Management of spasticity

Age and Ageing, March, 1998 by Michael P. Barnes

Keywords: physiotherapy, rehabilitation, spasticity.

Introduction

Spasticity is a major challenge to the rehabilitation team. Spasticity can prevent or hamper function, cause pain, disturb sleep, cause unnecessary complications and present major difficulties for care workers. This article reviews the variety of options available for the clinical management of spasticity. The need for clear treatment goals and robust outcome measures is emphasized. The initial management should focus on the alleviation of external exacerbating causes before specific treatment is considered. Physiotherapy is vital for correct positioning, seating, use of orthoses, splints and casts and for other anti-spastic measures such as use of heat and cold and electrical stimulation. The use of oral medication is discussed. Peripheral nerve blocks and botulinum toxin are two local treatments which are proving very useful and are under-used and undervalued. In more severe cases intrathecal medication can be helpful. Surgical procedures such as rhizotomy anti orthopaedic corrections may sometimes be necessary, but usually only for the most severe cases or for those who have been poorly managed in the earlier stages. Overall, the clinical management of spasticity often depends on a variety of different approaches, necessitating the involvement of a comprehensive rehabilitation team.

Definitions of spasticity

Most physicians and therapists working with physically disabled people probably feel that they can recognize spasticity when they see or feel it. However, defining it is much more difficult. Spasticity has been narrowly defined as a motor disorder characterized by velocity-dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks [1]. This narrow definition, however, does not do justice to the additional symptoms that are often associated with increased muscle tone. Spasticity is usually accompanied by permanent or at least intermittent voluntary muscle activation, resulting in weakness and clumsiness of voluntary movements. The definition can be broadened further to include other positive characteristics of the upper motor neuron syndrome such as flexor or extensor spasms and the `clasp-knife' phenomenon, exaggerated cutaneous reflexes and contractures [2]. Yet even these broader definitions do not give any flavour of the bewildering variety of problems that can occur in different individuals and even in the same individual at the same time. The extent and type of spasticity can fluctuate widely according to position, fatigue, stress and drugs. One limb may have one pattern of spasticity whilst another may have a different pattern.

Goals and outcomes

The treatment of spasticity, like all rehabilitation processes, must start with the establishment of specific achievable goals and a carefully planned strategy to achieve those goals. The first question is: is it necessary to treat the spasticity at all? Spasticity can be useful for the individual. For example, spasticity in a leg may serve as a brace to support the individual's weight for transferring or walking. Some consideration also needs to be given to the side effects of some treatments, particularly the weakness and fatigue induced by antispastic medication.

In general terms, there are three potential aims of treatment -- to improve function, to reduce the risk of unnecessary complication and to alleviate pain. Occasionally, a justifiable aim is not specifically to help the patient, who may not perceive any problems with spasticity, but to make nursing easier for the main carers anti to assist with the maintenance of hygiene, dressing and transferring.

Once a goal has been established, an outcome measure should be chosen that allows goal attainment and progress to be monitored. Most measures of spasticity are measures of impairment and not measures of disability or handicap. The clinical goal should have an appropriate clinical outcome measure. For example, if the aim of treatment is to reduce pain, then little is achieved by monitoring muscle spasticity and a pain scale should be used. There are a number of motor-orientated disability scores that can be used to monitor functional effects of anti-spastic treatment programmes, from the broad-based Barthel index [3] to the more comprehensive Functional Independence Measure [4] to more specific walking or hand function tests [5].

Occasionally, a specific measure of spasticity is useful, particularly in a research environment. Unfortunately there are very few properly validated and reliable clinical assessments. The modified Ashworth scale [6] is the best known but there have been only two studies of its reliability [6, 7]. The original paper by Bohannon and Smith [6] was only concerned with the elbow joint; the second paper by Sloan and co-workers [7] confirmed reliability for the elbow, but showed a rather poor inter-rater reliability for the knee flexors. The validity and reliability of this scale for other joints are not known. A variety of other assessment procedures are available. These tend to be either biomechanical or neurophysiological. In the former category, attempts have been made to use mechanical techniques to measure torque/angle relationships with spastic joints during passive flexion and extension [8-12]. A valid technique for the measurement of spasticity of the knee is the pendulum test [13], which is a more sensitive measure of spasticity than the Ashworth scale. The pendulum test involves the appropriate joint, such as the knee, being held in extension and released, with spasticity measured as the rate of decay of oscillation of the limb. Obviously this is a difficult test to perform in smaller joints or in severe spasticity. Quantitative neurophysiological measurements of spasticity have largely been developed as research tools. Measurements mainly focus on characteristics of the H reflex, particularly suppression of the reflex by vibration and by reciprocal inhibition. These techniques are well reviewed by Shahani and Cross [14].