Pablo Arias

Effects of rhythmic sensory stimulation (auditory, visual) on gait in Parkinson’s disease patients

This study has focused on how sensory stimulation affects gait in Parkinson’s disease (PD). The kinematic parameters of gait [cadence, step amplitude, velocity, coefficient of variation of stride time (CVstride-time), and the coefficient of variation of the step amplitude (CVstep-amplitude)] were analysed in 25 PD patients and 10 control subjects. Step amplitude, velocity and CVstride-time were altered in the patients with PD. However, when kinematic parameters were analysed as a function of disease severity, none of the parameters differed between early PD (I–II Hoehn and Yahr) and the controls. Nevertheless, more severely affected PD patients (III–IV Hoehn and Yahr) walked with a reduced step amplitude, lower velocity, higher CVstride-time, and higher CVstep-amplitude than the controls. The administration of auditory stimulation at a frequency matching the preferred walking cadence led to a decrease in the CVstride-time in PDIII–IV patients, and to an increase in step amplitude in PDIII–IV and controls. Visual stimulation at the same frequency did not modify any of the altered kinematic parameters in PDIII–IV patients. When different stimulation frequencies were utilised, auditory stimulation significantly changed some of the altered walking parameters in Parkinson patients. Frequencies matching preferred walking cadence or above this, up to the fastest walking, were those that seem to interact most effectively with the abnormal kinematic parameters in PDIII–IV patients. Visual stimulation negatively modulated cadence in PDIII–IV in the frequency range used. Sensory stimulation facilitates gait in PD. Studies using sensory stimulation as a tool to facilitate walking should take into account the grade of disability of the patients.

Effect of Rhythmic Auditory Stimulation on Gait in Parkinsonian Patients with and without Freezing of Gait

Freezing of gait (FOG) in Parkinsons disease (PD) rises in prevalence when the effect of medications decays. It is known that auditory rhythmic stimulation improves gait in patients without FOG (PD-FOG), but its putative effect on patients with FOG (PD+FOG) at the end of dose has not been evaluated yet. This work evaluates the effect of auditory rhythmic stimulation on PD+FOG at the end of dose. 10 PD+FOG and 9 PD-FOG patients both at the end of dose periods, and 10 healthy controls were asked to perform several walking tasks. Tasks were performed in the presence and absence of auditory sensory stimulation. All PD+FOG suffered FOG during the task. The presence of auditory rhythmic stimulation (10% above preferred walking cadence) led PD+FOG to significantly reduce FOG. Velocity and cadence were increased, and turn time reduced in all groups. We conclude that auditory stimulation at the frequency proposed may be useful to avoid freezing episodes in PD+FOG.

Aquatic therapy versus conventional land-based therapy for Parkinson's disease: an open-label pilot study

OBJECTIVES To assess and compare 2 different protocols of physiotherapy (land or water therapy) for people with Parkinsons disease (PD) focused on postural stability and self-movement, and to provide methodological information regarding progression within the program for a future larger trial. DESIGN Randomized, controlled, open-label pilot trial. SETTING Outpatients, Parkinsons disease Center of Ferrol-Galicia (Spain). PARTICIPANTS Individuals (N=11) with idiopathic PD in stages 2 or 3 according to the Hoehn and Yahr Scale completed the investigation (intervention period plus follow-up). INTERVENTIONS After baseline evaluations, participants were randomly assigned to a land-based therapy (active control group) or a water-based therapy (experimental group). Participants underwent individual sessions for 4 weeks, twice a week, for 45 minutes per session. Both interventions were matched in terms of exercise features, which were structured in stages with clear objectives and progression criteria to pass to the next phase. MAIN OUTCOME MEASURES Participants underwent a first baseline assessment, a posttest immediately after 4 weeks of intervention, and a follow-up assessment after 17 days. Evaluations were performed OFF-dose after withholding medication for 12 hours. Functional assessments included the Functional Reach Test (FRT), the Berg Balance Scale (BBS), the UPDRS, the 5-m walk test, and the Timed Up and Go test. RESULTS A main effect of both therapies was seen for the FRT. Only the aquatic therapy group improved in the BBS and the UPDRS. CONCLUSIONS In this pilot study, physiotherapy protocols produced improvement in postural stability in PD that was significantly larger after aquatic therapy. The intervention protocols are shown to be feasible and seem to be of value in amelioration of postural stability-related impairments in PD. Some of the methodological aspects detailed here can be used to design larger controlled trials.

