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Cortical-evoked potentials from deep brain stimulation
Published in Hans O Lüders, Deep Brain Stimulation and Epilepsy, 2020
Kenneth B Baker, Erwin B Montgomery
Exogenous-evoked potentials are useful for helping to identify functional connections or pathways within the nervous system and, as an extension of the clinical examination, can provide an objective measure of the integrity of those pathways. The focus of the typical, short-latency clinical-evoked potential examination is to study neural conduction along well-understood sensory pathways in an effort to detect the presence of clinical abnormalities. For the most part, however, such studies in humans are limited to accessible pathways and typically are evoked by stimulation of the extremes of a given subsystem (i.e. sensory receptors, peripheral nerves). Basic science takes advantage of concepts similar to the evoked potential in the form of, for example, peri-event rasters or histograms, which are based on the time-locked effects of some behavior or evoking event on neuronal activity. Using non-human animal models, investigators are able to explore various regions of the brain directly, deriving information pertaining to the nature of the interconnectiv-ity and dynamics between those regions. Unfortunately, our ability to apply such direct techniques, whether based on micro- or macrolevel recordings, specifically for the purpose of exploring functional cortico- subcortical networks is typically quite limited in humans.
Clinical Test Paradigms and Problems: Human Otoprotection Studies
Published in Stavros Hatzopoulos, Andrea Ciorba, Mark Krumm, Advances in Audiology and Hearing Science, 2020
Colleen G. Le Prell, Kathleen C. M. Campbell
To optimize the assessment of such agents in clinical trials and select appropriate drug interventions for patients (once such drugs are approved), it will be critically important to be able to precisely diagnose the specific pathology driving a patient’s functional deficits. This issue was noted by Staecker et al. (2016) in their discussion of clinical trials for agents that induce OHC regeneration. In those cases where audiometric threshold sensitivity is the primary outcome (i.e., the clinical gold standard), ABR wave I or AP threshold could be considered for use as objective metrics that would supplement and confirm the improvements measured during conventional audiometric threshold testing. Evoked potential thresholds have also been suggested as appropriate for monitoring in patient populations that are not able to participate in behavioral testing due to attention issues or illness, or side effects of therapeutic drugs, such as cisplatin and the aminoglycoside antibiotics [for review, see Campbell and Le Prell (2018)].
Monitoring Disease Activity in Multiple Sclerosis
Published in Richard K. Burt, Alberto M. Marmont, Stem Cell Therapy for Autoimmune Disease, 2019
The use of evoked potentials for monitoring disease activity has been controversial. Many studies supporting their use were performed before the widespread availability of MRI.45,46 Multimodality (visual, brainstem and median somatosensory evoked potentials) were used in a clinical trial of azathioprine. A statistically significant difference in EP stability was evident with one treatment, not evident with placebo or the other treatment arm. A similar pattern was seen in the clinical examination, but did not reach statistical significance.45 Correlation between clinical and evoked potential abnormalities has been poor in other studies.47 Visual evoked potentials, generally easy to perform and well tolerated, may be the most sensitive evoked potential for therapeutic trial.45 Further consideration of EPs for clinical trial may be dependent on the specific question of the clinical trial. For example, visual evoked potentials (VEPs) may be most useful in assessing therapy aimed at treating or stabilizing visual loss. Most large trial do not incorporate evoked potentials because MRI has been considered superior to quantify extent of disease, including “silent disease,” which traditionally was detected by evoked potentials.
