Inconsistent subthalamic local field potential beta activity amid in- and antiphasic neuronal bursts

Elevated subthalamic (STN) beta (12-32 Hz) local field potentials (LFP) are a hallmark of Parkinson's disease and closely tied to synchronized spiking. The biomarker guides deep brain stimulation (DBS) lead implantation and is under investigation to inform DBS programming and adaptive DBS, yet its prevalence has not been independently assessed. This study assesses the biomarkers prevalence and investigating its relationship to synchronized beta-bursting neurons. STN LFPs and spiking activity of n = 156 patients with Parkinson's disease from seven DBS centers recorded via microelectrodes were examined and spectral LFP peaks classified. The distribution of phase angles between beta LFP and beta-bursting neurons was explored. Beta LFPs were bilaterally expressed in 47.25% of patients (65.59% of hemispheres). LFP-synchronized neuronal spiking clustered in two peaks, 182.84° phase shifted. This applied on the group level and for individual patients. Beta-LFP-informed approaches mandate reliable biomarker expression, a requirement not met by 52.75% of patients. This is particularly troublesome for intraoperative guidance wherein the cause of biomarker absence, including DBS lead misplacement or a balanced ratio of phasic and antiphasic spiking neurons, cannot be determined. While STN-LFP beta remains a valuable biomarker, multiple biomarkers should be evaluated simultaneously to increase robustness.