Disagreement about the Lance spasticity definition
A proposed alternative definition of spasticity by Pandyan et al.
Over the years there has been reluctance to accept the Lance definition of spasticity. This reluctance seems to arise from the observation that there are many changes to the sensori-motor system that may occur after a stroke. These changes may include:
- loss of, or decrease in muscle activation (flaccid, weak muscles),
- amplified reflex responses (hyperreflexia),
- loss of co-ordination, excessive muscle activation when attempting to move
- soft tissue adaptations such as stiffness and contracture.
Some or all of these may occur after an upper motor neurone lesion such as a stroke.
These varied possible sequelae after stroke have led medical staff, therapists and medical companies involved with outcomes after stroke to find the Lance definition of spasticity limiting (Pandyan 2005). The Lance definition, they claim, excludes these other neural and muscular changes that may be observed after stroke.
To compensate for this perceived limitation, Pandyan et al have proposed an alternative definition of spasticity that allows for inclusion of many of these other possible sequelae after a stroke. Here is their definition:
‘disordered sensori-motor control, resulting from an upper motor neuron lesion, presenting as intermittent or sustained involuntary activation of muscles’
Using this definition, spasticity is something that might, or might not happen (intermittent), might happen all the time (sustained) and the person doesn’t intend to do it (involuntary). In other words, this definition includes virtually all sequelae that may occur after a stroke. Pandyan et al acknowledge that this is a “generic” definition.
Is this alternative proposed definition helpful?
In a word, no.
For a definition to be clinically useful it needs to provide a clear identification/description and measurement of the entity it describes. A useful definition will also distinguish the thing it describes from something else which may be similar. This proposed new definition of spasticity does neither of these things. Any sensori-motor movement problem can be included in this definition. Importantly, this definition does not provide measurement of spasticity.
This “generic” definition allows for any sensori-motor problem to be included in a box labelled spasticity. This similar to describing a bowl of fruit as “fruit” instead of describing the individual types of fruit within the bowl each of which has a clear definition (eg bananas, apples, oranges and pineapples etc). The new definition can include both neural as well as non-neural features. For example, resistance to movement may be caused by neural factors (eg hyperreflexia) or non-neural factors (changes in soft tissue such as stiffness). Its generic nature inadvertently encourages imprecise clinical reasoning, possibly poor clinical decisions and provides an opportunity for medicalisation of motor control problems which may be amenable to non-medical interventions such as task specific training. Consequently this definition may lead to excessive use of medical solutions such as botulinum toxin instead of specific training interventions that may be more effective in restoring motor function.
Is this a problem?
Yes! If you don’t know what you are measuring then you can’t determine the effectiveness of your chosen intervention for that problem. If you choose an intervention for spasticity then you need to be able to measure spasticity objectively before and after intervention to demonstrate the effectiveness (or not) of your intervention.
Using the Pandyan definition, a clinican could assume an observed movement problem to be spasticity when in fact it isn’t (eg muscle stiffness). Inadequate or superficial analysis of the underlying causes of an observed movement problem are likely to lead to ineffective intervention decisions.
In short, this proposed definition does not offer clarity for clinicians or stroke survivors.
This confusion has been acknowledged by a recent consensus paper of clinicians and researchers (van den Noort et al).
The next blog will look at strategies to distinguish between stiffness, contracture and spasticity.
Pandyan AD, Gregoric M, Barnes MP, et al. Spasticity: clinical perceptions, neurological realities and meaningful measurement. Disabil Rehabil. 2005; 27: 2–6.
van den Noort et al. European Journal of Neurology 2017, 24: 981–991