Cutting-edge insights on the value of deep brain stimulation of the subthalamic nucleus in Parkinson disease.
The value of deep brain stimulation of the subthalamic nucleus (STN-DBS) in Parkinson disease (PD) was the topic of several research reports presented at the International Congress of Parkinson’s Disease and Movement Disorders in Hong Kong. Included was a Chinese study that sought to clarify whether reduction in dyskinesia following STN-DBS is a direct effect of DBS or simply related to a decrease in levodopa dose.
Another study, emerging from Korea, examined whether STN-DBS can have a long-term effect on the amelioration of freezing gait, and a Spanish study confirmed that STN-DBS results in improvement in Unified Parkinson Disorder Rating Scale (UPDRS) part III (motor) scores and allows for reduced need for medication.
The Chinese study, conducted by Yan Zhang, PhD, of Peking University in Beijing and Jia-Yu Li, MD, of the Beijing Institute of Functional Neurosurgery, confirmed the value of STN-DBS in ameliorating levodopa-induced dyskinesia.1 The team evaluated 20 patients with severe levodopaâinduced peakâdose dyskinesia who underwent bilateral STNâDBS implantation. Postoperative medication was unchanged for the first 3 months and then gradually reduced.
Patients were examined prior to DBS implantation and 3 months and 1 year postoperatively. PD symptom severity was assessed by the UPDRS and severity of dyskinesia was measured by the Unified Dyskinesia Rating Scale. At follow-ups, all of the patients were dyskinesiaâfree whether they underwent medication reduction or not. Zhang and Li concluded that STN-DBS apparently does directly suppress levodopaâinduced dyskinesia in PD.
A team from Seoul National University Hospital in Seoul, Korea, found that STNâDBS can have a longâterm effect on freezing gait in relation to medication “off” mode, but not “on” mode.2 The team evaluated patients with bilateral STNâDBS whose patient registry data included a complete set of 5âmeter walking task videos, including at baseline and at 5â or 7âyears’ postoperative followâup.
Freezing gait severity and incidence were evaluated along with UPDRSâIII axial score, UPDRSâII Item 14 (freezing) score, and Freezing of Gait Questionnaire (FOG-Q). The videos were evaluated according to “Medâoff”/DBSâoff, Medâoff/DBSâon, Medâon/DBSâoff, and Medâon/DBSâon. UPDRSâII item 14 and FOGâQ were evaluated according to Medâoff/DBSâon and Medâon/DBSâon.
Freezing gait and axial score improved under Medâoff/DBSâon conditions. Axial score also improved under Med-on/DBS off conditions, but freezing gait only showed improvement at 2-years’ follow-up, not the final 5- or 7-year follow-up.
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The Spanish team, from the ClÃnica Universidad de Navarra in Pamploma, evaluated the efficacy of STN-DBS in reducing need for medication in PD.3 The team retrospectively assessed clinical outcome in 44 patients. Medications were converted to the levodopa-equivalent daily dose to calculate changes in total levodopa-equivalent daily dose. Changes in UPDRS scores and the presence of nonmotor symptoms during follow-up also were measured.
The researchers found a marked 46% reduction in levodopa-equivalent dose after surgery. The reduction rate was maintained after 6 month, with no statistical differences at 2 years follow-up. A 48% reduction in UPDRS-III was seen, and held steady at the 2-year follow-up. The team concluded that STN-DBS is effective in the treatment of PD and offers a long-term effect that includes reduction in medication and improvement in motor symptoms.
1. Li J, Zhang Y. STN deep brain stimulation can directly suppress levodopaâinduced dyskinesia in Parkinson’s disease. Abstract #30. Abstracts of the 2018 International Congress of Parkinson’s Disease and Movement Disorders. Mov Disord. 2018;33(S2):S14-S15.
2. Kim R, Shin CW, Park H, Kim A, Kim HJ, Paek SH, Jeon B. Longâterm effect of subthalamic nucleus deep brain stimulation on freezing of gait in patients with advanced Parkinson’s disease. Abstract #323. Abstracts of the 2018 International Congress of Parkinson’s Disease and Movement Disorders. Mov Disord. 2018;33(S2):S142.
3. Carmona-AbellÃ¡n M, de Ulibarri G, Guridi J, Clavero P, Alegre M, Luquin-Piudo R. Impact of STN-DBS on medication reduction. Abstract #583. Abstracts of the 2018 International Congress of Parkinson’s Disease and Movement Disorders. Mov Disord. 2018;33:S271.