Transcutaneous ultrasound level check for selective dorsal rhizotomy

Single-level selective dorsal rhizotomy (SDR) surgery requires an intra-operative level check to identify the L1 vertebral level or the conus medullaris. Typically, this requires a pre-operative or intra-operative x-ray. We present our experience using initial transcutaneous ultrasound as an alternative to x-ray level check.

A prospective SDR database was used to identify patients. The operation notes were reviewed to identify the level check method and any complications or wrong-level surgery.

Data are reported for the first 160 SDR surgeries performed within our centre, mean age 6.47 years (range 2.5-19 years). The first 11 patients had combined x-ray and transcutaneous ultrasound for pre-incision level check. This allowed the neurosurgeon to assess the accuracy and feasibility of using transcutaneous ultrasound instead of x-ray. The subsequent 149 patients had ultrasound alone for transcutaneous pre-incision level check. An intra-operative ultrasound level check was performed for all patients following skin incision and dissection down to the spinal lamina. In this way, the conus level was confirmed before dural opening. For all patients at all ages, the combination of initial transcutaneous ultrasound followed by intra-operative ultrasound allowed accurate identification of the conus. There were no instances of wrong-level surgery. Learning points are presented within this paper.

Combined use of transcutaneous ultrasound followed by intra-operative ultrasound can allow accurate identification of the conus, saving radiation exposure and potentially improving theatre efficiency. Appropriate training and experience are required for any neurosurgeon using these techniques.