Shopping bag tremor: insights from kinematic analysis

Background: Shopping bag tremor (SBT) is a rare activation-specific tremor characterized by weight-dependent oscillations, with uncertain nosological classification. Case report: We report a 74-year-old woman with a right upper limb tremor triggered by carrying a shopping bag, with mild rest component. Kinematic analysis demonstrated a non-linear load-response relationship, with low tremor amplitude when unloaded, maximal at low loads (1 kg), and progressively decreasing as weight increased. No abnormalities were detected on finger tapping analysis. Discussion: This case expands the phenotypic spectrum of SBT and supports quantitative kinematic analysis as a feasible first-line tool within diagnostic algorithms for complex tremor presentations. Keywords: Isometric tremor; Kinematic analysis; Position-specific tremor; Shopping bag tremor.