Objective This systematic review synthesized evidence on quantitative EEG (qEEG) correlates of Parkinson's disease (PD) across five domains: cognition, motor function, pharmacological interventions, neuromodulation, and sleep/non-motor features, evaluating qEEG's potential as a biomarker across these clinical domains. Methods Following PRISMA, we searched PubMed, Embase, Web of Science, and Scopus for studies published from 1991 to 2025. We included studies with ≥10 idiopathic PD patients, resting-state qEEG, and empirical data. Methodological quality was assessed using JBI checklists and AMSTAR. Results We included 89 studies. Spectral slowing – reduced posterior dominant frequency and increased theta power – was the most consistent correlate of cognitive impairment. Connectivity measures (PLV, graph metrics) showed stronger associations with motor dysfunction, gait impairment, and freezing than spectral power alone. qEEG changed with dopaminergic drugs (increased alpha/beta) and neuromodulation (DBS, tDCS, rTMS, neurofeedback). Sleep studies revealed spindle density reductions linked to dementia risk. Conclusions qEEG is a promising biomarker for PD, with distinct electrophysiological correlates across cognitive, motor, pharmacological, and neuromodulatory domains. However, methodological standardization is needed before clinical use. Significance With standardized protocols and multicenter validation, qEEG could aid diagnosis, progression tracking, and personalized therapy in PD.
Objective This study evaluated concordance between referral impressions, structured pre-test assessment, and electrodiagnostic findings (EDX), compared the concordance of an electrodiagnostic consultant's (EC) pre-test assessment and the referring clinician's impression with the final EDX diagnosis. Methods A single-center, prospective observational study enrolled 104 participants over 9 months; 101 completed testing. The EC recorded a diagnostic impression before nerve conduction studies and needle electromyography (EMG). Final diagnoses were categorized using an ICD-10 root-based schema. Referral, pre-test, and final diagnoses were compared using exact agreement between the first-listed primary ICD-10 diagnosis codes. Results Among 101 patients (mean age 59 years; 59.4% female), referral-final concordance was 34.7% (35/101), compared with 71.3% (72/101) for EC pre-test-final concordance (matched OR, 6.29; 95% CI, 2.81–16.54; p < 0.001). EDX produced a clinically meaningful diagnostic change in 67 patients (66.3%) and modified management in 53 (52.5%); subsequent implementation was not assessed. The EC pre-test diagnosis differed from the final EDX diagnosis in 29 cases (28.7%). Conclusions EDX frequently identified diagnoses that differed from referral impressions and sometimes differed from the consultant's pre-test assessment. The higher pre-test-final concordance reflects within-clinician agreement after a focused history and examination; it does not establish that the electrodiagnostic consultant is more diagnostically accurate than referring clinicians. Significance This single-center exploratory study supports the clinical value of a focused pre-test assessment and of EDX as a diagnostic consultation. Larger, multicenter studies using independent assessment are needed.
