Soleus H reflex and motor unit number estimation after tibial nerve block and neurotomy in patients with spastic equinus foot

Neuro-orthopaedic assessment and management in patients with prolonged disorders of consciousness: A review

BACKGROUND

Following a severe acquired brain injury, neuro-orthopaedic disorders are commonplace. While these disorders can impact patients' functional recovery and quality of life, little is known regarding the assessment, management and treatment of neuro-orthopaedic disorders in patients with disorders of consciousness (DoC).

OBJECTIVE

To describe neuro-orthopaedic disorders in the context of DoC and provide insights on their management and treatment.

METHODS

A review of the literature was conducted focusing on neuro-orthopaedic disorders in patients with prolonged DoC.

RESULTS

Few studies have investigated the prevalence of spastic paresis in patients with prolonged DoC, which is extremely high, as well as its correlation with pain. Pilot studies exploring the effects of pharmacological treatments and physical therapy show encouraging results yet have limited efficacy. Other neuro-orthopaedic disorders, such as heterotopic ossification, are still poorly investigated.

CONCLUSION

The literature of neuro-orthopaedic disorders in patients with prolonged DoC remains scarce, mainly focusing on spastic paresis. We recommend treating neuro-orthopaedic disorders in their early phases to prevent complications such as pain and improve patients' recovery. Additionally, this approach could enhance patients' ability to behaviourally demonstrate signs of consciousness, especially in the context of covert awareness.

Motor Unit Number Estimation in Spastic Biceps Brachii Muscles of Chronic Stroke Survivors Before and After BoNT Injection

OBJECTIVE

The study aims to characterize the motor unit (MU) loss in spastic biceps brachii muscle (BBM) of chronic stroke survivors before and after botulinum neurotoxin (BoNT) injection.

METHODS

High-density weighted average (HDWA) motor unit number estimation (MUNE) was employed to estimate the number of functioning motor units of BBMs of eight chronic stroke survivors 1-week before (1st visit) and 3-week after (2nd visit) BoNT injection based on the surface electromyography (sEMG) signals recorded during voluntary contraction and supramaximal electrical stimulation.

RESULT

Significant lower MUNE was estimated from the spastic BBMs compared to the non-spastic MUNEs during two visits. A surprisingly higher MUNE was obtained from the spastic side during the 2nd visit after BoNT injection.

CONCLUSIONS

The HDWA MUNE technique can be employed to characterize the motor unit loss in spastic muscle caused by upper motor neuro lesions at contraction level up to 30% MVC, but may fail to detect the MU loss caused by the chemodenervation effect of BoNT due to the non-uniform denervation of small and large size MUs.

SIGNIFICANCE

This study presents the first effort to evaluate the applicability of HDWA MUNE technique to characterize the MU loss in the spastic muscle following stroke and the subsequent BoNT injection for the treatment of post-stroke spasticity. The finding of this study suggests that HDWA MUNE can be a sensitive approach to detect the MU loss in spastic muscles after stroke, but the large inter-subject MUNE variability after the BoNT injection should be interpreted with caution.

Neuro-Orthopedic Surgery for Equinovarus Foot Deformity in Adults: A Narrative Review

Neuro-orthopedic surgery is an alternative to the conservative treatment of spastic equinovarus foot (SEF) in adults. The objective of the present narrative review was to summarize current practice with regard to patient assessment, the choice of treatment, the various neuro-orthopedic procedures, and the latter's outcomes. We searched literature databases (MEDLINE, EMBASE, Cochrane) for original articles or opinion papers on surgical treatment of spastic equinovarus foot in adults. Neuro-orthopedic approaches require a careful analysis of the patient's and/or his/her caregiver needs and thus relevant treatment goals. Surgical planning requires detailed knowledge of impairments involved in the spastic equinovarus foot deformity based on a careful clinical examination and additional information from diagnostic nerve blocks and/or a quantitative gait analysis. Procedures mainly target nerves (neurotomy) and tendons (lengthening, transfer, tenotomy). These procedures reduce impairments (spasticity, range of motion, and foot position), improve gait and walking function, but their impact on participation and personalized treatment goals remains to be demonstrated. Neuro-orthopedic surgery is an effective treatment option for spastic equinovarus foot in adults. However, practice is still very heterogeneous and there is no consensus on the medical strategies to be applied before, during and after surgery (particularly the type of anesthesia, the need for immobilization, rehabilitation procedures).

