[Reevaluation of physiological mechanisms generating the stretch reflex: new hypotheses on the physiopathology of spasticity]

[Anal tone: Physiology, clinical and instrumental characteristics]

INTRODUCTION

The anal tone allows the maintenance of anorectal continence. Its regulation depends on spinal segmental mechanisms under supra-sacral control.

MATERIAL AND METHODS

A systematic review was performed using Medline database, according to PRISMA methodology, using following keywords anal tone ; anal sphincter ; anorectal function ; reflex ; digital rectal examination.

RESULTS

Anal hypertonia is an increase in the muscle's resistance to passive stretching. Muscular hypotonia is a decrease in muscle tone. It is associated with a decrease in resistance to passive mobilization. It is not possible to quantify the prevalence of anal tone alterations in the general population and in specific pathological conditions (urinary disorders, neurogenic or non-neurogenic anorectal disorders). In case of hypotonia, most often due to a lower motor neuron lesion, fecal incontinence may occur. Hypertonia (anal sphincter overactivity) is not always due to perineal spasticity. Indeed, in the majority of the cases, the cause of this anal hypertonia in a neurologic context, can be secondary to an upper motor neuron disease due to spinal or encephalic lesion, leading to recto-anal dyssynergia, giving distal constipation. In another way, this anal hypertonia can be purely behavioral, with no direct pathological significance. The evaluation of anal tone is clinical with validated scores but whose sensitivity is not absolute, and instrumental with, on the one hand, the measurement of anal pressure in manometry and, on the other hand, electrophysiological testing which still require validation in this indication.

CONCLUSION

Anal tone assessment is of interest in clinical practice because it gives diagnostic arguments for the neurological lesion and its level, in the presence of urinary or anorectal symptoms.

[Spasticity and everyday life in multiple sclerosis]

Spasticity is one of the most commonly seen symptoms in patients with multiple sclerosis. However, evaluation of the symptom often uses clinical scales that do not incorporate its impact on activities of daily living and quality of life. The everyday life of patients is affected primarily in actions related to mobility and walking capacity, such as the use of transport, gardening, household activities and, ultimately, basic activities such as bathing and dressing. Yet, so far, no study has described the impact of spasticity on the daily life of patients with multiple sclerosis. Nevertheless, assessing the effects of spasticity on such a young population would appear to be essential for meeting the needs of these patients with appropriate therapeutic interventions.

Radiculalgie après implantation de pompe à baclofène

INTRODUCTION

Intrathecally delivered baclofen has been used as a treatment for severe spasticity since 1984. After a successful intrathecal baclofen trial, a programmable drug delivery system was implanted. Few early complications such as infection or hematoma are observed after this surgery.

OBJECTIVE

To describe an unusual and unknown complication of intrathecal baclofen therapy.

METHOD

We report 2 cases of complications of intrathecal baclofen therapy, radiculalgy, that appeared early after pump implantation. The clinical symptoms and computed tomography (CT) results are described.

RESULTS

The first patient described pain, which evoked left S1 radiculopathic features. The second had left L5 radiculopathic involvement. The mean pain level was estimated on a 10-point visual analog scale as 7.5 (range 4-9). Lumbar CT scan showed a conflict between the symptomatic root and the catheter and eliminated other causes of the symptoms. Treatment with analgesic drugs was successful in 1 patient. The other presented with proximal disconnection of the catheter, which led to surgical replacement of the catheter. The pain disappeared after this surgery.

CONCLUSION

Intrathecal baclofen therapy with a subcutaneously implanted progammable pump can be complicated by radiculalgy secondary to a conflict between the catheter and symptomatic root. The diagnosis is made by CT lumbar scan. If medical treatment is not sufficient, surgery could be proposed to replace the catheter.

