The exact cause of Parkinson disease is unknown, but it is assumed to be the result of a combination of environmental influences superimposed on genetic predisposition or susceptibility (Table ...2).14-16 There is increasing evidence that the genetic and environmental insults leading to Jankovic J. Parkinson disease commonly lead to abnormal forms of a normal protein, α-synuclein, which seems to contribute to cell death.16,23 The onset of Parkinson disease can be categorized as juvenile (age < 21 yr), early onset (21-50 yr) and late onset (generally > 60 yr).24,25 The juvenile form is rare, is often familial (in as many as 50% of cases), is most frequently associated with a parkin gene mutation and has an atypical presentation.25,26 Of patients with Parkinson disease, 10%-16% have an affected first- or second-degree relative; first-degree relatives may have double the risk of Parkinson disease compared with the general population.26-29 In early- and late-onset Parkinson disease, the frequency of a positive family history is not statistically different.24 In advanced Parkinson disease, the efficacy of levodopa can decline and fluctuate throughout the day switching between "on" and "off' medication periods.92 The motor and nonmotor fluctuations mirror those seen in levodopa plasma concentrations resulting from levodopa's short half-life.93 Providing continuous dopaminergic stimulation is the goal of treating fluctuations in patients with advanced Parkinson disease.94-96 We now have surgical options, including deep brain stimulation and levodopacarbidopa intestinal gel, to provide treatment to such patients. Currently, deep brain stimulation has the highest level of evidence with the largest number of randomized controlled trials.97 Emerging therapies currently being studied in Parkinson disease are listed in Appendix 7, available at www.cmaj.ca/lookup/suppl/doi :10.1503/cmaj.151179/-/DC1. The response to deep brain stimulation is equal to the best response on levodopa, but more effective than medical therapy in improving "on" time without troublesome dyskinesias.101,102 Deep brain stimulation typically improves levodoparesponsive symptoms (e.g., tremor, bradykinesia, rigidity) and on-off fluctuations and dyskinesias, whereas impairments in gait, balance and speech are less likely to improve. Patients should be considered for deep brain stimulation only if adequate trials of multiple medications for Parkinson disease (e.g., levodopa-carbidopa, dopamine agonists, monoamine oxidase B inhibitors and amantadine) have been unsuccessful.100 Although duration of efficacy is not clearly established, patients who undergo deep brain stimulation may have sustained benefit for at least 10 years.100 A recent study suggests that deep brain stimulation for Parkinson disease may be offered earlier for patients (mean age 52 yr, disease duration 7.5 yr) just beginning to have motor fluctuations.103 Thalamic deep brain stimulation may be considered as an option in patients who predominantly have disabling tremor where subthalamic nucleus stimulation cannot be performed.57
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.
Parkinson's disease is associated with hyperactivity of the subthalamic nucleus (STN), contributing to motor and gait disturbances. Although deep brain stimulation of the STN alleviates certain motor ...dysfunction, its specific effect on gait abnormalities remains controversial. This study investigated the long-term changes in locomotion following direct infusions of botulinum toxin-A into the globus pallidus internal segment (GPi) to suppress the flow of information from the STN to the GPi in a hemiparkinsonian rat model. Static and dynamic gait parameters were quantified using a CatWalk apparatus. Interestingly, botulinum toxin-A at 0.5 ng significantly reduced only the dynamic gait parameters of hemiparkinsonian rats at 1 week and 1 month post-infusion, while static gait parameters did not change. This study offers new insights into the complexity of basal ganglia in locomotor control and shows the potential of central infusion of botulinum toxin-A as a novel intervention in the study of experimental hemiparkinson's disease.
Background
There are no effective symptomatic treatments for progressive supranuclear palsy (PSP). Recent studies report benefits of spinal cord stimulation (SCS) for freezing of gait (FOG) and gait ...disorders in Parkinson’s disease and atypical Parkinsonism patients. This is the first study to report therapeutic effects of SCS in Richardson’s syndrome PSP (PSP-RS) patients.
Methods
Epidural SCS was implanted in three female PSP-RS participants (3.2 ± 1.3 years with disease). Six programs (300–400 µs/30–130 Hz) were randomly tested at suprathreshold intensity on separate days. The setting that best improved gait/FOG was used daily by each participant in the study. Protokinetics walkway captured spatiotemporal gait measures and FOG episodes (turning on the spot and while walking) and clinical scales including FOG questionnaire, UPDRS-III (OFF-/ON-
l
-dopa), and participant-perceived global impression of change (GISC) were collected at pre-SCS, and 3, 6, 12 months post-SCS.
Results
Participant #1 demonstrated the highest GISC score (6.5/10) with a consistent reduction of FOGs by 43.8%, UPDRS-III score (− 5 points), and improved step length and stride velocity (33.6%) while maintaining a
l
-dopa response of ~ 12% over the 12 months. Participant #2, walking FOG frequency and turning duration was reduced by 39.0% (OFF-
l
-dopa), and ON-
l
-dopa UPDRS-III score worsened (+ 5 points) at 12 months. Participant #3, FOG frequency reduced by 75% up to 6 months rating a GISC 3/10 score, however disease severity worsened at 12 months. Ambulatory gait parameters universally improved by 29.6% in all participants.
Conclusion
The results support the benefit of SCS for FOG and gait symptoms in PSP-RS and suggests early SCS intervention for dopaminergic-resistant gait should be considered.
