China
Africa
Explore chapters and articles related to this topic
Movement disorders
Published in Henry J. Woodford, Essential Geriatrics, 2022
Essential tremor (ET) has an estimated prevalence of around 4% in people aged 65–74, 5% in those aged 75–84, and 7% in those aged 85 and over.143 Characteristically, it causes a tremor when maintaining a fixed body position (postural) or on movement (action). It does not usually cause a resting tremor, never causes the classic pill-rolling tremor of PD nor does it usually cause a tremor that worsens on approaching a target (intention), which is seen with cerebellar disorders. It may be confused with an exaggerated physiological tremor, which is seen with metabolic disorders (e.g. thyrotoxicosis and alcohol withdrawal) or medication-induced (e.g. sodium valproate, beta-agonists, cholinesterase inhibitors, lithium and antidepressants). Previously, the prefix ‘benign' was attached to ET. This was misleading. Some people may become severely disabled due to this disorder.
MRCPsych Paper A1 Mock Examination 4: Answers
Published in Melvyn WB Zhang, Cyrus SH Ho, Roger Ho, Ian H Treasaden, Basant K Puri, Get Through, 2016
Melvyn WB Zhang, Cyrus SH Ho, Roger CM Ho, Ian H Treasaden, Basant K Puri
Explanation: B2 antagonist is not associated with tremor but B2 agonist does. Amphetamine, B2 agonist and caffeine are associated with physiological tremor. Risperidone is associated with extrapyramidal side effects.
Essential Tremor – Deep Brain Stimulation vs. Focused Ultrasound
Published in Expert Review of Neurotherapeutics, 2023
Yuri Ferreira Felloni Borges, Cletus Cheyuo, Andres M Lozano, Alfonso Fasano
Essential Tremor (ET) is a progressive neurological disorder with a still undetermined pathophysiology, although several mechanisms have been hypothesized [1,2]. ET is the second most common tremor syndrome after enhanced physiological tremor [3,4], and is one of the most common movement disorders, which prevalence is around 0.5–5% [5], affecting about 0.9% of adults in general and 4% of adults older than 65 [1,2]. ET is currently known as a heterogeneous syndrome with several underlying etiologies [4]. Clinically, its main feature is the presence of a tremor, which is a hyperkinetic movement disorder defined as an involuntary, rhythmic, oscillatory movement of a body part [6,7]. In ET, this is typically a 4–12 Hz bilateral action (i.e. postural and/or kinetic) tremor, affecting mainly the upper limbs, but also head, voice, legs, and trunk [5,6,8–11]. ET has no impact on life expectancy, although, when severe enough, it can affect the quality of life (QoL), functional activities, mood, and socialization [12]. There is a high level of evidence that first-line medications propranolol and primidone reduce tremor by approximately 50–60% in 50–70% of patients with ET [9,13], while benzodiazepines and gabapentin have been suggested as second-line therapy [13]. Topiramate has now enough evidence to be considered a first-line medication.
Surgical treatments for essential tremor
Published in Expert Review of Neurotherapeutics, 2018
Rodger J. Elble, Ludy Shih, Jeffrey W. Cozzens
In this review, we computed αS for scales used in various studies by assuming α4 = 0.4, and with this value in Equation 2, we estimated the percentage change in tremor amplitude. This value of α4 is at the lower range of values reported, so estimates of efficacy in this review are conservative. A previous review using this methodology assumed α4 = 0.5 [10]. For α4 = 0.4 in Equation 2, a change in rating from 4 to 2 is an 84% reduction in tremor, and a change in rating from 2 to 1 is a 60% reduction. For α4 = 0.5 in Equation 2, a change in rating from 4 to 2 is a 90% reduction in tremor, and a change in rating from 2 to 1 is a 68% reduction. Note that the estimated percentage change in tremor will never be 100%, consistent with the reality that tremor is never completely abolished, for physiologic tremor always remains even when the pathologic tremor is abolished.
Using Corticomuscular and Intermuscular Coherence to Assess Cortical Contribution to Ankle Plantar Flexor Activity During Gait
Published in Journal of Motor Behavior, 2019
Peter Jensen, Rasmus Frisk, Meaghan Elizabeth Spedden, Svend Sparre Geertsen, Laurent J. Bouyer, David M. Halliday, Jens Bo Nielsen
Coherence at low frequencies (alpha band; 5–15 Hz) between pairs of motor unit populations has been reported previously for other muscles and other tasks, although corticomuscular coherence is generally not seen at such frequencies (Halliday et al., 2003; Petersen et al., 2012; Semmler, Sale, Meyer, & Nordstrom, 2004). This was also the case in the present study. One possibility is that this alpha band coherence is generated from the motor cortex similar to the coherence at higher frequencies as some studies have been able to detect significant corticomuscular coherence in the alpha range (Raethjen et al., 2002). There is also evidence of oscillatory activity in cerebellar-thalamus-motor cortex circuitries recorded by electrodes inserted for deep brain stimulation during surgery (Marsden, Ashby, Limousin, Rothwell, & Brown, 2000). This oscillatory activity, which is likely related also to physiological tremor, may be transmitted via the motor cortex or other descending tracts to the spinal motor neurons and cause the observed coherence between the motor unit populations (McAuley, Rothwell, & Marsden, 1997). In all likelihood this requires oscillatory activity in the alpha frequency band of last order neurons with branches to both populations of motor units similar to what has been shown for coherence at higher frequencies (Conway et al., 1995). The failure to detect corticomuscular coherence in the alpha band in this and other studies may also suggest that the circuitries, which are responsible for generating the intermuscular coherence in the alpha band involve a more indirect pathway from the motor cortex than the pathways responsible for coherence at higher frequencies. Other sources that influence corticospinal coherence include spinal interneurons. Matsuya and colleagues reported a close connection between recurrent inhibition and peak soleus corticomuscular coherence during a maintained plantarflexion. They thus reported a positive correlation between the amount of corticospinal coherence between Cz EEG and SOL and the level of recurrent inhibition indicating that spinal mechanisms indeed modulate the corticomuscular coherence. In the present study, the source of the oscillatory activity cannot be isolated and both cortical and spinal mechanisms most likely contribute and modulate the observed coherence (Matsuya, Ushiyama, & Ushiba, 2017).