Cortical excitability in amyotrophic; lateral sclerosis

ABSTRACT

The primary purpose of this study was to provide insight into the central changes that occur in amyotrophic lateral sclerosis with a view to pointing out that these could contribute to symptoms, Seventeen patients with definite ALS and 17 control healthy volunteers were included in the study. Clinical examination, amyotrophic lateral sclerosis severity score [ALSSS] and transonic magnetic stimuli investigations including measurement of resting and active motor threshold [RMT, and AMT], motor evoked potential [MEP], input-output curve, contralateral silent period and transcallosal inhibition [CSP and TI] were measured for each participant. There were no significant differences in RMT or AMT in either hemisphere between patients and the control group. Despite this there was a significant negative correlation between ALSSS and RMT, and AMT meaning that increased seventy was associated with higher thresholds. MEPs were significantly smaller in ALS patients in comparison to the control group [P=0.03]. There was a significant decrease in the slope of the I/O relationship of MEP amplitude to TMS intensity in patients group in comparison to controls. ALS patients had a significant prolongation of CSP and TI for both hemispheres. There was a tendency for there to be a significant negative correlation between left TI and ALSSS [P= 0.051]. Measurements of cortical motor excitatory and inhibitory changes in ALS confirm the presence of hypoexcitability and GABAb dysfunction, that was correlated with the severity of ALS