Rigidity in Parkinson's disease: evidence from biomechanical and neurophysiological measures.

Although rigidity is a cardinal motor sign in patients with Parkinson's disease (PD), the instrumental measurement of this clinical phenomenon is largely lacking, and its pathophysiological underpinning remains still unclear. Further advances in the field would require innovative methodological approaches able to measure parkinsonian rigidity objectively, discriminate the different biomechanical sources of muscle tone (neural or visco-elastic components), and finally clarify the contribution to 'objective rigidity' exerted by neurophysiological responses, which have previously been associated with this clinical sign (i.e. the long-latency stretch-induced reflex). Twenty patients with PD (67.3 ± 6.9 years) and 25 age- and sex-matched controls (66.9 ± 7.4 years) were recruited. Rigidity was measured clinically and through a robotic device. Participants underwent robot-assisted wrist extensions at seven different angular velocities randomly applied, when ON therapy. For each value of angular velocity, several biomechanical (i.e. elastic, viscous and neural components) and neurophysiological measures (i.e. short and long-latency reflex and shortening reaction) were synchronously assessed and correlated with the clinical score of rigidity (i.e. Unified Parkinson's Disease Rating Scale-part III, subitems for the upper limb). The biomechanical investigation allowed us to measure 'objective rigidity' in PD and estimate the neuronal source of this phenomenon. In patients, 'objective rigidity' progressively increased along with the rise of angular velocities during robot-assisted wrist extensions. The neurophysiological examination disclosed increased long-latency reflexes, but not short-latency reflexes nor shortening reaction, in PD compared with control subjects. Long-latency reflexes progressively increased according to angular velocities only in patients with PD. Lastly, specific biomechanical and neurophysiological abnormalities correlated with the clinical score of rigidity. 'Objective rigidity' in PD correlates with velocity-dependent abnormal neuronal activity. The observations overall (i.e. the velocity-dependent feature of biomechanical and neurophysiological measures of objective rigidity) would point to a putative subcortical network responsible for 'objective rigidity' in PD, which requires further investigation.

Stiff-person syndrome: an atypical presentation and a review of the literature.

Introduction: Stiff-person syndrome (SPS) is a rare autoimmune neurological disorder associated with muscle rigidity and spasms. A number of antibodies have been associated with disorder, including anti-glutamic acid decarboxylase and anti-amphiphysin.Case report; In this report, we present a rare case of a 79-year-old woman who presented with bilateral lower extremity weakness who was ultimately diagnosed with stiff-limb syndrome, a rare variant of SPS. Extensive laboratory and CSF studies were unrevealing. Electromyography showed significant peroneal motor neuropathy and complex repetitive discharges in the left tibialis anterior muscle. Antibodies to glutamic acid decarboxylase were significantly elevated at 124 units/mL. She was subsequently started on oral diazepam with significant improvement in her symptoms.Conclusion: The presentation of SPS can vary based on epidemiologic factors, clinical symptoms, and associated disorders. These forms can have overlapping features which may make the categorization of patients into one of these forms challenging.

Progressive encephalomyelitis with rigidity: A Taiwanese case and review of literature.

INTRODUCTION: Progressive encephalomyelitis with rigidity and myoclonus (PERM) is a rare disorder. However, the outcome is still variable with different serological and tumor associations, and the elements to good response with less relapse is yet to be elucidated. METHOD: We present a case and obtain a literature review of patients with PERM and make comparisons based on different serological groups. We also analyze patients with idiopathic PERM that had detailed medical records. RESULTS: 81 patients were collected and analyzed. The largest group were glycine receptor-antibody (GlyR-Ab)-positive (70%), and the seropositive-GlyR-Ab-negative group had better response to immunotherapy. Malignancy can occur up to 2 years from the presentation of PERM. Among the 18 cases with detailed records, the patients who had good outcome initiate immunotherapy within 2 months from presentation. 9 of the 12 patients who experienced no relapse had non-steroid immunotherapy. The maximal interval time of relapse was 24 months. CONCLUSION: We recommend tumor surveillance up to 2 years in patients with PERM and early administration of immunotherapies and maintain with non-steroid immunotherapy with or without oral corticosteroid for a minimum of 2 years to reduce the risk of relapse in GlyR-Ab-positive patients.

