Objective: To describe an unusual wrist tremor according the existing classification and discuss its aetiological diagnosis.

Background: Although Parkinson’s disease (PD) is usually associated with rest tremor, action tremor has also been in PD, suggesting that it could also be a manifestation of the underlying basal ganglia disease. In patients with Parkinson’s disease, for example, an isometric action tremor is often inducible by fist clenching. Some have argued that shopping bag tremor, an unusual variant recently described, could be associated in some cases with PD.

Method: Description of clinical case history, followed by relevant examination and investigations and discussion of the results.

Results: Clinical Case: A 69 year-old right-handed male presented with a 1-year history of left wrist tremor only occurred whenever he carry a shopping bag. Examination revealed an increasingly moderate to marked amplitude tremor, mainly involving flexion–extension movements when a weighted shopping bag was placed in the left arm; the tremor waned if he clench a tight fist or change hand position. The remainder of the neurological examination was unremarkable, except for an imperfect left finger tapping. Additionally, his wife reported dream enactment behavior during sleep and scored 7 in the RDB Screening Questionnaire. Surface EMG recordings revealed alternating rhythmic discharge of forearm flexor muscles and EDC with a frequency of 5-6 Hz while the patient was holding a bag with around 1 kg weighted. This rhythmic activity disappears at rest and with arm hanging along the body. DaTSCAN imaging showed a right striatal dopaminergic deficit. Inertial measurement units, complementing clinical examination, showed a near-normal gait and finger tapping performance.

Conclusion: This shopping bag tremor shares characteristics with both task-specific, position-specific and isometric tremor. Taking in account tremor frequency, its latency and a crescendo-like quality, the presence of RBD and positive DaTSCAN, we consider that this can be an atypical prediagnostic presentation of Parkinson’s disease.

References: [1] Zesiewicz T, Vu T, Carranza MA, et al. Unusual wrist tremor: Unilateral isometric tremor? Tremor Other Hyperkinet Mov 2014;4:tre-04-194-4738-1. [2] Louis ED, Levy G, C^ote LJ, et al. Clinical correlates of action tremor in Parkinson disease. Arch Neurol 2001;58(10):1630-4.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/can-a-shopping-bag-tremor-be-a-pre-diagnostic-sign-of-parkinsons-disease/