The effect of suboccipital muscle dysfunction on the biomechanics of the upper cervical spine: a study based on finite element analysis.

OBJECTIVE: Muscle dysfunction caused by repetitive work or strain in the neck region can interfere muscle responses. Muscle dysfunction can be an important factor in causing cervical spondylosis. However, there has been no research on how the biomechanical properties of the upper cervical spine change when the suboccipital muscle group experiences dysfunction. The objective of this study was to investigate the biomechanical evidence for cervical spondylosis by utilizing the finite element (FE) approach, thus and to provide guidance for clinicians performing acupoint therapy. METHODS: By varying the elastic modulus of the suboccipital muscle, the four FE models of C0-C3 motion segments were reconstructed under the conditions of normal muscle function and muscle dysfunction. For the two normal condition FE models, the elastic modulus for suboccipital muscles on both sides of the C0-C3 motion segments was equal and within the normal range In one muscle dysfunction FE model, the elastic modulus on both sides was equal and greater than 37 kPa, which represented muscle hypertonia; in the other, the elastic modulus of the left and right suboccipital muscles was different, indicating muscle imbalance. The biomechanical behavior of the lateral atlantoaxial joint (LAAJ), atlanto-odontoid joint (ADJ), and intervertebral disc (IVD) was analyzed by simulations, which were carried out under the six loadings of flexion, extension, left and right lateral bending, left and right axial rotation. RESULTS: Under flexion, the maximum stress in LAAJ with muscle imbalance was higher than that with normal muscle and hypertonia, while the maximum stress in IVD in the hypertonic model was higher than that in the normal and imbalance models. The maximum stress in ADJ was the largest under extension among all loadings for all models. Muscle imbalance and hypertonia did not cause overstress and stress distribution abnormalities in ADJ. CONCLUSION: Muscle dysfunction increases the stress in LAAJ and in IVD, but it does not affect ADJ.

Skin and not dorsal root stimulation reduces hypertonus in thoracic motor complete spinal cord injury: a single case report.

On demand and localized treatment for excessive muscle tone after spinal cord injury (SCI) is currently not available. Here, we examine the reduction in leg hypertonus in a person with mid-thoracic, motor complete SCI using a commercial transcutaneous electrical stimulator (TES) applied at 50 or 150 Hz to the lower back and the possible mechanisms producing this bilateral reduction in leg tone. Hypertonus of knee extensors without and during TES, with both cathode (T11-L2) and anode (L3-L5) placed over the spinal column (midline, MID) or 10 cm to the left of midline (lateral, LAT) to only active underlying skin and muscle afferents, was simultaneously measured in both legs with the pendulum test. Spinal reflexes mediated by proprioceptive (H-reflex) and cutaneomuscular reflex (CMR) afferents were examined in the right leg opposite to the applied LAT TES. Hypertonus disappeared in both legs but only during thoracolumbar TES, and even during LAT TES. The marked reduction in tone was reflected in the greater distance both lower legs first dropped to after being released from a fully extended position, increasing by 172.8% and 94.2% during MID and LAT TES, respectively, compared with without TES. Both MID and LAT (left) TES increased H-reflexes but decreased the first burst, and lengthened the onset of subsequent bursts, in the cutaneomuscular reflex of the right leg. Thoracolumbar TES is a promising method to decrease leg hypertonus in chronic, motor complete SCI without activating spinal cord structures and may work by facilitating proprioceptive inputs that activate excitatory interneurons with bilateral projections that in turn recruit recurrent inhibitory neurons.NEW & NOTEWORTHY We present proof of concept that surface stimulation of the lower back can reduce severe leg hypertonus in a participant with motor complete, thoracic spinal cord injury (SCI) but only during the applied stimulation. We propose that activation of skin and muscle afferents from thoracolumbar transcutaneous electrical stimulation (TES) may recruit excitatory spinal interneurons with bilateral projections that in turn recruit recurrent inhibitory networks to provide on demand suppression of ongoing involuntary motoneuron activity.

Opening Pressure and Post-Lumbar Puncture Headache in Children Undergoing Intrathecal Baclofen Trial.