Transverse myelitis associated with primary biliary cirrhosis: clinical, laboratory, and neuroradiological features
Published in International Journal of Neuroscience, 2022
Mangsuo Zhao, Mingjie Zhang, Shimei Zhou, Bingxin Shi, Yan Wei, Fangjie Huang, Jing Wang, Jingfeng Huang, Liyan Qiao
On laboratory workup, the results of routine blood tests, urine test, stool analysis, and measurements of liver, renal, and thyroid functions, homocysteine, folic acid, and vitamin B12 levels, and the erythrocyte sedimentation rate (ESR) were all within the normal limits. Anti-nuclear (ANA), anti-double-stranded DNA, anti-extractable nuclear antigen, and anti-neutrophil cytoplasmic antibodies were not found in the serum. The results of routine and biochemical tests of the cerebrospinal fluid (CSF) were normal. Oligoclonal bands (OB) were positive. Anti-AQP4 IgG was not detected in serum or CSF. Serum and CSF were negative for the following antibodies: anti-N-methyl-d-aspartic acid receptor, anti-contactin-associated protein-like 2, anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor 1 and 2, anti-leucine-rich glioma-inactivated 1, anti-gamma-aminobutyric acid B receptor, and anti-dipeptidyl-peptidase-like protein 6 for autoimmune encephalitis. As biomarkers of paraneoplastic syndromes, Hu (anti-neuronal nuclear antibody 1), Yo (Purkinje cell autoantibody, PCA1), Ri (anti-neuronal nuclear antibody 2), Ma2, CV2/CRMP5, and amphiphysin were not detected in serum or CSF. Magnetic resonance imaging (MRI) studies of the brain and spinal cord were performed. Abnormal enhancement of the spinal cord was observed at T8–T9, suggestive of incomplete TM (Figure 1). Brain MRI showed no obvious abnormalities. Visual evoked potential and brainstem auditory evoked potential were within the respective normal ranges. The P40 wave of the somatosensory evoked potential disappeared bilaterally.
Electrophysiological findings in specific language impairment: a scoping review
Published in Hearing, Balance and Communication, 2021
Animesh Barman, Prashanth Prabhu, V. G. Mekhala, Kavya Vijayan, Swapna Narayanan
There are studies which report that the difficulty faced by children with SLI could be related to subtle auditory perceptual problems or auditory agnosia [4]. It has been proposed that specific language impairment is the consequence of low-level abnormalities in auditory perception [1]. A deficit in the ability to perceive rapidly changing temporal (on the order of milliseconds) and spectral characteristics of speech results in an unstable or blurred representation of speech sound (phoneme) in the brain. These unstable phoneme representations could impact speech perception and the language learning abilities of phonology, syntax, or semantics [5,6]. Previously conducted research has shown that there is an underlying neurobiological cause for SLI with subtle deficits in information processing [7]. Some studies also point out that the difficulty faced by children with SLI could be similar to the problems seen in individuals with neuro-audiological abnormalities [4]. Thus, electrophysiological studies assessing the auditory structures for possible functional abnormality in children with SLI are essential. The electrophysiological studies can highlight the subtle auditory neural deficits which might in turn affect the expressive and receptive language in children. A fine-grained analysis of the brain’s response to auditory input in millisecond range can be obtained through electrophysiological measures. Unlike speech and other behavioural auditory processing tests, auditory evoked potentials can be recorded regardless of a child’s developmental age or language, motivation or attention level [8].
Developing therapeutic strategies to promote myelin repair in multiple sclerosis
Published in Expert Review of Neurotherapeutics, 2019
Laura E. Baldassari, Jenny Feng, Benjamin L.L. Clayton, Se-Hong Oh, Ken Sakaie, Paul J. Tesar, Yanming Wang, Jeffrey A. Cohen
Evoked potentials are objective, noninvasive, in vivo electrophysiological measures that assess the function of the CNS sensory and motor pathways. Many of the symptoms in MS result from abnormal nerve impulse generation and axonal conduction resulting from demyelination [73]. Therefore, evoked potentials have been used as outcome measures in several recent remyelination trials. After standardized repetitive stimulus administration, the amplitude and latency of the resultant summated response in the corresponding tract can be quantified. Reduced amplitude reflects a decreased number of functional axons. Axonal demyelination results in both conduction delay (increasing latency) and block (reducing amplitude). Several evoked potential modalities can be measured in MS. VEPs assess functional integrity of the afferent visual pathways from the optic nerve to occipital cortex. Somatosensory evoked potentials (SSEPs) assess functional integrity of the sensory pathways from the upper or lower limbs to parietal cortex. Brainstem auditory evoked potentials assess conduction from the cochlea to temporal cortex. Motor evoked potentials (MEPs) assess motor pathways from motor cortex to target muscles.