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Stikvoort García DJL, Sleutjes BTHM, van Schelven LJ, Goedee HS, van den Berg LH. Diagnostic accuracy of nerve excitability and compound muscle action potential scan derived biomarkers in amyotrophic lateral sclerosis. Eur J Neurol 2023; 30:3068-3078. [PMID: 37354059 DOI: 10.1111/ene.15954] [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] [Received: 04/03/2023] [Revised: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 06/26/2023]
Abstract
BACKGROUND AND PURPOSE The lack of reliable early biomarkers still causes substantial diagnostic delays in amyotrophic lateral sclerosis (ALS). The aim was to assess the diagnostic accuracy of a novel electrophysiological protocol in patients with suspected motor neuron disease (MND). METHODS Consecutive patients with suspected MND were prospectively recruited at our tertiary referral centre for MND in Utrecht, The Netherlands. Procedures were performed in accordance with the Standards for Reporting of Diagnostic Accuracy. In addition to the standard diagnostic workup, an electrophysiological protocol of compound muscle action potential (CMAP) scans and nerve excitability tests was performed on patients' thenar muscles. The combined diagnostic yield of nerve excitability and CMAP scan based motor unit number estimation was compared to the Awaji and Gold Coast criteria and their added value was determined. RESULTS In all, 153 ALS or progressive muscular atrophy patients, 63 disease controls and 43 healthy controls were included. Our electrophysiological protocol had high diagnostic accuracy (area under the curve [AUC] 0.85, 95% confidence interval [95% CI] 0.80-0.90), even in muscles with undetectable axon loss (AUC 0.78, 95% CI 0.70-0.85) and in bulbar-onset patients (AUC 0.85, 95% CI 0.73-0.95). Twenty-four of 33 (73%) ALS patients who could not be diagnosed during the same visit were correctly identified, as well as 8/13 (62%) ALS patients not meeting the Gold Coast criteria and 49/59 (83%) ALS patients not meeting the Awaji criteria during this first visit. CONCLUSIONS Our practical and non-invasive electrophysiological protocol may improve early diagnosis in clinically challenging patients with suspected ALS. Routine incorporation may boost early diagnosis, enhance patient selection and generate baseline measures for clinical trials.
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Affiliation(s)
- D J L Stikvoort García
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | - B T H M Sleutjes
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | - L J van Schelven
- Department of Medical Technology and Clinical Physics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - H S Goedee
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | - L H van den Berg
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
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Tyberghein M, Janssen A, Wang FC. Strength-duration time constant and rheobase measurements: Comparison of the threshold tracking method and a manual procedure. Clin Neurophysiol 2023; 154:27-33. [PMID: 37541074 DOI: 10.1016/j.clinph.2023.06.026] [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] [Received: 04/25/2023] [Revised: 05/22/2023] [Accepted: 06/29/2023] [Indexed: 08/06/2023]
Abstract
OBJECTIVE To compare the strength-duration time constant (SDTC) and rheobase measurements obtained by the threshold tracking method (TT) and by a non-automated method (MM). METHODS The MM procedure involved measuring, using a routine electrodiagnostic device, the intensity required to evoke a motor response whose amplitude corresponds to 40% of the maximum amplitude for four stimulus duration (1.0, 0.7, 0.5, 0.2 ms), and studying the linear relationship between stimulus charge and stimulus duration (slope = rheobase, intercept on the x-axis = SDTC). Using TT and MM, 30 successive healthy subjects (mean age = 38 years old) underwent a prospective evaluation of SDTC and rheobase of the median nerve motor axons at the wrist. Nerve stimulation and bipolar recording of evoked motor responses were performed with disposable self-adhesive surface electrodes. RESULTS The Spearman correlations between the two methods were 0.78 (p < 0.0001) for SDTC and 0.96 (p < 0.0001) for the rheobase. The Bland-Altman analysis did not reveal any systematic bias of MM compared to TT. CONCLUSIONS The MM procedure was reliable for strength-duration relationship analysis. SIGNIFICANCE We encourage neurophysiologists, who do not have dedicated threshold tracking equipment, not to hesitate to use these simple tools to assess peripheral nerve excitability.
