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Metabolic Laboratory Data
Published in Michael M. Rothkopf, Jennifer C. Johnson, Optimizing Metabolic Status for the Hospitalized Patient, 2023
Michael M. Rothkopf, Jennifer C. Johnson
Hypomagnesemia is a very common problem in the hospitalized patient. Some studies suggest it occurs in 12% of general ward patients (Agus, 1999) and as much as 65% in the ICU (Tong, 2005). It manifests as neuromuscular excitability, including muscle spasms, tremor, tetany and convulsions. It can widen the QRS, peak the T-wave and prolong the PR interval.
Disorders of the nervous system
Published in Judy Bothamley, Maureen Boyle, Medical Conditions Affecting Pregnancy and Childbirth, 2020
The excitability of individual neurons is affected by cell membrane properties, genetics, cell structure, spontaneous brain lesions or those occurring as a result of injury as well as the balance of inhibitory and excitatory neurotransmitters. In simple terms, each person has a seizure threshold, which is the brain’s individualised level of sensitivity to seizures, and this sensitivity is probably genetically determined. People with epilepsy have a lower than normal seizure threshold.
Direct cortical electrical stimulation in the treatment of epilepsy
Published in Hans O Lüders, Deep Brain Stimulation and Epilepsy, 2020
Dileep R Nair, Riki Matsumoto, Hans O Lüders, Richard Burgess, William Bingaman
Another modality of electrical stimulation being studied in research settings is repetitive transcranial magnetic stimulation (rTMS). This has been described as inducing a lasting effect on reducing cortical excitability.6 There is evidence to suggest that using low frequency TMS applied to the brain can temporarily induce improvements in patients with intractable epilepsy.7
Adolf Kussmaul (1822–1902), and the naming of “poliomyelitis”
Published in Journal of the History of the Neurosciences, 2022
Nadeem Toodayan, Eric Matteson
In paralysis générale spinale antérieure subaiguë, [I]mmediately after the symptoms of paralysis have appeared, we find a very considerable reduction in the electromotoric excitability, indeed in some muscles the excitability for the strongest currents has disappeared, without the atrophy in them being particularly high. … Not so with progressive muscular atrophy [however, in which] we almost always see the decrease in electrical excitability keep pace with the atrophy of the affected muscle. … It is difficult to say in how far the fibrillar twitchings [referring to fasciculations], which are very frequently observed in progressive muscular atrophy and are hardly observed in paral. général, spin. antér. subaiguë can be used for the differential diagnosis.
Clinical care and therapeutic trials in PLS
Published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 2020
Mary Kay Floeter, Deborah Warden, Dale Lange, James Wymer, Sabrina Paganoni, Hiroshi Mitsumoto
Changes in cortical excitability and loss of cortical motor neurons are the basis of the clinical deficits in PLS. TMS has been used for more than 30 years as a means to test cortical excitability (32). There are several methods to assess motor cortex excitability. Resting motor threshold (RMT) is stimulus intensity needed to elicit motor responses in 50% or more of consecutive stimuli. An increased RMT or unresponsive motor cortex is present when there is no response recorded from a hand muscle when stimulating the motor cortex. For clinical trials, a reproducible change over time (in either direction, i.e. hyper or hypo excitable) would be a potential means for a validated measure of upper motor neuron deterioration or improvement. The cortical silent period (CSP) utilizes the fact that voluntary activity is inhibited after motor cortex stimulation and is measured from the onset of the motor evoked potential until the return of voluntary EMG activity. CSP is decreased in the hyper excitable motor cortex and increased in the inexcitable cortex. How these measures change with disease progression will dictate their utility in becoming a validated biomarker for UMN change in patients with PLS. Paired pulse studies are also used to measure cortical excitability and may be useful in measuring clinically relevant change (33,34).
Laser thermal therapy for epilepsy surgery: current standing and future perspectives
Published in International Journal of Hyperthermia, 2020
Ajmal Zemmar, Bradley J. Nelson, Joseph S. Neimat
In epilepsy, nerve cells of a seizure focus undergo sudden depolarization that triggers an uncontrolled chain-reaction of action-potential activation. The resulting discharge of neuronal ensembles together with dysfunctional inhibitory inputs manifests as a seizure. This spread may continue along axonal pathways intra-hemispherically on the same side of the brain or inter-hemispherically to contralateral regions. Causally, genetic, structural, metabolic, idiopathic or cryptogenic features lead to altered cellular properties and/or synaptic connections resulting in the above-mentioned imbalance between increased excitability and decreased inhibition. Anatomically, most seizures arise in the mesial aspect of the temporal lobe including the hippocampus, parahippocampal gyrus (PHG), amygdala and the entorhinal cortex. TLE is frequently associated with hippocampal sclerosis. As such, mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is a specific epilepsy constellation in the 2017 International League Against Epilepsy (ILAE) classification system portraying its critical role in seizures.