Spasticity and muscle contracture following stroke

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Clinical Neurology

Background:

• Functional deficits post-brain damage are often attributed to weakness and loss of dexterity, rather than spasticity.
• Spasticity is considered distinct from dexterity loss but may influence contracture and strength recovery.

Purpose of the Study:

• To investigate the relationship between spasticity, contracture, strength, and dexterity in the upper limb after stroke.
• To differentiate between hypertonia and reflex hyperexcitability in spasticity.

Main Methods:

• Assessed spasticity via tonic stretch reflexes and resistance to passive stretch (hypertonia).
• Recruited 24 non-selective stroke patients within 13 months post-stroke.
• Evaluated contracture, strength, and dexterity in the affected upper limb.

Main Results:

• Half of the patients presented with muscle contracture, with the earliest detected at 2 months post-stroke.
• Hypertonia correlated with contracture but not reflex hyperexcitability.
• Increased tonic stretch reflexes were infrequent, observed mainly at the end of the muscle range in a subgroup with contracture.
• No significant relationship was found between spasticity (both hypertonia and reflex hyperexcitability) and weakness or loss of dexterity.

Conclusions:

• Contracture may potentiate spasticity, challenging the notion that spasticity directly causes contracture.
• The focus on reflex hyperexcitability in spasticity management may be disproportionate to its functional impact.
• Distinguishing between hypertonia and reflex hyperexcitability is crucial for effective clinical management of spasticity post-stroke.