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Affiliation(s)
- Maelle Tyberghein
- CHU Liège, Department of Neurophysiology, Sart Tilman B35, 4000 Liège, Belgium
| | - Arnaud Janssen
- CHU Liège, Department of Neurophysiology, Sart Tilman B35, 4000 Liège, Belgium
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Ros LA, Sleutjes BT, Stikvoort García DJ, Goedee HS, Asselman FL, van den Berg LH, van der Pol WL, Wadman RI. Feasibility and tolerability of multimodal peripheral electrophysiological techniques in a cohort of patients with spinal muscular atrophy. Clin Neurophysiol Pract 2023; 8:123-131. [PMID: 37554725 PMCID: PMC10404501 DOI: 10.1016/j.cnp.2023.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 05/27/2023] [Accepted: 06/17/2023] [Indexed: 08/10/2023] Open
Abstract
OBJECTIVE Electrophysiological techniques are emerging as an aid in identifying prognostic or therapeutic biomarkers in patients with spinal muscular atrophy (SMA), but electrophysiological assessments may be burdensome for patients. We, therefore, assessed feasibility and tolerability of multimodal peripheral non-invasive electrophysiological techniques in a cohort of patients with SMA. METHODS We conducted a single center, longitudinal cohort study investigating the feasibility and tolerability of applying multimodal electrophysiological techniques to the median nerve unilaterally. Techniques consisted of the compound muscle action potential scan, motor nerve excitability tests, repetitive nerve stimulation and sensory nerve action potential. We assessed tolerability using the numeric rating scale (NRS), ranging from 0 (no pain) to 10 (worst possible pain), and defined the protocol to be tolerable if the NRS score ≤ 3. The protocol was considered feasible if it could be performed according to test and quality standards. RESULTS We included 71 patients with SMA types 1-4 (median 39 years; range 13-67) and 63 patients at follow-up. The protocol was feasible in 98% of patients and was well-tolerated in up to 90% of patients. Median NRS score was 2 (range 0-6 at baseline and range 0-4 at follow-up (p < 0.01)). None of the patients declined follow-up assessment. CONCLUSIONS Multimodal, peripheral, non-invasive, electrophysiological techniques applied to the median nerve are feasible and well-tolerated in adolescents and adults with SMA types 1-4. SIGNIFICANCE Our study supports the use of non-invasive multimodal electrophysiological assessments in adolescents and adults with SMA types 1-4.
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Affiliation(s)
- Leandra A.A. Ros
- Department of Neurology, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands
| | - Boudewijn T.H.M. Sleutjes
- Department of Neurology, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands
| | - Diederik J.L. Stikvoort García
- Department of Neurology, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands
| | - H. Stephan Goedee
- Department of Neurology, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands
| | - Fay-Lynn Asselman
- Department of Neurology, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands
| | - Leonard H. van den Berg
- Department of Neurology, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands
| | | | - Renske I. Wadman
- Corresponding author at: Department of Neurology, University Medical Center Utrecht, UMC Utrecht Brain Center, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands.
