Papers by Marcelo Merello
Clinical Autonomic Research, Feb 6, 2020
Purpose: Huntington's disease (HD) patients have a high prevalence of falls. Autonomic nervous sy... more Purpose: Huntington's disease (HD) patients have a high prevalence of falls. Autonomic nervous system dysfunction has been reported from the early stages of the disease. There is no evidence analyzing the relationship between heart rate variability (HRV) and falls in this population. This research aimed to evaluate the relationship between HRV and falls in HD. Methods: HD patients enrolled in a prospective study of Fear of Falling and falls were assessed using short-term HRV analyses and blood pressure measures in resting and standing states. Time-frequency domains and nonlinear parameters were calculated. Data regarding falls, the risk of falling (RoF) and disease-specific scales were collected at baseline and six-month follow-up. Results: Twenty HD patients were recruited. 35% of HD patients reported at least one fall (single fallers) and, 65% reported two or more falls (recurrent fallers) in the previous 12-months. At baseline, recurrent fallers had lower RMSSD-resting (root-mean-square-of-the-RR), higher LF/HF ratio (low/high frequency) in both states, and higher DFA-α1 parameter (short-term-detrended-fluctuation-analyses) in both states. This association was similar at a six-month follow-up for recurrent fallers showing lower RMSSD-resting and higher LF/HF-standing ratio than single fallers. Significant correlations were found between the number of falls, RMSSD-resting, and LF/HF-standing ratio. No differences were found between recurrent and single fallers for any blood pressure measures. The observed HRV pattern is consistent with a higher sympathetic prevalence associated with a higher RoF. Reduced parasympathetic HRV values predict being a recurrent faller at six-months of follow-up, independently of orthostatic phenomena in this population.
Parkinsonism & Related Disorders, Nov 1, 2021
Introduction: The implementation of accepted clinical diagnostic criteria has improved the accura... more Introduction: The implementation of accepted clinical diagnostic criteria has improved the accuracy of a clinical diagnosis of Parkinson's disease (PD). Time frames of 3 to 10 years have been empirically proposed to reach a diagnosis of clinically established PD. Methods: We explored the time to a Final Clinical Diagnosis (FCD) and the factors that predict faster diagnoses in patients presenting with parkinsonism and/or tremor between 2009 and 2015 at our tertiary center. All patients underwent a standardized workout process to reach a FCD, which included an acute levodopa challenge (LDC) after the first visit. Results: Among the 326 patients included, 215 (66%) received a FCD within the first six months after the LDC. A FCD was reached in 95% and 100% of patients in 33 and 108 months, respectively. PD was the FCD in 196 patients (60.1%). The FCD was reached faster in patients with a positive response to levodopa and when the FCD was PD. The time needed to reach a final diagnosis in the clinical setting was 2.75 years in 95% of patients presenting initially with parkinsonism and/or tremor. Patients with positive responses to levodopa at the LDC, benefited from shorter delays until the FCD.
Movement Disorders
BackgroundAs gene‐targeted therapies are increasingly being developed for Parkinson's disease... more BackgroundAs gene‐targeted therapies are increasingly being developed for Parkinson's disease (PD), identifying and characterizing carriers of specific genetic pathogenic variants is imperative. Only a small fraction of the estimated number of subjects with monogenic PD worldwide are currently represented in the literature and availability of clinical data and clinical trial‐ready cohorts is limited.ObjectiveThe objectives are to (1) establish an international cohort of affected and unaffected individuals with PD‐linked variants; (2) provide harmonized and quality‐controlled clinical characterization data for each included individual; and (3) further promote collaboration of researchers in the field of monogenic PD.MethodsWe conducted a worldwide, systematic online survey to collect individual‐level data on individuals with PD‐linked variants in SNCA, LRRK2, VPS35, PRKN, PINK1, DJ‐1, as well as selected pathogenic and risk variants in GBA and corresponding demographic, clinical,...
