Objective

Sacral neuromodulation is usually used to treat non-obstructive urinary retention when other forms of treatment have failed. An improvement greater than 50% in urinary symptoms after 40 months of follow-up has been shown:

– moreover, it also has few complications: infections, technical failures, discomfort;

– we report a case of dystonia of the lower limb, appeared after sacral neuromodulation implantation.

Observations

MMP is a 16-year-old boy with early puberty as noteworthy medical history. It began in 2012, with dysuria and a loss of urinary feeling (not improved by antibiotics and anticholinergics), after a viral diarrhea episode with abdominal pain treated with morphine. In 2013, he had an acute painless urinary retention after a viral infection and had a bladder catheter for 3 weeks, then a neuromodulation of the 3rd sacral nerve was implanted with disappearance of the urinary symptoms. However, a few months later, a dystonia of the right lower limb appeared, with a shaking limb at knee flexion, a stiff-legged gait and claw toes. The cerebral and spine MRI, the lumbar puncture were normal. When the sacral neuromodulation was stopped, the dystonia declined, but he had several urinary retentions and used self-catheterizations with difficulties and pain. In our hospital (March 2016), neuromodulation was on, with no more effectiveness on the urinary symptoms, but the dystonia and claw toes were still there. When neuromodulation was stopped, claw toes disappeared. We also did a motor branch block of the rectus femoris and after 30 minutes, the knee flexion was nearly complete without any dystonia, and the gait was normal.

Discussion/Conclusion

This dystonia of the lower limb was probably due to the sacral neuromodulation because it appeared when it was on, and had intensity correlated to the intensity of the stimulation. However, it may have a psychological part to this process because such side effect has never been described before and the motor block was very quickly effective.