Fariborz Rahimi

Proprioceptive deficits in Parkinson's disease patients with freezing of gait.

Recent research has proposed that proprioceptive deficits may exist in Parkinsons disease (PD); however, proprioception has not been studied in those who experience freezing of gait (FOG). Proprioception was investigated through stimulation of proprioceptive receptors via patellar tendon vibration. In a force matching task to either 10% or 30% maximal voluntary contraction, response to vibration with and without vision of a force target was compared between 15 PD with FOG (PD-FOG), 16 PD without FOG (PD non-FOG), and 15 non-PD control participants (Controls). In a 15-s trial, vision of the target was provided for the first 10 s but in the last 5 s, four conditions were possible: (i) vision, no vibration; (ii) vision, vibration; (iii) no vision, no vibration; or (iv) no vision, vibration. The expected healthy response to vibration was an overshoot of the target. Controls and PD non-FOG did not perform significantly different with or without: vibration or vision. PD-FOG performed similarly to Controls and PD non-FOG in the baseline condition (i). Errors by PD-FOG on the other conditions (ii-iv) were significantly different from the baseline condition but were not significantly different from each other. The PD-FOG group significantly undershot the target when vibration was added [F((2,36))=4.8376, P<0.02] and when vision was removed [F((2,36))=4.8376, P<0.02]. It is suggested that any deviation from normal sensory availability contributes to severe deficits in PD-FOG.

Capturing whole-body mobility of patients with Parkinson disease using inertial motion sensors: Expected challenges and rewards

While many studies have reported on the use of kinematic analysis on well-controlled, in-laboratory mobility tasks, few studies have examined the challenges of recording dynamic mobility in home environments. This preliminary study evaluated whole body mobility in eleven patients with Parkinson disease (H&Y 2–4). Patients were recorded in their home environment during scripted and non-scripted mobility tasks while wearing a full-body kinematic recording system using 11 inertial motion sensors (IMU). Data were analyzed with principal component analysis (PCA) in order to identify kinematic variables which best represent mobility tasks. Results indicate that there was a large degree of variability within subjects for each task, across tasks for individual subjects, and between scripted and non-scripted tasks. This study underscores the potential benefit of whole body multi-sensor kinematic recordings in understanding the variability in task performance across patients during daily activity which may have a significant impact on rehabilitation assessment and intervention.

Effectiveness of BoNT A in Parkinson's disease upper limb tremor management.

OBJECTIVE One the greatest challenges of BoNT A therapy for tremor lies in the complexity and variation of components involved in tremor movement, and the lack of objective measures to determine these components. This 3 month open-label single injection study aims to couple clinician best judgment with kinematics to improve effect of BoNT A (incobotulinumtoxinA) injection in 7 patients with upper limb Parkinsons disease (PD) tremor. METHODS Injection was guided with clinical and kinematic assessment of tremor using angular wrist position in 3 degrees of freedom: flexion/extension, pronation/supination, and radial/ulnar deviation. Overall tremor severity and change were measured by linear finger acceleration. RESULTS Kinematic data from static and functional tasks demonstrate no improvement at one month post-injection, but significant improvement at two and three months. Clinical scales across UPDRS Items 20 (1, 2, 3 months post) and 21 (2 months), and spiral drawings (3 months) showed significant improvement from baseline, while line drawings did not. CONCLUSIONS This study suggests injection of BoNT A as a viable focal management option for upper limb PD tremor. In addition to clinical judgment, objective quantification of tremor dynamics by kinematics may be a feasible assessment and guidance tool which can be used to optimize injection conditions for focal tremor therapy. Kinematic analysis of tremor across a variety of joints in all degrees of movement may provide important insight into tremor dynamics, allowing optimized, targeted focal therapy.