Tremor and Other Hyperkinetic Movements, 2018
Background: Cerebrotendinous xanthomatosis is a rare autosomal recessive neurometabolic disorder ... more Background: Cerebrotendinous xanthomatosis is a rare autosomal recessive neurometabolic disorder characterized by chronic diarrhea, tendon xanthomas, juvenile cataracts, and neurological symptoms. Case Report: An adult patient with cerebrotendinous xanthomatosis exhibited ataxia and palatal tremor in the absence of tendon xanthomas and cataracts. Discussion: The importance of this case resides on the fact that cerebrotendinous xanthomatosis should be considered as a possible etiology of the syndrome of progressive ataxia with palatal tremor, even in the absence of tendon xanthomas and cataracts. Early diagnosis is critical to the institution of specific treatment with chenodeoxycholic acid.
Clinical Autonomic Research, 2020
Purpose: Huntington's disease (HD) patients have a high prevalence of falls. Autonomic nervous sy... more Purpose: Huntington's disease (HD) patients have a high prevalence of falls. Autonomic nervous system dysfunction has been reported from the early stages of the disease. There is no evidence analyzing the relationship between heart rate variability (HRV) and falls in this population. This research aimed to evaluate the relationship between HRV and falls in HD. Methods: HD patients enrolled in a prospective study of Fear of Falling and falls were assessed using short-term HRV analyses and blood pressure measures in resting and standing states. Time-frequency domains and nonlinear parameters were calculated. Data regarding falls, the risk of falling (RoF) and disease-specific scales were collected at baseline and six-month follow-up. Results: Twenty HD patients were recruited. 35% of HD patients reported at least one fall (single fallers) and, 65% reported two or more falls (recurrent fallers) in the previous 12-months. At baseline, recurrent fallers had lower RMSSD-resting (root-mean-square-of-the-RR), higher LF/HF ratio (low/high frequency) in both states, and higher DFA-α1 parameter (short-term-detrended-fluctuation-analyses) in both states. This association was similar at a six-month follow-up for recurrent fallers showing lower RMSSD-resting and higher LF/HF-standing ratio than single fallers. Significant correlations were found between the number of falls, RMSSD-resting, and LF/HF-standing ratio. No differences were found between recurrent and single fallers for any blood pressure measures. The observed HRV pattern is consistent with a higher sympathetic prevalence associated with a higher RoF. Reduced parasympathetic HRV values predict being a recurrent faller at six-months of follow-up, independently of orthostatic phenomena in this population.
Tourette syndrome: Clinical benefit with unilateral stimulation after bilateral pallidal implant
Movement Disorders, 2019
Data on deep brain stimulation (DBS) for severe Tourette syndrome (TS), including target location... more Data on deep brain stimulation (DBS) for severe Tourette syndrome (TS), including target location, need for bilateral procedures, safety and efficacy, and results on long-term follow-up remains scarce. We present a 29-year-old right-handed woman with TS whose symptoms emerged in early childhood. In the past 10 years, she progressively experienced marked obsessivecompulsive disorder and severe phonic and motor tics refractory to multiple, high-dose drug combinations including neuroleptics, benzodiazepines, tricyclic antidepressants, selective serotonin reuptake inhibitors, calcium channel blockers, antiepileptic drugs, and botulinum toxin injections. Her daily living activities were severely affected, and she was unable to maintain steady employment, remaining secluded at home. Severe tics provoked symptomatic cervical myelopathy, requiring surgical decompression (Supporting Information Video, segment A). At 6 months later, bilateral DBS of the anteromedial part of the internal globus pallidus (GPI) was performed (for procedure methodology and programming settings, see Supporting Information Material). At 2 weeks after surgery, the patient experienced clear improvement in both the severity and frequency of motor and phonic tics as well as in activities of daily living and social life, but less in obsessive-compulsive disorder (Table 1 and Supporting Information Video, segment B). At 14 months after surgery, during routine DBS programming follow-up, high impedance compatible with open-circuit lead failure was detected in the left electrode. The implantable pulse generator warned that stimulation delivery was absent in all 4 left lead contacts; therefore, left output was intentionally interrupted, and the patient was informed about it. Abnormal impedance measurements persisted during subsequent programming sessions; however, no worsening of clinical features was observed, nor were skin erosions, abrasions, or