Combined saccades and turning parameters for early identification of PIGD-subtype Parkinson’s disease

Background Early identification of the postural instability and gait difficulty (PIGD)-subtype PD remains challenging. Because PD patients often have concurrent impairments in eye movements and gait, we assessed whether integrating these two modalities could improve early identification of PIGD-PD. Methods We enrolled 46 PIGD-PD patients and 22 healthy controls (HC) and collected eye-movement and gait parameters using video nystagmography (VNG) and wearable gait analysis devices. We established an integrated model for early identification of PIGD-PD using multivariate stepwise logistic regression. Results Compared with HC, PIGD-PD patients at Hoehn-Yahr stages 1–2 and 3–4 showed significantly lower saccadic accuracy in all directions, and longer saccadic latency only in the upward direction. Similarly, both PD subgroups exhibited longer turning duration and lower turning velocity. In the Hoeh-Yahr stage 1–2 PD subgroup, the areas under the curve (AUCs) for mean horizontal saccadic accuracy (cut-off = 91%, AUC = 0.819, P < 0.001) and turning velocity (cut-off = 177°/s, AUC = 0.888, P < 0.001) were both greater than 0.7. The combined use of these two indicators effectively differentiated symptomatic early-stage PD patients from HC (P < 0.001), with a sensitivity of 76%, a specificity of 100%, and an AUC of 0.939. Conclusions The combination of horizontal saccadic accuracy and turning velocity has high value for identifying patients with early-stage (Hoehn-Yahr stage 1–2) PIGD-PD. Trial registration: This study was registered in the Chinese Clinical Trial Registry (ChiCTR1900022655, date: April 20, 2019).