Tremor suppression orthoses for parkinson’s patients: A frequency range perspective

While the majority of tremor-afflicted Parkinso-nian (PD) patients suffer from rest tremors, which is not considered highly disabling, a portion of these PD patients also demonstrate action tremors that interfere with their daily lives. Two main considerations in designing an orthosis that aims at suppressing the tremor, are the frequency bands of the tremor and the joints tremor affects. Nine subjects, which included six healthy people, two PD patients with typical tremor afflictions, and a PD patient with severe tremor of not only in her fingers and wrist, but also in her elbow, participated in this study. The highly afflicted patient displayed the need for tremor suppression in action as well as when in rest. The study focuses on uncommon elbow tremors and demonstrates that, for typically afflicted patients, tremor amplitudes are comparable to healthy subjects, but the frequency distribution of the tremors are different at high levels of elbow torque. For the highly afflicted patient, both tremor amplitude and its frequency distribution are different at all levels of elbow torque. The study further investigates the tremors in two bands of frequency on both hands of the highly troubled patient before, and after medication. The two bands are those of classical Parkinsonian tremor (4-6 Hz) and physiological (or enhanced physiological) tremor (8-12 Hz). Power spectrum and tremor amplitude comparisons reveal that, for part of tremulous PD patients, both tremors coexist and, depending on the level of affliction, the designed orthosis needs to suppress tremors in both bands, even at more proximal joints, such as the elbow.

Variability of hand tremor in rest and in posture — A pilot study

Previous, studies have demonstrated variability in the frequency and amplitude in tremor between subjects and between trials in both healthy individuals and those with disease states. However, to date, few studies have examined the composition of tremor. Efficacy of treatment for tremor using techniques such as Botulinum neurotoxin type A (BoNT A) injection may benefit from a better understanding of tremor variability, but more importantly, tremor composition. In the present study, we evaluated tremor variability and composition in 8 participants with either essential tremor or Parkinson disease tremor using kinematic recording methods. Our preliminary findings suggest that while individual patients may have more intra-trial and intra-task variability, overall, task effect was significant only for amplitude of tremor. Composition of tremor varied among patients and the data suggest that tremor composition is complex involving multiple muscle groups. These results may support the value of kinematic assessment methods and the improved understanding of tremor composition in the management of tremor.

Functional Ability Improved in Essential Tremor by IncobotulinumtoxinA Injections Using Kinematically Determined Biomechanical Patterns – A New Future

Objective Effective treatment for functional disability caused by essential tremor is a significant unmet need faced by many clinicians today. Current literature regarding focal therapy by botulinum toxin type A (BoNT-A) injections uses fixed dosing regimens, which cannot be individualized, provides only limited functional benefit and unacceptable muscle weakness commonly occurs. This 38-week open label study, the longest to-date, demonstrates how kinematic technology addressed all these issues by guiding muscle selection. Method Participants (n = 24) were assessed at weeks 0, 6, 16, 22, 32, and 38 and injected with incobotulinumtoxinA at weeks 0, 16, and 32. Clinical assessments including UPDRS tremor items, Fahn-Tolosa-Marin (FTM) tremor rating scale assessing tremor severity, writing and functional ability, quality of life questionnaire (QUEST) and objective kinematic assessments were completed at every visit. Participants performed two postural and two weight-bearing scripted tasks with motion sensors placed over the wrist, elbow and shoulder joints. These sensors captured angular tremor amplitude (RMS units) and acceleration joint motion that was segmented into directional components: flexion-extension (F/E), pronation-supination and radial-ulnar at the wrist, F/E at the elbow, and F/E and adduction-abduction at the shoulder. Injection parameters were determined using kinematics, followed by the clinician’s determination of which muscles would contribute to the specific upper limb tremor biomechanics and dosing per participant. Results Multi-joint biomechanical recordings allowed individualized muscle selection and showed significant improvement in whole-arm function, FTM parts A-C scores, at week 6 which continued throughout the study. By week 38, the total FTM score statistically significantly reduced from 16.2±4.6 at week 0 to 9.5±6.3 (p<0.0005). UPDRS item 21 score rating action tremor was significantly reduced from 2.6±0.5 at week 0 to 1.6±1.1 (p = 0.01) at week 32. Quality of life (QUEST) significantly improved from 40.3±15.8 at week 0 to 31.1±15.3 (p = 0.035) at week 32 and to 27.8±15.3 (p = 0.028) at week 38. Kinematics provided an objective, secondary outcome measure, which showed a significant decrease in tremor amplitude in the wrist and shoulder joints (p<0.05). Eight participants (40%) self-reported mild weakness in injected muscles but had no interference in arm function. Conclusion Kinematic tremor assessments provide the injector unique insight to objectively individualize and personalize injection parameters demonstrating BoNT-A effectively alleviates functional disability caused by essential tremor. Kinematic technology is a promising method for standardizing assessments and for focal upper limb tremor treatment. Trial Registration ClinicalTrials.gov NCT02427646