Aims: Post-lumbar puncture headache occurs in 5% to 12% of children. The purpose of this study was to determine the frequency and predictors of post-lumbar puncture headache in children with hypertonia undergoing lumbar puncture for intrathecal baclofen trial. Methods: This was a retrospective single-center review of all 43 children (<18 years) with hypertonia and/or dyskinesia undergoing intrathecal baclofen trial from 2013-2022. Predictors of post-lumbar puncture headache were evaluated via 2-way paired t test and Fisher exact test. Results: Seven subjects (16.3%) developed post-lumbar puncture headache. Of patients who developed post-lumbar puncture headache, 3 required emergency care or hospitalization. One was misdiagnosed with constipation. The 16 patients without opening pressure measured were excluded from subsequent analyses. Of the 27 patients with documented opening pressure, the mean opening pressure was 24.0 cm H2O (SD 6.5) and 5 (18.5%) had elevated opening pressure (>28 cm H2O). Mean opening pressure was higher for those with post-lumbar puncture headache (28.6 vs 22.4 cm H2O, P = .014). Sixty percent of patients with elevated opening pressure developed post-lumbar puncture headache. Baclofen pumps were placed in 4 (80%) patients with elevated opening pressure and 6 (85.7%) with post-lumbar puncture headaches without complications. Interpretation: The risk of post-lumbar puncture headache after intrathecal baclofen trial was higher than reported in the literature, likely because of greater rates of elevated opening pressure. Physicians may use opening pressure to predict risk for post-lumbar puncture headache and should educate families about symptoms. Elevated opening pressure or post-lumbar puncture headache may not preclude baclofen pump placement.

A Young Woman With Hypertonia, Severe Scoliosis, and Encephalopathy.

A 31-year-old woman was seen with contractures in her fingers and toes, carpal inversion, dysarthria, dysphagia, hypertonia, decreased tendon reflexes, absence of Babinski sign, and no psychiatric problems and significant global atrophy. What is your diagnosis?

From one to many: Hypertonia in schizophrenia spectrum psychosis an integrative review and adversarial collaboration report.

Different types of resistance to passive movement, i.e. hypertonia, were described in schizophrenia spectrum disorders (SSD) long before the introduction of antipsychotics. While these have been rediscovered in antipsychotic-naïve patients and their non-affected relatives, the existence of intrinsic hypertonia vs drug-induced parkinsonism (DIP) in treated SSD remains controversial. This integrative review seeks to develop a commonly accepted framework to specify the putative clinical phenomena, highlight conflicting issues and discuss ways to challenge each hypothesis and model through adversarial collaboration. The authors agreed on a common framework inspired from systems neuroscience. Specification of DIP, locomotor paratonia (LMP) and psychomotor paratonia (PMP) identified points of disagreement. Some viewed parkinsonian rigidity to be sufficient for diagnosing DIP, while others viewed DIP as a syndrome that should include bradykinesia. Sensitivity of DIP to anticholinergic drugs and the nature of LPM and PMP were the most debated issues. It was agreed that treated SSD should be investigated first. Clinical features of the phenomena at issue could be confirmed by torque, EMG and joint angle measures that could help in challenging the selectivity of DIP to anticholinergics. LMP was modeled as the release of the reticular formation from the control of the supplementary motor area (SMA), which could be challenged by the tonic vibration reflex or acoustic startle. PMP was modeled as the release of primary motor cortex from the control of the SMA and may be informed by subclinical echopraxia. If these challenges are not met, this would put new constraints on the models and have clinical and therapeutic implications.

Prevalence and Treatment Characteristics of Spastic Hypertonia on First-Time Admission to Acute Inpatient Rehabilitation.

OBJECTIVE: The aim of the study was to report the prevalence of spasticity and treatment patterns during first-time admission to inpatient rehabilitation after acute stroke, traumatic brain injury, and spinal cord injury. DESIGN: This is a retrospective cohort study. METHODS: A review of 285 adult patients consecutively admitted to inpatient rehabilitation was conducted. Patients with a history of spasticity and inpatient rehabilitation course and those younger than 18 yrs were excluded. Main outcome measures are as follows: admitting diagnosis, length of stay, time from injury to admission, acute transfer rate, prevalence and severity of spasticity using Modified Ashworth Scale at admission and discharge, Functional Independence Measure scores at admission and discharge, Functional Independence Measure efficiency, and treatments for spasticity. RESULTS: Stroke patients had the highest prevalence of spasticity: 68% on admission and 50% at discharge. In traumatic brain injury, spasticity prevalence was 55% on admission and 30% at discharge. In spinal cord injury, spasticity prevalence was 48% on admission and 46% at discharge. Patients with spinal cord injury received the most medications to control spasticity, whereas those with traumatic brain injury and stroke received the most procedural interventions. CONCLUSIONS: Spasticity is a common sequela of upper motor neuron injury for patients admitted to inpatient rehabilitation. Early recognition and management are essential to prevent contractures, minimize pain, and maximize functional recovery.

