Significant Changes In Latency Research Articles

Evaluating somatosensory evoked potentials in predicting treatment outcomes for thoracolumbar spinal compression fractures using closed reduction and over-extension techniques.

To evaluate the predictive value of somatosensory evoked potentials (SEPs) for the efficacy of closed reduction combined with over-extension reduction technique (PVP) in managing thoracolumbar spinal compression fractures. Data were collected from 125 patients who underwent closed reduction with PVP and SEP monitoring from February 2021 to July 2023. We evaluated surgery success rates, incidence of bone cement leakage, and patient recovery outcomes including vertebral anterior height, Oswestry Disability Index (ODI), and Cobb angle restoration. SEP results were analyzed to categorize patients into effective and ineffective treatment groups. Differences in SEP waveforms between these groups were examined, and ROC analysis was used to assess the predictive value of these differences. Multivariate logistic regression was employed to identify risk factors affecting treatment efficacy. Post-treatment assessments showed significant improvements in vertebral anterior height, ODI, and Cobb angle. SEP monitoring correlated well with intraoperative findings and physical examinations. During reduction, changes in SEP latency and amplitude were noted in 37 patients, with 7 patients meeting SEP amplitude alarm criteria, which normalized after adjustments. During PVP, 28 patients exhibited SEP amplitude fluctuations and 5 experienced a 30% reduction in amplitude following initial cement injection, with no significant latency changes. Treatment was deemed effective in 93 patients and ineffective in 32. SEP amplitudes during vertebral compression and PVP were significantly lower in the effective group (P<0.05). The AUC for predicting treatment efficacy was 0.819 and 0.859, respectively. Multivariate analysis revealed low preoperative vertebral compression ratio, number of fractures, and abnormal SEP amplitudes as independent risk factors for treatment outcomes. SEP monitoring provides an accurate reflection of spinal cord function during closed reduction with PVP, aiding in predicting treatment safety and efficacy. The use of SEP monitoring is thus recommended for clinical application in this context.

Effects of Medications and Subthalamic Nucleus-Deep Brain Stimulation on the Cutaneous Silent Period in Patients With Parkinson's Disease

ObjectivesWe sought to evaluate whether the cutaneous silent period (CSP) could be an electrophysiological indicator reflective of the effects of therapy for Parkinson's disease (PD), including anti-PD medications or deep brain stimulation (DBS). Material and MethodsWe recorded the CSP in 43 patients with PD prior to and following the administration of medication during a pre-DBS evaluation (30 cases) and the “on” and “off” states of subthalamic nucleus DBS (13 cases). The CSP was elicited from the abductor pollicis brevis muscle by an electrical stimulation of the index finger that was 2, 4, and 15 times stronger than the sensory threshold (ST). We measured changes in latencies, including the onset, duration, and end of CSP, and waveform scores from 0 to 3. The correlation between the CSP score and unified PD rating score part III (UPDRS-III) also was assessed. ResultsThe onset latency and duration of CSP were significantly different between high- (15ST) and low-strength stimulations (2ST and 4ST). However, there were no significant latency changes (onset, duration, end of CSP) before and after receiving medication, or during the on and off state of the DBS. Anti-PD medications substantially increased the CSP waveform score only in the 4ST state. However, the waveform score significantly increased in all stimuli states during the DBS-on state. Both medication and the DBS-on state decreased the UPDRS-III. Nevertheless, there was no statistically significant correlation between the UPDRS-III and CSP waveform scores. ConclusionDifferent onset latencies and the duration of CSP between low- and high-strength stimuli support the hypotheses proposing two different reflex pathways. Despite being independent from the UPDRS-III, the CSP may be an electrophysiological indicator reflective of the changes in inhibitory activity to the spinal α-motoneuron in response to anti-PD medications and DBS.

