1. Aetna considers neurosurgical procedures medically necessary for the management of members with refractory spasticity when all of the following selection criteria are met:

   1. The member has tried and failed non-surgical, medical management for spasticity including baclofen or other muscle relaxants; and
   2. The member has good intrinsic lower extremity motor power, but is limited in ambulation by spasticity; and
   3. The member has the functional capacity and motivation to participate in post-operative rehabilitation.

   Aetna considers the following procedures medically necessary for the management of members with spasticity:

   1. Selective posterior (dorsal) rhizotomy*
   2. Percutaneous radiofrequency (or thermal) rhizotomy
   3. Peripheral neurotomy
   4. Microsurgical dorsal root entry zone lesion (DREZotomy)
   5. Longitudinal myelotomy.

   Members 2 to 6 years of age are optimal candidates for selective posterior rhizotomy.

   * Based on a review of the medical literature, Aetna considers selective posterior rhizotomy experimental and investigational when the member has any of the following contraindications:

   1. Concomitant dystonia or rigidity; or
   2. Severe damage to basal ganglia; or
   3. Severe fixed joint deformities or scoliosis; or
   4. Progressive neurological disorders, choreoathetosis, or cerebellar ataxia; or
   5. Profound weakness in lower extremity muscles such that the spasticity actually serves to assist in standing.

2. Aetna considers selective posterior rhizotomy experimental and investigational for the treatment of spasticity in children with hemiplegic cerebral palsy because these children are unlikely to benefit from this procedure.

3. Aetna considers spinal cord stimulation (dorsal column stimulator) or neurectomy experimental and investigational for the treatment of spasticity because the effectiveness of these approaches has not been established.

4. Aetna considers magnetic stimulation experimental and investigational for the treatment of spasticity due to multiple sclerosis and other causes because the effectiveness of these approaches has not been established.

See also CPB 113 - Botulinum Toxin, CPB 161 - Infusion Pumps, and CPB 677 - Functional Electrical Stimulation and Neuromuscular Electrical Stimulation.

Cerebral palsy (CP) refers to a wide variety of non-progressive brain disorders resulting from insults to the central nervous system during the perinatal period.  Traditionally, the adverse effects of spasticity such as contractures and bony deformities in patients with CP are managed by means of drug therapy, phenol injections, spinal blocks, physical therapy, bracing, and orthopedic surgeries.  In the last three decades, selective posterior rhizotomy (SPR) has been used in the management of these patients for reduction of spasticity which may result in an improvement of their active functional mobility.  The use of total posterior rhizotomies of lumbar and sacral nerve roots in reducing lower limb spasticity commenced approximately 80 years ago.  However, the lack of functional improvement despite a reduction in spasticity as well as the adverse side effects such as stasis ulceration, sensory ataxia, and hypesthesia (sensory loss) stimulated the development of partial rhizotomy and SPR is the most sophisticated version of the partial rhizotomy.  Currently, SPR is increasing being used for the treatment of lower extremity spasticity in patients with CP.

The rationale for SPR is that intraoperative electrostimulation of spinal nerve rootlets in conjunction with electromyographic (EMG) monitoring and direct observation of muscle activity in the lower extremity allow for the identification of afferent posterior rootlets that terminate on relatively uninhibited alpha motoneurones.  Direct observation allows for identification of the diffusion of contraction to other muscle groups.  If these uninhibited rootlets are severed, spasticity can be reduced without the unacceptable side effects.  This technique employs microsurgical dissection of nerve rootlets from the level of L2 to S1 or S2 (if there is a spastic toe flexion).  Individual sensory rootlets (usually 3 to 8 comprising the posterior roots from L2 to S1) are isolated and electrically stimulated.  Those rootlets which produce an abnormal response are cut, while those generating a normal response are preserved.  Responses which are considered to be abnormal include (i) clonus, (ii) contraction of ipsilateral muscles not normally innervated by that nerve, (iii) contralateral muscle contraction, (iv) clinical or EMG contraction that continues after the cessation of stimulation, and (v) an EMG crescendo pattern during the stimulus.  If no abnormal responses are observed, the 30 to 60% of the rootlets giving the strongest tetanic contraction are severed.  In general, no more than 75% of the sensory rootlets are sectioned.