Muscle Tone Physiology and Abnormalities.

The simple definition of tone as the resistance to passive stretch is physiologically a complex interlaced network encompassing neural circuits in the brain, spinal cord, and muscle spindle. Disorders of muscle tone can arise from dysfunction in these pathways and manifest as hypertonia or hypotonia. The loss of supraspinal control mechanisms gives rise to hypertonia, resulting in spasticity or rigidity. On the other hand, dystonia and paratonia also manifest as abnormalities of muscle tone, but arise more due to the network dysfunction between the basal ganglia and the thalamo-cerebello-cortical connections. In this review, we have discussed the normal homeostatic mechanisms maintaining tone and the pathophysiology of spasticity and rigidity with its anatomical correlates. Thereafter, we have also highlighted the phenomenon of network dysfunction, cortical disinhibition, and neuroplastic alterations giving rise to dystonia and paratonia.

A validated measure of rigidity in Parkinson's disease using alternating finger tapping on an engineered keyboard.

INTRODUCTION: Reliable and accurate measures of rigidity have remained elusive in remote assessments of Parkinson's disease (PD). This has severely limited the utility of telemedicine in the care and treatment of people with PD. It has also had a large negative impact on the scope of available outcomes, and on the costs, of multicenter clinical trials in PD. The goal of this study was to determine if quantitative measures from an engineered keyboard were sensitive and related to clinical measures of rigidity. METHODS: Sixteen participants with idiopathic PD, off antiparkinsonian medications, and eleven age-matched control participants performed a 30 second repetitive alternating finger tapping task on an engineered keyboard and were assessed with the Unified Parkinson's Disease Rating Scale - motor (UPDRS-III). RESULTS: The speed of the key release was significantly slower in the PD compared to control cohorts (p < 0.0001). In the PD cohort key release speed correlated with the lateralized upper extremity UPDRS III rigidity score (r = - 0.58, p < 0.0001), but not with the lateralized upper extremity tremor score (r = - 0.14, p = 0.43). CONCLUSIONS: This validated measure of rigidity complements our previous validation of temporal metrics of the repetitive alternating finger tapping task with the UPDRS III, bradykinesia and with the ability to quantify tremor, arrhythmicity and freezing episodes, and suggests that 30 seconds of alternating finger tapping on a portable engineered keyboard could transform the treatment of PD with telemedicine and the precision of multicenter clinical trials.

Paratonia in Dementia: A Systematic Review.

BACKGROUND: Paratonia is a dementia-induced motor abnormality. Although paratonia affects virtually all people with dementia, it is not well known among clinicians and researchers. OBJECTIVE: The aim of this study was to perform a systematic review of the literature on the definition, pathogenesis, diagnosis, and intervention of paratonia as well as to propose a research agenda for paratonia. METHODS: In this systematic review, the Embase, PubMed, CINAHL, and Cochrane CENTRAL databases were searched for articles published prior to December 2019. Two independent reviewers performed data extraction and assessed the risk of bias of the studies. The following data were extracted: first author, year of publication, study design, study population, diagnosis, assessment, pathogenesis, therapy and interventions. RESULTS: Thirty-five studies met the inclusion criteria and were included. Most studies included in the review mention clinical criteria for paratonia. Additionally, pathogenesis, method of assessment, diagnosis, and paratonia severity as are interventions to address paratonia are also discussed. CONCLUSION: This systematic review outlines what is currently known about paratonia, as well as discusses the preliminary research on the underlying mechanisms of paratonia. Although paratonia has obvious devastating impacts on health and quality of life, the amount of research to date has been limited. In the last decade, there appears to have been increased research on paratonia, which hopefully will increase the momentum to further advance the field.

