Comment on the paper by Doshi et al. Entitled 'bilateral pedunculopontine nucleus stimulation for progressive supranuclear palsy'.

The pedunculopontine nucleus (PPN) is a potential target for gait disorders. We report 4 cases of bilateral PPN stimulation in progressive supranuclear palsy (PSP) patients with short-term (6 months) and long-term (18 months) follow-ups. Patients with PSP who had gait disturbances, but were able to walk with or without assistance, were selected. The patients' median age was 64 years and the disease duration 3 years. Bilateral PPN deep brain stimulation (DBS) was performed. The pacemaker was programmed using a bipolar mode and lower frequencies (20-45 Hz). The PSP rating scores (PSPRS) and their gait subscores (No. 25, 26, 27 and 28) along with PSP staging scores were used as primary end points. The total Unified Parkinson's Disease Rating Scale (UPDRS), UPDRS III and the 39-item Parkinson's Disease Questionnaire were considered as secondary end points. Video recordings of the gaits were performed before surgery and at the 6- and 18-month follow-ups. These were retrospectively reviewed by a blinded neurologist for the primary end points. At the 6- and 18-month follow-ups, the median change in PSPRS was from 33 (baseline) to 37.5 and 47, respectively. Similarly, the PSP staging changed from 3 to 2.5 and 3.5, item 25 from 1.5 to 2 and 3.5, item 26 from 2.5 to 2 and 3.5, item 27 from 3.5 to 3 and 3.5 and item 28 from 1.5 to 1.5 and 3. Two patients in the study with the PSP-parkinsonism phenotype experienced improvement in their gait until the last follow-up. Bilateral PPN DBS can be safely performed in PSP patients despite mid-brain atrophy.