How is spasticity treated, and does botulinum toxin help?

What is spasticity?

After a stroke, spinal cord injury, brain injury, multiple sclerosis or cerebral palsy, the nerve signals that normally keep muscle tone in balance are disrupted. Some muscles become overactive and resist being stretched, especially when moved quickly. This is spasticity. It often affects the muscles that bend the elbow, wrist and fingers and the muscles that straighten the knee and point the foot.

Spasticity can come with spasms, where a leg suddenly kicks or bends, and with clonus, a rhythmic jerking of the ankle. Over time, muscles held in a shortened position can lose length and the joint may become fixed, which is called a contracture. Preventing that is one of the main aims of treatment.

Does spasticity always need treatment?

No. Some stiffness can be useful, for example helping a weak leg support weight when standing. Treatment is aimed at problems the stiffness causes, not at the stiffness itself. Typical reasons to treat are pain, difficulty washing or dressing, a hand that is clenched so tightly that the skin breaks down, a foot that turns inwards when walking, disturbed sleep from spasms, or early loss of joint range.

Setting clear goals before treatment, such as being able to open the hand for cleaning or wearing a splint comfortably, makes it possible to judge whether a treatment worked. Guidance on botulinum toxin treatment emphasises agreeing these goals in advance 1.

What can make spasticity suddenly worse?

Anything that sends extra signals up the nervous system can increase spasticity: a urinary tract infection, constipation, an ingrown toenail, a pressure sore, tight clothing, pain or anxiety. A sudden increase in stiffness should prompt a search for such a trigger before treatment is increased.

Treating the trigger often brings stiffness back to its previous level. This is particularly important in people who cannot easily report pain, such as those with communication difficulties after a stroke or brain injury.

Which physical treatments help?

Regular stretching, careful positioning in bed and in the chair, standing practice with support, and active exercise are the foundation. Splints and serial casting, where a series of plaster casts gradually lengthens a tight muscle, can maintain or improve range of movement. Active practice of useful movements helps the person use any reduction in stiffness.

Stroke rehabilitation guidelines recommend that treatment of spasticity is combined with a therapy programme rather than given on its own 2. Without practice and stretching, the benefit of medicines or injections is often short-lived.

How do tablets and botulinum toxin compare?

Tablets such as baclofen and tizanidine act on the whole nervous system and are used for widespread spasticity and spasms. In multiple sclerosis, UK guidance suggests baclofen or gabapentin as first choices 3. The main drawbacks are drowsiness, weakness and dizziness, so doses are increased slowly and reviewed.

Botulinum toxin is injected directly into selected overactive muscles, often with ultrasound or electrical stimulation to find the right spot. It reduces the signal from nerve to muscle, and the effect typically builds over the first couple of weeks and wears off over about three months, when injections can be repeated if the goals were met 1. Because it is targeted, it avoids most whole-body side effects, but it also weakens the injected muscle, so dosing needs care.

What if spasticity is severe or does not respond?

For severe spasticity affecting both legs, often after spinal cord injury or in advanced multiple sclerosis, baclofen can be delivered directly into the fluid around the spinal cord through a small pump placed under the skin. This allows much lower doses than tablets.

When a muscle has become permanently shortened, surgery to lengthen or release tendons may be considered, particularly for the foot and ankle or the hand. These decisions are made by a specialist team after a trial of less invasive treatment, and rehabilitation follows any procedure.

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