Proximal-distal motor unit number estimationdynamic changes in patients with amyotrophic lateral sclerosis A one-year follow-up

摘要

BACKGROUND:Amyotrophic lateral sclerosis(ALS) is the most common of all the motor neuron diseases and the absence of a biologic marker has made both diagnosis and tracking evolution of the disease difficult.Electrodiagnostic tests play a fundamental role in quantifying pathological changes in the motor unit pool.OBJECTIVE:We assessed distal-proximal Motor Unit(MU) loss and changes using the method of motor unit number estimation(MUNE).DESIGN,TIME AND SETTING:A case-control study was performed at the Department of Neuroscience,Pisa University Medical School,Italy from December 1999 to November 2009.PARTICIPANTS:A total of 50 ALS patients were recruited,30 males:mean age(59.6 ± 13.3) years 20 females:mean age(63.9 ± 11.7) years;range(30-82) years;all patients had probable or definite ALS.Thirty healthy volunteers were recruited from department staffs,including 20 males and 10 females;mean age(57.7 ± 13.8) years served as controls.METHODS:MUNE was performed for both the biceps brachii and abductor digiti minimi muscles o the same side.The technique used relayed substantially on manual incremental stimulation of the motor nerve,known as the McComas technique(50 ms sweep duration,a gain of 2 mV/Div for M wave,0.5 mV/Div for each step;filters 10-20 kHz).MAIN OUTCOME MEASURES:MUNE results were measured.RESULTS:Functioning MU numbers,measured by MUNE,decreased in the biceps brachii and abductor digiti minimi muscles over the entire one-year follow-up period(one assessment every three months) compared with baseline determination,the rate of MU decrease was similar in both muscles,but steeper distally.CONCLUSION:MUNE is a feasible method for ALS patients both proximally and distally to track changes over time in muscle MUs during the disease's evolution.