Síndrome de persona rígida: presentación de caso clínico y abordaje terapéutico / Stiff man Syndrome Clinical case presentation and therapeutic approach

Introducción: El síndrome del hombre rígido representa una rara enfermedad neuromuscular caracterizada por rigidez muscular progresiva y espasmos musculares dolorosos que afecta a 1 persona por cada millón de habitantes por año en el mundo. En la mayoría de los pacientes se encuentran niveles elevados de anticuerpos descarboxilasa del ácido glutámico. En Colombia solo se han publicado alrededor de 3 casos, lo que motiva la presentación de un nuevo informe que aporte a la discusión actual en el campo de la neurología clínica. Caso clínico: Paciente de sexo femenino de 35 años con cuadro clínico progresivo de varios años, caracterizado por contracciones paroxísticas dolorosas, parestesias y pérdida de fuerza. Se documentó la presencia de anticuerpos anti-GAD compatibles con el síndrome del hombre rígido. Tras un tratamiento integral, que incluyó la infusión farmacológicamente intratecal con baclofeno, se obtuvo mejoría clínica en el índice de Barthel. Conclusiones: El síndrome del hombre rígido es una condición infradiagnosticada que se asocia a un deterioro de la calidad de vida de quienes lo padecen.

Introduction: Stiff man syndrome represents a rare neuromuscular disease characterized by progressive muscle rigidity and painful muscle spasms that affects 1 person for every million habitants per year in the world. High levels of glutamic acid antibodies decarboxylase are found in most patients. In Colombia, only around 3 cases have been published, which motivates the presentation of a new report that contributes to the current discussion in the field of clinical neurology. Clinical Case: 35-year-old female patient with a progressive clinical picture of several years, characterized by painful paroxysmal contractions, paresthesias and loss of strength. The presence of anti-GAD antibodies was documented, compatible with Stiff man syndrome. After comprehensive treatment, which included pharmacologically intrathecal infusion with baclofen, clinical improvement was obtained in the Barthel index. Conclusions: Stiff man syndrome is an underdiagnosed condition which is associated with a deterioration in the quality of life for those who suffer from it.

Transferencia de trapecio: reanimación de hombro en lesiones tardías de plexo braquial / Trapezius transfer: shoulder reanimation in late brachial plexus injuries

Antecedentes y Objetivo. Las secuelas tardías de las lesiones altas del plexo braquial incluyen el compromiso de la abducción y la rotación externa del hombro. El objetivo de nuestro trabajo es presentar nuestra experiencia inicial con una serie de casos de tratamiento tardío en pacientes en quienes la reconstrucción nerviosa no está indicada. Materiales y método. Presentamos nuestra experiencia preliminar en 5 pacientes con ausencia completa de los movimientos del hombro. Transferimos la parte superior del trapecio para restaurar la abducción en casos en los que otros procedimientos han fallado o no están indicados, por ausencia de actividad del dorsal ancho y largo tiempo de evolución. Resultados. La transferencia muscular permitió restaurar la abducción del hombro en todos los pacientes. Tras el procedimiento, la abducción media fue de 47 grados. Dos casos presentaron rigidez postoperatoria transitoria; otros 2 pacientes sufrieron fractura incompleta del húmero que requirió osteosíntesis con consolidación ósea a las 8 semanas. Conclusiones. Consideramos que este grupo de pacientes de mal pronóstico encuentra en este procedimiento una opción de reconstrucción cuyos resultados deben ser evaluados a más largo plazo y con mayor número de pacientes para dar recomendaciones precisas. Es un procedimiento que ofrece una alternativa a los pacientes con secuelas severas de lesiones de plexo braquial, con mínima morbilidad