The Effect of Cold on the Trigeminal Reflexes

Objective: Effects of muscle cooling on the spinal stretch and monosynaptic reflexes have been studied to describe the properties of Group I and II afferents of muscle spindles. Masseter muscle differs from extremity muscles in structural and numerical features of the muscle spindles. The aim of this study was to examine the muscle spindle afferent features of masseter muscle by applying cold to understand the role of Group I and II afferents in reflexes of masseter. Patients and Methods: We included 12 healthy subjects (7 females and 5 males) in the study. Masseter inhibitory reflex (MIR), jaw tendon reflex (JTR), trigeminal motor evoked potential (MEP), and trigeminal somatosensory evoked potential (SEP) were studied before and after cold application. Left masseter muscle was cooled down to 18°C. We compared the data obtained before and after cold application. Results: After cold application, the mean total duration of MIR was shortened and it was absent in four subjects. The mean amplitude of JTR was higher after cold application (P = 0.018) without any significant change in latency. The mean latency of MEP was delayed without any change in amplitude (P = 0.003). There was no significant difference in SEPs. Conclusions: Changes observed in MIR, JTR, and MEP could not be ascribed to any specific type of muscle spindle afferents. Delayed mean reflex latencies were attributed to the effect of cold on nerve conduction. Summation of peripheral cold and pain receptor features, spindle afferents, and cortical mechanisms might have caused cold-associated changes.

Latency of Multifocal Visual Evoked Potential in Multiple Sclerosis: A Visual Pathway Biomarker for Clinical Trials of Remyelinating Therapies.

Acute focal demyelination is the characteristic feature of multiple sclerosis, with the majority of damaged axons undergoing limited remyelination and forming chronic lesions. Potential remyelinating agents are currently under development and there is therefore an urgent need for reliable in vivo biomarkers of remyelination. This study aimed to investigate potential changes in multifocal visual evoked potentials' (mfVEPs) latency in a cohort of relapsing-remitting multiple sclerosis (RRMS) patients. The potential sample size required for a remyelination-based clinical trial using different treatment effect sizes and the mfVEP latency as an outcome measure was also estimated. A total of 50 RRMS consecutive patients with no previous history of optic neuritis in at least one eye and 15 normal controls of similar age and gender composition were prospectively enrolled. Fifteen patients had a history of unilateral ON more than 12 months earlier, whereas 41 patients demonstrated optic radiations lesions on MRI at baseline. Most patients were on disease modifying therapy. A mfVEP was recorded at baseline and 12 months later. At baseline, the mfVEP latency in RRMS patients was delayed compared with normal controls in both optic neuritis and nonoptic neuritis eyes. Latency delay was significantly correlated to optic radiation lesion volume (R2 = 0.38, P < 0.001). There was no significant latency change in multiple sclerosis patients' eyes or optic neuritis and nonoptic neuritis eyes over the follow-up period with latency remaining remarkably constant. This was despite the fact that 46 of 50 patients were on disease-modifying therapies, implying current treatments do not affect myelination in chronic RRMS cases. Sample size calculations to evaluate an additional or alternative remyelinating agent, based on a 40% treatment effect, revealed that a relatively small sample size (78 patients) would be required to demonstrate efficacy in future trials of remyelination therapies. Given its known sensitivity for latency changes and the stability found in this RRMS population, the mfVEP represents an ideal biomarker to assess the degree of latency recovery that may be achieved by remyelination in multiple sclerosis.

The Effect of Recording Montage and Tone Burst Duration on Cervical and Ocular Vestibular Evoked Myogenic Potential Latency and Amplitude.

