What are Some Muscle Tone Management Options for Cerebral Palsy?

Oral Medication:

Medications are usually used as the first line of treatment to relax tight or overactive muscles. While easy to use and appropriate to consider for children who need only mild reduction in muscle tone or for children with widespread spasticity, the use of oral medication for the management of abnormal tone has been somewhat disappointing in that impacts are often not ideal. For spasticity, dantrolene, baclofen, diazepam and tizanidine have been used. Other medications such as Artane have been used for dystonia and there are some preliminary reports of success with modafinil. There has been very limited success in using medications to treat dyskinesias, including dystonia, athetosis and hemiballismus.

Botulinum Toxin:

Botulinum toxin A therapy (Botox, Allergan, Corporation, Irvine, CA) is FDA approved for strabismus, hemifacial spasm, cervical dystonia, severe primary axillary hyperhydrosis and for cosmesis (wrinkles). Although approved throughout the world for treatment of spasticity in children with cerebral palsy, it is not approved by the FDA for this use in the United States. It has been used as an off label drug for this indication since the late 1980s. There are other preparations on the market including Dysport and Myobloc, which is Botulinum Toxin B and acts through a different mechanism than Botulinum toxin A.

Extensive literature exists to show that botox is effective for children and adults who have spasticity and/or dystonia. A combination of muscle weakening and strengthening of the antagonist muscle may minimize or prevent contracture development with bone growth. This type of intervention is used when a limited number of muscles are causing deformities such as spasticity of the gastrocnemius muscle causing a child to walk on their toes or hamstring spasticity being responsible for a crouch gait. Recovery of the muscle tone occurs because of the sprouting of the nerve terminals, a process which peaks at approximately 60 days.

Botox use in the upper extremity spasticity has been shown to improve cosmesis and function although the evidence is not conclusive.

Selective Dorsal Rhizotomy:

Selective dorsal rhizotomy (SDR) involves the cutting of approximately 50% of the dorsal sensory roots from the spinal cord, thereby decreasing the muscle tone in the lower extremities. As a result of the decrease in the muscle tone, discomfort or pain may be alleviated and sitting posture and/or gait may improve. The ideal candidate is a child who has normal or near normal strength in the lower extremities, has good trunk strength, who has not developed fixed contractures and whose alteration of tone will lead to the desired improvements in function. Combining the data from three separate studies that compared physical therapy with SDR revealed a direct relationship between the percentage of dorsal root tissue transected and functional improvement. SDR+PT are efficacious in reducing spasticity in children with spastic diplegia and have a small positive effect on gross motor function.

Intrathecal Baclofen Infusion (ITB):

Baclofen, a GABA agonist, administered intrathecally (next to the spinal cord) via an implanted pump (ITB) has been helpful to patients whose muscle tone is generalized and  interfering with function. As Baclofen does not cross the blood-brain barrier very effectively, large doses must be used orally to achieve success compared to administering baclofen intrathecally. Often, the patient on oral medication develops side effects such as sedation. These side effects are less common with ITB since small doses of medication are delivered directly at the site of action. Patients who have generalized tone interfering with activities such as hygiene, transferring from a chair to a bed or just maintaining a safe upright position are excellent candidates for ITB treatment. Although the complication rate, including infection and baclofen withdrawal symptoms (occurring as a result of catheter breakage or leakage), is about 50%, parent satisfaction is extremely high with this type of intervention. Once the complication is corrected, over 90% of the parents/caretakers/patients request that the pump to be reimplanted or the catheter be replaced. 

Certain patients are poor candidates for ITB treatment and may be affected aversely. This includes patients with significant underlying muscle weakness impacting their gait. SDR and/or ITB in these patients are contraindicated as the procedure will cause additional muscle weakness, possibly causing an ambulatory patient to become non-ambulatory.

See What are the Surgical Options Manage Tone.

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Resources:

Dystonia Medical Research Foundation
www.dystonia-foundation.org

Metachromatic Leukodystrophy Foundation
www.mldfoundation.org

Pelizaeus-Merzbacher Disease Foundation
www.pmdfoundation.org