The Role of the SLP and Assistive Technology in Life Care Planning
Roger O. Weed, Debra E. Berens in Life Care Planning and Case Management Handbook, 2018
Evoked potentials refer to normal electrical activities of the central nervous system that occur in response to specific and controlled sensory stimulation. Whether the sensory stimulus is visual, somatosensory, or auditory, evoked brain responses are recorded using electrodes referred to the spinal cord, brain stem, and scalp. Visual evoked potentials are used to evaluate electrical conduction along the optic nerve, optic tract, lateral geniculate, optic radiations, and visual cortex. Somatosensory evoked responses are elicited by simulation of contralateral peripheral nerves. Clinical conditions in which somatosensory evoked potentials are of diagnostic value include multiple sclerosis, brain injuries, brain death, posterior column spinal cord lesions, and lesions of the peripheral nerves. Evoked response audiometry is the electrophysiological assessment of auditory functions. It measures changes in neural activity that occur in the auditory acoustic stimuli. Evoked response audiometry is used for assessing the functioning of the auditory neural pathway to predict hearing thresholds in patient populations that are difficult to test. In evoked response audiometry, the most commonly measured responses are the auditory brain stem responses (brain stem auditory evoked response).
Functional Near-Infrared Spectroscopy
Yu Chen, Babak Kateb in Neurophotonics and Brain Mapping, 2017
Anesthetized male Wistar rats will be implanted with a fixation device using dental cement, allowing the optic fiber to be near the occipital cortex. Additionally, stainless steel skull screws will be implanted through the skull into the visual cortex (7 mm behind the bregma and 3 mm lateral of the midline) as the positive electrodes. A reference screw electrode will be placed on the midline, 3 mm rostral to the bregma. Dental cement will also be used to fix the screws. One week after, the skin on the head is closed and the animal has recovered from the surgery. After correct signal amplification, filtration, and processing, to evaluate the correlation between the FOS and the electroencephalographic signal, we will evoke visual potentials to evaluate the function of the visual pathway. Light stimulation of the eye evokes visual electrical signals in the visual cortex. The visual potentials are analogous to auditory somatosensory evoked potential, which produce electroencephalographic cortical evoked potentials.
Cortical-evoked potentials from deep brain stimulation
Hans O Lüders in Deep Brain Stimulation and Epilepsy, 2020
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.
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.
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.
Variability across countries for brain death determination in adults
Published in Brain Injury, 2023
Fang Yuan, Huiping Li, Tao Pan, Wanxin Wen, Lixin Wang, Shibiao Wu
The general criteria of brain death determination in China, USA, UK, Germany and France were presented in Table 3. Irreversible coma with a known etiology, absence of brainstem reflexes, and cessation of spontaneous respiration are mandatory in criteria of all the countries. The duration of apnea test is five minutes in British criteria, eight to ten minutes in American and Chinese criteria, and unspecified in German and French criteria. For patients who fulfil clinical criteria of brain death, confirmatory tests are not mandatory in USA, UK and Germany. Chinese criteria stipulate that two of the three confirmatory tests (EEG, TCD and SLSEP) must be fulfilled, and French criteria require at least one confirmatory test for the diagnosis of brain death. EEG is accepted in all five countries. Evoked potential test is accepted in China, UK, Germany, but were not recognized in US and France. To determine cerebral blood flow, TCD is accepted in China, UK, and Germany, but US and France recognize more advanced examinations, such as angiography (Table 3). Examinations of cerebral metabolism are accepted in USA, UK and Germany, but are not mandatory. The diagnosis of brain death should be made by two independent raters in China, UK, Germany and France, whereas it is not specified in American guidelines. China is the only country that organizes state certification for brain death diagnosis.
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