ulcerations visible on physical examination. The patient denied trauma or intentional manipulation of wires or implantable pulse generator. X-ray images revealed discontinuity of extension lead integrity at the level of the neck (Figure 1C). Because clinical status remained stable, surgical revision was deferred in agreement with the patient. At 12 months after unilateral right stimulation, clinical benefit remained unchanged (Supporting Information Video, segment C). No stimulation settings or additional pharmacological treatment changes were necessary. The use of unilateral (right side in 4 of 5 cases) stimulation to treat bilateral symptoms in TS has been reported and similar clinical improvements were observed. Unilateral stimulation (possibly the right side) may be effective to treat even bilateral symptoms as it may hypothetically restore or improve the imbalance between structural integration and segregation in right hemispheric functional networks involved in the planning, execution, and control of motor functions. In addition, it is not surprising to observe a bilateral control of abnormal behavior or movements by modulating one of the main outputs of the basal ganglia circuitry because these structures are implicated in the bimanual control of motor and nonmotor features. Despite the few cases reported, a comparison between unilateral and bilateral stimulation has not been properly evaluated. Data on the cessation of unilateral or bilateral stimulation in TS patients with bilateral DBS is limited and subject to controversy. The long-term persistence of clinical benefit with unilateral stimulation after left extension lead discontinuity, comparable with previous bilateral stimulation as observed in our patient, challenge the default indication of bilateral DBS implantation in TS. However, because a direct on-off stimulation comparison could not be done because of the patient’s reluctance to turn the active lead off, beneficial effects at the last follow-up could also be attributed to an acute change of the basal ganglia activity provided by DBS or also by a microlesion effects from either the electrodes or neuroplasticity or even a natural waning of disease severity, which is well known for this condition. Finally, because of the severity of the tics and the striking response to surgery, a psychogenic origin for some features exhibited by this patient might be suspected. However, we consider that this is not the case for a well-established diagnosis of severe TS followed-up for more than 10 years. The striking clinical benefit observed after surgery, which is further maintained with unilateral stimulation, adds casuistry to progress in terms of long-term outcomes for these complicated patients. Future double-blind crossover design studies should be conducted evaluating the alternate switching-off of 1 implantable pulse generator in patients with bilateral implants to clarify the need for bilateral stimulation in TS. *Correspondence to: Dr. Marcelo Merello, Servicio de Movimientos Anormales,…
The relevance of the neural code in the Basal Ganglia for the treatment of Parkinson's disease: Beyond the rate and pattern models
ABSTRACT
Phenomenology of abnormal movements in stuttering
Parkinsonism & Related Disorders, 2008
Stuttering is often accompanied by involuntary movements, abnormal gestures or changes in facial ... more Stuttering is often accompanied by involuntary movements, abnormal gestures or changes in facial expression. To describe the incidence and phenomenology of abnormal movements (AMs) in stuttering patients. Eighty-five consecutive patients with stuttering and 119 normal controls videotaped and subsequently reviewed, in which AMs were classified as voluntary or involuntary, and as concurrent or unrelated to speech. Movement phenomenology was correlated with disease severity. Of 85 stuttering patients studied, 51.7% had AMs and 22 more than one AM. Sixty-six different AMs were identified, of which 83.3% occurred during speech, 72.7% were classified as involuntary, and 27.2% as voluntary. Of 38 involuntary movements concurrent to speech, 25 were originally perceived as voluntary, but had since become involuntary through repeated use during stuttering. All involuntary movements not concurrent to speech fulfilled criteria for tics. AMs occurring during stuttering were not always involuntary; movements not concurrent with speech clearly fulfilled clinical criteria for tics and were similar in incidence to normal controls. Inverse correlation was found between conscious control of movement during speech and stuttering severity. Many involuntary movements occurring during speech were clearly referred by patients as initially voluntary early on in the development of their speech disorder (starters or unblockers), underlining the importance of repetitive use of complex motor sequences as a source for putative involuntary movement genesis.