Objectives The objectives of this study were (a) to investigate the optimal tone burst duration when recording the cervical vestibular evoked myogenic potential (cVEMP) and the ocular vestibular evoked myogenic potential (oVEMP) and (b) to determine whether monopolar recording influences the latency or amplitude of the cVEMP or the oVEMP. Method Fifteen subjects ( M = 27.7 years, SD = 6.73 years) participated in this study. The participants had no prior history of otological or neurological disease. Both oVEMPs and cVEMPs were recorded at a fixed stimulus level for stimulus durations of 2, 5, 10, and 25 ms. For both cVEMP and oVEMP, responses were obtained using a traditional differential recording montage and a monopolar recording montage. Results The cVEMP and the oVEMP had the greatest amplitude in the 2-ms stimulus condition. There was a statistically significant decrease in amplitude for durations greater than 2 ms. Monopolar and bipolar cVEMP and oVEMP latencies and amplitudes were not significantly different. Conclusion As stimulus duration increased beyond 2 ms, the amplitude of the response decreased for both the cVEMP and the oVEMP. There was no significant change in latency with increasing stimulus duration for either response. These results suggested the optimal stimulus duration for both the oVEMP and cVEMP is 2 ms, and there is no apparent advantage of using a bipolar recording technique.

Somatosensory evoked potential changes and decompression timing for spinal cord function recovery and evoked potentials in rats with spinal cord injury

ObjectiveThe study aimed to evaluate changes of somatosensory evoked potentials and the effects of decompression timing on spinal cord recovery and evoked potentials by measuring the somatosensory evoked potentials of rats with spinal cord injury at different time points. MethodsA total of 70 SD rats were divided into the control group (group A) and the experimental group. The experimental groups included group B–D according to the severity of spinal cord injury. Somatosensory evoked potentials were evaluated in the 4 study groups after the spinal cord was opened and spinal anesthesia. Continuous operations were performed to establish the rat models of spinal cord injury until surgical trauma was detected for stable somatosensory evoked potentials. The somatosensory evoked potentials of rats were determined before injury, and 5 min, 1 and 6 h, 3 and 7 days after injury. Evoked potentials were measured before decompression, and 5 min, 1 and 6 h, 3 and 7 days after decompression in the rat models. Latency and amplitude were determined. ResultsThere was no significant change in latency and amplitude of somatosensory evoked potentials before and after anesthesia and operation in the control group (P > 0.05). At 1 and 6 h after spinal cord injury, the more severe the spinal cord were hit, the more significant extension and decreases were observed in latency and in amplitude, respectively. Significant changes were identified in latency and vibration amplitude at 5 min after spinal cord injury in group B, C, and D than before injury with even more obvious changes in amplitude. The latency and amplitude of the somatosensory evoked potentials in the control group and each spinal cord injury group had great difference before increasing the spinal cord injury. The rats in the 30-minute compression group had significant longer latency than those in other groups after 7 days of compression; the somatosensory evoked potential amplitude recovered faster in rats with less time for compression. The wave amplitude was significantly lower in rats with 30 min’ compression than that in the other groups after 7 days. ConclusionsSomatosensory evoked potential can well reflect the severity of spinal cord injury. The longer the spinal cord was compressed, the more significant were changes in somatosensory evoked potential. Changes in the amplitude of somatosensory evoked potential following spinal cord injury are more sensitive than latency changes for early diagnosis and prompt assessment of spinal cord injury.

Haloperidol-induced parkinsonism is attenuated by varenicline in mice.

