Upper Limb Freezing without Gait Freezing in Parkinson's Disease: a Striking Case of a Rare Phenomenon

Freezing of gait (FOG) has just been redefined by an international consensus, as “paroxysmal episodes, wherein there is an inability to step effectively, despite attempting to do so, including any gait-repeated stepping movement, including gait initiation, turning and walking forwards, backwards or sideways.”1 In contrast, there is no widely accepted definition for other freezing phenomena in Parkinson's disease (PD), including upper limb freezing. To the best of our knowledge, the first mention of this term has been as late as 2012,2 whereas, limited earlier research, has conceptually described it as “motor blocks” or “motor interruptions” during upper limb movements.3, 4 Consequently, upper limb freezing has almost exclusively been assessed during movement (spiral, funnel test, alternating movements, finger tapping, and writing),5 but not as initiation failure. Here, we report a patient with upper limb freezing, manifesting as failure to initiate movements, in striking analogy to gait initiation failure in FOG, along with an illustrative video. This is a 39-year old right-handed gentleman of Greek origin with a 10-year history of young onset PD, starting with rest-tremor on the right arm. For the last 5 years he reports a failure to initiate movements with the right arm (Video 1). This has caused him a number of difficulties in everyday life, from simple tasks to more complicated, including driving and writing. He does not experience any FOG. He has never received any medical or physiotherapeutic advice for this symptom. The patient realized that different “cues,” such as briefly touching the arm, tapping on it, slightly move it with the other hand, or initiating a different movement than the desired (eg, in a different direction) are helpful (Video 1). He is currently on daily levodopa dose of 800 mg, taking 50 mg every hour and amantadine 300 mg/day. He does not experience freezing when in on-state. On examination, in off-state, the patient had broken smooth pursuit and slightly hypometric saccades upward; moderate bradykinesia and rigidity more on the right; and no dystonia, no apraxia or any other cortical signs, as well as a normal formal neuropsychometry. Despite extensive research on FOG, research on upper limb freezing, as well as other freezing phenomena in PD and atypical parkinsonism, is very limited with no standardized definition, assessment tools, or robust data on their impact on patient's functionality.5 The recent international consensus on FOG1 offers a valuable conceptual framework that should be extended to other freezing phenomena to improve care for patients experiencing freezing phenomena beyond gait. In conclusion, our case adds to previous reports by illustrating upper limb freezing presenting as initiation failure in the absence of FOG and may facilitate greater recognition of this phenomenon among clinicians, which is essential for research and development of targeted rehabilitation strategies. (1) Research project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the First Draft, B. Review and Critique. M.M.: 1B, 1C, 3B M.S.: 1A, 1B, 1C, 3A, 3B Ethical Compliance Statement: The patient provided informed written consent for publication of this case. Institutional review board approval was not required. We confirm that we have read the Journals position on ethical publication and affirm that this work complies with those guidelines. Funding Sources and Conflict of interest: There was no specific funding that was received for this work. The authors declare that there are no conflicts of interest relevant to this work. Financial Disclosures for Previous 12 Months: MS has received consulatincies from Abbvie, Roche and UCB, royalties from OUP and CUP, travel honoraria from MDS and EAN, research support from EREUNA GIA TIN NOSO PARKINSON (EUID ELGEMI.154221407000) Author disclosures are available in the Supporting Information. The data that support the findings of this study are available from the corresponding author upon reasonable request. Data S1. COI merged. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.