GOALS:
Spasticity remains the main obstacle in the treatment of cerebral palsy (cerebral palsy). Single-level selective dorsal risotomy (SDR) is a minimally invasive intervention that reduces spasticity in individual patients. We provide a descriptive set of regulatory data that practitioners can use to manage a single-level SDR procedure, including (1) physiological thresholds used to separate the ventral section from dorsal roots; (2) characteristics of muscle reaction; (3) descriptions of abnormal physiological reactions; and (4) percentage of roots cut during surgery.

METHODS:
We studied the data of 38 patients with CP who underwent SDR. Dorsal and ventral roots were classified based on the amplitude of electromyographic (EMG) responses, the number of muscles involved and the characteristics of the abnormal reaction.

RESULTS:
Ventral roots activated more muscles at significantly lower stimulation thresholds and showed higher EMG responses than dorsal roots. Of the intersections, 64.72 ± 1.69% of each rhizome were crossed. Ventral and dorsal roots can be easily separated based on several key physiological characteristics, including response thresholds and the spread of muscle activation. It was noted that the threshold of approximately 0.4 mA can be used to dissociate the ventral and dorsal roots during surgery.

CONCLUSIONS:
These data illustrate the range of physiological abnormalities observed during SDR in patients with spastic CP. In particular, we encountered patients whose roots demonstrated aberrant response characteristics and demonstrated unusually low thresholds of the dorsal root or abnormally high thresholds of the ventral root. Practices should be ready to individualize their threshold criteria and individualize treatment for each patient.