Background Parkinson's disease (PD) is a neurodegenerative disorder of the central nervous system (CNS). However, there is no known drug to stop/slow down this neurodegeneration. Varenicline is an anti-smoking drug and has the potential to prevent neurodegeneration. Thus, the present study was designed to evaluate the effect of varenicline in animal models of PD. Methods Levodopa and haloperidol were administered in doses of 30 and 1 mg/kg, intraperitoneally (i.p.), respectively. Group 1 was administered haloperidol; groups 2, 3 and 4 were administered haloperidol along with varenicline in doses of 0.5, 1.5 and 2.5 mg/kg, i.p., respectively and group 5 was administered levodopa along with haloperidol. Varenicline was administered daily, 30 min prior to the administration of haloperidol. Varenicline was administered for the first 8 days, and then from the 9th day until the 15th day. Behavioral assessment (rotarod and catalepsy tests) was performed on days 9 and 15. Assessment of striatal dopamine levels and histopathology were also performed. Results In the haloperidol-treated groups, significant decrease in latency to fall off (on rotarod) and increase in catalepsy duration (in catalepsy test) were observed as compared to the control group. In the levodopa-treated group, significant increase in latency to fall off the rotarod and significant decrease in catalepsy duration were observed as compared to the haloperidol-treated groups. Further, on day 9, varenicline (2.5 mg/kg) significantly increased the latency to fall off the rotarod, while varenicline (0.5 and 1.5 mg/kg) did not cause any significant change in latency to fall off the rotarod as compared to the haloperidol-treated group. On day 15, significant increase in latency to fall off the rotarod was observed in varenicline (at all doses) as compared to the haloperidol-treated group. In the catalepsy test, the varenicline-treated (at all doses) groups showed significant decrease in duration of catalepsy on day 9 and day 15 as compared to the haloperidol-treated group. Significant decrease in striatal dopamine levels was observed among the haloperidol-treated groups as compared to the control group. Further, varenicline-treated (at all doses) and levodopa-treated groups showed significant increase in striatal dopamine levels when compared with the haloperidol-treated group. In histology, varenicline (0.5 mg/kg) showed moderate decrease in neurons, while varenicline (1.5 and 2.5 mg/kg) showed mild decrease in neurons. However, the levodopa-treated group did not show any significant decrease in neurons. Thus, varenicline has shown promising results and has provided novel strategy for the treatment of PD.

Comparison of Wave V Latencies of Auditory Brainstem Responses by Bone Conduction and Air Conduction in Normal Hearing Infants and Toddlers

Received May 18, 2015 Revised July 10, 2015 Accepted July 20, 2015 Address for correspondence SungHee Kim, MD, PhD Department of OtolaryngologyHead and Neck Surgery, Daegu Fatima Hospital, 99 Ayang-ro, Dong-gu, Daegu 41199, Korea Tel +82-53-940-7350 Fax +82-53-940-7352 E-mail sungheekim@fatima.or.kr Background and ObjectivesZZBone conduction (BC) auditory brainstem response (ABR) is an important factor in determining the type of hearing loss especially in infants and other difficult-to-test populations. However, multiple constraints including technical difficulties make evaluating BC ABR less feasible in the clinic, and there is also lack of information that guides clinicians how to evaluate it. The purpose of this study is to compare the latency of wave V in BC and air conduction (AC) ABR in normal hearing infants and gather reference values for wave V latency of BC ABR. Subjects and MethodZZA total of 210 ears of normal hearing, of those not belong to the hearing loss risk group, were included. All the infants underwent ABR evoked by clicks via AC (3A insert phone) and BC (Radioear B-71, vibrator positioned on the mastoid) under sedation. The latency of wave V at 30 dB nHL by BC and AC was compared and analyzed according to age. ResultsZZThe results revealed that in every age group in the study, wave V latency at 30 dB nHL of BC ABR was shorter than that of AC ABR. There was a significant decrease in BC and AC latencies with age, but among each consecutive age group, significant latency change was not identified after 6 months old. ConclusionZZThe latency of BC ABR in young children was shorter than that of AC ABR, and it decreased significantly as age increased. However, the reference data should be considered by taking each laboratory’s test parameter into consideration. Korean J Otorhinolaryngol-Head Neck Surg 2015;58(10):676-81