The obliquus capitis inferioris (OCI) muscle is a significant driver of cervical dystonia with torticaput movements and a no-no head tremor. Limited data are available on the efficacy of OCI ...injections on patient outcomes. Our study aims to determine whether the botulinum toxin injection into OCI improves subjective patient quality of life in those with dystonic head tremors. A retrospective chart review was performed for 25 patients receiving injections into the OCI for a dystonic head tremor at the London Movement Disorders Clinic between January 2020 and January 2022. Toronto Western Spasmodic Torticollis Scale-2 (TWSTRS-2) subscale scores for disability and pain, TWSTRS-PSYCH scores, and the global impression of severity were extracted. The average TWSTRS-2 disability subscale change was -2.8 points (
< 0.003). The average TWSTRS-2 pain subscale change was -4.6 points (
< 0.003). The average TWSTRS-PSYCH score prior to injection was 5.6. After injection, the average score was 3.7 (
< 0.004). The patient self-reported average global impression of severity before injection was 7.0; after this, it was 4.2 (
< 0.0003). The OCI injection showed significant improvement in retrospective patient self-reported outcomes; it should be considered early in the treatment plan for cervical dystonia with a no-no head tremor.
Current pharmacological agents used to treat Parkinson disease (PD) tremor and essential tremor (ET) provide suboptimal benefit and are commonly associated with significant adverse effects. Botulinum ...toxin type A (BoNT-A) has been shown to be effective for wrist tremor though functionally bothersome muscle weakness frequently occurs. This is the longest study to date demonstrating that BoNT-A therapy coupled with kinematic guidance can provide efficacious outcomes for upper limb tremor with minimized unwanted weakness.
A total of 28 PD and 24 ET participants with bothersome, disabling tremor, received six serial BoNT-A treatments every 16 weeks starting at week 0 with a follow-up visit 6 weeks following a treatment, totaling 96 weeks. Clinical scales, including Fahn-Tolosa-Marin tremor rating scale (FTM), and sensor-based tremor assessments were conducted at each visit. Kinematics was utilized to identify which arm muscles contributed to the tremulous movements and the experienced injector used clinical expertise in determining BoNT-A dosages.
Following BoNT-A treatment, clinical ratings of tremor severity and functional ability (FTM) showed significant improvements following the first treatment which was maintained up to week 96 in PD and ET. Kinematics detected a significant reduction in PD and ET tremor amplitudes by 70% and 76% over the treatment course, respectively. By objectively distinguishing tremulous muscles and tremor severity, adverse effects were limited to mild perceived weakness by participants in injected muscles during follow-ups. Following the fourth treatment, BoNT-A dosages in flexor and extensor wrist muscles and biceps were reduced for those experiencing residual weakness which ultimately did not interfere with tremor relief or arm function.
Kinematics is an objective method that can aid clinicians in assessing and determining optimal BoNT-A parameters to alleviate both PD and ET tremor. BoNT-A injections are tolerable and effective when focal therapy regimens are determined and optimized kinematically over a long-term.
Integration of multi-modal sensory inputs and modulation of motor outputs based on perceptual estimates is called Sensorimotor Integration (SMI). Optimal functioning of SMI is essential for ...perceiving the environment, modulating the motor outputs, and learning or modifying motor skills to suit the demands of the environment. Growing evidence suggests that patients diagnosed with Parkinson's Disease (PD) may suffer from an impairment in SMI that contributes to perceptual deficits, leading to motor abnormalities. However, the exact nature of the SMI impairment is still unclear. This study uses a robot-assisted assessment tool to quantitatively characterize SMI impairments in PD patients and how they affect voluntary movements. A set of assessment tasks was developed using a robotic manipulandum equipped with a virtual-reality system. The sensory conditions of the virtual environment were varied to facilitate the assessment of SMI. A hundred PD patients (before and after medication) and forty-three control subjects completed the tasks under varying sensory conditions. The kinematic measures obtained from the robotic device were used to evaluate SMI. The findings reveal that across all sensory conditions, PD patients had 36% higher endpoint error, 38% higher direction error in reaching tasks, and 43% higher number of violations in tracing tasks than control subjects due to impairment in integrating sensory inputs. However, they still retained motor learning ability and the ability to modulate motor outputs. The medication worsened the SMI deficits as PD patients, after medication, performed worse than before medication when encountering dynamic sensory environments and exhibited impaired motor learning ability.
The spectrum of tauopathy encompasses heterogenous group of neurodegenerative disorders characterized by neural or glial deposition of pathological protein tau. Clinically they can present as ...cognitive syndromes, movement disorders, motor neuron disease, or mixed. The heterogeneity in clinical presentation, genetic background, and underlying pathology make it difficult to classify and clinically approach tauopathy. In the literature, tauopathies are thus mostly highlighted from pathological perspective. From clinical standpoint, cognitive syndromes are often been focussed while reviewing tauopathies. However, the spectrum of tauopathy has also evolved significantly in the domain of movement disorders and has transgressed beyond the domain of primary tauopathies. Secondary tauopathies from neuroinflammation or autoimmune insults and some other "novel" tauopathies are increasingly being reported in the current literature, while some of them are geographically isolated. Because of the overlapping clinical phenotypes, it often becomes difficult for the clinician to diagnose them clinically and have to wait for the pathological confirmation by autopsy. However, each of these tauopathies has some clinical and radiological signatures those can help in clinical diagnosis and targeted genetic testing. In this review, we have exposed the heterogeneity of tauopathy from a movement disorder perspective and have provided a clinical approach to diagnose them ante mortem before confirmatory autopsy. Additionally, phenotypic variability of these disorders (chameleons) and the look-alikes (mimics) have been discussed with potential clinical pointers for each of them. The review provides a framework within which new and as yet undiscovered entities can be classified in the future.