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Valko Y, Wirth MA, Fierz FC, Schesny MK, Rosengren S, Schmückle-Meier T, Bockisch CJ, Straumann D, Schreiner B, Weber KP. Accuracy of Repetitive Ocular Vestibular-Evoked Myogenic Potentials to Diagnose Myasthenia Gravis in Patients With Ptosis or Diplopia. Neurology 2024; 102:e209395. [PMID: 38669629 DOI: 10.1212/wnl.0000000000209395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND AND OBJECTIVES We developed repetitive ocular vestibular-evoked myogenic potentials (roVEMP) as an electrophysiologic test that allows us to elicit the characteristic decrement of extraocular muscles in patients with ocular myasthenia gravis (OMG). Case-control studies demonstrated that roVEMP reliably differentiates patients with OMG from healthy controls. We now aimed to evaluate the diagnostic accuracy of roVEMP for OMG diagnosis in patients with ptosis and/or diplopia. METHODS In this blinded prospective diagnostic accuracy trial, we compared roVEMP in 89 consecutive patients presenting with ptosis and/or diplopia suspicious of OMG with a multimodal diagnostic approach, including clinical examination, antibodies, edrophonium testing, repetitive nerve stimulation of accessory and facial nerves, and single-fiber EMG (SFEMG). We calculated the roVEMP decrement as the ratio between the mean of the first 2 responses compared with the mean of the sixth-ninth responses in the train and used cutoff of >9% (unilateral decrement) in a 30 Hz stimulation paradigm. RESULTS Following a complete diagnostic work-up, 39 patients (44%) were diagnosed with ocular MG, while 50 patients (56%) had various other neuro-ophthalmologic conditions, but not MG (non-MG). roVEMP yielded 88.2% sensitivity, 30.2% specificity, 50% positive predictive value (PPV), and 76.5% negative predictive value (NPV). For comparison, SFEMG resulted in 75% sensitivity, 56% specificity, 55.1% PPV, and 75.7% NPV. All other diagnostic tests (except for the ice pack test) also yielded significantly higher positive results in patients with MG compared with non-MG. DISCUSSION The study revealed a high sensitivity of 88.2% for roVEMP in OMG, but specificity and PPV were too low to allow for the OMG diagnosis as a single test. Thus, differentiating ocular MG from other neuro-ophthalmologic conditions remains challenging, and the highest diagnostic accuracy is still obtained by a multimodal approach. In this study, roVEMP can complement the diagnostic armamentarium for the diagnosis of MG. CLASSIFICATION OF EVIDENCE This study provides Class I evidence that in patients with diplopia and ptosis, roVEMP alone does not accurately distinguish MG from non-MG disorders. TRIAL REGISTRATION INFORMATION ClinicalTrials.gov: NCT03049956.
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Affiliation(s)
- Yulia Valko
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Magdalena A Wirth
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Fabienne C Fierz
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Marianne K Schesny
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Sally Rosengren
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Tanja Schmückle-Meier
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Christopher J Bockisch
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Dominik Straumann
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Bettina Schreiner
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Konrad P Weber
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
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Keene KR, Notting IC, Verschuuren JJ, Voermans N, de Keizer RO, Beenakker JWM, Tannemaat MR, Kan HE. Eye Muscle MRI in Myasthenia Gravis and Other Neuromuscular Disorders. J Neuromuscul Dis 2023; 10:869-883. [PMID: 37182896 PMCID: PMC10578256 DOI: 10.3233/jnd-230023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2023] [Indexed: 05/16/2023]
Abstract
INTRODUCTION MRI of extra-ocular muscles (EOM) in patients with myasthenia gravis (MG) could aid in diagnosis and provide insights in therapy-resistant ophthalmoplegia. We used quantitative MRI to study the EOM in MG, healthy and disease controls, including Graves' ophthalmopathy (GO), oculopharyngeal muscular dystrophy (OPMD) and chronic progressive external ophthalmoplegia (CPEO). METHODS Twenty recently diagnosed MG (59±19yrs), nineteen chronic MG (51±16yrs), fourteen seronegative MG (57±9yrs) and sixteen healthy controls (54±13yrs) were included. Six CPEO (49±14yrs), OPMD (62±10yrs) and GO patients (44±12yrs) served as disease controls. We quantified muscle fat fraction (FF), T2water and volume. Eye ductions and gaze deviations were assessed by synoptophore and Hess-charting. RESULTS Chronic, but not recent onset, MG patients showed volume increases (e.g. superior rectus and levator palpebrae [SR+LPS] 985±155 mm3 compared to 884±269 mm3 for healthy controls, p < 0.05). As expected, in CPEO volume was decreased (e.g. SR+LPS 602±193 mm3, p < 0.0001), and in GO volume was increased (e.g. SR+LPS 1419±457 mm3, p < 0.0001). FF was increased in chronic MG (e.g. medial rectus increased 0.017, p < 0.05). In CPEO and OPMD the FF was more severely increased. The severity of ophthalmoplegia did not correlate with EOM volume in MG, but did in CPEO and OPMD. No differences in T2water were found. INTERPRETATION We observed small increases in EOM volume and FF in chronic MG compared to healthy controls. Surprisingly, we found no atrophy in MG, even in patients with long-term ophthalmoplegia. This implies that even long-term ophthalmoplegia in MG does not lead to secondary structural myopathic changes precluding functional recovery.