Effect of Joint Traction and Approximation on H- Reflex in Normal Subjects

Introduction : Proprioceptive sensation (kinaesthesia and/or joint position sense), one of the most important somatosensory modalities, is known to play an important role in body balance and motor control. Joint traction and approximation are two proprioceptive stimuli applied at the joint. Studies reveal that an unidentified set of muscle afferent fibres and cutaneous receptors both contribute to the sense of movement and position. The Hoffmann reflex (H- reflex), an electrically evoked monosynaptic reflex, is a measure of the final common pathway, or the motor output. Objective : To find out the effect of traction and approximation on H-reflex. Method : Study performed on 20 normal subjects both males and females taken from the city Anand under the age group of 19-26 years. This is an experimental study, which is performed in the clinic of physiotherapy. The subject was made to lie prone comfortably on a plinth. The tibial nerve was stimulated at the popliteal fossa using 1 ms pulse and then finds H- latency and amplitude of Hwave. The subject was made to stand on the wooden board with same electrode arrangement to approximate the articular surfaces of the knee joint. The procedure was repeated to find H- latency, and amplitude of H- wave. The subject was made to sit on the stool with same electrode arrangement and right leg hanging freely off the stool. A 2 kg weight was tied at the ankle to distract the knee joint. The procedure was repeated to find H- latency, and amplitude of H- wave. Results : There is significant difference in H-reflex latency and amplitude in prone, joint traction and approximation. Conclusion : There is significant change in latency with proprioceptive input.

Effect of different stimulus configurations on the visual evoked potential (VEP)

The purpose of this study was to assess changes in the response profile of the pattern visual evoked potential (VEP) using three stimulus configurations simulating visual-field scotomas: central circular and central blank fields increasing incrementally in diameter from 1° to 15°, hemi-field, and quadrant patterns. Five visually normal adult subjects (ages 22-68 years) were tested binocularly at 1 m for each stimulus configuration on 5 separate days. A checkerboard test pattern (64 × 64 black-and-white checks, 85% contrast, 64 cd/m(2) luminance, 20 s of stimulus duration, 2-Hz temporal frequency) was used. The group mean VEP amplitude increased in a linear manner with increase in the central circular diameter (y = 0.805x + 2.00; r = 0.986) and decrease in central blank field diameter (y = -0.769x + 16.22; r = 0.987). There was no significant change in latency in nearly all cases. The group mean coefficient of variability results indicated that the VEP amplitude was repeatable for the different stimulus configurations. The finding of VEP response linearity for the circular stimulus fields, and repeatability for all stimulus configurations, suggests that the clinician may be able to use the VEP technique with the suggested test patterns as a rapid and simple tool for objective assessment for several types of visual-field defects for a range of abnormal visual conditions and special populations.

Laser acupuncture - innovative basic research: visual and laser-induced evoked potentials

Laser acupuncture is a therapeutic medical method. Innovative basic research is necessary within this fascinating area of research. This publication focuses on visual evoked potentials (VEP) elucidated by non-invasive and partially non-perceptible laser stimulation. Materials (Subjects) and Methods: The first part of this study presents systematic VEP-monitoring in connection with laser acupuncture and manual needle acupuncture in 40 healthy volunteers. The second part deals with bilateral non-perceptible laser needle (658 nm, 40 mW, 500 µm, 1 Hz) irradiation of the Neiguan acupoint (PC6) in a 26-year-old female healthy volunteer using a new 32-channel evoked potential analysis technique. We were not able to find significant changes in latency or amplitudes of VEPs during laser acupuncture within the first part of the study. However in the second part we report about human cerebral evoked potentials after non-perceptible laser stimulation. The findings indicate that exposure to laser needle stimulation with a frequency of 1 Hz can modulate the ascending reticular activating system. Further studies are necessary to confirm or refute the very interesting findings.

