Tune up and tone down: pediatric spasticity overview

By Elizabeth Moberg-Wolff, MD

A child with cerebral palsy reaches for a toy, but cannot open his hand. A teen with a brain injury tries to walk, but cannot untangle her legs. Both have spasticity – a functionally impairing movement disorder that now can be managed more effectively with a variety of treatment strategies.

Pediatric spasticity is an involuntary, velocity-dependent increase in muscle tone resulting in an imbalance of muscles and problems with muscle control. Its incidence has been increasing as children survive premature birth, stroke, spinal cord injury and traumatic brain injury.

Spasticity has many postulated causes, most revolving around altered afferent and efferent input to the alpha motor neuron in the spinal cord. A lag time may exist between injury and spasticity onset, and severity may wax and wane over time and vary by diagnosis. Spasticity also may be static (always present) or dynamic (increase with intentional movement) in nature.

Some causes are treatable – and a careful history differentiates the child who toe walks due to cerebral palsy from the child who toe walks due to a tethered spinal cord.

Treatable disorders that may cause sudden onset of pediatric spasticity include:

• Tethered spinal cord.
• Spinal cord tumor.
• Nerve impingement peripherally or entrally.
• Hydrocephalus.
• Intracranial, epidural or subdural bleeding.

Common spasticity patterns exist and recognizing them helps predict functional status and guides treatment decisions.

Typical cerebral palsy patterns include:

• Diplegic pattern of spasticity (scissoring, crouching and toe-walking).
• Quadriplegic pattern (diplegic patterning in addition to flexion of the elbow; internal rotation, pronation or adduction of the arms; flexion of the wrist and finger; and adduction of the thumb).
• Hemiplegic pattern (plantar flexion of the ankle; flexion of the knee; adduction of the hip; flexion, internal rotation, pronation and adduction of the arm; flexion of the wrist and finger; and adduction of the thumb).
• Equinovarus positioning of the foot is a common posture in the lower extremity. It can be a major limitation to standing transfers or gait as a child grows older. 

Careful assessment of the role spasticity plays in substituting for strength (for example, to facilitate transfers) is important in increasing rather than decreasing function. But while some spasticity may be advantageous, the negative long-term musculoskeletal affects of spasticity also must be considered. These may include:

• Orthopedic deformities such as hip dislocation, knee and ankle contractures or scoliosis.
• Pain from abnormal joint position and use.
• Skin breakdown secondary to positioning difficulties and shearing pressure.
• Poor weight gain secondary to high caloric expenditure.
• Sleep disturbance.
• Depression secondary to lack of functional independence.
• Caregiver back injury due to difficulty with transferring.

As life expectancies increase, the long-term sequelae of abnormal tone must be considered.

When spasticity suddenly increases, treatable factors must be addressed:  

• Infection (for example, otitis, urinary tract, pneumonia).
• Pressure sore.
• Noxious stimulus (for example, ingrown toenail, ill-fitting orthotics, occult fracture, malpositioning).
• Deep venous thrombosis.
• Bladder distention/bowel impaction.
• Colder temperature.
• Fatigue.
• Seizure activity.

It is important to consider a child's diagnosis, age and ability to function in many different environments (home, school, day care) when making treatment decisions. Options for treatment of movement disorders include:

• Physical, speech and occupational therapy.
• Splinting, casting, electric stimulation and positioning devices (wheelchairs, standers, walkers).
• Oral medications (baclofen, dantrium).
• Injectables (botulinum toxins and phenol).
• Orthopedic surgery.
• Selective dorsal rhizotomy.
• Intrathecal baclofen.
• Deep brain stimulation. 

Therapy intervention is the backbone of treatment as it augments most other interventions. Reduction of spasticity does not automatically improve selective motor control, sensory input, muscle strength or range of motion. These things often can be improved with therapy intervention.

Oral medications often reduce tone, but rarely are successful in treating spasticity completely. At higher doses, some children experience sedation, and few of the medications come in liquid form, making their use in children with gastrostomy tubes difficult. However, oral medications can be successful adjuvents to other therapies.

Injectable medications are temporary. They are used to stretch a muscle group that shortened during a growth spurt or allow a weak antagonist muscle time to strengthen. They can provide pre-operative guidance to a surgeon or post-operative protection. Most often, they "buy time" until surgical or other interventions are appropriate. Botulinum toxins are expensive, fairly short-lived and dosed based on weight. They are relatively easy to administer and are safe. Phenol is more technically difficult to inject, but is far less expensive, has a longer duration of action and often allows more muscle groups to be injected when used in combination with the botulinums. Often, small children are briefly sedated or anesthetized for the multiple injections needed.

Orthopedic surgery is a mainstay  of treatment, but its success increases when tone management precedes it, and when the child is at an age where a major growth spurt is not in progress. Tendon and muscle lengthenings and osteotomies are the most common interventions. 

Selective dorsal rhizotomy permanently alters spinal cord pathways by transection of spinal rootlets, which controls lower extremity tone. Only certain children benefit from the procedure, and a multidisciplinary approach is used in pre-operative selection and post-operative follow-up.

Intrathecal baclofen pumps reversibly alter spinal cord spasticity by bathing the rootlets of both the upper and lower extremities with medication. This drug delivery device is able to be adjusted to give a variety of medication doses to best improve a child's function.

Overall, it is important to realize that many factors go into diagnosing the cause of spasticity and determining the best treatment – including therapy support, the motivation and cognitive abilities of the child, the likely clinical course, the child and family's functional goals and the  available social and financial resources. Optimal treatment is a team effort, and as new interventions are developed, a coordinated treatment approach will be even more important.

Elizabeth Moberg-Wolff, MD, is program director of Tone Management and Mobility at Children's Hospital of Wisconsin. She also is an associate professor of Physical Medicine and Rehabilitation at the Medical College of Wisconsin.

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