Association of paraspinal and diaphragm denervation in ALS.
Paraspinal EMG needle examination is commonly performed in amyotrophic lateral sclerosis (ALS) for diagnosis. Because lower motor neurons for axial muscles and diaphragm are located medially in the anterior horn, we tested if involvement of axial muscles is associated with diaphragm weakness in ALS. Forty-four ALS patients were included with ALSFRS greater than 20/40. We used needle EMG to search for signs of denervation in biceps, tibialis anterior, C6 and T5 paraspinal muscles, and intercostal and diaphragm muscles. We also evaluated phrenic nerve motor responses and forced vital capacity (FVC). We tested specificity, sensitivity, and discriminative strength (ROC analysis). Fibs-sw in C6 and T5 paraspinal muscles, as well as fibs-sw in diaphragm and intercostal muscles showed high specificity and positive predictive value for FVC<80%. Discriminative strength was good for all the above tests, as well as for phrenic nerve amplitude and ALSFRS regarding FVC<80%. Axial muscles denervation is related to diaphragm denervation and therefore to poor respiratory function in ALS. We suggest that medially located lower motor neurons are affected concurrently in ALS.
de Carvalho
Mamede
M
Department of Neurology, St Maria Hospital, Institute of Molecular Medicine, Lisbon, Portugal. mamedemg@mail.telepac.pt <mamedemg@mail.telepac.pt>
Pinto
Susana
S
Swash
Michael
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000150:complications / Q000503:physiopathology*; D001132:Arm; D001415:Back; D003964:Diaphragm / Q000294:innervation* / Q000503:physiopathology*; D004576:Electromyography; D006801:Humans; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology; D018908:Muscle Weakness / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000294:innervation* / Q000503:physiopathology*; D009410:Nerve Degeneration / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D010791:Phrenic Nerve / Q000503:physiopathology; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity