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Accuracy of stimulating electrode placement in paediatric pallidal deep brain stimulation for primary and secondary
Daniel E Lumsden1, Jonathan Ashmore, Geoff Charles-Edwards
1Complex Motor Disorders Service, Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, Lambeth Palace Road, London, SE1 7EH, UK. Daniel.lumsden@gstt.nhs.uk
Insights
Deep brain stimulation (DBS) electrode placement accuracy in the globus pallidus interna (GPi) did not differ across primary, secondary, and NBIA dystonia types. This suggests surgical accuracy is not the reason for varied DBS treatment outcomes in these conditions.
Area of Science:
- Neurosurgery
- Neurology
- Medical Imaging
Background:
- Accurate electrode placement is crucial for successful deep brain stimulation (DBS) surgery outcomes.
- Limited data exists on the precision of globus pallidus interna (GPi) targeting in pediatric dystonia, especially non-primary forms.
- Pallidal DBS shows greater efficacy in primary dystonia than in secondary dystonia.
Purpose of the Study:
- To compare the accuracy of pallidal electrode placement in primary, secondary, and NBIA-associated dystonia.
- To investigate the relationship between electrode proximity to the target and motor outcomes post-surgery.
Main Methods:
- Retrospective review of 88 electrodes in 42 pediatric patients undergoing DBS surgery.
- Analysis of pre-operative MRI and post-operative CT scans to determine electrode placement accuracy using the Leskell stereotactic system.
- Calculation of coordinate differences and Euclidean distance from the planned target.
Main Results:
- Median differences between planned and actual electrode positions were within 1-2.5 mm across axes and Euclidean distance.
- No significant difference in placement accuracy was observed between left and right-sided electrodes.
- Electrode placement accuracy was consistent across primary, secondary, and NBIA-associated dystonia groups.
- No clear relationship was found between electrode proximity to the target and dystonia reduction at one year.
Conclusions:
- Surgical accuracy for pallidal DBS electrode placement is comparable across primary, secondary, and NBIA-associated dystonia in pediatric patients.
- The lower efficacy of pallidal DBS in secondary and NBIA-associated dystonia is unlikely due to challenges in achieving the intended electrode placement.
- Further research may be needed to explore other factors influencing DBS outcomes in different dystonia types.
Background:
Accuracy of electrode placement is an important determinant of outcome following deep brain stimulation (DBS) surgery. Data on accuracy of electrode placement into the globus pallidum interna (GPi) in paediatric patients is limited, particularly those with non-primary dystonia who often have smaller GPi. Pallidal DBS is known to be more effective in the treatment of primary dystonia compared with secondary dystonia.
Objectives:
We aimed to determine if accuracy of pallidal electrode placement differed between primary, secondary and NBIA (neuronal degeneration and brain iron accumulation) associated dystonia and how this related to motor outcome following surgery.
Methods:
A retrospective review of a consecutive cohort of children and young people undergoing DBS surgery in a single centre. Fused in frame preoperative planning magnetic resonance imaging (MRI) and postoperative computed tomography (CT) brain scans were used to determine the accuracy of placement of DBS electrode tip in Leskell stereotactic system compared with the planned target. The differences along X, Y, and Z coordinates were calculated, as was the Euclidean distance of electrode tip from the target. The relationship between proximity to target and change in Burke-Fahn-Marsden Dystonia Rating Scale at 1 year was also measured.
Results:
Data were collected from 88 electrodes placed in 42 patients (14 primary dystonia, 18 secondary dystonia and 10 NBIA associated dystonia). Median differences between planned target and actual position were: left-side X-axis 1.05 mm, Y-axis 0.85 mm, Z-axis 0.94 mm and Euclidean difference 2.04 mm; right-side X-axis 1.28 mm, Y-axis 0.70 mm, Z-axis 0.70 mm and Euclidean difference 2.45 mm. Accuracy did not differ between left and right-sided electrodes. No difference in accuracy was seen between primary, secondary or NBIA associated dystonia. Dystonia reduction at 1 year post surgery did not appear to relate to proximity of implanted electrode to surgical target across the cohort.
Conclusions:
Accuracy of surgical placement did not differ between primary, secondary or NBIA associated dystonia. Decreased efficacy of pallidal DBS in secondary and NBIA associated dystonia is unlikely to be related to difficulties in achieving the planned electrode placement.
