We present a video of three patients referred to a Movement Disorders specialist (E.D.L.) for evaluation and management of tremor. Two of the three (i.e., patients 1 and 3) had pre-existing diagnoses of ET; in a third (i.e., patient 2), the referring diagnosis was uncertain. On examination, patients were directed to fully straighten their arms at the elbow, wrist, and fingers, but without overstressing; they were assessed in three arm positions (i.e., pronation, “karate chop”, and wing positions). All patients exhibit hand tremor as well as asymmetric, dystonic posturing of the hands, specifically “spooning”, i.e., wrist flexion and metacarpophalangeal hyperextension (Video 1). In one patient (patient 2), the examination is further notable for concomitant cervical dystonia. In all cases, the diagnosis was ultimately revised to or established as dystonia given these features and failure to fulfill ET diagnostic criteria (e.g., irregularity or jerkiness of tremor).1
Given the heterogeneity of presentation and relative rarity of the disorder, the clinical diagnosis of dystonia can be challenging. Diagnostic confusion is particularly common between dystonia and other movement disorders. Among initially misdiagnosed cases, revision of diagnosis requires recognition of both features atypical for the initial diagnosis and features specifically suggestive of dystonia.2
Initial misdiagnosis of dystonia as ET is not uncommon. In a retrospective case series of 71 patients with pre-existing diagnoses of ET referred for evaluation at a movement disorders center, diagnosis (by Movement Disorders Society 1998 consensus guidelines3) was ultimately revised in 26 (36.6%); in six (8.5%) cases, the diagnosis was revised to isolated dystonia.4 The presence of dystonic posturing, including spooning, was associated with revision of diagnosis, noted to be over 10-fold more likely among those whose diagnosis was revised than those whose diagnosis was confirmed as ET. The presence of other dystonic features, including tremor null point or directionality, and sensory trick, was also associated with revision of diagnosis.
Spooning has not been documented in the general population, but it should be noted that overextending the arms may sometimes produce a posture that resembles spooning. Hence, it is important to ask examinees not to overstress their extended arms during the examination.
We propose that recognition of subtle clinical features of dystonia such as spooning during evaluation of tremor may aid in the diagnosis of underlying dystonia and, ultimately, initiation of appropriate treatment.
1 Funding: None.
2 Financial Disclosures: None.
3 Conflicts of Interest: The authors report no conflict of interest.
4 Ethics Statement: All patients that appear on video have provided written informed consent; authorization for the videotaping and for publication of the videotape was provided.
Bhatia, KP Bain, P Bajaj, N Elble, RJ Hallett, M Louis, ED et al. (2018). Consensus Statement on the classification of tremors. From the task force on tremor of the International Parkinson and Movement Disorder Society. Mov Disord 33: 75–87, DOI: https://doi.org/10.1002/mds.27121 [PubMed]
Deuschl, G, Bain, P and Brin, M (1998). Consensus statement of the Movement Disorder Society on Tremor. Ad Hoc Scientific Committee. Mov Disord 13: 2–23, DOI: https://doi.org/10.1002/mds.870131303
Jain, S, Lo, SE and Louis, ED (2006). Common misdiagnosis of a common neurological disorder: how are we misdiagnosing essential tremor?. Arch Neurol 63: 1100–1104, DOI: https://doi.org/10.1001/archneur.63.8.1100 [PubMed]