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Ros LAA, Goedee HS, Franssen H, Asselman FL, Bartels B, Cuppen I, van Eijk RPA, Sleutjes BTHM, van der Pol WL, Wadman RI. Longitudinal prospective cohort study to assess peripheral motor function with extensive electrophysiological techniques in patients with Spinal Muscular Atrophy (SMA): the SMA Motor Map protocol. BMC Neurol 2023; 23:164. [PMID: 37095427 PMCID: PMC10124000 DOI: 10.1186/s12883-023-03207-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 04/14/2023] [Indexed: 04/26/2023] Open
Abstract
BACKGROUND Hereditary spinal muscular atrophy (SMA) is a motor neuron disorder with a wide range in severity in children and adults. Two therapies that alter splicing of the Survival Motor Neuron 2 (SMN2) gene, i.e. nusinersen and risdiplam, improve motor function in SMA, but treatment effects vary. Experimental studies indicate that motor unit dysfunction encompasses multiple features, including abnormal function of the motor neuron, axon, neuromuscular junction and muscle fibres. The relative contributions of dysfunction of different parts of the motor unit to the clinical phenotype are unknown. Predictive biomarkers for clinical efficacy are currently lacking. The goals of this project are to study the association of electrophysiological abnormalities of the peripheral motor system in relation to 1) SMA clinical phenotypes and 2) treatment response in patients treated with SMN2-splicing modifiers (nusinersen or risdiplam). METHODS We designed an investigator-initiated, monocentre, longitudinal cohort study using electrophysiological techniques ('the SMA Motor Map') in Dutch children (≥ 12 years) and adults with SMA types 1-4. The protocol includes the compound muscle action potential scan, nerve excitability testing and repetitive nerve stimulation test, executed unilaterally at the median nerve. Part one cross-sectionally assesses the association of electrophysiological abnormalities in relation to SMA clinical phenotypes in treatment-naïve patients. Part two investigates the predictive value of electrophysiological changes at two-months treatment for a positive clinical motor response after one-year treatment with SMN2-splicing modifiers. We will include 100 patients in each part of the study. DISCUSSION This study will provide important information on the pathophysiology of the peripheral motor system of treatment-naïve patients with SMA through electrophysiological techniques. More importantly, the longitudinal analysis in patients on SMN2-splicing modifying therapies (i.e. nusinersen and risdiplam) intents to develop non-invasive electrophysiological biomarkers for treatment response in order to improve (individualized) treatment decisions. TRIAL REGISTRATION NL72562.041.20 (registered at https://www.toetsingonline.nl . 26-03-2020).
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Affiliation(s)
- Leandra A A Ros
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - H Stephan Goedee
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - Hessel Franssen
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - Fay-Lynn Asselman
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - Bart Bartels
- Child Development and Exercise Centre, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Inge Cuppen
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - Ruben P A van Eijk
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
- Biostatistics and Research Support, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Boudewijn T H M Sleutjes
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - W Ludo van der Pol
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - Renske I Wadman
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands.
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Sleutjes BTHM, Stikvoort García DJL, Kovalchuk MO, Heuberger JAAC, Groeneveld GJ, Franssen H, van den Berg LH. Acute retigabine-induced effects on myelinated motor axons in amyotrophic lateral sclerosis. Pharmacol Res Perspect 2022; 10:e00983. [PMID: 35881020 PMCID: PMC9318643 DOI: 10.1002/prp2.983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 06/11/2022] [Accepted: 06/15/2022] [Indexed: 11/24/2022] Open
Abstract
Altered motor neuron excitability in patients with amyotrophic lateral sclerosis (ALS) has been suggested to be an early pathophysiological mechanism associated with motor neuron death. Compounds that affect membrane excitability may therefore have disease‐modifying effects. Through which mechanism(s), these compounds modulate membrane excitability is mostly provided by preclinical studies, yet remains challenging to verify in clinical studies. Here, we investigated how retigabine affects human myelinated motor axons by applying computational modeling to interpret the complex excitability changes in a recent trial involving 18 ALS patients. Compared to baseline, the post‐dose excitability differences were modeled well by a hyperpolarizing shift of the half‐activation potential of slow potassium (K+)‐channels (till 2 mV). These findings verify that retigabine targets slow K+‐channel gating and highlight the usefulness of computational models. Further developments of this approach may facilitate the identification of early target engagement and ultimately aid selecting responders leading to more personalized treatment strategies.
