Technically, no. Motor deficits due to spasticity (e.g. muscles or actions that would be most limited) may be independent of the synergy pattern being experienced. The reason is because spasticity and synergistic movement patterns mean different things.
Spasticity is one of a number of ‘positive’ signs that materialize after an upper motor neuron (UMN) lesion. In humans, a lesion of the descending corticospinal motor tract produces both ‘negative’ signs such as muscle weakness during voluntary effort and in the same muscle, ‘positive’ signs such spasticity – which is defined as increased resistance to passive stretch. Typically, spasticity patterns can be clinically recognized based on the patient’s presentation i.e. the type of UMN lesion present e.g. elbow and finger flexion in a hemiplegic patient.
Nevertheless, UMN spasticity patterns need to be properly observed and documented because they present with extensive diversity than is commonly noted. For example, while flexed elbows and wrists are very common with hemiplegia, extended elbows and wrists can also be seen as well.
On the other hand, inequalities of muscle weakness and muscle overactivity within and across muscle groups often lead to a net balance of muscle torques acting across joints shared in common by these groups. Often, there is a loss of selective control i.e. loss of independent joint movement and an inability to perform separate movements of individual joints or to operate and control several joints selectively as a unit at will. Instead of autonomous control, the patient with UMN lesion, attempting to make selective joint movement, makes multijoint obligatory patterns of movement that reflect obligatory muscle activations within and across joints – this describes the synergy pattern of movement.
Synergy patterns can be described by the limb affected and which movement (flexion or extension) dominates. For instance, the commonest example of obligatory linkages across jointed limb segments during a movement effort such as seen in the upper extremity of a hemiplegic patient is the flexor synergy pattern which describes scapular retraction, shoulder abduction and external rotation, elbow flexion, forearm supination and both wrist and finger flexion.
When instructed to perform a task such as reaching forward to grasp an object, the patient dominated by an upper limb flexor synergy will demonstrate many, if not all the joint movements described above and will continue to produce a similar stereotyped behavior in an attempt to perform other unrelated tasks.
Ref; Brashear A. Spasticity; Diagnosis and Management. 2016. Second edition. Demos Medical Publishers. Chapter 3. Spasticity and Other Signs of The Upper Motor Neuron Syndrome.Pg 19.
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