Objective: To investigate the clinical and neurophysiological effects of levodopa treatment in a patient diagnosed with SWEDD.

Background: A subset of patients with clinical features suggestive of Parkinson’s disease (PD) have normal dopaminergic imaging, a condition referred to as scan without evidence of dopaminergic deficit (SWEDD). However, the etiology of SWEDD is still debated, complicating treatment decisions.

Method: We evaluated a 73-year-old man with minimal bradykinetic-rigid syndrome, asymmetric rest tremor, and re-emergent tremor predominantly on the right side. He had a recent negative DAT scan and was referred to our clinic while undergoing dopaminergic treatment. The patient was evaluated using standardized clinical scales and kinematic analysis of finger tapping and tremor in both the “ON” (with medication) and “OFF” (levodopa-withdrawn) states.

Results: Clinical scales showed no differences between the ON and OFF states. Kinematic analysis revealed increased re-emergent tremor amplitude in the OFF state (0.177 vs 0.285 GRMS²), while rest, kinetic, and head tremor remained unchanged. Finger tapping velocity was consistently lower on the right side (ON: 1215 vs 1358 °/sec, OFF: 1012 vs 1152 °/sec). In OFF, overall tapping velocity declined (1082 vs. 1287°/sec), with a more pronounced sequence effect (-0.16 vs. -0.43°/sec/movement). The data suggest a subtle but measurable impact of levodopa withdrawal on motor performance and re-emergent tremor amplitude.

Conclusion: This case underscores the role of clinical and neurophysiological assessments in evaluating treatment response in SWEDD patients. The observed motor changes suggest a mild dopaminergic response despite normal imaging, offering insights into both therapeutic and pathophysiological aspects of the condition.

Figure 1

Table 1

« Back to 2025 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/levodopa-effects-in-swedd-clinical-and-kinematic-insights-from-a-case-report/