Herrmann, DN

Mountain, JM

Panosyan, FB

Reilly, MM

Shy, ME

UCL Discovery

From the Morton and Gloria Shulman Movement Disorders Clinicand the Edmond J. Safra Program in Parkinson’s Disease, Divisionof Neurology (A.F.), Division of Neurosurgery (F.S., M.L., A.M.L.),Toronto Western Hospital–UHN, University of Toronto and Krem-bil Research Institute (A.F., A.M.L), Toronto, Ontario, Canada.Author contributions: Alfonso Fasano: drafting/revising the manu-script, study concept or design, analysis or interpretation of data, acceptsresponsibility for conduct of research and will give final approval,acquisition of data, study supervision. Francesco Sammartino: draft-ing/revising the manuscript, study concept or design, analysis or inter-pretation of data, accepts responsibility for conduct of research and willgive final approval, acquisition of data, statistical analysis. MahelethLlinas: drafting/revising the manuscript, analysis or interpretation ofdata, accepts responsibility for conduct of research and will give finalapproval, statistical analysis, study supervision. Andres M. Lozano:drafting/revising the manuscript, study concept or design, analysis orinterpretation of data, accepts responsibility for conduct of research andwill give final approval, contribution of vital reagents/tools/patients,acquisition of data, statistical analysis, study supervision, obtainingfunding.Study funding: No targeted funding reported.Disclosure: A.M.L. is a consultant to the Focused UltrasoundFoundation and has received research support from InSightec inthe past. Dr. Fasano has received grant support from the Univer-sity of Toronto, the McLaughlin Centre, and the Michael J. FoxFoundation; he received speaking honoraria from UCB Pharma,Medtronic, Boston Scientific, AbbVie, Novartis, Chiesi Pharma-ceutical, and TEVA; he is on an advisory board for AbbVie andprovided consultancies for UCB Pharma, Medtronic, Boston Sci-entific, and AbbVie. Ms. Llinas and Dr. Sammartino report nodisclosures. Dr. Lozano holds stock ownership in medically relatedfields (Functional Neuromodulation) and provided consultanciesfor Medtronic St. Jude, Boston Scientific, and InSightec. Go toNeurology.org for full disclosures.Received January 8, 2016. Accepted in final form May 3, 2016.Correspondence to Dr. Fasano: alfonso.fasano@uhn.ca© 2016 American Academy of Neurology1. Fasano A, Deuschl G. Therapeutic advances in tremor. MovDisord 2015;30:1557–1565.2. Lipsman N, Schwartz ML, Huang Y, et al. MR-guidedfocused ultrasound thalamotomy for essential tremor:a proof-of-concept study. Lancet Neurol 2013;12:462–468.3. Elias WJ, Huss D, Voss T, et al. A pilot study of focusedultrasound thalamotomy for essential tremor. N Engl J Med2013;369:640–648.4. ChangWS, Jung HH, Kweon EJ, Zadicario E, Rachmilevitch I,Chang JW. Unilateral magnetic resonance guided focused ultra-sound thalamotomy for essential tremor: practices and clinicor-adiological outcomes. J Neurol Neurosurg Psychiatry 2015;86:257–264.5. Sammartino F, Krishna V, Kon Kam King N, Lozano A,Hodaie M. Tractography-based ventral intermediatenucleus targeting: novel methodology and intraoperativevalidation. Mov Disord Epub 2016 May 23.6. Huss DS, Dallapiazza RF, Shah BB, Harrison MB,Diamond J, Elias WJ. Functional assessment and qualityof life in essential tremor with bilateral or unilateral DBSand focused ultrasound thalamotomy. Mov Disord 2015;30:1937–1943.7. Jung HH, Kim SJ, Roh D, et al. Bilateral thermal capsulot-omy with MR-guided focused ultrasound for patients withtreatment-refractory obsessive-compulsive disorder: a proof-of-concept study. Mol Psychiatry 2015;20:1205–1211.RYDEL-SEIFFER FORK REVISITED: BEYONDA SIMPLE CASE OF BLACK AND WHITEIn 1903, A. Rydel and F.W. Seiffer published the use ofwhat is now commonly known as the Rydel-Seiffer tun-ing fork.1 In their paper, they described an adaptation ofthe standard tuning fork to make it semiquantitative onan 8-point scale in measuring vibration sensing. TheRydel-Seiffer tuning fork has been used extensively overthe past century and normative values have been pub-lished.2 It has also been validated with the use of moremodern sensory nerve action potentials.3 Vibrationthreshold measurement with the Rydel-Seiffer tuningfork is therefore increasingly used in outcomemeasuresassessing neuropathy from diverse etiologies:chemotherapy-induced peripheral neuropathy,4Charcot-Marie-Tooth disease,5 multifocal motor neu-ropathy,6 and immune-mediated neuropathies.7The modern Rydel-Seiffer tuning fork has a blacktriangle on one prong and a white triangle on the sec-ond prong (figure, A). After the fork is snapped intomotion, the prongs start to oscillate and the illusion of2 triangles becomes