Dynamic decomposition of motion in essential and parkinsonian tremor.

BACKGROUND Treatment options for essential (ET) and Parkinson disease (PD) tremor are suboptimal, with significant side effects. Botulinum toxin type A (BoNT A) is successfully used in management of various focal movement disorders but is not widely used for tremor. METHOD This study examines complexity of wrist tremor in terms of involvement of its three anatomical degrees of freedom (DOF) in two common situations of rest and posture. The study examines tremor in 11 ET and 17 PD participants by kinematic decomposition of motion in 3-DOF. RESULTS Tremor decomposition showed the motion involved more than one DOF (<70% contribution in one DOF) in most ET (rest: 100%, posture: 64%) and PD (rest: 77%, posture: 77%) patients. Task variation resulted in change in both amplitude and composition in ET, but not in PD. Amplitude significantly increased from rest to posture in ET. Directional bias was observed at the wrist for ET (pronation), and PD (extension, ulnar deviation, pronation). Average agreement between clinical visual and kinematic selection of muscles was 55% across all subjects. CONCLUSION This study shows the complexity of tremor and the difficulty in visual judgment of tremor, which may be key to the success of targeted focal treatments such as BoNT A.

Analysis of different fuzzy CPM network planning procedures

With great progress in fuzzy set theory there have been also several efforts in using this theory in network planning methods such as PERT and CPM to make more realistic usage of them and better dealing with uncertainties that is intrinsic in estimating duration of activities. In this paper, using noninteractive fuzzy subtraction, we have proposed an algorithm that reads fuzzy numbers as activity durations along with their initial and final node numbers; constructs network and computes earliest expected time, latest allowable time, and slack time for each node. At the end, critical path, or paths for different a-cuts are calculated. Instead of classical descriptive methods, we have used numeric methods and whenever the shape of the fuzzy number differs from initial shape (e.g. triangular), using defuzzification with center of gravity and refuzzification; we convert the number to its initial shape.

Quantifying the short-term effects of deep brain stimulation surgery on bradykinesia in Parkinson's disease patients

Clinical scale-based follow-up of patients undergoing bilateral subthalamic deep brain stimulation (STN-DBS) surgery has shown inconsistent effects on bradykinesia in Parkinsons disease patients. Furthermore, quantitative assessment of STN-DBS effect on bradykinesia has not been fully explored yet. Our group uses multisensory kinematic technologies to study short-term and long-term DBS effects on Parkinsons disease. In this paper we present a kinematic analysis of the short term (3 month) effects of STN-DBS on bradykinesia in five PD patients and compare the results with data obtained from healthy age-matched controls.

Analysis of high-voltage flyback converter in color TVs, and its regulation

Due to its low-cost and simplicity, flyback converter is used to generate high-voltage in color TVs. In addition, using flyback converter has the advantage of driving Horizontal-Yoke with the same circuit. In this paper operation of this converter in TV sets is analyzed. Some analytical formulas are derived and confirmed by simulation and experimental measurements. Regulation of high-voltage is examined and its dependence on component values is derived. Finally a method to calculate component values for best regulation of high-voltage is proposed.