Spasticity

What spasticity is

Muscle tone is controlled by a balance of signals. Reflex loops in the spinal cord tell muscles to contract when stretched, while pathways from the brain (upper motor neurons) dampen that reflex. When these pathways are damaged, the stretch reflex becomes overactive. The muscle then resists passive stretch, and the faster the stretch, the stronger the resistance. This is called velocity-dependent tone.

Spasticity is one part of the upper motor neuron syndrome, which also includes weakness, loss of fine control, brisk reflexes, clonus and an upgoing big toe (Babinski sign).

Spasticity is not always harmful. Some people use leg stiffness to help them stand or transfer. Treatment aims to reduce problems, not necessarily all tone.

Symptoms

• muscle stiffness and tightness, often in the calves, thighs, hip adductors, elbow and wrist flexors
• involuntary spasms, which can be painful and may wake you at night
• clonus: rhythmic, repetitive jerking, often of the ankle when the foot is pushed up
• abnormal postures: a bent elbow and clenched fist, pointed foot, or legs crossing ("scissoring")
• difficulty walking, dressing, washing or sitting comfortably
• pain and fatigue
• over time, shortened muscles and fixed joints called contractures

Causes

What makes spasticity worse

Any irritation below the level of the nervous system damage can increase spasticity:

• urinary tract infections and a full bladder
• constipation
• pressure sores, ingrown toenails and tight clothing or shoes
• infections and fever
• cold weather, fatigue and stress
• poor posture or positioning
• menstrual periods in some women

Checking for these triggers is the first step when spasticity suddenly increases.

Spasticity vs rigidity

Dystonia is another cause of abnormal postures, but it involves patterned twisting contractions rather than stretch-dependent tone.

Diagnosis

A doctor, often a neurologist or rehabilitation (physiatry) specialist, examines muscle tone by moving the limbs at different speeds, tests reflexes and clonus, and assesses strength, joint range and function. Severity is rated using the Modified Ashworth Scale (0 for no increase in tone up to 4 for a limb rigid in flexion or extension) or the Tardieu scale. MRI and other tests identify the underlying cause if it is not already known.

Treatment

Treatment is tailored to goals, such as easier walking, hygiene, comfort or preventing contractures. Several approaches are usually combined.

Physical measures

• Daily stretching, held for at least 30 to 60 seconds, by the person or a caregiver
• Physical and occupational therapy: strengthening, positioning, gait training and functional practice
• Splints, braces and serial casting to hold muscles in a lengthened position (for example, an ankle-foot orthosis)
• Standing frames and good seating
• Treating triggers such as infections, constipation and skin problems

Oral medicines

• Baclofen: the most commonly used drug. It acts on the spinal cord. Side effects include drowsiness and weakness. Never stop it suddenly, because withdrawal can cause seizures, hallucinations and high fever.
• Tizanidine: similar effect; can cause drowsiness, low blood pressure and liver problems.
• Dantrolene: acts directly on muscle; liver function must be monitored.
• Benzodiazepines such as diazepam: used less often due to sedation and dependence.
• Gabapentin and cannabinoids (such as nabiximols, licensed in some countries for MS spasticity) help some people.

Botulinum toxin injections

Injections into specific overactive muscles weaken them for about 3 months. They suit focal spasticity, such as a clenched fist after stroke or a tight calf in cerebral palsy, and work best combined with stretching, splinting and therapy.

Intrathecal baclofen pump

A small pump implanted under the skin of the belly delivers baclofen directly into the spinal fluid. It works at much lower doses with fewer side effects than tablets, and suits severe spasticity in the legs or whole body. Refills are needed every few months. Pump failure or a missed refill can cause dangerous withdrawal.

Surgery

• Selective dorsal rhizotomy: cutting selected sensory nerve rootlets in the lower spine, mainly for children with spastic cerebral palsy affecting the legs
• Orthopedic surgery: tendon lengthening or transfers to correct contractures
• Nerve blocks with phenol or alcohol for longer-lasting effects in some muscles

Complications

• contractures and joint deformity
• pressure sores from abnormal postures
• pain and poor sleep
• falls and fractures
• difficulty with hygiene and dressing
• hip dislocation in children with cerebral palsy

Living with spasticity

Spasticity often changes over time and with the underlying condition. Regular review with a rehabilitation team helps adjust treatment. Keeping active, stretching daily, maintaining good posture and seating, managing bladder and bowel care, and watching skin closely all reduce flare-ups.

Frequently asked questions

What causes spasticity?

Spasticity is caused by damage to the brain or spinal cord pathways that control muscle tone. Common causes are stroke, spinal cord injury, multiple sclerosis, cerebral palsy and traumatic brain injury. It is not caused by a problem in the muscle itself.

What is the difference between spasticity and spasms?

Spasticity is a constant increase in muscle tone that resists stretching. Spasms are sudden involuntary contractions that come and go. People with spasticity often have spasms too, and both are treated with similar approaches.

Is spasticity permanent?

It depends on the cause. Spasticity after stroke or spinal cord injury is often long-term but can improve with treatment and change over time. In progressive conditions like MS, it may fluctuate. Treatment can reduce symptoms and prevent complications even when spasticity persists.

What is the best medicine for spasticity?

There is no single best medicine. Baclofen and tizanidine are the most commonly used oral drugs. Botulinum toxin injections work well for spasticity in specific muscles, and an intrathecal baclofen pump helps severe, widespread spasticity. The right choice depends on your goals and side effects.

Can exercise help spasticity?

Yes. Regular stretching, strengthening and activities such as walking, cycling or aquatic therapy can reduce stiffness and improve function. A physical therapist can design a safe program. Exercise works best combined with medicines or injections when needed.