Tuning Frequencies Across Leads with Interleaving Deep Brain Stimulation to Treat Asymmetric Tremor in Parkinson’s Disease

[...]keeping left STN voltages below the threshold of side effects, frequencies were raised up to 220 Hz with a complete control of right-side tremor but with the concurrent onset of a facial pulling on the left side. ILS is an advanced programming technique, which is adopted to sculpt the electrical field with the drawback of a quicker battery drain.1,5 Each electrode could host a couple of virtual leads with a frequency ceiling of 125 Hz, which was imposed by the manufacturer in order to avoid excessive electrical charge density (e.g. occurring over 250 Hz).1,5 On a clinical point of view, higher frequencies (i.e. >130 Hz) are often required to achieve a better control of tremor.4 Therefore, the possibility to select different frequencies per lead (e.g. higher frequencies contralateral to the trembling body side) would be of help in treating asymmetric frequency-sensitive tremors. The approach we described here would be a further resource in the management of asymmetric PD tremor. [...]it could also be speculated that the use of ILS and of higher frequencies would be of help in reducing the exaggerated oscillatory activity pattern in the beta band, a well-known finding in tremor-dominant PD patients.7 Finally, more studies are warranted to better understand the mechanism behind the ILS effect and how it could help clinicians in “tailoring” DBS therapy for their patients.