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Neurophysiologie Clinique = Clinical... May 2015We aimed to analyze functional changes at brainstem and spinal levels in essential tremor (ET), Parkinson's disease (PD) and coexisting essential tremor and Parkinson's...
OBJECTIVE
We aimed to analyze functional changes at brainstem and spinal levels in essential tremor (ET), Parkinson's disease (PD) and coexisting essential tremor and Parkinson's disease (ET-PD).
PATIENTS AND METHOD
Age- and gender-matched patients with tremor (15 ET, 7 ET with resting tremor, 25 ET-PD and 10 PD) and 12 healthy subjects were enrolled in the study. Diagnosis was established according to standardized clinical criteria. Electrophysiological studies included blink reflex (BR), auditory startle reaction (ASR) and long latency reflex (LLR).
RESULTS
Blink reflex was normal and similar in all groups. Probability of ASR was significantly lower in ET-PD group whereas it was similar to healthy subjects in ET and PD (P<0.001). LLR was recorded during voluntary activity in all three groups. LLR II was more common in ET, PD and ET-PD groups. LLR III was far more common in the PD group (n=3, 13.6% in ET; n=4, 16.0% in ET-PD and n=7, 46.7% in PD; p=0.037).
CONCLUSIONS
Despite the integrity of BR pathways, ASR and LLR show distinctive abnormalities in ET-PD. In our opinion, our electrophysiological findings support the hypothesis that ET-PD is a distinct entity.
Topics: Aged; Blinking; Brain Stem; Essential Tremor; Female; Humans; Male; Middle Aged; Parkinson Disease; Pyramidal Tracts; Reflex, Abnormal; Reflex, Startle
PubMed: 25892331
DOI: 10.1016/j.neucli.2015.01.001 -
The Journal of Neuroscience : the... Jan 2024Spasticity is a hyperexcitability disorder that adversely impacts functional recovery and rehabilitative efforts after spinal cord injury (SCI). The loss of evoked...
Spasticity is a hyperexcitability disorder that adversely impacts functional recovery and rehabilitative efforts after spinal cord injury (SCI). The loss of evoked rate-dependent depression (RDD) of the monosynaptic H-reflex is indicative of hyperreflexia, a physiological sign of spasticity. Given the intimate relationship between astrocytes and neurons, that is, the tripartite synapse, we hypothesized that astrocytes might have a significant role in post-injury hyperreflexia and plasticity of neighboring neuronal synaptic dendritic spines. Here, we investigated the effect of selective Rac1KO in astrocytes (i.e., adult male and female mice, transgenic cre-flox system) on SCI-induced spasticity. Three weeks after a mild contusion SCI, control Rac1 animals displayed a loss of H-reflex RDD, that is, hyperreflexia. In contrast, transgenic animals with astrocytic Rac1KO demonstrated near-normal H-reflex RDD similar to pre-injury levels. Reduced hyperreflexia in astrocytic Rac1KO animals was accompanied by a loss of thin-shaped dendritic spine density on α-motor neurons in the ventral horn. In SCI-Rac1 animals, as expected, we observed the development of dendritic spine dysgenesis on α-motor neurons associated with spasticity. As compared with WT animals, SCI animals with astrocytic Rac1KO expressed increased levels of the glial-specific glutamate transporter, glutamate transporter-1 in the ventral spinal cord, potentially enhancing glutamate clearance from the synaptic cleft and reducing hyperreflexia in astrocytic Rac1KO animals. Taken together, our findings show for the first time that Rac1 activity in astrocytes can contribute to hyperreflexia underlying spasticity following SCI. These results reveal an opportunity to target cell-specific molecular regulators of H-reflex excitability to manage spasticity after SCI. Spinal cord injury leads to stretch reflex hyperexcitability, which underlies the clinical symptom of spasticity. This study shows for the first time that astrocytic Rac1 contributes to the development of hyperreflexia after SCI. Specifically, astrocytic Rac1KO reduced SCI-related H-reflex hyperexcitability, decreased dendritic spine dysgenesis on α-motor neurons, and elevated the expression of the astrocytic glutamate transporter-1 (GLT-1). Overall, this study supports a distinct role for astrocytic Rac1 signaling within the spinal reflex circuit and the development of SCI-related spasticity.