Amantadine improves gait in PD patients with STN stimulation
Parkinsonism & Related Disorders, 2013
In advanced Parkinson&amp... more In advanced Parkinson's disease (PD), axial symptoms such as speech, gait, and balance impairment often become levodopa-unresponsive and they are difficult to manage, even in patients with subthalamic nucleus deep brain stimulation (STN-DBS). We anecdotally observed that oral administration of amantadine was very effective in treating both residual and stimulation-induced axial symptoms after bilateral STN-DBS in one PD patient. Therefore, we conducted a prospective multicenter observational study to evaluate the effects of amantadine on speech, gait and balance in PD patients with STN-DBS and incomplete axial benefit. Primary outcomes were changes in speech (UPDRS III, item 18), gait (item 29) and postural stability (item 30) with amantadine treatment compared to baseline. Secondary outcome was the patients' subjective scoring of axial symptoms with amantadine compared to baseline. Forty-six PD patients with STN-DBS were enrolled in the study and followed for 10.35 ± 8.21 months (median: 9.00; range: 1-31). The mean daily dose of amantadine was 273.44 ± 47.49 mg. Gait scores significantly improved (from 1.51 ± 0.89 to 1.11 ± 0.92, P = 0.015) with amantadine treatment, whereas postural stability and speech scores were similar before and after treatment. Thirty-five (76.1%) patients reported subjective improvement in speech, gait or balance with amantadine, whereas thirty (65.2%) patients reported improvement in gait and balance. In conclusion, our data suggest that amantadine may have new beneficial effects on axial symptoms in PD patients with STN-DBS.
Limb‐kinetic apraxia in corticobasal degeneration: Clinical and kinematic features
Movement Disorders, 2002
Current concepts regarding the organisation of the motor system indicate the existence of a front... more Current concepts regarding the organisation of the motor system indicate the existence of a frontoparietal circuit involved in prehension and manipulation, whose damage may result in a motor behavioural disorder strongly resembling the one originally described as limb‐kinetic apraxia. To determine the specific clinical and kinematic features of this distinctive praxic disorder, 5 patients with corticobasal degeneration (apraxic group), 5 with Parkinson's disease (nonapraxic group), and 10 control subjects were studied by a comprehensive apraxic battery, three‐dimensional motion analysis of manipulative movements and motor evoked potentials. A mathematical model [quality of movement coefficient (QMC)] was applied to quantify differential kinematic characteristics between elementary motor deficits and the praxic disorder. Transcranial magnetic stimulation was used to evaluate corticomotoneural projections and cortical inhibition. All five patients in the apraxic group exhibited a ...
Unilateral radiofrequency lesion versus electrostimulation of posteroventral pallidum: A prospective randomized comparison
Movement Disorders, 1999
Microelectrode-guided posteroventral pallidotomy (PVP) has shown to be an effective method in the... more Microelectrode-guided posteroventral pallidotomy (PVP) has shown to be an effective method in the treatment of a group of patients with advanced Parkinson's disease. A nonlesioning approach by means of deep brain electrodes connected to a programmable neuropacemaker has also been used to inhibit the internal segment of globus pallidus (posteroventral stimulation [PVS]) reporting comparable clinical efficacy to the one obtained with the ablative method. Nevertheless, no controlled studies have been performed to compare the efficacy of both procedures. A prospective series of 13 patients with a clinical indication for globus pallidus surgery was randomized either to a pallidotomy or stimulator implantation, and comparisons on motor and neuropsychologic measurements were made on a 3-month follow-up basis. Primary measurements of efficacy showed a comparable effect on Unified Parkinson's Disease Rating Scale and activities of daily living score after both procedures. Secondary measurements of efficacy showed that although both techniques improve hand tapping score and dyskinesia score, the bilateral improvement in the former was greater after PVS whereas the latter improved more significantly after PVP. No significant changes in neuropsychologic parameters were observed after either PVP or PVS. Side effects and surgery complications occurred in six of 13 patients (three after PVP and three after PVS): they were mild, transient, and unrelated to optic tract injury. In conclusion, the short-time effect and safety of both procedures is comparable.