visible on each damper. The inter-sect between the 2 virtual triangles moves up the scalewith gradual attenuation of the amplitude of theoscillation. The position of the intersect is recordedon an arbitrary scale from 0 to 8 once the subject isno longer perceiving vibration.We have observed consistent discrepancy betweenthe values obtained from the black triangle in compari-son to the white triangle on the Rydel-Seiffer fork. Val-ues obtained from the virtual intersect of the whitetriangle are consistently lower in comparison to that fromthe black triangle (figure, C and D). This discrepancycan be as much as 25% or 2 units in the scale of 0 to 8.This is best appreciated during the motion of the prongs(video on the Neurology® Web site at Neurology.org).There is currently no report distinguishing betweenthe black and white scales and both are used inter-changeably.2,3 Of note, the original publication fromRydel and Seiffer depicts the tuning fork with 2 blacktriangles on the dampers (figure, B). It is unclear as towhy or when a modification was made and one of theblack triangles was substituted with a white triangle.Remarkably, the observed discrepancy between the 2scales can be eliminated by simply darkening the whitetriangle on the fork with a marker (figure, E and F). It isof interest that, upon introducing color to the whitetriangle (purple or red), the readings obtained fromthe black triangle showed lower values in comparisonFrancis B. Panosyan, MD,PhDJoan M. Mountain, RNMary M. Reilly, MDMichael E. Shy, MDDavid N. Herrmann,MBBChSupplemental dataat Neurology.org738 Neurology 87 August 16, 2016ª 2016 American Academy of Neurology. Unauthorized reproduction of this article is prohibited.to the colored triangle (video). The perceived intersec-tion between the triangles seems to be therefore influ-enced by the contrast and the color of the triangles. Thisis likely attributable to visual afterimage processing,although a more tangible explanation remains elusive.To maintain an acceptable interrater reliability inthe use the Rydel-Seiffer tuning fork, we suggest thatthe original design with the 2 black triangles is consid-ered. Alternatively, consensus should be establishedon which triangle to use in the future for clinical prac-tice and clinical research.From the Department of Neurology (F.B.P., J.M.M., D.N.H.), Uni-versity of Rochester Medical Center, NY; MRC Centre for Neuro-muscular Diseases (M.M.R.), UCL Institute of Neurology,London, UK; and Department of Neurology (M.E.S.), Universityof Iowa Hospitals and Clinics, Iowa City.Author contributions: Francis B. Panosyan: concept and design, acqui-sition of data, analysis and interpretation of data. Joan M. Mountain:revising the manuscript for content, acquisition of data. Mary M. Reilly:analysis and interpretation of data, revising the manuscript for content.Michael E. Shy: analysis and interpretation of data, revising the man-uscript for content. David N. Herrmann: analysis and interpretation ofdata, revising the manuscript for content, supervisor.Study funding: Supported by NIH-RDCRNU54 (U54NS065712).Disclosure: F. Panosyan, J. Mountain, M. Reilly, and M. Shy reportno disclosures relevant to the manuscript. D. Herrmann receivedgrant support from NINDS (U54NS065712), FARA, MDA, andhas received funds for consulting or adjudication activities fromMedpace, Guidepoint Global, Voyager, Inc., and LAM Therapeu-tics. Go to Neurology.org for full disclosures.Received March 9, 2016. Accepted in final form May 5, 2016.Correspondence to Dr. Panosyan: Francis_Panosyan@urmc.rochester.edu© 2016 American Academy of NeurologyFigure Rydel-Seiffer tuning fork(A) An example of a modern-day Rydel-Seiffer tuning fork. (B) Original design of the tuning fork as published by Rydel andSeiffer in 1903 (reprinted with permission of Springer).1 (C) Rydel-Seiffer tuning fork at rest. (D) Rydel-Seiffer tuning fork inmotion with the black triangle showing intersect between 4 and 5 (on the 0 to 8 scale) and white triangle showing intersectbetween 3 and 4 (discrepancy is better appreciated in the video). (E) Same Rydel-Seiffer tuning fork with the white triangleblacked out at rest. (F) Rydel-Seiffer tuning forkwith 2 black triangles inmotion showing equivalent reading with intersect at 4.Neurology 87 August 16, 2016 739ª 2016 American Academy of Neurology. Unauthorized reproduction of this article is prohibited.1. Rydel A, Seiffer W. Examinations of feelings of vibrations orso-called “bone sensitivity” (pallaesthesia). Arch PsychiatrNervenkr 1903;37:488–536.2. Martina IS, van Koningsveld R, Schmitz PI, van derMeché FG, van Doorn PA. Measuring vibration thresholdwith a graduated tuning fork in normal aging and in pa-tients