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Affiliation(s)
- Kevin R. Keene
- Department of Radiology, CJ Gorter MRI Center, Leiden University Medical Center, Leiden, The Netherlands
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | - Irene C. Notting
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - N. Voermans
- Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Jan-Willem M. Beenakker
- Department of Radiology, CJ Gorter MRI Center, Leiden University Medical Center, Leiden, The Netherlands
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, The Netherlands
| | - Martijn R. Tannemaat
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | - Hermien E. Kan
- Department of Radiology, CJ Gorter MRI Center, Leiden University Medical Center, Leiden, The Netherlands
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Adam I, Maxwell A, Rößler H, Hansen EB, Vellema M, Brewer J, Elemans CPH. One-to-one innervation of vocal muscles allows precise control of birdsong. Curr Biol 2021; 31:3115-3124.e5. [PMID: 34089645 DOI: 10.1016/j.cub.2021.05.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 04/13/2021] [Accepted: 05/04/2021] [Indexed: 11/29/2022]
Abstract
The motor control resolution of any animal behavior is limited to the minimal force step available when activating muscles, which is set by the number and size distribution of motor units (MUs) and muscle-specific force. Birdsong is an excellent model system for understanding acquisition and maintenance of complex fine motor skills, but we know surprisingly little about how the motor pool controlling the syrinx is organized and how MU recruitment drives changes in vocal output. Here we developed an experimental paradigm to measure MU size distribution using spatiotemporal imaging of intracellular calcium concentration in cross-sections of living intact syrinx muscles. We combined these measurements with muscle stress and an in vitro syrinx preparation to determine the control resolution of fundamental frequency (fo), a key vocal parameter, in zebra finches. We show that syringeal muscles have extremely small MUs, with 40%-50% innervating ≤3 and 13%-17% innervating a single muscle fiber. Combined with the lowest specific stress (5 mN/mm2) known to skeletal vertebrate muscle, small force steps by the major fo controlling muscle provide control of 50-mHz to 7.3-Hz steps per MU. We show that the song system has the highest motor control resolution possible in the vertebrate nervous system and suggest this evolved due to strong selection on fine gradation of vocal output. Furthermore, we propose that high-resolution motor control was a key feature contributing to the radiation of songbirds that allowed diversification of song and speciation by vocal space expansion.
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Affiliation(s)
- Iris Adam
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
| | - Alyssa Maxwell
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
| | - Helen Rößler
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
| | - Emil B Hansen
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
| | - Michiel Vellema
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
| | - Jonathan Brewer
- PhyLife, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
| | - Coen P H Elemans
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark.
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Lienbacher K, Ono S, Fleuriet J, Mustari M, Horn AKE. A Subset of Palisade Endings Only in the Medial and Inferior Rectus Muscle in Monkey Contain Calretinin. Invest Ophthalmol Vis Sci 2018; 59:2944-2954. [PMID: 30025142 PMCID: PMC5989861 DOI: 10.1167/iovs.18-24322] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 05/06/2018] [Indexed: 12/11/2022] Open
Abstract
Purpose To further chemically characterize palisade endings in extraocular muscles in rhesus monkeys. Methods Extraocular muscles of three rhesus monkeys were studied for expression of the calcium-binding protein calretinin (CR) in palisade endings and multiple endings. The complete innervation was visualized with antibodies against the synaptosomal-associated protein of 25 kDa and combined with immunofluorescence for CR. Six rhesus monkeys received tracer injections of choleratoxin subunit B or wheat germ agglutinin into either the belly or distal myotendinous junction of the medial or inferior rectus muscle to allow retrograde tracing in the C-group of the oculomotor nucleus. Double-immunofluorescence methods were used to study the CR content in retrogradely labeled neurons in the C-group. Results A subgroup of palisade and multiple endings was found to express CR, only in the medial and inferior rectus muscle. In contrast, the en plaque endings lacked CR. Accordingly, within the tracer-labeled neurons of the C-group, a subgroup expressed CR. Conclusions The study indicates that two different neuron populations targeting nontwitch muscle fibers are present within the C-group for inferior rectus and medial rectus, respectively, one expressing CR, one lacking CR. It is possible that the CR-negative neurons represent the basic population for all extraocular muscles, whereas the CR-positive neurons giving rise to CR-positive palisade endings represent a specialized, perhaps more excitable type of nerve ending in the medial and inferior rectus muscles, being more active in vergence. The malfunction of this CR-positive population of neurons that target nontwitch muscle fibers could play a significant role in strabismus.
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Affiliation(s)
- Karoline Lienbacher
- Institute of Anatomy and Cell Biology, Ludwig-Maximilians-Universität, Munich, Germany
- German Center for Vertigo and Balance Disorders, Klinikum Grosshadern, Ludwig-Maximilians Universität, Munich, Germany
| | - Seiji Ono
- Faculty of Health and Sport Science, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Jérome Fleuriet
- Washington National Primate Research Center, Seattle, Washington, United States
- Department of Ophthalmology, University of Washington, Seattle, Washington, United States
| | - Michael Mustari
- Washington National Primate Research Center, Seattle, Washington, United States
- Department of Ophthalmology, University of Washington, Seattle, Washington, United States
| | - Anja K. E. Horn
- Institute of Anatomy and Cell Biology, Ludwig-Maximilians-Universität, Munich, Germany
- German Center for Vertigo and Balance Disorders, Klinikum Grosshadern, Ludwig-Maximilians Universität, Munich, Germany
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