Identification of a new syndrome: ASS-SSA or anal sphincter syndrome.

AIM: The author proposes a new, original Syndrome, observing the relationship between some of the most frequent anal pathologies, apparently different from each other in terms of morphological aspect and symptomatologic expression, but united by the same pathogenic cause, represented by the hypertonicity of the anal sphincter apparatus. There are already descriptions of other "syndromes" of the pelvic floor, inaccurate and subject to different interpretations. The proposed syndrome, instead, called Anal Sphincter Syndrome - ASS (in Italian SSA - Sindrome dello Sfintere Anale) presents clarity on the determining cause (sphincter hypertonicity) and descriptive simplicity, including only two welldefined pathological conditions: anal fissure and anal thrombosis; other ancillary conditions or symptoms are inconstantly possible, but not decisive. The author will present, as soon as possible, in subsequent works, a retrospective study (still to be completed) on a wide personal case history, dating back to the 1990s. KEY WORDS: Anal sphincter hypertonia, Anal thrombosis, Anal fissure, Syndrome, Proctology, Somatization.

The Effect of Depressor Anguli Oris Muscle Block on Facial Symmetry in Synkinetic Facial Paralysis Patients and Its Role in Preoperative Assessment.

BACKGROUND: Depressor anguli oris muscle hypertonicity in synkinetic facial paralysis patients may have an overpowering antagonistic effect on facial symmetry. Depressor anguli oris muscle block is a crucial diagnostic test before any treatment planning. Presented is the largest patient cohort analysis to date on static and dynamic facial symmetry changes after depressor anguli oris muscle block. METHODS: Unilateral synkinetic patients with depressor anguli oris muscle hypertonicity were included. Resting symmetry and smile modiolus angle, excursion, and exposure of teeth were measured on both synkinetic and healthy hemifaces before and after depressor anguli oris muscle block using Emotrics and FaceGram photographic analyses. RESULTS: Thirty-six patients were included. Before depressor anguli oris block, resting modiolus height was elevated on the synkinetic side (p = 0.047). During open-mouth smile, reduced modiolus angle (p < 0.0001), modiolus excursion (p < 0.0001), and exposure of teeth (p < 0.0001) were observed on the synkinetic hemiface. After depressor anguli oris block, resting modiolus height became symmetric (p = 0.64). During open-mouth smile, modiolus angle and exposure of teeth significantly increased (both p < 0.0001); excursion did not improve on the synkinetic side (p = 0.13) but unexpectedly improved in open-mouth smile on the healthy side (p = 0.0068). CONCLUSIONS: Depressor anguli oris muscle block improved resting symmetry and modiolus angle and exposure of teeth during smile, demonstrating the inhibitory mimetic role of a hypertonic depressor anguli oris muscle in synkinesis. It is a critical diagnostic and communication tool in the assessment and treatment planning of depressor anguli oris muscle hypertonicity, suggesting the potential effects of future depressor anguli oris myectomy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Partial Division of Puborectalis Muscle with Lateral Internal Sphincterotomy: A Novel Surgical Technique for Management of Anal Hypertonia-Associated Anismus.

BACKGROUND: Treatment of anismus usually starts with biofeedback therapy and injection of botulinum toxin in the puborectalis muscle (PRM). Patients refractory to conservative treatment may require surgery. The present cohort study aimed to assess a combined technique of partial division of PRM and tailored lateral internal sphincterotomy (LIS) in treatment of anismus. METHODS: Patients with anismus who failed conservative treatments were assessed clinically and with high-resolution anal manometry (HRAM), EMG, defecography, and underwent combined partial division of PRM on one side and tailored LIS on the contralateral side. Main outcome measures were improvement in symptoms and quality of life, changes in HRAM and defecography postoperatively, complications, and patient satisfaction. RESULTS: A total of 73 patients (61 male) of a mean age of 37 years were included to the study. In total, 89% of patients showed a significant improvement in symptoms at 12 months postoperatively. The mean modified Altomare score decreased significantly (p < 0.0001) from 16.4 ± 1.7 to 6.6 ± 1 at 12 months postoperatively. There was a significant increase in the mental and physical components of quality of life at 12 months postoperatively. The numbers of patients with positive findings of anismus in postoperative defecography, EMG, and balloon expulsion test were significantly less than before surgery. The mean total satisfaction score was 86.5 ± 8.7. Five (6.5%) patients developed minor complications. CONCLUSION: Partial division of puborectalis muscle combined with LIS is an effective technique in the management of anal hypertonia-associated anismus with satisfactory results and low incidence of complications.

