TY - JOUR
T1 - McArdle Sign
T2 - A Specific Sign of Multiple Sclerosis
AU - Savoldi, Filippo
AU - Nasr, Z.
AU - Hu, Wei
AU - Schilaty, Nathan D.
AU - Delgado, Adriana M.
AU - Mandrekar, Jay
AU - Kaufman, Kenton R.
AU - Berglund, Lawrence
AU - Weinshenker, Brian G.
N1 - Publisher Copyright:
© 2019 Mayo Foundation for Medical Education and Research
PY - 2019/8
Y1 - 2019/8
N2 - Objective: To measure McArdle sign (rapidly reversible weakness induced by neck flexion) both qualitatively and quantitatively and to evaluate its specificity and clinical utility for diagnosis of multiple sclerosis (MS). Patients and Methods: In this prospective study, McArdle sign was evaluated by a technician blinded to diagnosis by measuring changes in finger extensor strength in successive trials of neck extension and flexion, first clinically and then with a torque measurement device. We studied 25 healthy controls and 81 patients with finger extensor weakness. Patients were not selected for having McArdle sign. Fifty-two patients had MS, 24 had other myelopathies, and 5 had peripheral nerve lesions accounting for their weakness. The study was conducted between February 1, 2016, and June 30, 2017. Results: The median clinical McArdle sign and the 2 quantitative measures of neck flexion–induced strength reduction were greater in patients with MS than in the other groups (P<.001). Baseline strength did not confound the difference. The area under the receiver operating characteristic curve was 0.84 (95% CI, 0.75-0.93) comparing patients with MS vs healthy controls and 0.84 (95% CI, 0.75-0.93) comparing MS vs patients with other myelopathies. The 2 quantitative and 1 clinical measurement of McArdle sign by the technician who performed the quantitative testing were correlated (r=.57 and r=.58; P<.001), and in turn, the technician's and unblinded referring physician's clinical assessments were correlated (r=.58; P<.001). McArdle sign was evident in some patients who had minor disability and who were in early phases of MS. Conclusion: McArdle sign, when defined as greater than 10% neck flexion–induced reduction in strength, is entirely specific and 65% sensitive for a diagnosis of MS when compared with other conditions that mimic MS-associated myelopathy. It may facilitate diagnosis in certain clinical situations. Trial Registration: clinicaltrials.gov Identifier: NCT03122873.
AB - Objective: To measure McArdle sign (rapidly reversible weakness induced by neck flexion) both qualitatively and quantitatively and to evaluate its specificity and clinical utility for diagnosis of multiple sclerosis (MS). Patients and Methods: In this prospective study, McArdle sign was evaluated by a technician blinded to diagnosis by measuring changes in finger extensor strength in successive trials of neck extension and flexion, first clinically and then with a torque measurement device. We studied 25 healthy controls and 81 patients with finger extensor weakness. Patients were not selected for having McArdle sign. Fifty-two patients had MS, 24 had other myelopathies, and 5 had peripheral nerve lesions accounting for their weakness. The study was conducted between February 1, 2016, and June 30, 2017. Results: The median clinical McArdle sign and the 2 quantitative measures of neck flexion–induced strength reduction were greater in patients with MS than in the other groups (P<.001). Baseline strength did not confound the difference. The area under the receiver operating characteristic curve was 0.84 (95% CI, 0.75-0.93) comparing patients with MS vs healthy controls and 0.84 (95% CI, 0.75-0.93) comparing MS vs patients with other myelopathies. The 2 quantitative and 1 clinical measurement of McArdle sign by the technician who performed the quantitative testing were correlated (r=.57 and r=.58; P<.001), and in turn, the technician's and unblinded referring physician's clinical assessments were correlated (r=.58; P<.001). McArdle sign was evident in some patients who had minor disability and who were in early phases of MS. Conclusion: McArdle sign, when defined as greater than 10% neck flexion–induced reduction in strength, is entirely specific and 65% sensitive for a diagnosis of MS when compared with other conditions that mimic MS-associated myelopathy. It may facilitate diagnosis in certain clinical situations. Trial Registration: clinicaltrials.gov Identifier: NCT03122873.
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U2 - 10.1016/j.mayocp.2019.01.047
DO - 10.1016/j.mayocp.2019.01.047
M3 - Article
C2 - 31303427
AN - SCOPUS:85068558323
SN - 0025-6196
VL - 94
SP - 1427
EP - 1435
JO - Mayo Clinic proceedings
JF - Mayo Clinic proceedings
IS - 8
ER -