Transcranial static magnetic field stimulation of the human motor cortex

Non‐Technical Summary  Non‐invasive neuromodulation of the human brain – with pulsed magnetic fields or small direct currents – is becoming increasingly popular for treating a variety of neurological and neuropsychiatric disorders. In the present work we investigated in healthy humans the possibility of a non‐invasive modulation of motor cortex excitability by the application of static magnetic fields through the scalp. We found that transcranial static magnetic field stimulation (tSMS) can reduce the excitability of the motor cortex for a period that outlasts the time of the application of the magnetic field. Moreover, we demonstrated that these excitability changes take origin at the cortical level. These results suggest that tSMS using small static magnets may be a promising tool to modulate cerebral excitability in a non‐invasive, painless and reversible way.

Effect of whole body vibration in Parkinson's disease: a controlled study

In the search of new strategies to improve the quality of life of Parkinsons disease patients, recent work has reported an amelioration of Parkinsonian symptoms using Whole Body Vibration (WBV). A double‐blinded, placebo controlled design was used to evaluate the effect of a 12 WBV sessions‐programme on a number of motor and clinical tests in 23 Parkinsons disease patients. Patients were assigned to one of two groups, one receiving WBV and the other a placebo group. At the end of the programme as well as during intra‐session evaluation, there was no difference between the experimental (vibration) and placebo groups in any outcomes. These results suggest that reported benefits of vibration are due to a placebo response.

Controlled Trial on the Effect of 10 Days Low-Frequency Repetitive Transcranial Magnetic Stimulation (rTMS) on Motor Signs in Parkinson's Disease

We evaluated the effect of low‐frequency rTMS on motor signs in Parkinsons disease (PD), under a double‐blind placebo‐controlled trial design. PD patients were randomly assigned to received either real (n = 9) or sham (n = 9) rTMS for 10 days. Each session comprises two trains of 50 stimuli each delivered at 1 Hz and at 90% of daily rest motor threshold using a large circular coil over the vertex. The effect of the stimulation, delivered during the ON‐period, was evaluated during both ON and OFF periods. Tests were carried out before and after the stimulation period, and again 1 week after. The effect of the stimulation was evaluated through several gait variables (cadence, step amplitude, velocity, the CVstride‐time, and the turn time), hand dexterity, and also the total and motor sections of the UPDRS. Only the total and motor section of the UPDRS and the turn time during gait were affected by the stimulation, the effect appearing during either ON or OFF evaluation, and most importantly, equally displayed in both real and sham group. The rest of the variables were not influenced. We conclude the protocol of stimulation used, different from most protocols that apply larger amount of stimuli, but very similar to some previously reported to have excellent results, has no therapeutic value and should be abandoned. This contrasts with the positive reported effects using higher frequency and focal coils. Our work also reinforces the need for sham stimulation when evaluating the therapeutic effect of rTMS.

Validity of the finger tapping test in Parkinson’s disease, elderly and young healthy subjects: Is there a role for central fatigue?

OBJECTIVE The main goal of this work is to evaluate the validity of the finger tapping test (FT) to detect alterations in rhythm formation. METHODS We use FT to study the alterations in motor rhythm in three different groups: Parkinsons patients, elderly healthy controls, and young healthy control subjects (HY). The test was performed in COMFORT and FAST tapping modes and repeated on two different days. RESULTS For the variables analyzed (frequency and variability) both modes were repeatable in all groups. Also, intra-class correlation coefficients showed excellent levels of consistency between days. The test clearly differentiated the groups in both FAST and COMFORT modes. However, when fatigue was analyzed, a decrease in the tapping frequency was observed in HY during the FAST mode only. The amplitude of motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS) was early-potentiated but not delayed-depressed, both for COMFORT and FAST modes. This suggests that fatigue was not of cortico-spinal origin. Other forms of central fatigue are discussed. CONCLUSIONS FT at FAST mode is not a valid test to detect differences in rhythm formation across the groups studied; fatigue is a confounding variable in some groups if the test is performed as fast as possible. SIGNIFICANCE COMFORT mode is recommended in protocols including the FT for evaluating rhythm formation.

Acute effects of whole-body vibration at 3, 6, and 9 hz on balance and gait in patients with Parkinson's disease.