with polyneuropathy. European Inflammatory Neu-ropathy Cause and Treatment (INCAT) Group. J NeurolNeurosurg Psychiatry 1998;65:743–747.3. Pestronk A, Florence J, Levine T, et al. Sensory exam witha quantitative tuning fork: rapid, sensitive and predictive ofSNAP amplitude. Neurology 2004;62:461–464.4. Cavaletti G, Cornblath DR, Merkies IS, et al. Thechemotherapy-induced peripheral neuropathy outcomemeasures standardization study: from consensus to thefirst validity and reliability findings. Ann Oncol 2013;24:454–462.5. Murphy SM, Herrmann DN, McDermott MP, et al. Reli-ability of the CMT neuropathy score (second version) inCharcot-Marie-Tooth disease. J Peripher Nerv Syst 2011;16:191–198.6. Cats EA, van der Pol WL, Piepers S, et al. Correlates ofoutcome and response to IVIg in 88 patients with multifo-cal motor neuropathy. Neurology 2010;75:818–825.7. Merkies ISJ, Schmitz PIM, van der Meche FGA, vanDoorn PA. Reliability and responsiveness of a graduatedtuning fork in immune mediated polyneuropathies.The Inflammatory Neuropathy Cause and Treatment(INCAT) Group. J Neurol Neurosurg Psychiatry 2000;68:669–671.Look What’s New at the 2016 AAN Fall ConferenceVisit AAN.com/view/fall to register for the 2016 AAN Fall Conference, set for October 14–16, atThe Cosmopolitan of Las Vegas. This is your year-end destination for acquiring the latest clinicaladvances in key disease states, improving your practice’s efficiency and bottom line, and earning upto 15.75 CME credits.Look What’s New!• All-inclusive registration rate offers greater value than ever• Flexible meeting format lets you build your own tailored schedule and select the programs ofmost interest—while on the go on-site• New Topics: Update in Stroke, AAN Leadership University Course: Challenges of Leader-ship in Private Practice, Headache Skills Workshop (pre-registration required)MACRA Changes How Neurologists Are PaidWhat Is MACRA, and Why Is It Necessary?The Medicare Access and CHIP Reauthorization Act of 2015—MACRA—replaced theMedicare Sustainable Growth Rate formula for calculating physician payments. The rapidly risingcosts of health care in the US are unsustainable. Changes in the health care system are essential andmust happen now.How Will MACRA Affect Physician Payment?Our health care system is moving from “fee-for-service” payments to a wider array of “value-based”payment models that put the patient at the center of care by calling for the improvement of thequality, safety, and overall experience of patient care while demonstrating cost-effectiveness byproviding care that is less expensive and delivers similar or improved clinical outcomes.Learn more at AAN.com/view/MACRA.740 Neurology 87 August 16, 2016ª 2016 American Academy of Neurology. Unauthorized reproduction of this article is prohibited.DOI 10.1212/WNL.00000000000029912016;87;738-740 Published Online before print July 13, 2016Neurology Francis B. Panosyan, Joan M. Mountain, Mary M. Reilly, et al. Rydel-Seiffer fork revisited: Beyond a simple case of black and whiteThis information is current as of July 13, 2016ServicesUpdated Information & http://www.neurology.org/content/87/7/738.full.htmlincluding high resolution figures, can be found at:Supplementary Material 002991.DC1http://www.neurology.org/content/suppl/2016/07/13/WNL.0000000000Supplementary material can be found at: References http://www.neurology.org/content/87/7/738.full.html##ref-list-1This article cites 7 articles, 4 of which you can access for free at: Subspecialty Collections http://www.neurology.org//cgi/collection/clinical_neurology_historyClinical neurology history onhttp://www.neurology.org//cgi/collection/clinical_neurology_examinatiClinical neurology examination http://www.neurology.org//cgi/collection/all_neuromuscular_diseaseAll Neuromuscular Diseasefollowing collection(s): This article, along with others on similar topics, appears in the  Permissions & Licensing http://www.neurology.org/misc/about.xhtml#permissionsits entirety can be found online at:Information about reproducing this article in parts (figures,tables) or in  Reprints http://www.neurology.org/misc/addir.xhtml#reprintsusInformation about ordering reprints can be found online:rights reserved. Print ISSN: 0028-3878. Online ISSN: 1526-632X.1951, it is now a weekly with 48 issues per year. Copyright © 2016 American Academy of Neurology. All ® is the official journal of the American Academy of Neurology. Published continuously sinceNeurology 

Rydel-Seiffer fork revisited: Beyond a simple case of black and white

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Rydel-Seiffer fork revisited: Beyond a simple case of black and white

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