Spasticity

Spasticity is an abnormal increase in muscle tone — a stiffness or tightness of the muscles — caused by disruption to the nerve signals that normally regulate muscle activity. It is not a disease in itself but a symptom of damage to the upper motor neurons, which run from the brain through the spinal cord to control voluntary movement.

**Underlying conditions that cause spasticity:** - Cerebral palsy (CP) - Multiple sclerosis (MS) - Stroke - Traumatic brain injury (TBI) - Spinal cord injury - Hypoxic brain injury

Voluntary movement requires a finely tuned exchange of signals between the muscles, spinal cord, and brain. When a neurological condition damages the pathways that carry these signals, the spinal cord's own reflex circuits become overactive, producing the characteristic increased tone and exaggerated reflexes of spasticity.

**Spasticity in cerebral palsy** results from damage to the brain's motor control areas occurring during development. The arms and legs may be affected, and the pattern varies by CP type — diplegia, quadriplegia, or hemiplegia.

**Spasticity in multiple sclerosis** typically affects the legs and hips. Flexor spasticity locks the legs and hips in a bent position; extensor spasticity holds the legs rigidly straight, occasionally causing the ankles to cross.

**Spasticity after stroke or brain injury** can appear within days of the event as swelling resolves and abnormal tone emerges. Its severity often correlates with the size and location of the lesion.

**Symptoms and complications:** - Stiff, rigid, or tight muscles resistant to passive movement - Painful involuntary muscle spasms - Exaggerated stretch reflexes and clonus - Difficulty with gait, transfers, and daily activities - Scissor gait (in spastic diplegia) - Joint contractures and fixed deformities if untreated - Pressure sores from abnormal posture - Urinary tract infections and chronic constipation

**Untreated spasticity** progressively worsens joint deformity, causes chronic pain, and erodes independence and quality of life. Treatment aims to relax the muscles, relieve pain and stiffness, encourage optimal growth and development in children, and improve the person's ability to function at home and in the community.

Management combines pharmacological approaches (oral medications, focal injections, intrathecal baclofen), neuromodulation, and intensive physiotherapy and occupational therapy — tailored to the individual's pattern of spasticity and goals.