Pathophysiology of spastic paresis. II: Emergence of muscle overactivity

In the subacute and chronic stages of spastic paresis, stretch-sensitive (spastic) muscle overactivity emerges as a third fundamental mechanism of motor impairment, along with paresis and soft tissue contracture. Part II of this review primarily addresses the pathophysiology of the various forms of spastic overactivity. It is argued that muscle contracture is one of the factors that cause excessive responsiveness to stretch, which in turn aggravates contracture. Excessive responsiveness to stretch also impedes voluntary motor neuron recruitment, a concept termed stretch-sensitive paresis. None of the three mechanisms of impairment (paresis, contracture, and spastic overactivity) is symmetrically distributed between agonists and antagonists, which generates torque imbalance around joints and limb deformities. Thus, each may be best treated focally on an individual muscle-by-muscle basis. Intensive motor training of the less overactive muscles should disrupt the cycle of paresis-disuse-paresis, and concomitant use of aggressive stretch and focal weakening agents in their more overactive and shortened antagonists should break the cycle of overactivity-contracture-overactivity.

Treatment of spasticity with intrathecal Baclofen administration: long-term follow-up, review of 40 patients

STUDY DESIGN

Case series of a consecutive sample. Retrospective audit.

OBJECTIVE

To analyze the long-term safety and efficacy of intrathecal baclofen (ITB), and technical incidents.

SETTING

Neurosurgical and Physical Medicine Departments of two university hospitals in western France.

METHODS

The medical records of 40 patients who underwent ITB pump placement for the treatment of severe chronic spasticity were reviewed. Patients were eligible independently of the origin of the spasticity (spinal cord origin 33, brain damage 8). They underwent a final assessment with clinical examination and questionnaire in 2001. Ashworth scale scores were assessed, patient satisfaction was rated on a visual analog scale (VAS), functional independence before and after treatment was classified as bed-ridden, wheelchair dependent or ambulant, and the frequency and nature of complications were noted.

RESULTS

The average follow-up period was of 4 years. The average Ashworth score at the final assessment was 1.8+/-0.6. Average patients satisfaction was 7.4/10+/-2.21 on VAS. In all, 85% would have undergone the procedure again if they had to make the decision. In 85% of the cases the ambulation status was unchanged. Technical incidents occurred at least once in 37% of the patients (due to the catheter in 58% and to the pump in 42%). They included catheter disconnections (4), migration (4), kinks (3), obstruction (3), development of fibrosis (3), disconnection of pump reservoir (2), porosity of pump membrane (2), unexplained pump dysfunction (4) leakage, and subcutaneous collection (5). Severe pharmacological side effects requiring transfer to intensive care unit occurred in 12% of cases, 80% of which were directly related to pump refill procedures.

CONCLUSION

ITB remained effective in the long term and patients were satisfied. Nevertheless, complications were frequent, involving mainly the catheters, which would require further technical improvements.

[Evaluation of pendulum testing of spasticity]

OBJECTIVES

To identify valid measurements of spasticity derived from the pendulum test of the leg in a representative population of spastic patients.

MATERIAL AND METHODS

Pendulum testing was performed in 15 spastic and 10 matched healthy subjects. The reflex-mediated torque evoked in quadriceps femoris, as well as muscle mechanical parameters (viscosity and elasticity), were calculated using mathematical modelling. Correlation with the two main measures derived from the pendulum test reported in the literature (the Relaxation Index and the area under the curve) was calculated in order to select the most valid.

RESULTS, DISCUSSION

Among mechanical parameters, only viscosity was found to be significantly higher in the spastic group. As expected, the computed integral of the reflex-mediated torque was found to be larger in spastics than in healthy subjects. A significant non-linear (logarithmic) correlation was found between the clinically-assessed muscle spasticity (Ashworth grading) and the computed reflex-mediated torque, emphasising the non-linear behaviour of this scale. Among measurements derived from the pendulum test which are proposed in the literature for routine estimation of spasticity, the Relaxation Index exhibited an unsuitable U-shaped pattern of variation with increasing reflex-mediated torque. On the opposite, the area under the curve revealed a linear regression, which is more convenient for routine estimation of spasticity.

CONCLUSION

The pendulum test of the leg is a simple technique for the assessment of spastic hypertonia. However, the measurement generally used in the literature (the Relaxation Index) exhibits serious limitations, and would benefit to be replaced by more valid measures, such as the area under the goniometric curve, especially for the assessment of therapeutics.