Chronic Inhibition of Central Angiotensin-Converting Enzyme Ameliorates Colchicine Induced Memory Impairment in Mice

Preclinical and clinical studies indicated involvement of the central renin-angiotensin system (RAS) in memory functions. However, the role of central angiotensin-converting enzyme (ACE) in memory function is still unclear. The present study investigated the involvement of central ACE in colchicine-induced memory impairment in the context of cholinergic function and oxidative stress. Memory impairment was induced by intracerebral colchicine administration in mice. The ACE inhibitor, perindopril (0.05 and 0.1 mg/kg/day), was administered orally for 14 days. Memory function was evaluated by the Morris water maze (MWM) test from the 14th day on after colchicine injection. Donepezil was used as a standard. Parameters of oxidative stress and cholinergic function, ACE activity in serum and the brain were estimated after the completion of behavioral studies. Colchicine caused memory impairment as revealed by no significant change in latency to reach a hidden platform in the MWM test. Furthermore, there was a significant increase in MDA, ROS, and nitrite levels with a reduction in GSH level and acetylcholinesterase (AChE) activity in the brain of colchicine-treated mice. Colchicine significantly increased brain ACE activity without affecting serum ACE. Donepezil prevented colchicine-induced memory impairment in mice. The antidementic effect of perindopril may be attributed to reduced oxidative stress and improvement in cholinergic function. Moreover, the elevated brain ACE activity was also inhibited by perindopril. The study showed that central ACE plays an important role in colchicine-induced memory deficit, corroborating a number of studies that show that treatment with ACE inhibitors could be neuroprotective.

Effects of Isolated Hyperinsulinaemia on Sensory Function in Healthy Adults

Gastrointestinal symptoms such as pain, bloating, nausea and vomiting are more frequent in pre-diabetic states as well as established diabetes, compared to healthy individuals. The mechanisms behind these symptoms are multi-factorial and complex. Furthermore, the effect of isolated hyperinsulinaemia on visceral and peripheral sensory function is poorly understood. Thus, the current study aimed to evaluate effects of acute hyperinsulinaemia on sensory function in healthy adults. The sensitivity to electrical oesophageal and median nerve stimulation was assessed in 15 healthy volunteers together with recording of evoked brain potentials. All subjects were studied both fasting and using a euglycaemic hyperinsulinaemic clamp. There was on average a 15% increased sensitivity to oesophageal electrical stimulation during hyperinsulinaemia compared to fasting state (P<0.05), but the sensation after median nerve stimulation remained stable (P=0.58). No significant changes in latencies and amplitudes of evoked brain potentials were observed after oesophageal or median nerve stimulation (all P>0.05). This study suggests that acute isolated hyperinsulinaemia increases visceral sensitivity, but does not influence the somatic sensory function. The lack of changes in the evoked brain potentials may indicate that hyperinsulinaemia affects the visceral sensory system at a peripheral level. Our result suggests distinct functions of insulin in the various parts of the nervous system, and yields further clues to the significance of insulin as a satiety signal.

The effects of fexofenadine at steady-state on sleep architecture: a study using polysomnography in healthy Korean volunteers

Objectives: To compare the effects of a first-generation antihistamine, chlorpheniramine, with those of the second-generation antihistamine, fexofenadine, at steady-state, on nocturnal sleep architecture in healthy Korean volunteers using polysomnography and the Multiple Sleep Latency Test. We evaluated whether a genetic polymorphism of multi-drug resistance 1 gene (MDR1) could produce variations in pharmacokinetic and pharmacodynamic parameters of fexofenadine. Design/methods: Ten healthy male volunteers received one capsule of fexofenadine 180 mg once each morning or chlorpheniramine 6 mg (2 mg in the morning and 4 mg after 12 h) for 3 days, in a single-site, randomized, double-blind, two-treatment, multiple-dosing, two-way crossover study, with a washout period of 7 days. Overnight polysomnography was measured on the second night of the treatment period. The Multiple Sleep Latency Test was carried out the next morning. Blood samples were taken for the assessment of fexofenadine pharmacokinetics and MDR1 genotyping on the third day. Results: Compared with baseline and fexofenadine, chlorpheniramine significantly increased the latency in rapid eye movement (REM) sleep, with no significant decrease in the percentage of REM sleep. No significant change in latency for REM sleep or percentage REM sleep after dosing with fexofenadine was observed. There was no significant change in the daytime sleepiness with fexofenadine and chlorpheniramine. The effects of MDR1 genotypes and haplotypes on the pharmacokinetics and pharmacodynamics of fexofenadine were not significant. Conclusions: Our findings suggest that fexofenadine and chlorpheniramine at steady-state have no significant effect on nocturnal sleep variables and daytime sleepiness, when compared to baseline.