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Affiliation(s)
- Boudewijn T H M Sleutjes
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Maria O Kovalchuk
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | | | - Hessel Franssen
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Leonard H van den Berg
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
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Stikvoort García DJL, Kovalchuk MO, Goedee HS, van Schelven LJ, van den Berg LH, Franssen H, Sleutjes BTHM. Motor unit integrity in multifocal motor neuropathy: A systematic evaluation with CMAP scans. Muscle Nerve 2021; 65:317-325. [PMID: 34854491 PMCID: PMC9300115 DOI: 10.1002/mus.27469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 11/18/2021] [Accepted: 11/23/2021] [Indexed: 11/09/2022]
Abstract
Introduction/Aims Progressive axonal loss in multifocal motor neuropathy (MMN) is often assessed with nerve conduction studies (NCS), by recording maximum compound muscle action potentials (CMAPs). However, reinnervation maintains the CMAP amplitude until a significant portion of the motor unit (MU) pool is lost. Therefore, we performed more informative CMAP scans to study MU characteristics in a large cohort of patients with MMN. Methods We derived the maximum CMAP amplitude (CMAPmax), an MU number estimate (MUNE), and the largest MU amplitude stimulus current required to elicit 5%, 50%, and 95% of CMAPmax (S5, S50, S95) and relative ranges ([S95 − S5] × 100 / S50) from the scans. These metrics were compared with clinical, laboratory, and NCS results. Results Forty MMN patients and 24 healthy controls were included in the study. CMAPmax and MUNE were reduced in MMN patients (both P < .001). Largest MU amplitude as a percentage of CMAPmax was increased in MMN patients (P < .001). Disease duration and treatment duration were not associated with MUNE. Relative range was larger in patients with anti‐GM1 antibodies than in those without anti‐GM1 antibodies (P = .016) and controls (P < .001). The largest MU amplitudes were larger in patients without anti‐GM1 antibodies than in patients with anti‐GM1 antibodies (P = .037) and controls (P = .044). Discussion We found that MU loss is common in MMN and accompanied by enlarged MUs. Presence of anti‐GM1 antibodies was associated with increased relative range of MU thresholds and reduction in largest MU amplitude. Our findings indicate that CMAP scans complement routine NCS, and may have potential for practical monitoring of treatment efficacy and disease progression.
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Affiliation(s)
| | - Maria O Kovalchuk
- Department of Neurology, Brain Centre Utrecht, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - H Stephan Goedee
- Department of Neurology, Brain Centre Utrecht, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Leonard J van Schelven
- Department of Medical Technology and Clinical Physics, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Leonard H van den Berg
- Department of Neurology, Brain Centre Utrecht, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Hessel Franssen
- Department of Neurology, Brain Centre Utrecht, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Boudewijn T H M Sleutjes
- Department of Neurology, Brain Centre Utrecht, University Medical Centre Utrecht, Utrecht, The Netherlands
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Klein CS, Rymer WZ, Fisher MA. Altered nerve excitability properties after stroke are potentially associated with reduced neuromuscular activation. Clin Neurophysiol 2020; 131:1407-1418. [PMID: 32184063 DOI: 10.1016/j.clinph.2020.02.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 01/22/2020] [Accepted: 02/16/2020] [Indexed: 12/17/2022]
Abstract
OBJECTIVE To determine limb differences in motor axon excitability properties in stroke survivors and their relation to maximal electromyographic (EMG) activity. METHODS The median nerve was stimulated to record compound muscle action potentials (CMAP) from the abductor pollicis brevis (APB) in 28 stroke subjects (57.3 ± 7.5 y) and 24 controls (56.7 ± 9.3 y). RESULTS Paretic limb axons differed significantly from non-paretic limb axons including (1) smaller superexcitability and subexcitability, (2) higher threshold during subthreshold depolarizing currents, (3) greater accommodation (S3) to hyperpolarization, and (4) a larger stimulus-response slope. There were smaller differences between the paretic and control limbs. Responses in the paretic limb were reproduced in a model by a 5.6 mV hyperpolarizing shift in the activation voltage of Ih (the current activated by hyperpolarization), together with an 11.8% decrease in nodal Na+ conductance or a 0.9 mV depolarizing shift in the Na+ activation voltage. Subjects with larger deficits in APB maximal voluntary EMG had larger limb differences in excitability properties. CONCLUSIONS Stroke leads to altered modulation of Ih and altered Na+ channel properties that may be partially attributed to a reduction in neuromuscular activation. SIGNIFICANCE Plastic changes occur in the axon node and internode that likely influence axon excitability.
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Affiliation(s)
- C S Klein
- Guangdong Work Injury Rehabilitation Center, Guangzhou 510440, China; Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA.
| | - W Z Rymer
- Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA; Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - M A Fisher
- Department of Neurology, Hines VAH, Hines, IL 60141, USA; Loyola University Chicago Medical Center, 2160 S. First Ave., Maywood, IL 60153, USA
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