Objective: To report the short and long term outcome of bilateral PPN DBS.

Background: Deep brain stimulation (DBS) of peducolopontin nucleus (PPN) has been proposed to reduce freezing of gait (FOG) and falls in advanced Parkinson’s disease (PD).

Method: PPN-GAB-PARK is a monocentric prospective pilot study that has been conducted in Nice University hospital in 2009 to study PPN-DBS in advanced PD patients with Gait And Balance (GAB) dysfunction. The primary objective was to determine the optimal stimulation parameters, secondary endpoints to evaluate efficacy and tolerance of PPN-DBS. After an open label optimisation period, efficacy of DBS was tested in double-blind conditions. Patients were then followed up to ten years. In this poster we report the short term outcome in 3 patients and the long term outcome in one patient.

Results: Three female patients with PD and severe axial symptoms aged 68 to 69 received bilateral PPN-DBS. All patients were still able to walk. During the optimisation period, the first patient showed improvement of FOG with best results for 70 Hz stimulation and 60 microseconds. For all patients, amplitudes were limited to 1,5 to 1,8 V for monopolar stimulation and 2,5V for bipolar stimulation due to oscillopsia. Overall, stimulation was well tolerated. The other 2 patients did not show significant benefit of DBS on gait and falls. Double-blind evaluations of unilateral versus bilateral versus off stimulation did not show benefit of DBS on gait and balance evaluations. Quality of life remained unchanged. 17 months after PPN-DBS implantation, the first patient complained about worsening of FOG. DBS was stopped, and within 24 hours she showed acute worsening of FOG with total incapacity to walk. When DBS was switched on, she could walk again within one day. At three years of PPN-DBS she was wheelchair bound. Nine years after PPN-DBS, she was not longer able to stand and DBS was switched « off » without consequence.

Conclusion: According to reports in the literature, few patients seem to benefit from PPN-DBS with marked improvement of FOG in an open label condition. In our study, double blind evaluations were negative. This might be due to placebo effect, the difficulty to reproduce FOG in a laboratory condition and due to too short wash-out of stimulation. Long-term outcome is disappointing, probably as a consequence of disease worsening.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/ppn-gab-park-short-time-outcome-and-long-term-follow-up-in-ppn-dbs/