Whether the newly modified rhizotomy protocol is applicable to guide single-level approach SDR to treat spastic quadriplegia and diplegia in pediatric patients with cerebral palsy?

Abstract

Purpose: Our aim was to test whether the newly modified rhizotomy protocol which could be effectively used to guide single-level approach selective dorsal rhizotomy (SL-SDR) to treat spastic hemiplegic cases by mainly releasing those spastic muscles (target muscles) marked pre-operatively in their lower limbs was still applicable in spastic quadriplegic or diplegic cerebral palsy (CP) cases in pediatric population.

Methods: In the current study, we retrospectively conducted a cohort review of cases younger than 14 years of age diagnosed with spastic quadriplegic or diplegic CP who undergone our modified protocol-guided SL-SDR in the Department of Neurosurgery, Children's Hospital of Shanghai since July 2016 to November 2017 with at least 12 months post-op intensive rehabilitation program (pre-op GMFCS level-based). Clinical data including demographics, intra-operative EMG responses interpretation, and relevant assessment of included cases were taken from the database. Inclusion and exclusion criteria were set for the selection of patients in the current study. Muscle tone (modified Ashworth scale) and strength of those spastic muscles (muscle strength grading scale), range of motion (ROM) of those joints involved, the level of Gross Motor Function Classification System (GMFCS), and Gross Motor Function Measure 66 items (GMFM-66) score of those cases were our focus.

Results: A total of 86 eligible cases were included in our study (62 boys). Among these patients, 61.6% were quadriplegic. Pre-operatively, almost 2/3 of our cases were with GMFCS levels II and III. Mean age at the time of surgery in these cases was 6.2 (3.5-12) years. Pre-op assessment marked 582 target muscles in these patients. Numbers of nerve rootlets tested during SDR procedure were between 52 and 84 across our cases, with a mean of 66.5 ± 6.7/case. Among those tested (5721 in 86 cases), 47.9% (2740) were identified as lower limb-related sensory rootlets. Our protocol successfully differentiated sensory rootlets which were considered to be associated with spasticity of target muscles across all our 86 cases (ranged from 3 to 21). Based on our protocol, 871 dorsal nerve rootlets were sectioned 50%, and 78 were cut 75%. Muscle tone of those target muscles reduced significantly right after SL-SDR procedure (3 weeks post- vs. pre-op, 1.7 ± 0.5 vs. 2.6 ± 0.7). After an intensive rehabilitation program for 19.9 ± 6.0 months, muscle tone continued to decrease to 1.4 ± 0.5. With the reduction of muscle tone, strength of those target muscles in our cases improved dramatically with statistical significance achieved (3.9 ± 1.0 at the time of last follow-up vs. 3.3 ± 0.8 pre-op), and as well as ROM. Increase in GMFCS level and GMFM-66 score was observed at the time of last follow-up with a mean of 0.4 ± 0.6 and 6.1 ± 3.2, respectively, when compared with that at pre-op. In 81 cases with their pre-op GMFCS levels II to V, 27 (33.3%) presented improvement with regard to GMFCS level upgrade, among which 4 (4.9%) even upgraded over 2 levels. Better results with regard to upgrading in level of GMFCS were observed in cases with pre-op levels II and III when compared with those with levels IV and V (24/57 vs. 3/24). Upgrading percentage in cases younger than 6 years at surgery was significantly greater than in those older (23/56 vs. 4/25). Cases with their pre-op GMFM-66 score ≥ 50 had greater score increase of GMFM-66 when compared with those less (7.1 ± 3.4 vs. 5.1 ± 2.8). In the meanwhile, better score improvement was revealed in cases when SDR performed at younger age (6.9 ± 3.3 in case ≤ 6 years vs. 4.7 ± 2.7 in case > 6 years). No permanent surgery-related complications were recorded in the current study.

Conclusion: SL-SDR when guided by our newly modified rhizotomy protocol was still feasible to treat pediatric CP cases with spastic quadriplegia and diplegia. Cases in this condition could benefit from such a procedure when followed by our intensive rehabilitation program with regard to their motor function.

Keywords: Dorsal rhizotomy; Intra-operative neuroelectrophysiology; Outcome; Rootlet selection; Spastic cerebral palsy.

Fig. 1

Scheme of our modified rhizotomy protocol

Fig. 2

Example of EMG response interpretation. a, Single pulse stimulation elicited EMG responses in Lt. peroneus longus which was not the “target muscle”, the rootlet was left spared; b, EMG responses elicited in Rt. hip adductor which was the “target muscle”, but abnormal EMG responses were not seen on the Lt. side when train stimulation was given, the rootlet was cut 50%; c, EMG responses mainly seen in Lt. gastrocnemius medialis which was the “target muscle” when single pulse stimulation was given, but train stimulation did not elicit abnormal EMG responses on the Rt. side, the rootlet was cut 50%; d, Triggered EMG responses observed in Rt. gastrocnemius medialis which was the “target muscle”, train stimulation did evoke abnormal EMG responses on the Lt. side (mainly the lateral gastrocnemius), the rootlet was cut 75%

Fig. 3

Framework of pre-op GMFCS level–based post-op rehabilitation program

Fig. 4

Association between outcomes and pre-op status in our cases. a Better results were observed in cases with pro-op GMFCS levels II and III; b Cases younger than 6 years had more chance to upgrade (81 cases with their pre-op GMFCS levels II–V); c Score increased more in cases with pre-op GMFM-66 ≥ 50 than those with score below; d Cases younger than 6 years improved more with regard to score increase of GMFM-66 after SDR. Number sign indicates statistically significant difference obtained with p < 0.05. Asterisk indicates statistically significant difference obtained with p < 0.01

Fig. 5

EMG responses obtained in one of our cases with pre-op GMFCS level IV, muscle tone of grade 2 in his Lt. rectus femoris. EMG responses were observed mainly in Lt. hip adductor (one of the target muscles in this case), which met our rhizotomy criteria. The rootlet was cut based on our protocol. In the meanwhile, the EMG responses were seen in Lt. rectus femoris as well. Its muscle tone decreased to grade 1.5 right after the surgery