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Toxicology
Published in Aruna Bakhru, Nutrition and Integrative Medicine, 2018
Case 4: A 57-year-old male engineer presented with personality changes, fatigue, and tremor. His wife describes unusual mood swings and hostility not previously present, over the past 6 months. The physical examination confirmed an intention tremor. The tremor was not found at rest and there was no Parkinsonian-type tremor. A neurological evaluation included a urinary heavy metal screen, which indicated marked elevated urinary mercury levels. No source could be found in investigating his workplace as he worked from home whereas his wife worked outside the home. There were no children involved. Eventually, elevated mercury levels were found in his home water supply. Criminal investigation found that mercury was being purposely added by a neighbor and an arrest was made. He responded to chelation therapy over time, as well as modification to his water supply.
Diagnosis and differential diagnosis of Parkinson’s disease
Published in Jeremy Playfer, John Hindle, Andrew Lees, Parkinson's Disease in the Older Patient, 2018
Tremor is an involuntary rhythmic oscillatory movement of a body part. Action tremor is any tremor that is present during voluntary contraction of muscle and includes postural and kinetic tremor. Postural tremor is seen with a sustained posture against gravity, e.g. arms outstretched. Kinetic tremor occurs during any movement. Intention tremor is a form of kinetic tremor and occurs when amplitude of tremor increases during visually guided movements towards a target at the termination of the movement. Resting tremor emerges maximally when a body part is not voluntarily activated and may be seen when a hand rests in the lap or dangles over an armrest. To be certain a tremulous limb is completely supported against gravity, the examiner may need to rest the patient on a bed or couch.
Discussions (D)
Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017
At times, however, even two types of tremor in a single patient may be described as one tremor. For example, DeJong writes that ““Occasionally the tremor of Parkinson’s disease is of both the intention and nonintention [= resting] type” (1979, p. 404). The following statement by Walton is ambiguous in this regard: “this tremor is generally abolished by movement, though occasionally in Parkinson’s disease an action tremor is present as well” (1975, p. 184). Though Walton mentions “an action tremor,” as if it is distinct from the static tremor, his phrasing suggests that the action tremor is really a continuation (nonabolishment) of the static tremor. Walton’s usage is also ambiguous in the following passage: “Intention tremor is virtually diagnostic of disease of the cerebellum or of its brain—stem connections.… Whereas the lesion, if severe, may give rise to some degree of static tremor, this invariably becomes very much worse towards the end of movement. … (p. 185).
Advances in the understanding of hereditary ataxia – implications for future patients
Published in Expert Opinion on Orphan Drugs, 2018
Anna Zeitlberger, Heather Ging, Suran Nethisinghe, Paola Giunti
The most common and only recently recognized adult-onset X-linked ataxia is fragile X-associated tremor/ataxia syndrome (FXTAS). The typical clinical presentation is characterized by intention tremor, gait ataxia, and Parkinsonism in combination with variable cognitive decline [46]. FXTAS is caused by what was previously considered as a premutation of 55–200 CGG·CCG repeats in the 5ʹ untranslated region of the FMR1 gene [46]. Similarly to SCA8, RAN translation results in the transcription of toxic proteins (FXTAS-polyglycine, FXTAS-polyproline, FXTAS-polyalanine) which have been detected in different brain regions [47]. In addition, the RNA-mediated sequestering of proteins has been described [48]. These pathological mechanisms are in contrast to the hypermethylation-associated silencing of the FMR1 gene in fragile X-syndrome [49].
Role of the Personal KinetiGraph in the routine clinical assessment of Parkinson’s disease: recommendations from an expert panel
Published in Expert Review of Neurotherapeutics, 2018
Rajesh Pahwa, Stuart H. Isaacson, Diego Torres-Russotto, Fatta B. Nahab, Peter M. Lynch, Katya E. Kotschet
Tremor is recognized as one of the cardinal symptoms of PD and occurs in approximately 75% of people with PD [42]. There are several forms of tremor associated with PD, and classification is based on the distinction between rest, postural, kinetic, and intention tremor [43]. The classic asymmetric, resting tremor of PD has a frequency of 4–6 Hz, is inhibited by movement and may re-emerge with posture. Postural/kinetic tremors are typically 1.5 Hz greater than rest tremor and there are also other postural and kinetic tremors in PD whose frequencies are between 4 and 9 Hz [43].
Deep brain stimulation programming strategies: segmented leads, independent current sources, and future technology
Published in Expert Review of Medical Devices, 2021
Bhavana Patel, Shannon Chiu, Joshua K. Wong, Addie Patterson, Wissam Deeb, Matthew Burns, Pamela Zeilman, Aparna Wagle-Shukla, Leonardo Almeida, Michael S. Okun, Adolfo Ramirez-Zamora
Several studies have analyzed LFP data from GPi and thalamic DBS collected from Tourette syndrome (TS) subjects. These studies have proposed potential electrophysiologic biomarkers [133–136]. The studies have identified low-frequency oscillatory activity (1–10 Hz) prior to and during motor tics. Algorithms for aDBS in TS have been proposed and studies assessing these algorithms are currently ongoing. A variation of aDBS using external data has also been applied for intention tremor in ET patients. Basu et al. demonstrated 100% sensitivity of tremor detection using surface EMG in both ET and PD with a 85.7% and 80.2% accuracy, respectively [137]. Yamamoto et al. examined the feasibility of an ‘on-demand’ stimulation trigger based on external EMG sensors in four ET patients [138]. In this study, four patients underwent surface EMG analysis, and the results revealed a consistent 3 Hz disabling intention tremor. A signal processor was programmed to turn on the DBS system externally when the 3 Hz power reached a trigger threshold and to turn off the DBS system when the 3 Hz power was below the threshold. The authors completely suppressed the intention tremor using this method. A similar pilot study utilizing external sensing aDBS was conducted in ten PD patients with STN-DBS [139]. Upper extremity tremor data was collected via a wearable smart watch. During a 30-minute trial, aDBS provided a mean improvement of 37% more tremor suppression than cDBS while requiring 48% less stimulation time and 76% lower stimulation voltage. Cabrera et al. highlight the potential use of electrochemical sensing to detect changes in neurotransmitters across diseases as a method to serve as a biomarker in a closed-loop DBS system [140]. Additional studies are still needed to determine the use, safety, and feasibility of electrochemical sensing.