; r = −0.89), and the N10 peak latency increased exponentially and least steeply (N10 T e = 1.033 37−T e · N10 37; r = −0.87). Anesthetic doses of fentanyl (75 μg/kg) did not affect the SEPs. Isoflurane (inspired concentration, 0.25–2.0%) produced dose-dependent increases in CCT of up to 13% and decreased N20 amplitude. All patients had normal CTs after rewarming and none suffered postoperative neurological deficits. Differences in slopes of the latency-temperature functions indicate that cooling produces more conduction slowing in central than in peripheral segments of the pathway and can be accounted for by estimates of the effects of cooling on synaptic delay and axonal conduction between wrist and cortex. The consistency of SEps between patients both during stable hypothermia and when temperature was changing suggests their potential as a sensitive monitor of cerebral status during hypothermic cardiopulmonary bypass.

Central somatosensory conduction time: Normative data

Central somatosensory conduction time: Normative data