• The disease
• Diagnosis
• Treatment options

Definition

Spasticity is due to an exaggerated contraction of the muscle reflex which is triggered by suddenly stretching the muscle. This hypertonia is caused by disinhibition of the myotatic reflex (the reflex that contracts the muscle in response to stretching it) following damage to the brain or spinal cord. The term spasticity is used to describe all muscular activity secondary to central nervous system damage.

The increase in muscle tone can be very disabling and cause continuous and sometimes very powerful contraction at rest, and extremely intense contractions in response to the slightest stimulation. It may become impossible to straighten out the limb, creating motor difficulties and pain for patients.

Symptoms and impact on health

Spasticity develops gradually and generally takes several weeks to become established. It always concerns a small or large muscle group, and the location depends on the location of the damage to the brain or spinal cord:

• Location in cases of cerebral stroke or traumatic brain injury: generally speaking, one side of the brain is affected and causes either partial (paresis) or complete paralysis of the opposite side of the body. Here, spasticity can affect the whole of one side of the body, the upper or lower limb.
• Location in cases of multiple sclerosis (MS): patients with MS may have lesions that affect the brain and/or the spinal cord. In MS, spasticity essentially affects the lower limbs and causes problems with walking.

In clinical terms, there are two signs of spasticity:

• an increase in the stretch reflex, or in other words, an exaggerated contraction of the muscle reflex, which is triggered by stretching;
• muscular hypertonia, which is the characteristic elastic resistance to continuous stretching of the muscle.

Complications vary: when spasticity is severe, changes to the muscular structure take place over time (muscular retraction or contracture), which are difficult to differentiate from the actual spasticity itself. Movement and balance problems, shaking, pain, inhibition of growth in children, and impacts on quality-of-life are also possible.

Etiologies

Appearing in different forms, spasticity is found with the majority of neurological deficit conditions, as a result of:

• cerebral stroke (CAV),
• head trauma,
• spinal cord injury,
• multiple sclerosis,
• cerebral palsy.

Cerebral stroke is the leading cause of spasticity and effects 40% of patients post-stroke. An artery that irrigates cells in the brain is obstructed or ruptured; the flow of blood no longer gets to that part of the brain and it dies. The brain function responsible for regulating the myotatic reflex may be partially destroyed and spasticity is the result.