Background and Objective. Late sequels of brachial plexus injuries include deficit in abduction and external rotation of the shoulder. The aim of this paper is to present our initial experience with a clinical series of late presentation, in whom primary nerve reconstruction is not indicated. Methods. We present our initial experience including a series of 5 cases. All patients presented a complete paralyzed shoulder. The superior part of the trapezius muscle was transferred to restore shoulder abduction, in cases where other procedures had failed or are not indicated because of latissimus dorsi palsy or late presentation. Results. The trapezius functional transfer was able to restore shoulder abduction in all patients. After the procedure the mean active range of motion was 47 degrees. In 2 cases there was transitory shoulder rigidity. Partial humeral fracture was presented in other 2 cases, but after internal fixation, bone consolidation was achieved after 8 weeks. Conclusions. The trapezius transfer offers minimal morbidity. It continues to be a useful tool in secondary reconstruction in late brachial plexus injuries, but our small series does not allow us to evaluate results and a longer follow up period is needed

New Sensor and Wearable Technologies to Aid in the Diagnosis and Treatment Monitoring of Parkinson's Disease.

Parkinson's disease (PD) is a degenerative disorder of the brain characterized by the impairment of the nigrostriatal system. This impairment leads to specific motor manifestations (i.e., bradykinesia, tremor, and rigidity) that are assessed through clinical examination, scales, and patient-reported outcomes. New sensor-based and wearable technologies are progressively revolutionizing PD care by objectively measuring these manifestations and improving PD diagnosis and treatment monitoring. However, their use is still limited in clinical practice, perhaps because of the absence of external validation and standards for their continuous use at home. In the near future, these systems will progressively complement traditional tools and revolutionize the way we diagnose and monitor patients with PD.

Using wearables to assess bradykinesia and rigidity in patients with Parkinson's disease: a focused, narrative review of the literature.

The potential of using wearable technologies for the objective assessment of motor symptoms in Parkinson's disease (PD) has gained prominence recently. Nonetheless, compared to tremor and gait impairment, less emphasis has been placed on the quantification of bradykinesia and rigidity. This review aimed to consolidate the existing research on objective measurement of bradykinesia and rigidity in PD through the use of wearables, focusing on the continuous monitoring of these two symptoms in free-living environments. A search of PubMed was conducted through a combination of keyword and MeSH searches. We also searched the IEEE, Google Scholar, Embase, and Scopus databases to ensure thorough results and to minimize the chances of missing relevant studies. Papers published after the year 2000 with sample sizes greater than five were included. Studies were assessed for quality and information was extracted regarding the devices used and their location on the body, the setting and duration of the study, the "gold standard" used as a reference for validation, the metrics used, and the results of each paper. Thirty-one and eight studies met the search criteria and evaluated bradykinesia and rigidity, respectively. Several studies reported strong associations between wearable-based measures and the gold-standard references for bradykinesia, and, to a lesser extent, rigidity. Only a few, pilot studies investigated the measurement of bradykinesia and rigidity in the home and free-living settings. While the current results are promising for the future of wearables, additional work is needed on their validation and adaptation in ecological, free-living settings. Doing so has the potential to improve the assessment and treatment of motor fluctuations and symptoms of PD more generally through real-time objective monitoring of bradykinesia and rigidity.

Fact-finding survey on diagnostic procedures and therapeutic interventions for parkinsonism accompanying dementia with Lewy bodies.

BACKGROUND: We performed a questionnaire survey of medical doctors engaged in the management of dementia to identify the actual status of treatment for dementia with Lewy bodies (DLB) in Japan. METHODS: Among participating medical doctors, we selected neurologists (Group N) and psychiatrists (Group P) because these physicians are usually involved in the management of DLB patients. The two groups were compared based on their diagnosis and treatment of DLB and in particular, parkinsonism. RESULTS: Neurological examinations and biomarker tests were less frequently performed by Group P than Group N. Antipsychotics and other psychotropics excluding anti-dementia drugs were significantly more frequently administered by Group P than Group N. The proportion of physicians who selected L-dopa as a first-line therapy for parkinsonism was significantly higher in Group N than in Group P. Despite these between-group differences, the following findings were common to the two groups: there was a discrepancy between the symptom that patients expressed the greatest desire to treat, and the awareness of physicians regarding the treatment of these symptoms; the initial agent was L-dopa; and physicians exercised caution against the occurrence of hallucinations, delusions, and other adverse drug reactions. CONCLUSIONS: The results of the present survey offer valuable insight for the formulation of future DLB therapeutic strategies.

