Martina Hoskovcová

Grooved Pegboard Predicates More of Cognitive Than Motor Involvement in Parkinson’s Disease

The Grooved Pegboard Test (GPT) was conceived as a test of manual dexterity, upper-limb motor speed, and hand–eye coordination. The aim of our study was to test the componential structure of the GPT on an archetypal model of motor impairment, Parkinson’s disease (PD). A total of 45 PD patients (33 males, 12 females; age M = 67, range = 49-81; PD duration M = 10, range = 6-20 years; H/Y stage 2, range = 2-3) and 20 age- and education-matched controls (14 males, 6 females; age M = 66, range = 48-80) were included. All participants were investigated using the GPT, Short Falls Efficacy Scale–International, Frontal Assessment Battery (FAB), Montreal Cognitive Assessment (MoCA), and Non-Motor Symptom Scale. Patients were followed for 6 months, using fall diaries and monthly phone calls to define PD fallers (falls ≥ 1; n = 27) and PD nonfallers (falls = 0; n = 18). Using structural equation modeling, the GPT predicted performance on the MoCA (p < .001), but not on the FAB (p = .29). In conclusion, analysis of the structure of the GPT provided evidence about important cognitive features, in addition to the motor component of this test in PD.

Predicting Falls in Parkinson Disease: What Is the Value of Instrumented Testing in OFF Medication State?

Background Falls are a common complication of advancing Parkinsons disease (PD). Although numerous risk factors are known, reliable predictors of future falls are still lacking. The objective of this prospective study was to investigate clinical and instrumented tests of balance and gait in both OFF and ON medication states and to verify their utility in the prediction of future falls in PD patients. Methods Forty-five patients with idiopathic PD were examined in defined OFF and ON medication states within one examination day including PD-specific clinical tests, instrumented Timed Up and Go test (iTUG) and computerized dynamic posturography. The same gait and balance tests were performed in 22 control subjects of comparable age and sex. Participants were then followed-up for 6 months using monthly fall diaries and phone calls. Results During the follow-up period, 27/45 PD patients and 4/22 control subjects fell one or more times. Previous falls, fear of falling, more severe motor impairment in the OFF state, higher PD stage, more pronounced depressive symptoms, higher daily levodopa dose and stride time variability in the OFF state were significant risk factors for future falls in PD patients. Increased stride time variability in the OFF state in combination with faster walking cadence appears to be the most significant predictor of future falls, superior to clinical predictors. Conclusion Incorporating instrumented gait measures into the baseline assessment battery as well as accounting for both OFF and ON medication states might improve future fall prediction in PD patients. However, instrumented testing in the OFF state is not routinely performed in clinical practice and has not been used in the development of fall prevention programs in PD. New assessment methods for daylong monitoring of gait, balance and falls are thus required to more effectively address the risk of falling in PD patients.

Validation of a new tool for automatic assessment of tremor frequency from video recordings

We present a validation study for TremAn--a tool for automatic detection of tremor and measurement of its frequency from video recordings. To assess the validity of TremAn we designed a study consisting of tremor assessment from video, by accelerometry and by clinical evaluation using Fahn-Tolosa-Marin scale. 26 patients with essential tremor and 5 healthy volunteers underwent the examination in four standardized positions with focus on the hand tremor. Results showed that the frequencies of tremor measured with TremAn and with accelerometry are closely related, attaining agreement with less than 0.1 Hz difference in 80% and less than 0.5 Hz in 94% of measured samples. The reproducibility of frequency measurements using TremAn was comparable to the accelerometry, with the TremAn/accelerometry ratio of measurement error standard deviations equal to 0.99 (95% confidence interval (0.84, 1.17)).

Tremor analysis by decomposition of acceleration into gravity and inertial acceleration using inertial measurement unit

Decomposition of acceleration was investigated as an alternative to commonly used direct spectral analysis of measured acceleration or angular velocity for tremor quantification. Orientation estimation algorithm was devised to decompose the measured acceleration into inertial acceleration caused by sensor movement in inertial reference frame and gravitational artifact. Resulting signals, beside measured acceleration and angular velocity, were used to assess tremor amplitude and frequency by spectral peak detection. The algorithm was tested on experimental data from a clinical study including patients with essential tremor. Influence of sensor calibration and connections of results to analytic approach are analyzed briefly.

Intermittent bilateral coherence in physiological and essential hand tremor

OBJECTIVE To investigate the prevalence and the temporal structure of bilateral coherence in physiological (PT) and essential (ET) hand tremor. METHODS Triaxial accelerometric recordings from both hands in 30 healthy subjects and 34 ET patients were analyzed using spectral coherence and wavelet coherence methods. In 12 additional healthy subjects, the relation between the hand tremor and the chest wall acceleration was evaluated using partial coherence analysis. RESULTS The majority of both PT and ET subjects displayed significant bilateral coherence. While in PT, bilateral coherence was most frequently found in resting hand position (97% of subjects), in ET the prevalence was comparable for resting (54%) and postural (49%-57%) positions. In both PT and ET, epochs of strong coherence lasting several to a dozen seconds were separated by intervals of insignificant coherence. In PT, bilateral coherence at the main tremor frequency (8-12Hz) was coupled with the ballistocardiac rhythm. CONCLUSION The oscillations of the two hands are intermittently synchronized in both PT and ET. We propose that in postural PT, bilateral coherence at the main tremor frequency arises from transient simultaneous entrainment of the left and right hand oscillations to ballistocardiac forcing. SIGNIFICANCE Bilateral coherence of hand kinematics provides a sensitive measure of synchronizing influences on the left and right tremor oscillators.