French clinical guidelines for peripheral motor nerve blocks in a PRM setting

INTRODUCTION

Motor nerve blocks with anesthetic drug for local anesthesia are commonly used in physical and rehabilitation medicine (PRM), especially in the field of spasticity. Guidelines in this context are currently lacking.

METHOD

Eighteen experts selected on the basis of their recognized experience by the scientific committees of the French PRM (SOFMER) and Anesthesia and Intensive care (SFAR) societies were invited to work and propose guidelines for the use of loco-regional anesthetic drug for motor nerve blocks in PRM setting. Eight issues were addressed: which neural blocks for which indications; drugs and contraindications; medical survey and attitude in case of adverse event; injection and guidance material; patient preparation and pain relief; efficacy assessment; patient information; education of PRM physiatrists. The Medline, Cochrane and Embase databases for the period 1999 to 2018 were consulted and 355 papers analyzed. The drafts were commented then approved by the whole group using electronic vote, before final approval by scientific committee of each society.

RESULTS

No scientific evidence emerged from the literature. Thus, these guidelines are mainly based on the opinion of the expert panel. Guidelines for each issue are reported with the main points of arguments. The main question deals with the recommendation about doses for each drug: for lidocaine - up to 2mg/kg - "check contraindications, emergency truck available, no need of previous anesthetic consultation nor presence of anesthetic physician"; for ropivacaine - up to 1.5mg/kg, with a maximum of 100mg - the same but after intravenous line. Beyond these doses, SFAR guidelines have to be applied with the need of anesthetic physician.

CONCLUSION

These are the first organizational guidelines devoted to increase the security of motor nerve block use in PRM settings.

Clinical and electrophysiological investigation of spastic muscle overactivity in patients with disorders of consciousness following severe brain injury

OBJECTIVE

The clinical and electrophysiological profile of spastic muscle overactivity (SMO) is poorly documented in patients with disorders of consciousness (DOC) following severe cortical and subcortical injury. We aim at investigating the link between the clinical observations of SMO and the electrophysiological spastic over-reactivity in patients with prolonged DOC.

METHODS

We prospectively enrolled adult patients with DOC at least 3 months post traumatic or non-traumatic brain injury. The spastic profile was investigated using the Modified Ashworth Scale and the Hmax/Mmax ratio. T1 MRI data and impact of medication were analyzed as well.

RESULTS

21 patients were included (mean age: 41 ± 11 years; time since injury: 4 ± 5 years; 9 women; 10 traumatic etiologies). Eighteen patients presented signs of SMO and 11 had an increased ratio. Eight patients presented signs of SMO but no increased ratio. We did not find any significant correlation between the ratio and the MAS score for each limb (all ps > 0.05). The presence of medication was not significantly associated with a reduction in MAS scores or Hmax/Mmax ratios.

CONCLUSIONS

In this preliminary study, the Hmax/Mmax ratio does not seem to reflect the clinical MAS scores in patients with DOC. This supports the fact they do not only present spasticity but other forms of SMO and contracture.

SIGNIFICANCE

Patients with DOC are still in need of optimized tools to evaluate their spastic profile and therapeutic approaches should be adapted accordingly.

Botulinum toxin type A or selective neurotomy for treating focal spastic muscle overactivity?

OBJECTIVE

To discuss the effectiveness, indications, limitations and side effects of botulinum toxin type A and selective neurotomy for treating focal spastic muscle overactivity to help clinicians choose the most appropriate treatment.

METHODS

Expert opinion based on scientific evidence and personal experience.