The Role of Piriform Cortex Adenosine A1 Receptors on Hippocampal Kindling

The hippocampus and piriform cortex have a critical role in seizure propagation. In this study, the role of adenosine A1 receptors of piriform cortex on CA1 hippocampal kindled seizures was studied in rats. Animals were implanted with a tripolar electrode in the right hippocampal CA1 region and two guide cannulae in the left and right piriform cortex. They were kindled by daily electrical stimulation of hippocampus. In fully kindled rats, N6- cyclohexyladenosine (CHA; a selective adenosine A1 receptors agonist) and 1,3-dimethyl-8-cyclopenthylxanthine (CPT a selective adenosine A1 receptor antagonist) were microinfused into the piriform cortex. The animals were stimulated at 5, 15 and 90 minutes (min) after drug injection. Obtained data showed that CHA (10 and 100 microM) reduced afterdischarge duration, stage 5 seizure duration, and total seizure duration at 5 and 15 min after drug injection. There was no significant change in latency to stage 4 seizure. CPT at concentration of 20 microM increased afterdischarge duration, stage 5 seizure duration, and total seizure duration and decreased latency to stage 4 seizure at 5 and 15 min post injection. Pretreatment of rats with CPT (10 microM), 5 min before CHA (100 microM), reduced the effect of CHA on seizure parameters. These results suggested that activity of adenosine A1 receptors in the piriform cortex has an anticonvulsant effect on kindled seizures resulting from electrical stimulation of the CA1 region of the hippocampus.

Effect of a Whole-Body Vibration Session on Knee Stability

The aim of the study was to investigate the effect of WBV on stretch reflexes involved in knee joint control. We evoked stretch reflexes of the hamstring muscles by inducing an anterior tibial translation during standing in 23 healthy subjects which were divided into a control and an intervention group. WBV with a frequency of 30 Hz and a vertical amplitude of 4 mm was induced by an uniformly oscillating platform. The WBV session lasted 60 seconds and was repeated twice. Short (SLR) and medium latency responses (MLR) of the hamstring muscles and maximum tibia translation were assessed using surface EMG and linear potentiometers. While there were no significant changes in latency, the size of the lateral and medial hamstring SLR was significantly increased after WBV (p = 0.039 and p = 0.043, respectively). No significant differences were found for the hamstring MLR size after WBV. Maximum tibial translation was significantly decreased after WBV (p = 0.031). Our results suggest that single WBV exposure has a positive effect on knee joint stability as a short-term adaptation on neuromuscular level. This appears to be directly associated with an increase of hamstring SLR size in response to the anterior tibial movement which may cause the decrease in anterior tibial translation.

The effect of post prandial glucose changes on oscillatory potentials in subjects with type 2 diabetes mellitus

To investigate the effect of elevated plasma glucose levels on oscillatory potentials (OPs) in patients with diabetes mellitus. 15 patients with type 2 diabetes mellitus, with no ophthalmoscopically visible signs of diabetic retinopathy (NDR), were recruited, mean (SD) age 65.1 (10.91) years and duration 5.95 (4.95) years. Plasma glucose levels and OPs were recorded before, during and after a meal tolerance test (MTT), at times 0, 90 and 210 min. OPs were recorded following 5 min adaptation to a blue mesopic background (1.17 cd m(-2)), and elicited using a white 5 ms stimulus flickering at 5 Hz frequency over the blue background. Plasma glucose increased significantly from 0 to 90 min during the MTT. This corresponded with an increase in mean amplitude of OP1-4, and a significant increase in the summed amplitudes. Summed OP amplitudes were 14.52 microv and 18.38 microv at time 0 and 90 min respectively. Between times 90 and 210 min plasma glucose levels decreased significantly back to baseline. OP1 and OP2 amplitudes increased slightly and OP3 and OP4 amplitudes decreased markedly, resulting in a non-significant reduction of the summed amplitudes. No significant changes in latencies were seen. Summed OP amplitudes, which are known to reflect the efficiency of the retinal circulation, increased with elevated plasma glucose. This effect was not immediately reversible. Latencies appear not to be affected.

