Has anybody had any similar experiences with Precedex?

16 y/o male | T2 to Sacral Fusion (To preserve respiratory fxn) with SEP and MEP

History:
Scoliosis
Duchenne Muscular Dystrophy
- confined to wheelchair in the last year
- PFTís okay
- Echo normal with LVEF 55%

Previous appendectomy in Mexico Ė No previous anesthesia record available.

Plan for TIVA due to MH Precautions.
- Nitrous: 0.5 MAC
- Propofol drip: 200 mcg/kg/min
- Sufentanil drip: 0.1 to 0.3 mcg/kg/hr
- Amicar drip (standard protocol for spine surgery)
- Precedex drip: 0.7 mcg/kg/hr

Baseline SSEP and MEPís taken at start of case. 4-5 hours into the case tech stated that she has had a steady decrease in MEPís and that she has had to increase stimulation. While searching for causes for the decrease, the tech wanted to blame the use of versed. Surgeon stated that it was probably not the versed as last dose was well over 3.5 hours ago and that most all patients get versed at the start of the case and he has never had that problem before. Surgeon mentioned that nitrous has been the culprit in the past. So I turned off the nitrous without a significant change in MEPís. The tech asked about the Precedex. I had not seen or heard a report of Precedex causing a decrease in MEPís. MDA and surgeon also have used Precedex for this type of case without a decrease in MEP. So, in effort to solve the problem, it was decided to stop Precedex to see if it was the culprit. Low and behold, the MEPís increased and the tech was able to turn down the amount of stimulation required to about the baseline settings.

Thanks in advance for your input/advice