Topics: Mice; Male; Female; Animals; Reflex, Abnormal; Astrocytes; Spinal Cord Injuries; Motor Neurons; Spinal Cord; Animals, Genetically Modified; H-Reflex; Amino Acid Transport System X-AG
PubMed: 37963762
DOI: 10.1523/JNEUROSCI.1670-22.2023 -
Journal of Neuroengineering and... Aug 2020Stiff-Knee gait (SKG) after stroke is often accompanied by decreased knee flexion angle during the swing phase. The decreased knee flexion has been hypothesized to...
BACKGROUND
Stiff-Knee gait (SKG) after stroke is often accompanied by decreased knee flexion angle during the swing phase. The decreased knee flexion has been hypothesized to originate from excessive quadriceps activation. However, it is unclear whether hyperreflexia plays a role in this activation. The goal of this study was to establish the relationship between quadriceps hyperreflexia and knee flexion angle during walking in post-stroke SKG.
METHODS
The rectus femoris (RF) H-reflex was recorded in 10 participants with post-stroke SKG and 10 healthy controls during standing and walking at the pre-swing phase. In order to attribute the pathological neuromodulation to quadriceps muscle hyperreflexia and activation, healthy individuals voluntarily increased quadriceps activity using electromyographic (EMG) feedback during standing and pre-swing upon RF H-reflex elicitation.
RESULTS
We observed a negative correlation (R = - 0.92, p = 0.001) between knee flexion angle and RF H-reflex amplitude in post-stroke SKG. In contrast, H-reflex amplitude in healthy individuals in presence (R = 0.47, p = 0.23) or absence (R = - 0.17, p = 0.46) of increased RF muscle activity was not correlated with knee flexion angle. We observed a body position-dependent RF H-reflex modulation between standing and walking in healthy individuals with voluntarily increased RF activity (d = 2.86, p = 0.007), but such modulation was absent post-stroke (d = 0.73, p = 0.296).
CONCLUSIONS
RF reflex modulation is impaired in post-stroke SKG. The strong correlation between RF hyperreflexia and knee flexion angle indicates a possible regulatory role of spinal reflex excitability in post-stroke SKG. Interventions targeting quadriceps hyperreflexia could help elucidate the causal role of hyperreflexia on knee joint function in post-stroke SKG.
Topics: Adult; Biomechanical Phenomena; Female; Gait Disorders, Neurologic; Humans; Knee Joint; Male; Middle Aged; Quadriceps Muscle; Reflex, Abnormal; Stroke; Walking
PubMed: 32843057
DOI: 10.1186/s12984-020-00724-z -
World Neurosurgery Mar 2024Spasticity is a form of muscle hypertonia secondary to various diseases, including traumatic brain injury, spinal cord injury, cerebral palsy, and multiple sclerosis.... (Review)
Review
OBJECTIVE
Spasticity is a form of muscle hypertonia secondary to various diseases, including traumatic brain injury, spinal cord injury, cerebral palsy, and multiple sclerosis. Medical treatments are available; however, these often result in insufficient clinical response. This review evaluates the role of epidural spinal cord stimulation (SCS) in the treatment of spasticity and associated functional outcomes.
METHODS
A systematic review of the literature was performed using the Embase, CENTRAL, and MEDLINE databases. We included studies that used epidural SCS to treat spasticity. Studies investigating functional electric stimulation, transcutaneous SCS, and animal models of spasticity were excluded. We also excluded studies that used SCS to treat other symptoms such as pain.
RESULTS
Thirty-four studies were included in the final analysis. The pooled rate of subjective improvement in spasticity was 78% (95% confidence interval, 64%-91%; I = 77%), 40% (95% confidence interval, 7%-73%; I = 88%) for increased H-reflex threshold or decreased Hoffman reflex/muscle response wave ratio, and 73% (65%-80%; I = 50%) for improved ambulation. Patients with spinal causes had better outcomes compared with patients with cerebral causes. Up to 10% of patients experienced complications including infections and hardware malfunction.