There is sufficient evidence that selective posterior rhizotomy is safe and effective for the management of children with cerebral palsy.  Studies have consistently shown that selective posterior rhizotomy can reduce spasticity and improve motor function.  Additionally, if performed during early childhood, it may prevent the development of muscle contractures and orthopedic deformities.  On the other hand, due to the minimal degree of their impairment, children with hemiplegic cerebral palsy are unlikely to benefit from this procedure.

In a review published in the New England Journal of Medicine, Park and Owen (2002) concluded that SPR can reduce spasticity and improve motor function, and if the operation is performed during early childhood, it may prevent the development of muscle contractures and orthopedic deformities.  Additionally, a Diagnostic and Therapeutic Technology Assessment of SPR published by the American Medical Association stated that in selected patients who have ambulatory potential, this procedure can reduce spasticity and facilitate walking and other movement (Brown, 1990).

An assessment of SPR by the National Institute for Health and Clinical Excellence (2006) concluded that current evidence on the safety of SPR for spasticity in cerebral palsy "appears adequate; however, there is evidence of only limited efficacy." The assessment cites the results of a meta-analysis of three randomized controlled trials (McLaughlin, et al., 2002) comparing physiotherapy and SPR with physiotherapy alone, which found that, compared with physiotherapy alone, gross motor function improved by an additional 4% with physiotherapy and SPR (8% and 4% improvements, respectively; p = 0.008). The follow-up period in the primary studies was 9–12 months. Specialist advisors to NICE commented that there is some controversy about the role of SPR in relation to other management options for spasticity in cerebral palsy. They also commented that a reduction in spasticity does not always improve motor function.  The NICE assessment noted that adverse events seen clinical studies of SPR included bladder and bowel disturbances, severe postoperative pain, and dysthesia.  The specialisty advisors to NICE also noted among adverse events limb weakness, joint subluxation, progressive scoliosis or kyphosis, and sensory disturbance. Theoretical adverse events included paralysis, dividing the wrong nerve rootlets, hypotonicity, weight gain and death.

Appropriate candidates for SPRs should have tried and failed other more conservative types of medical management for spasticity including baclofen or other muscle relaxants. In addition, candidates should have good intrinsic lower extremity motor power, but are limited in ambulation by spasticity. It is also important that candidates  have capacity and motivation to participate in postoperative rehabilitation. Children 2 to 6 years of age are optimal candidates for this procedure.

Patients with one or more of the following condition(s) are generally not considered candidates for selective posterior rhizotomy: concomitant dystonia or rigidity; severe damage to basal ganglia; severe fixed joint deformities or scoliosis; progressive neurological disorders, choreo-athetosis, or cerebellar ataxia; or p rofound weakness in lower extremity muscles, and spasticity serves to assist in standing.

Valle et al (2007) examined the use of low and high frequency repetitive transcranial magnetic stimulation (TMS) for the treatment of spasticity. A total of 17 subjects (8 males, 9 females; mean age of 9 years 1month) with CP and spastic quadriplegia were randomized to receive sham, active 1-Hz, or active 5-Hz repetitive TMS of the primary motor cortex. Stimulation was applied for 5 consecutive days (90 % of motor threshold). The results showed that there was a significant reduction of spasticity after 5-Hz, but not sham or 1-Hz, stimulation as indexed by the degree of passive movement; however this was not evident when using the Ashworth scale, although a trend for improvement was seen for elbow movement. The safety evaluation showed that stimulation with either 1-Hz or 5-Hz did not result in any adverse events as compared with sham stimulation. The authors stated that results of this trial provide initial evidence to support further trials exploring the use of cortical stimulation in the treatment of spasticity.