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Shaky legs: More than meets the eyes (or ears)
Parkinsonism and Related Disorders 21 (2015) 162
Contents lists available at ScienceDirect
Parkinsonism and Related Disorders journal homepage: www.elsevier.com/locate/parkreldis
Correspondence
Shaky legs: More than meets the eyes (or ears) To the editor: I read the recent article “Orthostatic tremor: a review of 45 cases” by Yaltho and Ondo with interest, and the authors are to be congratulated for publishing this large series of orthostatic tremor (OT) patients [1]. However, their paper contains some questionable assertions. For example, they stipulate that, “auscultation with a stethoscope can reveal a repetitive thumping sound, and palpation of calf muscles reveals a vibration sensation,” which they imply are reliable indicators of OT. In my recently published series of 95 patients with “shaky legs,” of whom 32 had orthostatic myoclonus, 8 primary OT, and 55 neither orthostatic hyperkinesia (NOH) who were all diagnosed with surface electromyography (EMG), neither auscultation nor palpation of leg muscles was accurate in distinguishing one group from another [2]. The authors indicate that the “majority” of their cases were “confirmed with surface EMG,” but they do not cite a precise number. Was it merely 23 or higher? Perhaps this is why their OT cohort's demographics are different from other published ones [3e5] in which all patients were diagnosed with surface EMG; theirs is the only one that I am aware of that has equal numbers of male and female patients. Other series typically are approximately 70% female. Also, I am not aware of a patient with OT being definitively diagnosed before the age of 45 years. In my series, patients below this age had NOH, yet the age range in Yaltho's and Ondo's series ranges from 32 to 77 years. Given the above concerns, one wonders whether all 45 patients in Yaltho's and Ondo's series have OT? Large, prospective studies of patients with “shaky legs” undergoing both surface EMG and auscultation of leg muscles by independent investigators would be useful because if the latter method is truly reliable at distinguishing between OT, OM, and NOH, then clinicians could be
http://dx.doi.org/10.1016/j.parkreldis.2014.10.030 1353-8020/© 2014 Elsevier Ltd. All rights reserved.
confident that orthostatic hyperkinesias may be accurately diagnosed with simple bedside examination techniques alone. I am skeptical that this is the case. Conflict of interest None. References [1] Yaltho TC, Ondo WG. Orthostatic tremor: a review of 45 cases. Parkinsonism Relat Disord 2014;20:723e5. [2] Van Gerpen JA. A retrospective study of the clinical and electrophysiological characteristics of 32 patients with orthostatic myoclonus. Parkinsonism Relat Disord 2014;20:889e93. [3] Thompson PD, Rothwell JC, Day BL, Berardelli A, dick JP, Kachi T, et al. The physiology of orthostatic tremor. Arch Neurol 1986;43:584e7. [4] Mestre TA, Lang AE, Ferreira JJ, Almeida V, de Carvalho M, Miyasaki J, et al. Associated movement disorders in orthostatic tremor. J Neurol Neurosurg Psychiatr 2012;83:725e9. [5] Gerschlager W, Muenchau A, Katzenschlager R, Brown P, Rothwell JC, Quinn N, et al. Natural history and syndromic associations of orthostatic tremor: a review of 41 patients. Mov Disord 2004;19:788e95.
Jay A. van Gerpen* Department of Neurology, Mayo Clinic, 4500 San Pablo Road South, Jacksonville, FL 32224, USA * Tel.: þ1 904 953 7228. E-mail address: [email protected].
8 September 2014
Contents lists available at ScienceDirect
Parkinsonism and Related Disorders journal homepage: www.elsevier.com/locate/parkreldis
Correspondence
Shaky legs: More than meets the eyes (or ears) To the editor: I read the recent article “Orthostatic tremor: a review of 45 cases” by Yaltho and Ondo with interest, and the authors are to be congratulated for publishing this large series of orthostatic tremor (OT) patients [1]. However, their paper contains some questionable assertions. For example, they stipulate that, “auscultation with a stethoscope can reveal a repetitive thumping sound, and palpation of calf muscles reveals a vibration sensation,” which they imply are reliable indicators of OT. In my recently published series of 95 patients with “shaky legs,” of whom 32 had orthostatic myoclonus, 8 primary OT, and 55 neither orthostatic hyperkinesia (NOH) who were all diagnosed with surface electromyography (EMG), neither auscultation nor palpation of leg muscles was accurate in distinguishing one group from another [2]. The authors indicate that the “majority” of their cases were “confirmed with surface EMG,” but they do not cite a precise number. Was it merely 23 or higher? Perhaps this is why their OT cohort's demographics are different from other published ones [3e5] in which all patients were diagnosed with surface EMG; theirs is the only one that I am aware of that has equal numbers of male and female patients. Other series typically are approximately 70% female. Also, I am not aware of a patient with OT being definitively diagnosed before the age of 45 years. In my series, patients below this age had NOH, yet the age range in Yaltho's and Ondo's series ranges from 32 to 77 years. Given the above concerns, one wonders whether all 45 patients in Yaltho's and Ondo's series have OT? Large, prospective studies of patients with “shaky legs” undergoing both surface EMG and auscultation of leg muscles by independent investigators would be useful because if the latter method is truly reliable at distinguishing between OT, OM, and NOH, then clinicians could be
http://dx.doi.org/10.1016/j.parkreldis.2014.10.030 1353-8020/© 2014 Elsevier Ltd. All rights reserved.
confident that orthostatic hyperkinesias may be accurately diagnosed with simple bedside examination techniques alone. I am skeptical that this is the case. Conflict of interest None. References [1] Yaltho TC, Ondo WG. Orthostatic tremor: a review of 45 cases. Parkinsonism Relat Disord 2014;20:723e5. [2] Van Gerpen JA. A retrospective study of the clinical and electrophysiological characteristics of 32 patients with orthostatic myoclonus. Parkinsonism Relat Disord 2014;20:889e93. [3] Thompson PD, Rothwell JC, Day BL, Berardelli A, dick JP, Kachi T, et al. The physiology of orthostatic tremor. Arch Neurol 1986;43:584e7. [4] Mestre TA, Lang AE, Ferreira JJ, Almeida V, de Carvalho M, Miyasaki J, et al. Associated movement disorders in orthostatic tremor. J Neurol Neurosurg Psychiatr 2012;83:725e9. [5] Gerschlager W, Muenchau A, Katzenschlager R, Brown P, Rothwell JC, Quinn N, et al. Natural history and syndromic associations of orthostatic tremor: a review of 41 patients. Mov Disord 2004;19:788e95.
Jay A. van Gerpen* Department of Neurology, Mayo Clinic, 4500 San Pablo Road South, Jacksonville, FL 32224, USA * Tel.: þ1 904 953 7228. E-mail address: [email protected].
8 September 2014