CONCLUSIONS
Our review of the literature suggests that SCS may be a safe and useful tool for the management of spasticity; however, there is significant heterogeneity among studies. The quality of studies is also low. Further studies are needed to fully evaluate the usefulness of this technology, including various stimulation paradigms across different causes of spasticity.
Topics: Animals; Humans; Spinal Cord Stimulation; Spinal Cord Injuries; Pain; Muscle Spasticity; Walking; Reflex, Abnormal; Spinal Cord
PubMed: 38181878
DOI: 10.1016/j.wneu.2023.12.158 -
The Canadian Journal of Neurological... Sep 2023Long latency reflexes (LLRs) are impaired in a wide array of clinical conditions. We aimed to illustrate the clinical applications and recent advances of LLR in various...
BACKGROUND
Long latency reflexes (LLRs) are impaired in a wide array of clinical conditions. We aimed to illustrate the clinical applications and recent advances of LLR in various neurological disorders from a systematic review of published literature.
METHODS
We reviewed the literature using appropriately chosen MeSH terms on the database platforms of MEDLINE, Web of Sciences, and Google Scholar for all the articles from 1st January 1975 to 2nd February 2021 using the search terms "long loop reflex", "long latency reflex" and "C-reflex". The included articles were analyzed and reported using synthesis without meta-analysis (SWiM) guidelines.
RESULTS
Based on our selection criteria, 40 articles were selected for the systematic review. The various diseases included parkinsonian syndromes (11 studies, 217 patients), Huntington's disease (10 studies, 209 patients), myoclonus of varied etiologies (13 studies, 127 patients) including progressive myoclonic epilepsy (5 studies, 63 patients) and multiple sclerosis (6 studies, 200 patients). Patients with parkinsonian syndromes showed large amplitude LLR II response. Enlarged LLR II was also found in myoclonus of various etiologies. LLR II response was delayed or absent in Huntington's disease. Delayed LLR II response was present in multiple sclerosis. Among the other diseases, LLR response varied according to the location of cerebellar lesions while the results were equivocal in patients with essential tremor.
CONCLUSIONS
Abnormal LLR is observed in many neurological disorders. However, larger systematic studies are required in many neurological disorders in order to establish its role in diagnosis and management.
Topics: Humans; Myoclonus; Huntington Disease; Reflex; Multiple Sclerosis; Neurology; Reaction Time; Electromyography
PubMed: 35801267
DOI: 10.1017/cjn.2022.270 -
The Journals of Gerontology. Series A,... Mar 2021Age-related changes in presynaptic inhibition (PSI) have not been observed during gait initiation, which requires anticipatory postural adjustment (APA). As APA is...
Age-related changes in presynaptic inhibition (PSI) have not been observed during gait initiation, which requires anticipatory postural adjustment (APA). As APA is centrally modulated and is impaired in older compared to young adults, here we aimed to study the presynaptic control and co-contraction levels in the ankle muscles during gait initiation in older compared to young adults. Fifteen older (age range 65-80 years) and 15 young adults (age range 19-30 years) performed a gait initiation task on a force platform under 3 conditions: (i) without electrical stimulation; (ii) test Hoffman reflex (H-reflex); and (iii) conditioned H-reflex. H-reflexes were evoked on the soleus muscle when the APA amplitude exceeded 10%-20% of the average baseline mediolateral force. Participants also performed quiet stance as a control task. Results showed that both age groups presented similar PSI levels during quiet stance (p = .941), while in the gait initiation older adults presented higher PSI levels, longer duration, and lower amplitude of APA than young adults (p < .05). Older adults presented higher co-contraction ratio in both tasks than young adults (p < .05). Correlations between the PSI levels and the APA amplitude (r = -0.61, p = .008), and between the PSI levels and the co-contraction ratio during gait initiation (r = -0.64, p = .005) were found for older adults only. APA amplitude explained 49% of the variance of the PSI levels (p = .003). Our findings suggest that older compared to young adults have increased presynaptic control to compensate for the decreased supraspinal modulation on impaired APAs during gait initiation.