A palm-worn device to quantify rigidity in Parkinson's disease.

BACKGROUND: Parkinsonian rigidity is identified on clinical examination as resistance to passive movement. Measurement of rigidity commonly relies on ordinal rating scales (MDS-UPDRS), however instrumented objective measures may provide greater mechanistic insight. NEW METHOD: We present a palm-worn instrument to objectively quantify rigidity on a continuous scale. The device employs a miniature motor to flex the third digit of the hand about the metacarpophalangeal joint whilst transducers record flexion/extension forces. We aim to determine congruence with the MDS-UPDRS, investigate sensitivity to the impact of deep brain stimulation (DBS) and contralateral movement, and make comparisons with healthy individuals. Eight participants with Parkinson's disease underwent evaluation during conditions: on and off DBS, and with and without contralateral limb movement to activate rigidity. During each DBS condition, wash-in/out effects were tracked using both our instrument and two blinded clinical raters. Sixteen healthy volunteers (age-matched/young) served as controls. RESULTS: Rigidity measured using our instrument had moderate agreement with the MDS-UPDRS and showed differences between therapeutic state, activation conditions, and disease/healthy cohorts. Rigidity gradually worsened over a one-hour period after DBS cessation, but improved more rapidly with DBS resumption. COMPARISON WITH EXISTING METHODS: Previous attempts to quantify rigidity include manual approaches where a clinician is required to manipulate limbs while sensors passively gather information, or large automated instruments to move the wrist or elbow. CONCLUSION: Given its ability to track changes in rigidity due to therapeutic intervention, our technique could have applications where continuous measurement is required or where a suitably qualified rater is absent.

Vastly Different Exercise Programs Similarly Improve Parkinsonian Symptoms: A Randomized Clinical Trial.

OBJECTIVES: To directly compare the effects of agility exergaming (EXE) and stationary cycling (CYC) exercise training on Parkinson's disease (PD) patients' mobility and clinical symptoms. DESIGN: Randomized clinical trial. SETTING: Outpatient physiotherapy clinic in a hospital. PARTICIPANTS: Seventy-four stage 2-3, nondemented PD patients were included in this study. INTERVENTION: The groups were as follows: EXE (n = 25), CYC (n = 25), and a wait-listed control group (CON; n = 24). The EXE and CYC groups exercised 5×/week for 5 weeks, matched at 80% of the age-predicted maximal heart rate. MAIN OUTCOMES: The primary outcome was the Movement Disorders Society Unified Parkinson's Disease Rating Scale (UPDRS-II) score. Secondary outcomes were Parkinson's Disease Quastionnaire-39 (PDQ-39), the Beck Depression Inventory (BDI), the Schwab and England Activities of Daily Living (SE-ADL) scale, Euro-Quality of Life-5 Dimensions (EQ-5D) questionnaire, the Berg Balance Scale (BBS), the Balance Evaluation Systems Test (BESTest), the Tinetti Assessment Tool (TAT), the Dynamic Gait Index, the 6-min walk test (6MWT), and standing posturography. RESULTS: After treatment, UPDRS-II scores improved (mean change: EXE, -4.5 points; CYC, -3.2 points). The results for the other outcomes (EXE and CYC, respectively) were: PDQ, 13 and 17%; BDI, -2.5 and -2.1 points; 6MWT, 129.6 and 141.6 m; and EQ-5D, 12 and 9% (all p < 0.05, but there was no difference between groups). EXE vs. CYC resulted in improved SE-ADL (8.4 and 4.0 points, effect size [ES]: 0.12), BBS (8.8 and 4.2 points, ES: 0.44), and 2 measures of posturography (ES: 0.11 and 0.21) (p < 0.05). BESTtest, TAT, the Dynamic Gait Index, and 4 out of 6 posturography measures did not change (p > 0.05). CONCLUSION: Two highly different exercise programs resulted in similar improvement of most motor and clinical symptoms in PD patients.

