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Hybrid learning control for improving suppression of hand tremor

As'arry A, Md Zain MZ, Mailah M, Hussein M

Proc Inst Mech Eng H, 2013 Nov;227(11):1171-80.
PMID: 23901066 DOI: 10.1177/0954411913494325

Patients with hand tremors may find routine activities such as writing and holding objects affected. In response to this problem, an active control technique has been examined in order to lessen the severity of tremors. In this article, an online method of a hybrid proportional-integral control with active force control strategy for tremor attenuation is presented. An intelligent mechanism using iterative learning control is incorporated into the active force control loop to approximate the estimation mass parameter. Experiments were conducted on a dummy hand model placed horizontally in a tremor test rig. When activated by a shaker in the vertical direction, this resembles a postural tremor condition. In the proportional-integral plus active force control, a linear voice coil actuator is used as the main active tremor suppressive element. A sensitivity analysis is presented to investigate the robustness of the proposed controller in a real-time control environment. The findings of this study demonstrate that the intelligent active force control and iterative learning controller show excellent performance in reducing tremor error compared to classic pure proportional, proportional-integral and hybrid proportional-integral plus active force control controllers.

Matched MeSH terms: Tremor/physiopathology*
Adult-onset neuronal intranuclear inclusion disease mimicking Fragile X-associated tremor-ataxia syndrome in ethnic Chinese patients

Lim SY, Ishiura H, Ramli N, Shibata S, Almansour MA, Tan AH, et al.

Parkinsonism Relat Disord, 2020 05;74:25-27.
PMID: 32289521 DOI: 10.1016/j.parkreldis.2020.03.025

Two ethnic Chinese men with clinico-radiologic features of Fragile X-associated tremor-ataxia syndrome (FXTAS) were found on genetic testing to have neuronal intranuclear inclusion disease (NIID), highlighting that NIID should be considered in the differential diagnosis of FXTAS. NIID may also be much more common than FXTAS in certain Asian populations.

Matched MeSH terms: Tremor/physiopathology
Bulbar signs in normal population

Lim KS, Hew YC, Lau HK, Lim TS, Tan CT

Can J Neurol Sci, 2009 Jan;36(1):60-4.
PMID: 19294890

BACKGROUND AND OBJECTIVES: There is lack of published data on bulbar signs among the healthy population. This study aims to determine the range of normality of bulbar signs particularly among the elderly.
METHODS: Systemic examination of bulbar signs was carried out according to a predetermined protocol on a cohort of young and elderly healthy subjects.
RESULTS: A total of 206 subjects were recruited in the study, 104 young adults with mean age of 20 years, and 102 elderly with mean age of 73 years. Uvula deviation was seen in 28 (26.9%) young subjects and 22 (21.6%) elderly. Irregular tongue border was seen in 17 subjects, unilateral in 4 subjects. Fourteen (6.8%) subjects had deviation on tongue protrusion. Occasional tremor of tongue on protrusion is common in both young and old. Persistent (severe) tongue tremor on protrusion was seen in 18.6% of the elderly, and 4.8% of the young. None of the subjects had tremor of tongue at rest. In gag reflex, absence of gagging response was common in elderly, seen in two thirds of the subjects on stimulation of the posterior pharyngeal wall. However, all the subjects had uvular movement. Habituation or suppression of gagging response was seen in close to 90% of young males.
CONCLUSION: There is wide range of normality in bulbar signs in normal population, particularly among the elderly.

Matched MeSH terms: Tremor/physiopathology
Comparison of posterior subthalamic area deep brain stimulation for tremor using conventional landmarks versus directly targeting the dentatorubrothalamic tract with tractography

Low HL, Ismail MNBM, Taqvi A, Deeb J, Fuller C, Misbahuddin A

Clin Neurol Neurosurg, 2019 Oct;185:105466.
PMID: 31466022 DOI: 10.1016/j.clineuro.2019.105466

OBJECTIVE: To compare posterior subthalamic area deep brain stimulation (PSA-DBS) performed in the conventional manner against diffusion tensor imaging and tractography (DTIT)-guided lead implantation into the dentatorubrothalamic tract (DRTT).
PATIENTS AND METHODS: Double-blind, randomised study involving 34 patients with either tremor-dominant Parkinson's disease or essential tremor. Patients were randomised to Group A (DBS leads inserted using conventional landmarks) or Group B (leads guided into the DRTT using DTIT). Tremor (Fahn-Tolosa-Marin) and quality-of-life (PDQ-39) scores were evaluated 0-, 6-, 12-, 36- and 60-months after surgery.
RESULTS: PSA-DBS resulted in marked tremor reduction in both groups. However, Group B patients had significantly better arm tremor control (especially control of intention tremor), increased mobility and activities of daily living, reduced social stigma and need for social support as well as lower stimulation amplitudes and pulse widths compared to Group A patients. The better outcomes were sustained for up to 60-months from surgery. The active contacts of Group B patients were consistently closer to the centre of the DRTT than in Group A. Speech problems were more common in Group A patients.
CONCLUSION: DTIT-guided lead placement results in better and more stable tremor control and fewer adverse effects compared to lead placement in the conventional manner. This is because DTIT-guidance allows closer and more consistent placement of leads to the centre of the DRTT than conventional methods.

Matched MeSH terms: Essential Tremor/physiopathology
Gamma knife thalamotomy for disabling tremor: a blinded evaluation

Lim SY, Hodaie M, Fallis M, Poon YY, Mazzella F, Moro E

Arch. Neurol., 2010 May;67(5):584-8.
PMID: 20457958 DOI: 10.1001/archneurol.2010.69

Gamma knife thalamotomy (GKT) has been used as a therapeutic option for patients with disabling tremor refractory to medications. Impressive improvement of tremor has been reported in the neurosurgical literature, but the reliability of such data has been questioned.

Matched MeSH terms: Essential Tremor/physiopathology