Abstract: P379
Type: Poster
Abstract Category: Clinical aspects of MS - 8 Clinical assessment tools
Background: McArdle's Sign (McS) refers to rapidly reversible motor weakness induced by head flexion in patients with multiple sclerosis (MS).
Objective: We quantified McS in finger extensors using a torque measuring device and assessed its specificity for MS.
Methods: We enrolled 25 healthy controls (HC) and 76 patients with detectable finger extensor weakness, 52 with MS, 24 with other myelopathies (OM), 5 with peripheral nerve lesions (PNL); patients were not selected for having McS. We evaluated McS blinded to diagnosis by measuring change in finger extensor strength in successive trials of head extension and flexion, first clinically and then with a torque measuring device. McS was clinically rated from 0 (absent) to 3 (marked). In the quantitative measurement, the patient applied maximum extension strength of 4 fingers on a bar using isometric (against fixed object) and isoinertial (against a constant resistance) maneuvers; we averaged the percentage decrease in strength over 4 trials.
Results: Baseline strength was similar in the 3 patient groups. The median clinical McS was 1 (range 0-3) in MS patients, 0 (0-2) in OM, 0 (0-1) in HC and 0 in all PNL (p< 0.001). The isometric and isoinertial maneuvers provided similar quantitative results, but the isoinertial maneuver had superior diagnostic performance. Head flexion resulted in 17% (±17%) isoinertial strength reduction in MS patients versus 1% (±6%) in OM, 1% (±5%) in HC and -3% (±10%) in PNL (p< 0.0001). A multivariate regression analysis eliminated confounding by baseline strength. Receiver operator curves were generated to assess the diagnostic properties of the test; the area under the curve was 0.82 in MS versus HC and 0.83 in MS versus OM for isoinertial testing. A 10% drop in strength with flexion was 100% specific and 62% sensitive for MS compared to OM and a 6% drop 92% specific and 73% sensitive for MS compared to HC. Quantitative McS correlated with clinical McS by referring physician and technician (r=0.58,
p< 0.001). McS correlated with Expanded Disability Status Scale (r=0.41, p=0.002) and pyramidal score (r=0.49, p< 0.001) in patients with MS, but was evident in some patients in very early phases of MS and minor disability.
Conclusion: McS, when defined as >10% neck flexion-induced reduction using isoinertial finger extension on a measurement device is highly specific and moderately sensitive for a diagnosis of MS. McS may facilitate diagnosis of MS in certain clinical situations.
Disclosure:
Filippo Savoldi has nothing to disclose.
Zahra Nasr has nothing to disclose.
Wei Hu has nothing to disclose.
Nathan Schilaty has nothing to disclose.
Adriana M. Delgado has nothing to disclose.
Jay Mandrekar has nothing to disclose.
Kenton Kaufman has nothing to disclose.
Lawrence Berglund has nothing to disclose.
Brian G. Weinshenker receives royalties from RSR Ltd, Oxford University, Hospices Civil de Lyon, and MVZ Labor PD Dr. Volkmann und Kollegen GbR for a patent of NMO-IgG as a diagnostic test for NMO and related disorders. He serves as a member of an adjudication committee for clinical trials in NMO being conducted by MedImmune and Alexion pharmaceutical companies. He is a consultant for Caladrius Biosciences regarding a clinical trial for NMO. He serves as a member of a data safety monitoring committee for clinical trials conducted by Novartis.
Abstract: P379
Type: Poster
Abstract Category: Clinical aspects of MS - 8 Clinical assessment tools
Background: McArdle's Sign (McS) refers to rapidly reversible motor weakness induced by head flexion in patients with multiple sclerosis (MS).
Objective: We quantified McS in finger extensors using a torque measuring device and assessed its specificity for MS.
Methods: We enrolled 25 healthy controls (HC) and 76 patients with detectable finger extensor weakness, 52 with MS, 24 with other myelopathies (OM), 5 with peripheral nerve lesions (PNL); patients were not selected for having McS. We evaluated McS blinded to diagnosis by measuring change in finger extensor strength in successive trials of head extension and flexion, first clinically and then with a torque measuring device. McS was clinically rated from 0 (absent) to 3 (marked). In the quantitative measurement, the patient applied maximum extension strength of 4 fingers on a bar using isometric (against fixed object) and isoinertial (against a constant resistance) maneuvers; we averaged the percentage decrease in strength over 4 trials.
Results: Baseline strength was similar in the 3 patient groups. The median clinical McS was 1 (range 0-3) in MS patients, 0 (0-2) in OM, 0 (0-1) in HC and 0 in all PNL (p< 0.001). The isometric and isoinertial maneuvers provided similar quantitative results, but the isoinertial maneuver had superior diagnostic performance. Head flexion resulted in 17% (±17%) isoinertial strength reduction in MS patients versus 1% (±6%) in OM, 1% (±5%) in HC and -3% (±10%) in PNL (p< 0.0001). A multivariate regression analysis eliminated confounding by baseline strength. Receiver operator curves were generated to assess the diagnostic properties of the test; the area under the curve was 0.82 in MS versus HC and 0.83 in MS versus OM for isoinertial testing. A 10% drop in strength with flexion was 100% specific and 62% sensitive for MS compared to OM and a 6% drop 92% specific and 73% sensitive for MS compared to HC. Quantitative McS correlated with clinical McS by referring physician and technician (r=0.58,
p< 0.001). McS correlated with Expanded Disability Status Scale (r=0.41, p=0.002) and pyramidal score (r=0.49, p< 0.001) in patients with MS, but was evident in some patients in very early phases of MS and minor disability.
Conclusion: McS, when defined as >10% neck flexion-induced reduction using isoinertial finger extension on a measurement device is highly specific and moderately sensitive for a diagnosis of MS. McS may facilitate diagnosis of MS in certain clinical situations.
Disclosure:
Filippo Savoldi has nothing to disclose.
Zahra Nasr has nothing to disclose.
Wei Hu has nothing to disclose.
Nathan Schilaty has nothing to disclose.
Adriana M. Delgado has nothing to disclose.
Jay Mandrekar has nothing to disclose.
Kenton Kaufman has nothing to disclose.
Lawrence Berglund has nothing to disclose.
Brian G. Weinshenker receives royalties from RSR Ltd, Oxford University, Hospices Civil de Lyon, and MVZ Labor PD Dr. Volkmann und Kollegen GbR for a patent of NMO-IgG as a diagnostic test for NMO and related disorders. He serves as a member of an adjudication committee for clinical trials in NMO being conducted by MedImmune and Alexion pharmaceutical companies. He is a consultant for Caladrius Biosciences regarding a clinical trial for NMO. He serves as a member of a data safety monitoring committee for clinical trials conducted by Novartis.