Relations between knee and ankle muscle coactivation and temporospatial gait measures in patients without hypertonia early after stroke.

It is unclear whether muscle coactivation during gait is altered early after stroke and among which muscles. We sought to characterize muscle coactivation during gait in subacute stroke subjects without hypertonia and explore the relationship with temporospatial parameters. In 70 stroke (23 ± 12 days post-onset) and 29 age-matched healthy subjects, surface electromyography signals were used to calculate coactivation magnitude and duration between rectus femoris and medial hamstring (knee antagonistic coactivation), tibialis anterior and medial gastrocnemius (ankle antagonistic coactivation), and rectus femoris and medial gastrocnemius (extensor synergistic coactivation) during early double-support (DS1), early single-support (SS1), late single-support (SS2), late double-support (DS2), and swing (SW). Compared to both free and very-slow speeds of controls, stroke subjects had bilaterally decreased ankle coactivation magnitude in SS2 and duration in SS1 and SS2 as well as increased extensor coactivation magnitude in DS2 and SW. Both non-paretic knee and ankle coactivation magnitudes in SS2 moderately correlated with most temporospatial parameters (|r| ≥ 0.40). Antagonistic and synergistic coactivation patterns of the knee and ankle muscles during gait are altered bilaterally in subacute stroke subjects without lower limb hypertonia suggesting impairments in motor control. Greater coactivation magnitudes in the non-paretic knee and both ankles during the terminal stance (SS2) are associated with the overall worse gait performance. Unlike previously reported excessive coactivation or no change in chronic stroke, bilaterally decreased and increased coactivation patterns are present in subacute stroke. These findings warrant longitudinal studies to examine the evolution of changes in muscle coactivation from subacute to chronic stroke.

Neurophysiological mechanisms of hypertonia and hypotonia in children with spastic cerebral palsy: surgical implications.

Mechanism of hypertonia in cerebral palsy children is dual: a neural component due to spasticity (velocity dependent) and a biomechanical component linked to soft tissue changes. Their differentiation-which might be clinically difficult-is however crucial, as only the first component will respond to anti-spastic treatments, the second to physiotherapy. Furthermore, spasticity is frequently associated with dystonia, which is a sustained hypertonic state induced by attempts at voluntary motion. Spasticity and dystonia have to be carefully distinguished as dorsal rhizotomy will not significantly influence the dystonic component. Spasticity, which by definition opposes to muscle stretching and lengthening, has two important consequences. First, the muscles tend to remain in a shortened position, which in turn results in soft tissue changes and contracture. The second is that movements are restricted. Thus, both hypertonia and lack of mobilization create a vicious circle leading to severe locomotor disability linked to irreducible musculotendinous retraction and joint ankylosis/bone deformities. These evolving consequences should be highly considered during the child's assessment for decision-making. The hypotonic effects of lumbosacral dorsal rhizotomy, which are not only segmental on the lower limbs but also supra-segmental through the reticular formation, are finally discussed.

The Impact of Intrathecal Baclofen Therapy on Health-related Quality of Life for Children with Marked Hypertonia.

Purpose: To investigate the effects of intrathecal baclofen therapy (ITB) on health-related quality of life for children with cerebral palsy and neurological conditions. Method: This study is part of a longitudinal, multicentre audit. The primary outcome measure, the Caregiver Priorities and Child Health Index of Life with Disabilities, was completed at baseline, 6 and 12 months post ITB implant. Results: Forty subjects with cerebral palsy and other neurological conditions demonstrated significant improvement in aspects of health-related quality of life following ITB therapy, mean change 42.3 (SD 14.9) at baseline to 53.3 (SD 14.7) at 12 months (p< .001). Conclusion: Evidence to demonstrate the utility of ITB in pediatric populations beyond spasticity and dystonia reduction is limited. Our findings suggest that ITB improves aspects of quality of life, comfort, and ease of caregiving in children with cerebral palsy and other neurological conditions.

Whole-body vibration modulates leg muscle reflex and blood perfusion among people with chronic stroke: a randomized controlled crossover trial.

