Im having a nevro high frequency scs fitted.stage 1 this week. what are the short and long term risks and possible complications?

Trials are very low : The biggest risk is that it may not work. If that happens you might need a trial of a different waveform in a generator like Spectra from Boston Scientific. Any trial involving your spine could create a spinal headache if there is Spinal fluid leak. Very rarely nerve roots can be irritated. Infection is a rare risk from a trial.