Deep cervical lymph nodes in Parkinson's disease and atypical Parkinson's disease: A potential ultrasound biomarker for differential diagnosis.

Background: Parkinson's disease (PD) is a common degenerative disease caused by abnormal accumulation of α-synuclein. The glymphatic pathway is essential for removing macromolecular proteins including α-synuclein from the brain, which flows into deep cervical lymph nodes (DCLNs) through meningeal lymphatics. As a terminal station for the cerebral lymphatic system drainage, DCLNs can be easily assessed clinically.

Objectives: Although the drainage function of the cerebral lymphatic system is impaired in PD, the correlation between DCLNs and PD remains unknown.

Design: Single-center retrospective cross-sectional study.

Methods: The size of the DCLNs were measured using ultrasound. The Movement Disorder Society Sponsored Revision Unified Parkinson's Disease Rating Scale and other scales were used to assess PD motor and non-motor symptoms.

Results: Compared with the healthy control (HC) and the atypical Parkinson's disease (AP) groups, the size of the second and third DCLNs in the Parkinson's disease (PD) group was significantly smaller (P < .05). The width diameter of the third DCLN (DCLN3(y)) was significantly smaller in the PD group than in the AP group (P = .014). DCLN3(y) combined with a variety of clinical features improved the sensitivity of AP identification (sensitivity = .813).

Conclusion: DCLNs were able to distinguish HC, PD and AP and were mainly located in Robbins ΙΙA level. PD and AP were associated with different factors that influenced the size of the DCLNs. DCLN3(y) plays an important role in differentiating PD from AP, which, combined with other clinical features, has the ability to distinguish PD from AP; in particular, the sensitivity of AP diagnosis was improved.