This study aimed to investigate the acute effect of whole-body vibration (WBV) on the reflex and non-reflex components of spastic hypertonia and intramuscular blood perfusion among individuals with chronic stroke. Thirty-six people with chronic stroke (age: 61.4 ± 6.9 years) participated in this randomized controlled cross-over study. Each participant underwent two testing conditions: static standing for 5 minutes with WBV (30 Hz, 1.5 mm) or no-vibration. We assessed the soleus H-reflex, shear modulus (ultrasound elastography) and vascular index (color power Doppler ultrasound) of the medial gastrocnemius (MG) muscle on either paretic or non-paretic side at baseline and every 1-min post-intervention up to 5 minutes. The results revealed a significant inhibition of the H/M ratio bilaterally for the WBV condition (absolute change on paretic side: 0.61 ± 0.35, p = 0.001; non-paretic side: 0.34 ± 0.23, p = 0.001), but not the control condition. The inhibition of H-reflex was sustained up to 4 minutes and 3 minutes on the paretic and non-paretic side, respectively. The vascular index of MG muscle was significantly increased only for the WBV condition [paretic: from 0.55 ± 0.07 to 1.08 ± 0.18 (p = 0.001); non-paretic: from 0.82 ± 0.09 to 1.01 ± 0.13 (p < 0.001)], which lasted for 3 minutes and 5 minutes, respectively. No significant change of the shear modulus in the MG muscle was observed, regardless of the testing condition. Based on our results, WBV had an acute effect on modulating spastic hypertonia dominated by hyperreflexia in people with chronic stroke and facilitating greater intramuscular blood perfusion. No acute effect on passive muscle stiffness was observed.

Effect of multichannel transcranial direct current stimulation to reduce hypertonia in individuals with prolonged disorders of consciousness: A randomized controlled pilot study.

BACKGROUND: Spasticity management in severely brain-injured patients with disorders of consciousness (DOC) is a major challenge because it leads to complications and severe pain that can seriously affect quality of life. OBJECTIVES: We aimed to determine the feasibility of a single session of transcranial direct current stimulations (tDCS) to reduce spasticity in chronic patients with DOC. METHODS: We enrolled 14 patients in this double-blind, sham-controlled randomized crossover pilot study. Two cathodes were placed over the left and right primary motor cortex and 2 anodes over the left and right prefrontal cortex. Hypertonia of the upper limbs and level of consciousness were assessed by the Modified Ashworth Scale (MAS) and the Coma Recovery Scale-Revised (CRS-R). Resting state electroencephalography was also performed. RESULTS: At the group level, spasticity was reduced in only finger flexors. Four responders (29%) showed reduced hypertonicity in at least 2 joints after active but not sham stimulation. We found no behavioural changes by the CRS-R total score. At the group level, connectivity values in beta2 were higher with active versus sham stimulation. Relative power in the theta band and connectivity in the beta band were higher for responders than non-responders after the active stimulation. CONCLUSION: This pilot study highlights the potential benefit of using tDCS for reducing upper-limb hypertonia in patients with chronic DOC. Large-sample clinical trials are needed to optimize and validate the technique.

Uterine hypertonus and fetal bradycardia occurred after combined spinal-epidural analgesia during induction of labor with oxytocin infusion: A case report.

RATIONALE: Pain management is an essential part of good obstetrical care. The rapid onset of pain relief after combined spinal-epidural (CSE) analgesia may cause a transient imbalance in maternal catecholamine level, leading to uterine hyperactivity and fetal heart rate (FHR) abnormalities. How to manage the uterine basal tone and FHR abnormalities after labor analgesia still remains controversial. PATIENT CONCERNS: A 33-year-old nulliparous woman at 40 weeks' gestation underwent induction of labor after premature rupture of membranes. CSE analgesia was provided when the patient described her pain as the top on a scale of 10 during induction of labor with oxytocin infusion. DIAGNOSES: Uterine hypertonus and fetal bradycardia were diagnosed within 10 minutes after CSE analgesia. INTERVENTIONS: Oxytocin infusion and CSE analgesia were immediately suspended, and measures of staying in left lateral decubitus position and giving supplemental oxygen were attempted to resuscitating the baby. Because of suspicious fetal distress, the baby was rapidly delivered by emergency cesarean section. OUTCOMES: The Apgar score of the baby was 8 and 10 at 1 and 5 minutes after birth. Subsequent follow-up confirmed that both mother and baby were in good condition. LESSONS: The loss of the tocolytic effect of epinephrine after CSE analgesia and continuous oxytocin infusion may work together to form a totally synergistic function, finally leading to inevitable uterine hypertonus and fetal bradycardia. Both the obstetrical provider and anesthesiologist should carefully monitor all patients in the first 15 minutes after CES analgesia induction. Oxytocin administration in this critical period deserves attention. Additionally, intraprofessional collaboration is also necessary to ensure high quality and safe delivery for all childbearing women.