A case report of rigidity and recurrent lower limb myoclonus: progressive encephalomyelitis rigidity and myoclonus syndrome, a chameleon.

BACKGROUND: Progressive encephalomyelitis with rigidity and myoclonus (PERM) syndrome is a rare neurological condition. Its clinical characteristics include axial and limb muscle rigidity, myoclonus, painful spasms and hyperekplexia. Diagnosis of this disease can be very challenging and optimal long-term treatment is unclear. CASE PRESENTATION: We report a case of a 62 year old patient admitted for repetitive myoclonus and rigidity in the lower limbs progressing since 10 years, associated with a fluctuating encephalopathy requiring stays in Intensive Care Unit. Multiple diagnostics and treatment were proposed, unsuccessfully, before the diagnosis of PERM syndrome was established. In association with the clinical presentation, a strong positive result for GAD (glutamic acid decarboxylase) antibodies lead to the diagnosis of PERM syndrome. CONCLUSIONS: PERM syndrome is a rare disease and its diagnosis is not easy. Once the diagnosis is established, the correct treatment should follow and could be lifesaving, regardless of a delayed diagnosis. Maintenance of long-term oral corticotherapy is suggested to prevent relapses.

Muscular MRI-based algorithm to differentiate inherited myopathies presenting with spinal rigidity.

OBJECTIVES: Inherited myopathies are major causes of muscle atrophy and are often characterized by rigid spine syndrome, a clinical feature designating patients with early spinal contractures. We aim to present a decision algorithm based on muscular whole body magnetic resonance imaging (mWB-MRI) as a unique tool to orientate the diagnosis of each inherited myopathy long before the genetically confirmed diagnosis. METHODS: This multicentre retrospective study enrolled 79 patients from referral centres in France, Brazil and Chile. The patients underwent 1.5-T or 3-T mWB-MRI. The protocol comprised STIR and T1 sequences in axial and coronal planes, from head to toe. All images were analyzed manually by multiple raters. Fatty muscle replacement was evaluated on mWB-MRI using both the Mercuri scale and statistical comparison based on the percentage of affected muscle. RESULTS: Between February 2005 and December 2015, 76 patients with genetically confirmed inherited myopathy were included. They were affected by Pompe disease or harbored mutations in RYR1, Collagen VI, LMNA, SEPN1, LAMA2 and MYH7 genes. Each myopathy had a specific pattern of affected muscles recognizable on mWB-MRI. This allowed us to create a novel decision algorithm for patients with rigid spine syndrome by segregating these signs. This algorithm was validated by five external evaluators on a cohort of seven patients with a diagnostic accuracy of 94.3% compared with the genetic diagnosis. CONCLUSION: We provide a novel decision algorithm based on muscle fat replacement graded on mWB-MRI that allows diagnosis and differentiation of inherited myopathies presenting with spinal rigidity. KEY POINTS: • Inherited myopathies are rare, diagnosis is challenging and genetic tests require specialized centres and often take years. • Inherited myopathies are often characterized by spinal rigidity. • Whole body magnetic resonance imaging is a unique tool to orientate the diagnosis of each inherited myopathy presenting with spinal rigidity. • Each inherited myopathy in this study has a specific pattern of affected muscles that orientate diagnosis. • A novel MRI-based algorithm, usable by every radiologist, can help the early diagnosis of these myopathies.