RESULTS

Botulinum toxin type A can decrease muscle tone in different types of spastic muscle overactivity, which allows for treating a large variety of spastic patterns with several etiologies. The toxin effect is sometimes insufficient to improve functional outcome and is transient, thereby requiring repeated injections. Selective neurotomy is a permanent surgical treatment of the reflex component of the spastic muscle overactivity (spasticity) that is effective for spastic equinovarus foot. The neurotomy provides a greater and more constant reduction in spasticity. However, the long-lasting effect on the non-reflex muscle overactivity, especially dystonia, is doubted. The effectiveness, clinical indications, advantages, side effects and limitations of both techniques are discussed.

CONCLUSION

Botulinum toxin type A has the highest level of evidence and the largest range of indications. However, the botulinum toxin effect is reversible and seems less effective, which supports a permanent surgical treatment such as selective neurotomy, especially for the spastic foot. Further research is needed to compare the effect of botulinum toxin type A and selective neurotomy for the different types of spastic muscle overactivity and clinical patterns.

Effects of tibial nerve neurotomy on posture and gait in stroke patients: A focus on patient-perceived benefits in daily life

OBJECTIVE

To evaluate the objective and subjective functional effectiveness of tibial nerve neurotomy (TNN) in post-stroke spastic equinovarus foot (SEF).

METHODS

In an open study, 23 hemiplegic patients were assessed immediately before TNN and then 5months after TNN. The main outcome measure was the Lower Limb Function Assessment Scale (LL-FAS), which provided an ecologic assessment of impairments in standing and walking (i.e. kinematic abnormalities) and their impacts on activities of daily living. Patients were also assessed for global clinical impression of change, fear of falling, neuromotor impairments, spatiotemporal and video gait parameters and walking capacities.

RESULTS

TNN had a very marked effect on the level of spasticity and the range of motion in dorsiflexion (p<10(-3)). These changes resulted in better foot positioning when standing and walking (particularly in stance), which was perceived very favorably by the patients. There was a clear, patient-perceived improvement in activities performed when standing and walking (LL-FAS (p<0.01)), the global clinical impression of change (p<10(-3)) and the fear of falling (p=0.022) that was not revealed by conventional, objective measurements (New Functional Ambulation Classification, Rivermead Mobility Index).

CONCLUSION

TNN is an effective treatment for post-stroke SEF; it is associated with a patient-reported improvement in standing and walking abilities during activities of daily living. Further research must now assess the long-term subjective efficacy of TNN.

Comparison between tibial nerve block with anaesthetics and neurotomy in hemiplegic adults with spastic equinovarus foot

OBJECTIVE

The aim of the study was to compare the effect of diagnostic motor nerve block with anaesthetics and of selective tibial neurotomy in the treatment of spastic equinovarus foot in hemiplegic adults.

METHODS

In this prospective observational study, 30 hemiplegic adults with spastic equinovarus foot benefited from a diagnostic nerve block with anaesthetics followed by a selective tibial neurotomy performed at the level of the same motor nerve branches of the tibial nerve. Spasticity (Ashworth scale), muscle strength (Medical Research Council scale), passive ankle dorsiflexion (ROM), gait parameters (10 meters walking test) and gait kinematics (video assessment) were assessed before and after the nerve block and two months and two years after selective tibial neurotomy.

RESULTS

The decrease in spasticity and the improvement in gait kinematics were similar after the diagnostic nerve block and two months and two years after neurotomy. The diagnostic nerve block did not revealed the slight increase in gait speed and in tibialis anterior muscle strength that was observed two years after neurotomy.

CONCLUSION

This study suggests that diagnostic nerve block with anaesthetics and selective neurotomy equally reduce spasticity and improve gait in case of spastic equinovarus foot in hemiplegic adults. Diagnostic nerve block can be used as a valuable screening tool before neurotomy.