Vibration as a stimulus to treat Parkinson’s disease (PD) patients was first recommended by Charcot in 1892, and although this approach was subsequently abandoned, recently, whole-body vibration (WBV) protocols have been suggested as a modern substitute.– A small number of studies have assessed the effects of WBV on motor symptoms in PD, with apparently positive results, obtained in open-trial designs. In each case, however, only a fixed frequency of stimulation was used, and no placebo group was included. It is therefore of fundamental interest to examine a range of “doses” (in this case, frequencies) in order to optimize potential therapeutic effects. Using an appropriate placebo-controlled experimental design, we have explored the use of different vibration frequencies, some of which had already been reported to have an effect after 1 session. Forty-eight patients with PD diagnosed as idiopathic participated in this study. Possible participants were excluded if any other disease or impairment potentially affected the validity of the results, and selected PD were naive to WBV protocols. Patients were randomly allocated to each of 4 groups: placebo, vibration at 3 Hz, vibration at 6 Hz, and vibration at 9 Hz (n = 12 each). The protocol followed previous work reporting excellent results of single-session WBV by means of a vibrating platform comprising 5 vibration sets of 1’ each (interset rest period, 1’). The stepped platform (amplitude of 13 mm) thrusts the right and left legs upward alternately. During stimulation, patients stood on the platform with their feet separated at a stable and comfortable position and with the knees slightly flexed. In the placebo group, patients adopted the same posture without vibration. Instead, they were required to stay still, trying to minimize hip oscillation; this controlled for a placebo effect. Stimulation and evaluation were done during ON periods. The protocol conformed to the Declaration of Helsinki. The effect of vibration on gait and balance was evaluated by the timed-up-and-go (TUG) and functional reach (FR) tests. Patients were evaluated just before (PRE), after (POST), and 48 hours after (POST-2) stimulation. Examiners were blind to protocol and group assignment.

Spatiotemporal Gait Patterns During Overt and Covert Evaluation in Patients With Parkinson’s Disease and Healthy Subjects: Is There a Hawthorne Effect?

Parkinsons disease (PD) and aging lead to gait impairments. Some of the disturbances of gait are focused on step length, cadence, and temporal variability of gait cycle. Under experimental conditions gait can be overtly evaluated, but patients with PD are prone to expectancy effects; thus it seems relevant to determine if such evaluation truly reflects the spontaneous gait pattern in such patients, and also in healthy subjects. Thirty subjects (15 subjects with PD and 15 healthy control subjects) were asked to walk using their natural, preferred gait pattern. In half of the trials subjects were made aware that they were being evaluated (overt evaluation), while in the rest of the trials the evaluation was performed covertly (covert evaluation). During covert evaluation the gait pattern was modified in all groups. Gait speed was significantly increased (P = .022); step cadence and average step length were also significantly modified, the average step length increased (P = .002) and the cadence was reduced (P ≤ .001). Stride cycle time variability was unchanged significantly (P = .084). These changes were not significantly different compared between elderly and young healthy controls either. Due to the small sample size, a note of caution is in order; however, the significant results suggest that covert evaluation of gait might be considered to complement experimental evaluations of gait.

Virtual Reality as a Tool for Evaluation of Repetitive Rhythmic Movements in the Elderly and Parkinson's Disease Patients

This work presents an immersive Virtual Reality (VR) system to evaluate, and potentially treat, the alterations in rhythmic hand movements seen in Parkinsons disease (PD) and the elderly (EC), by comparison with healthy young controls (YC). The system integrates the subjects into a VR environment by means of a Head Mounted Display, such that subjects perceive themselves in a virtual world consisting of a table within a room. In this experiment, subjects are presented in 1st person perspective, so that the avatar reproduces finger tapping movements performed by the subjects. The task, known as the finger tapping test (FT), was performed by all three subject groups, PD, EC and YC. FT was carried out by each subject on two different days (sessions), one week apart. In each FT session all subjects performed FT in the real world (FTREAL) and in the VR (FTVR); each mode was repeated three times in randomized order. During FT both the tapping frequency and the coefficient of variation of inter-tap interval were registered. FTVR was a valid test to detect differences in rhythm formation between the three groups. Intra-class correlation coefficients (ICC) and mean difference between days for FTVR (for each group) showed reliable results. Finally, the analysis of ICC and mean difference between FTVR vs FTREAL, for each variable and group, also showed high reliability. This shows that FT evaluation in VR environments is valid as real world alternative, as VR evaluation did not distort movement execution and detects alteration in rhythm formation. These results support the use of VR as a promising tool to study alterations and the control of movement in different subject groups in unusual environments, such as during fMRI or other imaging studies.