Orthopedic procedures

Orthopedic procedures may be very helpful at fixing particular mechanical impairments associated with spasticity. Tendon lengthening procedures, rotation of bone segments, or cutting tendons or muscles may reduce the mechanical effects of severe contraction and lead to significantly improved performance.

Orthopedic procedures may be helpful for children with spasticity; however, they are rarely beneficial for children with dystonia.

As with all treatments for spasticity, it is important to assess whether the spasticity is the cause of the child's functional problems or whether it is in fact helping to compensate for muscle weakness. Gait analysis may be particularly helpful in determining whether an orthopedic procedure is likely to be helpful or worsen the child's function. Before or as an adjunct to surgery, many orthopedists attempt serial casting. During casting, sequences of casts are applied to progressively lengthen a particular muscle by providing increasing stretch.

If the primary problem is dystonia or another movement disorder, surgery and casting are only rarely benefical.

Dorsal Rhizotomy

Because spasticity is probably due to increased activity in the stretch reflex, dorsal rhizotomy was developed as a procedure to cut the sensory nerve fibers from the muscles where they enter the spinal cord. This procedure was performed to lessen the "loop" from sensory fibers to excessive muscle activity. Experienced surgeons have reported excellent results with this procedure in some children; it is important to carefully select appropriate candidates for this surgery.

In particular, rhizotomy is not helpful for children with dystonia or parkinsonian rigidity. Dystonia, rigidity, and spasticity must be correctly diagnosed to determine which children are likely to benefit from this procedure.

Deep Brain Lesion

There is a long history of making lesions in the thalamus and basal ganglia as a treatment for tremor, parkinsonism, chorea, and dystonia. Modern, advanced neurosurgical techniques with precise localization of the lesions have led to a significant improvement in the efficacy of these procedures.

The results of deep brain lesions are often remarkable, with almost complete resolution of symptoms.

• Tremor may respond to lesions in the thalamus
• Dystonia may respond to lesions in the thalamus or sensorimotor region of the internal globus pallidus
• Parkinsonism may respond to lesions in the subthalamic nucleus or internal globus pallidus

In some cases, there has been almost complete resolution of symptoms.

In children, this surgery has been used to treat severe generalized dystonia. Unfortunately, many children do not achieve benefit with these procedures or are not candidates for the procedures due to medical issues or concern over side effects. When used to treat dystonia, the benefits of a lesion in the globus pallidus may not be evident for several months.

Children with dystonia due to an inherited genetic cause seem to be more likely to have good results than children with dystonia due to a brain injury. Results with treatment of chorea have been disappointing; however, continued efforts are underway. Currently, the success with deep brain stimulation (DBS) has led to a decrease in the use of lesions; there are still situations in which a lesion is more appropriate.

Deep Brain Stimulation (DBS)

Deep brain stimulation (DBS) is a modern technique that is based on the results of deep brain lesions. In DBS, a pacemaker is implanted in the chest wall; a wire from the pacemaker connects to a terminal within the basal ganglia. The procedure to implant the stimulator is lengthy, since the precise location must be found, using a combination of MRI and electrical measurement of basal ganglia activity. Older children may remain awake during most of the procedure, but younger children will require sedation or anesthesia. When the pacemaker is turned on at a rapid rate, it may block activity in the region of the basal ganglia near the end of the wire. In dystonia, the effect of treatment may not be evident until after several months, but some children have shown remarkable improvement.

The effects of DBS are thus similar to those of a deep brain lesion. The advantages of DBS are that the strength and frequency of the stimulation may be adjusted and the location may be adjusted since there are usually four possible contacts on the wire that may be alternately selected (using an external magnetic programmer). In addition, should the effects of DBS not be as desired, the wire and pacemaker may be removed.

The disadvantages of DBS are the need for occasional reprogramming of the pacemaker; the need for a surgical procedure to replace the batteries every few years; and the potential for infection at the pacemaker or the point where the wire enters the skull. DBS must be used with caution in children; it is difficult to predict who will benefit. The long-term side effects of DBS are not yet known. Nevertheless, this is a promising technique and active research programs continue throughout the world.

Baclofen Pump

Baclofen acts by stimulating GABA type B receptors in the spinal cord and is often helpful in the treatment of spasticity. In order to avoid the side effects of high oral doses of baclofen, the medicine may be continuously administered by implanting pump mechanism in the abdomen. The pump, containing a small reservoir filled with baclofen, is directly connected by tubing into the lower part of the spine. Very small doses are given directly to the spinal cord. The pump is refilled by injecting directly through the skin into its reservoir. This technique is extremely effective for some children. If it is not effective, the pump and tubing may be removed without significant permanent effects.

Unfortunately, there is a high rate of complications. These include infections as well as rapid and serious withdrawal reactions, if the medication in the reservoir is depleted.