Pharmacologic and physiologic influences affecting sensory evoked potentials: implications for perioperative monitoring.

Pharmacologic and physiologic influences affecting sensory evoked potentials: implications for perioperative monitoring.

Corticospinal function studied over time following incomplete spinal cord injury.

Longitudinal. (1) To perform standard clinical neurological examinations and establish the pattern of clinical change with time following incomplete spinal cord injury (iSCI). (2) To establish the pattern of change in corticospinal electrophysiological function with time after iSCI. (3) To correlate clinical with electrophysiological findings. The National Spinal Injuries Centre, Stoke Mandeville Hospital, Aylesbury, UK and Imperial College School of Medicine, Charing Cross Hospital, London, UK. Neurological assessments and classification were performed according to American Spinal Injuries Association and International Medical Society of Paraplegia (ASIA/IMSOP) standards. Twenty-one patients (ages 18 - 72 years) with iSCI (level C2 - C7, ASIA impairment grades C - D) and 10 healthy control subjects (ages 27 - 57 years) were studied. Electrophysiological tests of corticospinal function were carried out using transcranial magnetic stimulation (TMS) of the motor cortex and electromyographic (EMG) recordings from thenar muscles. Both tests were performed on a number of occasions, beginning 19 - 384 days and ending 124 - 1109 days post-injury, and the group data were pooled into time epochs of 50 or 100 days post-injury for analysis. Seven of the patients were studied on seven or more occasions and were also assessed individually. Individual and pooled data indicated that neurological scores improved progressively and tended to stabilise by around 300 days post-injury. When the patients were first assessed, the mean latency for motor evoked potentials (MEPs) and inhibition of voluntary EMG were significantly different from control values. There was no significant change in latency on subsequent sessions for either the grouped or individual patient data. There was no correlation between clinical assessment and electrophysiological data. We conclude that the weakened inhibition seen following iSCI is established within a few days of the time of spinal cord trauma. We argue that reduced corticospinal inhibition may be a prerequisite for the recovery of useful motor function. The work was supported by a project grant from The Wellcome Trust.

Interactive ERP recording increases the amplitude of the endogenous P300 peak in schizophrenia

The P300 is a long-latency cognitive event-related potential (ERP) elicited by the presentation of relevant target stimuli. Unfortunately, the standard ERP recording technique takes no account of the background EEG during stimulus presentation. However, a recently developed technique (interactive recording) controls for variability in the EEG by applying stimuli only when the background EEG is in a predetermined state. The use of the interactive technique has led to significant changes in the P300 amplitude in control studies. Since P300 amplitude data are commonly used in schizophrenia research, and have previously been associated with cognitive deficits in schizophrenia, we studied the effects of interactive recording in a schizophrenia population. The same ERP paradigm was implemented twice for each subject, using both standard ERP and the interactive recording techniques. There was a significant increase in the amplitude of the P300 peak with interactive recording, although no significant change in latency. The results indicate that the effect of background EEG may need to be taken into account when conducting general ERP-based studies in schizophrenia. The results also indicate that the method may be used to investigate the effects of EEG variation on ERP values and, by implication, on cognitive processes. In particular, the recognition of EEG states that lead to a higher amplitude ERP value may aid in the further development of EEG investigations of schizophrenia. A similar development is indicated between cognitive research in schizophrenia and the sub-second brain-states in which cognitive function may be reflected.