Neuromechanical assessment of lidocaine test block in spastic lower limbs

The objective of this study was to quantify in spastic lower limbs the changes in reflex EMGs and in ankle stiffness after a lidocaine block of the soleus nerve to better understand physiological effects of lidocaine. Twenty patients were prospectively included and assessed before and after lidocaine block of the soleus nerve. We studied clinical and neuromechanical parameters of the triceps surae, including quantification of the maximum Hoffmann’s reflex (Hmax) and tendinous reflex (T) normalized to the maximum direct motor response (Mmax), and passive ankle stiffness assessed by sinusoidal length perturbations. All patients whatever the aetiology of spasticity were improved in clinical parameters of spasticity after the block (62% reduction of the Ashworth score, 85% reduction of stretch reflex scores, increased score on the Physicians’ Rating Scale). All patients presented a reduction of the Hmax–Mmax ratio (mean reduction of 67%) and the T–Mmax ratio (82%). Ankle stiffness was decreased by an average of 23%. Measured stiffness was correlated with the Ashworth score and the T–Mmax ratio. Relatively greater change in the T reflex than in the H reflex suggests that lidocaine block reduces hyperreflexia not only by interfering with generation of afferent volleys in the injected nerve, but also probably by altering generation of the volleys at the level of muscle spindles in the affected spastic muscles, presumably by blocking the transmission along gamma-efferent fibers.

Time course of the soleus M response and H reflex after lidocaine tibial nerve block in the rat

Aims. In spastic subjects, lidocaine is often used to induce a block predictive of the result provided by subsequent surgery. Lidocaine has been demonstrated to inhibit the Hoffmann (H) reflex to a greater extent than the direct motor (M) response induced by electrical stimulation, but the timecourse of these responses has not been investigated. Methods. An animal (rat) model of the effects of lidocaine on M and H responses was therefore developed to assess this time course. M and H responses were recorded in 18 adult rats before and after application of lidocaine to the sciatic nerve. Results. Two to five minutes after lidocaine injection, M responses were markedly reduced (mean reduction of 44%) and H reflexes were completely abolished. Changes were observed more rapidly for the H reflex. The effects of lidocaine then persisted for 100 minutes. The effect of lidocaine was therefore more prolonged on the H reflex than on the M response. Conclusion. This study confirms that lidocaine blocks not only alpha motoneurons but also Ia afferent fibres responsible for the H reflex. The authors describe, for the first time, the detailed time course of the effect of lidocaine on direct or reflex activation of motoneurons in the rat.

Long-term neuromechanical results of selective tibial neurotomy in patients with spastic equinus foot

BACKGROUND

The neuromechanical consequences of tibial neurotomy have not been extensively studied.

METHODS

Fifteen patients were evaluated before and after selective tibial neurotomy (after 2 months and after 15 months) by means of clinical, neurophysiological [tendon (T) reflexes, Hoffmann (H) reflexes and maximum motor response, Mmax] and mechanical parameters (passive stiffness of plantar flexors at the ankle). The neurotomy concerned the soleus (100 % of cases), gastrocnemius (20 % of cases), posterior tibial (60 % of cases) and flexor digitorum longus (47 % of cases) nerves.

RESULTS

Neurotomy provided more than 90 % improvement of clinical spasticity scores, 20 % improvement of walking scores and the angle of passive dorsiflexion (APDF) of the ankle (mean angle: 7°), temporary reduction of the soleus Mmax (18 % at 2 months with return to the preoperative value at 15 months), and lasting reduction of the soleus Hmax/Mmax (68 % at 2 months, 78 % at 15 months) and T/Mmax (84 % at 2 months, 80 % at 15 months). M and H responses of the gastrocnemius (whether or not they were included in the neurotomy) were not modified, while T/Mmax decreased to the same degree as for soleus. Passive stiffness was lastingly decreased from 64.0 Nm/rad to 49.0 Nm/rad (2 months) and 49.5 Nm/rad (15 months).

CONCLUSION

Selective tibial neurotomy of the soleus nerve induces long-term reduction of reflex hyperexcitability and passive stiffness of plantar flexors in spastic patients, with no lasting impairment of motor efferents. In parallel, it modifies the tendon reflexes of synergistic muscles (gastrocnemius) not concerned by the neurotomy.