Neuronal activity of the zona incerta in Parkinson's disease patients
Movement Disorders, 2006
The objective of this study was to describe the firing characteristics of the zona incerta (ZI) i... more The objective of this study was to describe the firing characteristics of the zona incerta (ZI) in Parkinson's disease patients. The ZI constitutes a band of gray matter lying dorsal to the subthalamic nucleus, whose firing properties have not been well defined in humans yet. ZI proved to become hyperactive in 6-OHDA-lesioned rats as compared to normal rats, and regarding these noticeable changes in the discharge patterns it was suggested that ZI could be a putative target for the surgical treatment of Parkinson's disease. Twelve patients who underwent microrecording-guided subthalamic surgery consented to the study. Neurons from different tracts were classified as belonging to the ZI according to their firing features, background extracellular activity, anatomical mapping of trajectories, and atlas confirmation. Fifty-nine neurons were classified as belonging to ZI. The mean firing rate proved to be 29.5 Hz, with a broad dispersion band, even covering subthalamic nucleus (STN) frequency ranges. Pattern analysis showed heterogeneous neuronal signals ranging from tonic to burst and paused neurons. A decrease in extracellular background activity in the defined ZI was also observed. Five of the recorded neurons showed rhythmical spike trains with oscillations of 8 to 14 Hz, and two units were found to discharge trains at 4 Hz. None of the recorded ZI neurons responded to proprioceptive maneuvers. ZI presented firing activities with a broad spectrum in terms of frequency and tonicity. It is differentiated from STN recordings in Parkinson's disease patients mainly because of absent proprioceptive-related units and diminished extracellular background activity.
Protocol for the microelectrode recording of neuronal activity in head-restrained, alert animals
Journal of the Neurological Sciences, 2013
ABSTRACT Background: The microelectrode recording (MER) of neuronal activity is the gold standard... more ABSTRACT Background: The microelectrode recording (MER) of neuronal activity is the gold standard for intrasurgical target localization during the implantation of Deep Brain Stimulation (DBS) electrodes. Since MER in patients with Parkinson's disease (PD) are usually obtained under local anesthesia only , an important question is to what extent the neuronal discharge characteristics of the Basal Ganglia depend on dopamine deprivation and to what extent on the level of alertness of the subject. An appropriate experimental protocol for approaching this problem in animal models of PD is currently lacking.
Turbulence in Globus pallidum neurons in patients with Parkinson's disease: Exponential decay of the power spectrum
Journal of Neuroscience Methods, 2011
Exponential decay of the power spectrum is typically observed in turbulent flow patterns, as evid... more Exponential decay of the power spectrum is typically observed in turbulent flow patterns, as evidenced both in experiments and in the Navier-Stokes equations describing fluid dynamics. In this study, we present evidence on the exponential decay of power spectra belonging to interspike interval time series, registered in pallidal neurons from patients with Parkinson's disease. Extracellular neuronal recordings were obtained during functional neurosurgery and processed off-line. Interspike interval power spectra were calculated for single unit recordings. All power spectra analyzed were similar, presenting rapid decay of power with frequency. Regression coefficient (adjusted R squared) for exponential function fit was very high, over 0.99 (p<0.001) in every case. We therefore suggest that the neurons studied here show turbulent-like behavior from a spectral point of view, and theorize that Navier-Stokes-like equations may be potentially useful tools to model spectral patterns of firing activity in neurons of this type. We propose to classify neural systems according to the general form of their power spectrum into two major groups of physical systems: systems with scale invariance and a power-law behavior of the power spectrum, and systems with critical scale and an exponential decay of the power spectrum.
European Journal of Neurology, 1997
We examined, with single photon emission tomography (SPECT) and ( 99m Tc)_HMPAO, 18 patients with... more We examined, with single photon emission tomography (SPECT) and ( 99m Tc)_HMPAO, 18 patients with idiopathic Parkinson's disease and no dementia (PD), 12 patients with PD and dementia, 24 patients with probable Alzheimer's disease (AD), and 14 controls. While the three patient groups showed significantly lower perfusion in frontal inferior and temporal inferior areas as compared to controls, both demented groups showed significantly more severe bilateral hypoperfusion in superior frontal, superior temporal and parietal areas as compared to non-demented PD patients and controls. On the other hand, no significant differences in cerebral perfusion were found between patients with AD and patients with PD and dementia. In conclusion, our findings demonstrated specific but similar cerebral perfusion deficits in demented patients with either AD or PD.
