Grammatically, "a left L-5 ventral root to left S2–3" mean ...?

Grammatically, "a left L-5 ventral root to left S2–3" mean "a left L-5 ventral root to left S2–3 ventral root"?

Context:
An intradural somatic-to-autonomic anastomosis, or Xiao procedure, has been described to create a “skin-CNS-bladder” reflex that improves bladder and bowel function in patients with neurogenic bladder and bowel dysfunction. The authors present their experience with a 10-year-old boy with chronic neurogenic bladder and bowel dysfunction related to spinal cord injury who underwent the Xiao procedure. After undergoing a left L-5 ventral root to left S2–3 intradural anastomosis, the patient reported that his bladder and bowel dysfunction improved between 6 and 12 months. Two years after the procedure, however, he reported that there was no change in his bladder or bowel dysfunction as compared with his condition prior to the procedure. Frequent, systematic multidisciplinary evaluations produced conflicting data.

More:
http://thejns.org/doi/abs/10.3171/2013.4.PEDS12302