Effects of hypertonia on contracture development in rat spinal cord injury.

STUDY DESIGN: Experimental animal study. OBJECTIVES: Spastic hypertonia is originally believed to cause contractures from clinical observations. Botulinum toxin is effective for the treatment of spasticity and is widely used in patients who have joints with contractures. Using an established rat model with knee contractures after spinal cord injuries, we aimed to verify whether hypertonia contributes to contracture development, and the botulinum toxin improves structural changes in muscles and joint components responsible for contractures. SETTING: University laboratory in Japan. METHODS: To evaluate the effect of hypertonia on contracture development, the rats received botulinum toxin injections after spinal cord injuries. Knee extension motion was measured with a goniometer applying a standardized torque under anesthesia, and the contribution by muscle or non-muscle structures to contractures were calculated by measuring joint motion before and after the myotomies. We quantitatively measured the muscle atrophy, muscle fibrosis, and synovial intima length. RESULTS: Botulinum toxin injections significantly improved contractures, whereas did not completely prevent contracture development. Botulinum toxin was effective in improving the muscular factor, but little difference in the articular factor. Spinal cord injuries induced muscle atrophy, and botulinum toxin significantly accelerated muscle atrophy and fibrosis. The synovial intima length decreased significantly after spinal cord injuries, and botulinum toxin did not improve this shortening. CONCLUSIONS: This animal study provides new evidence that hypertonia is not the sole cause rather is the partial contributor of contractures after spinal cord injuries. Furthermore, botulinum toxin has adverse effects in the muscle.

Classic metaphyseal lesion acquired during physical therapy.

A classic metaphyseal lesion (CML) is highly specific for nonaccidental trauma. Missing CMLs can be devastating to the child as the child can continue to be exposed to inflicted trauma. Yet, there are rare case reports on CMLs that occur due to birth trauma, IV line placement, and treatment for clubfoot. We present a case of a CML in the tibia that occurred in the hospital secondary to physical therapy, that also caused a femoral shaft fracture, in a term child with hypertonic lower extremities secondary to myelomeningocele. Radiologists, as well as child abuse pediatricians, should be aware of the rare exception when CML is secondary to non-abusive injury.

Association of spasticity and motor dysfunction in chronic stroke.

BACKGROUND: The prevalence of increased muscle tone after stroke is frequently reported as 30% to 40%, and the condition is often concurrent with motor control deficits, manifesting as an inability to isolate paretic-limb joint movements. OBJECTIVE: The objectives of this retrospective analysis were to 1) report the prevalence of increased muscle tone in a convenience sample of 128 chronic stroke survivors with moderate/severe motor deficits and 2) quantify the relation between tone and motor impairment in chronic stroke survivors. METHODS: Analyses included descriptive statistics and multiple regression modeling, with the modified Ashworth Scale score (MAS; tone) as a predictor of isolated joint movement control (Fugl-Meyer score [FM]; motor impairment). RESULTS: Increased muscle tone was present in 97% of subjects. Increased muscle tone was associated with impaired motor control (FM; upper extremity, P=0.008; lower extremity, P=0.03) after adjusting for age, time since stroke and sex. We found a significant difference between flexor and extensor strength for finger, elbow, hip and knee joints (P<0.002). Participants were classified in high and low MAS score groups. With high MAS score and for muscles of finger flexion and forearm pronation, we found a trend toward impaired strength of antagonist muscles (finger extensors and forearm supinators, respectively) as compared with low MAS score for these same muscle pairings. CONCLUSIONS: The prevalence of increased tone was higher in this study than in previous reports. Increased muscle tone in chronic stroke survivors with persistent motor dysfunction could be associated with impaired motor control and differential muscle strength of antagonistic muscles.

Joint contractures and acquired deforming hypertonia in older people: Which determinants?

Joint contractures and acquired deforming hypertonia are frequent in dependent older people. The consequences of these conditions can be significant for activities of daily living as well as comfort and quality of life. They can also negatively affect the burden of care and care costs. However, etiological factors and pathophysiologic mechanisms remain only partly understood. As a result, preventive interventions and treatments focus entirely on controlling symptoms rather than the causes. Moreover, the effectiveness of these interventions remains to be validated. The purpose of this position paper is to present current data on etiological factors contributing to the development of joint contractures and acquired deforming hypertonia in older people. The pathophysiologic mechanisms of joint contractures in animal models are also presented.