Topics: Adult; Aged; Aging; Electric Stimulation; Gait; H-Reflex; Humans; Muscle, Skeletal; Postural Balance; Presynaptic Terminals; Reflex, Abnormal; Task Performance and Analysis
PubMed: 33428714
DOI: 10.1093/gerona/glab010 -
Neurourology and Urodynamics Jan 2020To evaluate the combined effect of age and multiparity on the micturition reflex, including pelvic floor muscle activation.
AIMS
To evaluate the combined effect of age and multiparity on the micturition reflex, including pelvic floor muscle activation.
METHODS
Young and mature nulliparous rabbits were compared to young and mature multiparas (n = 6 per group). Cystometrograms and urethral pressure (UP) were performed while simultaneously recording the electromyogram (EMG) activity of the pubococcygeus and bulbospongiosus muscles to establish their functional correlation to urological function.
RESULTS
Multiparity and age significantly influence the bladder and UP affecting the voiding efficiency and intercontraction interval. Such interaction also reduced the UP threshold, timing, and duration. Other bladder and urethral variables were predominantly affected only by age. Urodynamic alterations correlated with abnormal patterns or absent EMG activity of the pubococcygeus and bulbospongiosus muscles.
CONCLUSIONS
The present findings strongly suggest that multiparity and age affects specific pelvic floor muscle reflex activation during micturition, and may contribute to alterations in bladder and urethral function. This data broadens our understanding of the critical role of the appropriate activity of the individual pelvic floor muscles in micturition.
Topics: Animals; Electromyography; Female; Muscle, Skeletal; Parity; Pelvic Floor; Perineum; Pregnancy; Rabbits; Reflex; Urethra; Urinary Bladder; Urination; Urodynamics
PubMed: 31578766
DOI: 10.1002/nau.24176 -
Medicine and Science in Sports and... Oct 2020Prader-Willi Syndrome (PWS) is a form of congenital obesity characterized by excessive body fat, hypotonia, muscle weakness, and physical/cognitive disability. However,...
PURPOSE
Prader-Willi Syndrome (PWS) is a form of congenital obesity characterized by excessive body fat, hypotonia, muscle weakness, and physical/cognitive disability. However, the sources of muscle dysfunction and their contribution to mobility are unclear. The purposes of this study were to 1) compare plantar flexor function between adults with and without PWS; and 2) to examine the relationship between plantar flexor function and gait speed in adults with PWS.
METHODS
Participants included 10 adults with PWS, 10 adults without PWS and with obesity, and 10 adults without PWS and without obesity (matched on age and sex). Plantar flexor function was assessed using isokinetic dynamometry (peak torque [PT], early/late rate of torque development [RTD]), Hoffman reflex (H/M ratio), ultrasound imaging (cross-sectional area [CSA], echo intensity, pennation angle, and fascicle length), and peak propulsive force and plantar flexor moment during gait. Outcomes were compared between groups using one-way MANOVA. Associations between plantar flexor outcomes and gait speed were assessed using Pearson correlation in the PWS group.
RESULTS
Adults with PWS had lower absolute and normalized early RTD, and lower H/M ratio than controls with and without obesity; lower absolute PT and late RTD than controls with obesity (all P < 0.05). Cross-sectional area, propulsive force, and plantarflexor moment were lower, and echo intensity was higher, in adults with PWS compared with controls without obesity (all P < 0.05). Greater absolute PT (r = 0.64), absolute early RTD (r = 0.62), absolute late RTD (r = 0.64), gastrocnemii CSA (r = 0.55), and propulsive force (r = 0.58) were associated with faster gait speed (all P < 0.05).
CONCLUSIONS
Adults with PWS have impaired plantar flexor function likely attributable to reduced neuromuscular function and altered muscle morphology, which are associated with slower gait speeds.