Drug-Induced Parkinsonism in Schizophrenic Patients: Motor Response and Psychiatric Changes After Acute Challenge with L-Dopa and Apomorphine
Clinical Neuropharmacology, 1996
Acute single-dose response of drug-induced parkinsonism (DIP) to L-Dopa and apomorphine challenge... more Acute single-dose response of drug-induced parkinsonism (DIP) to L-Dopa and apomorphine challenge was evaluated in a double-blind crossover study in 12 schizophrenic patients. There were two noteworthy negative findings. First, neither L-Dopa nor apomorphine produced significant improvements in DIP and second, no changes (neither improvement nor worsening) were found in patients' psychiatric status. Findings suggest that, for a stimulation dose reaching almost 90% of the responsive dose for idiopathic Parkinson's disease, no significant changes may reasonably be expected in the parkinsonism of schizophrenic patients treated with neuroleptic drugs.
Prospective randomized 1-year follow-up comparison of bilateral subthalamotomy versus bilateral subthalamic stimulation and the combination of both in Parkinson's disease patients: a pilot study
British Journal of Neurosurgery, 2008
It has been suggested that potential risk of hemiballismus after subthalamotomy makes DBS prefera... more It has been suggested that potential risk of hemiballismus after subthalamotomy makes DBS preferable to ablation for IPD treatment; however, cost and the need for regular electrode control have also been observed as disadvantages to stimulation. The objective was to compare efficacy and safety of different surgical approaches to STN, in a prospective randomized pilot study. Sixteen consecutive IPD patients randomized to receive either: bilateral STN-DBS, bilateral subthalamotomy or unilateral subthalamotomy plus contralateral STN-DBS implantation, and followed for 12 months after surgery. One patient died and was excluded from the analysis. Total and motor UPDRS scores, as well as drug-induced dyskinesias improved significantly at 1 year follow-up, regardless of the procedure administered and without statistically significant differences between treatment modalities. Discrete changes were observed on ACE and MMSE scores. Psychiatric examination of patients subjected to bilateral stimulation and lesion, revealed slight increment in apathy and irritability scores, coinciding with significant deterioration of mentation, behaviour and mood as measured using the UPDRS. One patient presented persistent hemiballismus and required ulterior posteroventral pallidotomy. In this small group of patients, overall motor performance significantly improved after all three procedures, without major differences in outcome. Adverse events were, nevertheless, observed after both ablation and stimulation. The role of bilateral subthalamotomy in patients unable to receive a DBS electrode-implant merits further exploration in a larger series of patients with longer follow-up.
Brain, 1997
We studied 45 non-demented patients with Parkinson's disease Some PSP patients exhibited, in addi... more We studied 45 non-demented patients with Parkinson's disease Some PSP patients exhibited, in addition, a limbkinetic type of apraxia and a minority of them displayed deficits on tasks (PD), 12 with progressive supranuclear palsy (PSP), 10 with multiple system atrophy (MSA) and 12 with neuroleptic-involving multiple steps. Neither MSA nor NIP patients showed any disturbance of praxic functions. There were no induced parkinsonism (NIP) for the presence of apraxia. Our aim was to determine whether a standard comprehensive differences in age, disease duration, Mini Mental State Examination (MMSE), Unified Parkinson's Disease Rating assessment of different praxic functions would demonstrate specific types of errors not attributable to bradykinesia, Scale and Hoehn-Yahr scores between apraxic and nonapraxic PD patients, and ideomotor apraxia scores were rigidity, tremor or any other abnormal elementary motor deficit. PD patients on chronic levodopa treatment were similar in the 'on' and 'off' states. A correlation was found between ideomotor apraxia scores in PD patients and deficits examined in the 'on ' and 'off' (treatment) states. Based on apraxia assessment scores, bilateral ideomotor apraxia for in frontal lobe-related neuropsychological tasks such as the Tower of Hanoi, verbal fluency and the Trail Making Test. transitive movements was found in eight (75%) and 12 (27%) of PSP and PD patients, respectively. Ideomotor apraxia was Furthermore, PD patients with apraxia showed higher Hamilton depression scores than non-apraxic PD patients. mainly characterized by spatial errors (i.e. external and internal configuration, body-part-as-object and trajectory). In PSP patients, ideomotor apraxia scores correlated significantly with cognitive deficit as measured with MMSE. Four PSP but no PD patients exhibited ideomotor apraxia for intransitive movements. PSP as well as PD patients with The presence or absence of cortical involvement, and its severity and distribution might determine the presence and ideomotor apraxia also had difficulties in imitating hand and finger postures, but none of them failed on pantomime type of apraxia in PD and PSP. Apraxia in these conditions would therefore reflect combined cortico-striatal dysfunction. comprehension and pantomime recognition/discrimination.
