Examples

How It Works

Injectable medicines, like other antispasmodic medicines, relax muscles and reduce muscle spasticity. They act only on the nerves and muscles surrounding the area where they are injected. Doctors give the injections directly into the affected muscle.

Why It Is Used

Injectable medicines help relax tight muscles in the legs or arms affected by cerebral palsy. Injectable medicines may be used:

• When muscle tightness interferes with daily activities, especially walking.
• To increase the effectiveness of physical therapy.
• To determine whether nerve surgery is appropriate. Doctors often can predict the potential success of surgery by how nerves and muscles react to the injected medicine.

How Well It Works

These medicines may improve the effectiveness of physical therapy or delay the need for surgery on the muscles, tendons, and joints. If injectable medicines successfully relax the nerves and muscles, surgical cutting of the nerves may also be helpful. But the overall usefulness and safety of these medicines as treatment for cerebral palsy need more research.

Botulinum toxin (Botox) has been shown to improve the two main factors of leg spasticity: walking foot pattern and ankle position.¹ But more research is needed on its short-term and long-term effects on leg spasticity in children with cerebral palsy.²

In most cases, an injectable treatment relaxes tight muscles for a limited time. Alcohol and phenol start to work right away and last about 3 to 6 months. Botox usually begins to take effect within 3 days after injection, although the full effects are often not evident for 1 to 2 weeks. The effects of Botox last for about 4 to 8 months.

Side Effects

The side effects of alcohol and phenol injections include:³

• Pain as the injection is given.
• Muscle stiffness (rarely can become permanent).
• Loss of feeling in area, sometimes lasting for several weeks.

The side effects of Botox include:

• Pain at the site of the injection.
• Rash.
• Flu-like symptoms, such as nausea.

In rare cases, Botox use is related to severe side effects, such as trouble breathing or swallowing. They can occur as early as one day and as late as several weeks after treatment. Call your doctor right away if you or your child has muscle weakness, trouble breathing, or unexpected or increased trouble swallowing or talking.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Using injectable medicines helps loosen tight muscles and joints and may prevent the need for braces, casts, or splints. If injectable medicines relax nerves and muscles, surgery may be postponed or canceled.

Drowsiness, often caused by medicines taken by mouth to relax tight muscles and reduce muscle spasms, is not a problem with injectable medicines.

Using botulinum toxins to treat severe arm and leg muscle spasms (limb spasticity) in children or adults is an unlabeled use. More research is needed about the safety, dosage, and success of botulinum toxins in treating people who have cerebral palsy and for use in any condition in children younger than age 12.

Both alcohol and phenol can be injected directly into the nerve that supplies a muscle. This is called a nerve block or a motor point block.

Botulinum toxin is easier to give and causes less muscle pain than the other injectable medicines. But botulinum toxin costs more than alcohol or phenol.

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