General and selective brain connectivity alterations in essential tremor: A resting state fMRI study

Although essential tremor is the most common movement disorder, there is little knowledge about the pathophysiological mechanisms of this disease. Therefore, we explored brain connectivity based on slow spontaneous fluctuations of blood oxygenation level dependent (BOLD) signal in patients with essential tremor (ET). A cohort of 19 ET patients and 23 healthy individuals were scanned in resting condition using functional magnetic resonance imaging (fMRI). General connectivity was assessed by eigenvector centrality (EC) mapping. Selective connectivity was analyzed by correlations of the BOLD signal between the preselected seed regions and all the other brain areas. These measures were then correlated with the tremor severity evaluated by the Fahn-Tolosa-Marin Tremor Rating Scale (FTMTS). Compared to healthy subjects, ET patients were found to have lower EC in the cerebellar hemispheres and higher EC in the anterior cingulate and in the primary motor cortices bilaterally. In patients, the FTMTS score correlated positively with the EC in the putamen. In addition, the FTMTS score correlated positively with selective connectivity between the thalamus and other structures (putamen, pre-supplementary motor area (pre-SMA), parietal cortex), and between the pre-SMA and the putamen. We observed a selective coupling between a number of areas in the sensorimotor network including the basal ganglia and the ventral intermediate nucleus of thalamus, which is widely used as neurosurgical target for tremor treatment. Finally, ET was marked by suppression of general connectivity in the cerebellum, which is in agreement with the concept of ET as a disorder with cerebellar damage.

Wave Kurtosis: A Novel, Specific Parameter for TUG-Turn Quantification

The Timed Up and Go test (TUG) is widely used in both research and clinical settings. The most common parameter for quantification of functional decline is the duration of a performed TUG. Analysis of the turn part of the TUG could provide valuable information about functional decline. Notwithstanding, there are only a few studies that deals with the TUG turn processing. This study proposes a novelty parameter—wave kurtosis (WK) that provides quantitative metrics for describing and comparing turn patterns. The WK is designed to evaluate the shape of the signal waveform. The WK quantifies the peak of the signal, its position and tails. The TUG-turn angular rate was analysed. Intra-class correlations (ICC) of WK and the strength of a linear association between WK and established turn parameters (turn duration, peak angular rate, and mean angular rate) were calculated. The reliability of WK about the vertical axis was moderate (ICC > 0.50), while reliabilities of the frontal axis and sagittal axis varied according to the subject group. The WK about the vertical axis was moderately correlated with turn duration, mean value and peak value. Utilization of waveform parameters opens a new area of TUG turn analysis and may allow for a more sensitive determination of movement disorders or fall risk assessment. Therefore, future studies utilizing turn movement may benefit from the use of the wave kurtosis.

A New Approach to Gait Variability Quantification using Cyclograms.

Human gait is cyclic movement and its properties are not constant. Gait variability is widely assessed by fluctuation in spatio-temporal parameters. Since this method operate on a single parameter of the gait cycle, the cycle signal in its entirety does not affect the result. The objective of this work is to present new gait variability assessment method. In order to quantify the variability of entire gait cycle, we have proposed and tested the method based on synchronized cyclograms. The novel approach showed the ability to assess gait variability. The method is not restricted to gait variability assessment and would be beneficial in different areas of cyclic movement variability analysis.

P 056 - The effect of medication on walking turns in Parkinson disease

More than half of Parkinsons disease patients (PD) report difficulty in turning. We observed different numbers of turn steps, turn times, turn types, and turn qualities in PD patients compared to healthy adults. Although medication has an effect on motor impairments in PD, its effect on the complex walking turn task is still unclear. The aim of this paper is to investigate the effect of medication on the walking turn. All subjects performed an instrumented extended Timed Up & Go Test (TUG) wearing gyro-accelerometers. The PD patients were assessed twice, first after a withdrawal of medication (OFF) and then after taking a dose of medication (ON). The parameters calculated were duration, mean and the wave kurtosis of the angular rate. The mean angular rate and the waveform kurtosis showed significant differences between the CG and ON (p < 0.05), and the CG and OFF (p < 0.05) A significant difference between ON and OFF was found in the duration and mean angular rate parameters (p < 0.001 and p < 0.0001, respectively). Our findings showed a difference in some turning parameters, namely duration and mean angular rate, between PD patients with and without medication. According to our results, medication decreases turn duration. Moreover, the mean angular rate increased with medication. These results support the view that turning is positively affected by medication.

Early manifestation of spasticity after first stroke in the territory of the internal carotid artery: A prospective multicenter study

AIMS The main aim of this study was to provide an estimate of the incidence and prevalence of spasticity following stroke in the internal carotid artery territory for Regional Stroke Centers in the Czech Republic. A secondary goal was to identify predictors for the development of spasticity. METHODS In a prospective cohort study, 256 consecutive patients with clinical signs of central paresis due to a first-ever stroke were examined in the acute stage. All patients had primary stroke of carotid origin and paresis of the upper and/or lower limb for longer than 7 days after stroke onset. All were examined between 7-10 days after the stroke. We evaluated the degree and pattern of paresis, spasticity using the Modified Ashworth scale and the Barthel Index, baseline characteristics and demographic data. RESULTS Of 256 patients (157 males; mean age 69.9±12.4 years), 115 (44.9%) patients developed spasticity during the first 10 days after stroke onset. Eighty-three (32.5%) patients presented with mild neurological deficit (modified Rankin Scale 0 - 2) and 69 (27.0%) patients were bedridden. CONCLUSION Spasticity was noted in 44.9% patients with neurological deficit due to first-ever stroke in the carotid territory in the first 10 days after stroke onset. Severe spasticity was rare.