Objective-To examine neuropsychologi- cal and neuropsychiatric differences between patients with ... more Objective-To examine neuropsychologi- cal and neuropsychiatric differences between patients with probable Alzheimer's disease and patients with Parkinson's disease and dementia. Methods-Thirty three patients with probable Alzheimer's disease and 33 patients with Parkinson's disease and dementia were matched for age, sex, and mini mental state examination scores and given a battery of neuropsychological and neuropsychiatric tests. Results-Patients with Parkinson's disease with dementia had a significantly higher prevalence of major depression than patients with Alzheimer's disease; patients with Alzheimer's disease showed more severe anosognosia and disinhibi- tion than patients with Parkinson's disease. Whereas no significant between group differences were found on tests of memory and language, demented patients with Parkinson's disease had a significantly greater impairment on a test of visual reasoning than patients with Alzheimer's disease. Conclusion-There were significant psy- chiatric differences between patients with Alzheimer's disease and demented patients with Parkinson's disease, but neuropsychological differences were restricted to a single cognitive domain.
Revista Argentina de Bioingeniería, May 13, 2020
Background: Movement disorders are neurologic syndromes that produce abnormal movements, being Pa... more Background: Movement disorders are neurologic syndromes that produce abnormal movements, being Parkinson's disease (PD) the most frequent. Current diagnosis of Parkinson's disease is clinical: it is based on expertise, which can result in diagnostic errors and treatment deficits. Quantitative diagnosis is reached searching objective parameters, a quantity that correlates with the phenomenon we want to quantify. Quantitative measures of movement are a novel approach to assist physicians in the diagnosis of Parkinson's disease. Objective: To find a quantitative feature in accelerometery signals that distinguishes parkinsonian patients from age-matched control subjects. Method: We designed and developed an ergonomic wristband with proper electronics attached, including inertial sensors and control logic to manage the data signals. Additionally, we developed a mobile app for logging and administration of data signals. We measured limb acceleration in two groups of people: a group of patients with Parkinson's disease (n = 11) and an age-matched control group (n = 10). Acceleration signals were measured during the evaluation of finger tapping (from the motor subscore of the Unified Parkinson's Disease Rating Scale-UPDRS part III). To characterize the signals, we developed mathematical tools based on the analysis of temporal and frequency patterns. Power spectrum analysis of the signals exhibited a power law relationship between variables with different frequency ranges. Results: Interpreting the finger tapping task as an input to the motor system, variations in the scale invariance bandwidth can be related to the mechanic system's control response. Analyzing the power spectrum of the patient group signals, a statistical relevant reduction (p<0.005) is found in the frequency range that follows a power law (Linear Invariance Range, LIR) compared to the control group. LIR quantity calculated correlates with the gold standard clinical diagnosis MDS-UPDRS-III. Conclusion: The LIR quantity allows proposing a reduction of the scale. The quantity LIR found is proposed as a possible signal related biomarker of Parkinson's disease.
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Papers by Marcelo Merello