Topics: Adult; Body Mass Index; Cross-Sectional Studies; Female; Foot; Humans; Male; Motor Neurons; Muscle Strength; Muscle, Skeletal; Obesity; Prader-Willi Syndrome; Reflex, Abnormal; Torque; Ultrasonography; Walking Speed; Young Adult
PubMed: 32936593
DOI: 10.1249/MSS.0000000000002361 -
Journal of Neurology, Neurosurgery, and... Mar 2020Areflexia or hyporeflexia is a mandatory clinical criterion for the diagnosis of Guillain-Barré syndrome (GBS). A systematic review of the literature from 1 January...
Areflexia or hyporeflexia is a mandatory clinical criterion for the diagnosis of Guillain-Barré syndrome (GBS). A systematic review of the literature from 1 January 1993 to 30 August 2019 revealed 44 sufficiently detailed patients with GBS and hyper-reflexia, along with one we describe. 73.3% of patients were from Japan, 6.7% from the USA, 6.7% from India, 4.4% from Italy, 4.4% from Turkey, 2.2% from Switzerland and 2.2% from Slovenia, suggesting a considerable geographical variation. Hyper-reflexia was more frequently associated with antecedent diarrhoea (56%) than upper respiratory tract infection (22.2%) and the electrodiagnosis of acute motor axonal neuropathy (56%) than acute inflammatory demyelinating polyneuropathy (4.4%). Antiganglioside antibodies were positive in 89.7% of patients. Hyper-reflexia was generalised in 90.7% of patients and associated with reflex spread in half; it was present from the early progressive phase in 86.7% and disappeared in a few weeks or persisted until 18 months. Ankle clonus or Babinski signs were rarely reported (6.7%); spasticity never developed. 53.3% of patients could walk unaided at nadir, none needed mechanical ventilation or died. 92.9% of patients with limb weakness were able to walk unaided within 6 months. Electrophysiological studies showed high soleus maximal H-reflex amplitude to maximal compound muscle action potential amplitude ratio, suggestive of spinal motoneuron hyperexcitability, and increased central conduction time, suggestive of corticospinal tract involvement, although a structural damage was never demonstrated by MRI. Hyper-reflexia is not inconsistent with the GBS diagnosis and should not delay treatment. All GBS variants and subtypes can present with hyper-reflexia, and this eventuality should be mentioned in future diagnostic criteria for GBS.
Topics: Guillain-Barre Syndrome; Humans; Male; Middle Aged; Reflex, Abnormal
PubMed: 31937584
DOI: 10.1136/jnnp-2019-321890 -
Scientific Reports May 2023Hyperreflexia is common after neurological injury such as stroke, yet clinical interventions have had mixed success. Our previous research has shown that hyperreflexia...
Hyperreflexia is common after neurological injury such as stroke, yet clinical interventions have had mixed success. Our previous research has shown that hyperreflexia of the rectus femoris (RF) during pre-swing is closely associated with reduced swing phase knee flexion in those with post-stroke Stiff-Knee gait (SKG). Thus, reduction of RF hyperreflexia may improve walking function in those with post-stroke SKG. A non-pharmacological procedure for reducing hyperreflexia has emerged based on operant conditioning of H-reflex, an electrical analog of the spinal stretch reflex. It is currently unknown whether operant conditioning can be applied to the RF. This feasibility study trained 7 participants (5 neurologically intact, 2 post-stroke) to down-condition the RF H-reflex using visual feedback. We found an overall decrease in average RF H-reflex amplitude among all 7 participants (44% drop, p < 0.001, paired t-test), of which the post-stroke individuals contributed (49% drop). We observed a generalized training effect across quadriceps muscles. Post-stroke individuals exhibited improvements in peak knee-flexion velocity, reflex excitability during walking, and clinical measures of spasticity. These outcomes provide promising initial results that operant RF H-reflex conditioning is feasible, encouraging expansion to post-stroke individuals. This procedure could provide a targeted alternative in spasticity management.
Topics: Humans; Quadriceps Muscle; Reflex, Abnormal; Walking; Gait; Knee Joint; Muscle Spasticity; Stroke; Gait Disorders, Neurologic; Biomechanical Phenomena
PubMed: 37208394
DOI: 10.1038/s41598-023-34709-4