Upper-extremity spasticity and functionality after selective dorsal rhizotomy for cerebral palsy: a systematic review

Lumbosacral selective dorsal rhizotomy is a neurosurgical treatment option to reduce spasticity in the lower extremities in children with cerebral palsy. Surprisingly, concomitant improvement of spasticity in the upper extremities and functionality of the hands has been sporadically reported postoperatively. In this systematic review, the authors aimed to quantify the postoperative improvement in upper-extremity spasticity and functionality, identify predictors, and discuss underlying mechanisms.

The authors searched the MEDLINE and Embase databases for studies reporting upper-extremity outcomes in cerebral palsy patients after selective dorsal rhizotomy that reported one or more of the following clinical scales: the Ashworth Scale (AS), the Modified AS (MAS), the fine motor skills domain of the Peabody Developmental Motor Scales (PDMS), the Quality of Upper Extremity Skills Test (QUEST), the self-care domain of the Functional Independence Measure for Children (WeeFIM), or the self-care domain of the Pediatric Evaluation of Disability Inventory (PEDI). The authors arbitrarily divided postoperative follow-up into short-term (< 6 months), medium-term (6-24 months), and long-term (> 24 months) follow-up. A 1-point change in MAS score has been reported as clinically significant. To assess bias, the Cochrane Collaboration's tool and ROBINS-I tool were used.

The authors included 24 articles describing 752 patients. Spasticity reduction of the upper extremities ranged from 0.30 to 0.55 (AS) and between 0 and 2.9 (MAS) at medium-term follow-up. This large variability may partially be attributed to a floor effect since patients with normal upper-extremity function would not be expected to have further improvement. QUEST improvement ranged from 2.7% to 4.5% at medium-term follow-up. The mean improvements in functional skills of the self-care domain of the PEDI were 4.3 at short-term and 7 at medium-term follow-ups and ranged from 10.8 to 34.7 at long-term follow-up. There are insufficient data to draw meaningful conclusions regarding the PDMS fine motor skills and the WeeFIM self-care domains.

The literature suggests that a pronounced postoperative spasticity reduction in the lower extremities and a moderately severe preoperative upper-extremity spasticity may positively predict postoperative reduction in upper-extremity spasticity. There are at least 5 hypotheses that may explain the postoperative reduction in upper-extremity spasticity and functionality: 1) a somatosensory cortex reorganization favoring the hand region over the leg region, 2) a decrease in abnormal electrical transmission throughout the spinal cord, 3) an indirect result of improved posture due to improved truncal and leg stability, 4) an indirect consequence of occupational/physical therapy intensification, and 5) a maturation effect. However, all remain unproven to date.