Effect of bilateral subthalamic electrical stimulation in Parkinson's disease

BACKGROUND Bilateral high frequency subthalamic stimulation has been report ed to be effective in the treatment of Parkinson's disease and levodopa-ind uced dyskinesias. To analyze the results of this surgical procedure we crit ically reviewed 17 parkinsonian patients with advanced disease complicated by motor fluctuations and dyskinesias. METHODS Between January 1998 and June 1999 these 17 consecutive patients (a ge 48-68 years; illness duration 8-27 years) underwent bilateral stereotact ically guided implantation of electrodes into the subthalamic nucleus in th e Department of Neurosurgery of the Istituto Nazionale Neurologico "C. Best a." Parameters used for continuous high-frequency stimulation were: frequen cy 160 Hz, pulse width 90 mu sec, mean amplitude 2.05 +/-0.45 V. Parts II a nd III of the UPDRS were used to assess motor performance before and after operation by the neurologic team. The follow-up ranged between 6 and 18 mon ths. RESULTS At latest examination, mean UPDRS II and III scores had improved by 30% (on stimulation, off therapy) with mean 50% reduction in daily off tim e. Peak dyskinesias and early morning dystonias also improved in relation t o therapy reduction. Side effects were persistent postoperative supranuclea r oculomotor palsy and postural instability in one case, worsened off-medic ation hypophonia in three, and temporary nocturnal confusion episodes in th ree. Postoperative MRI revealed a clinically silent intracerebral haematoma in one case. One electrode required repositioning. CONCLUSIONS Continuous high frequency STN stimulation is an effective treat ment for advanced PD. A functionally useful and safe electrode placement ca n be performed without microrecording. (C) 2001 by Elsevier Science Inc.