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Published on: March 4, 2014
Sensory and motor cortical hyperexcitability in patients with amyotrophic lateral sclerosis: are they related? a
Giovanna Squintani1, Marta Di Muzio2, Andrea Rasera3
1Neurology and Neurophysiology Unit, Azienda Ospedaliera Universitaria Integrata, Verona, Italy.
Objective:
Our study evaluates sensory and motor cortical hyperexcitability as diagnostic biomarkers in ALS patients and investigates their relationship, identifying distinct or interconnected pathophysiological mechanisms in different sub-groups.
Methods:
We examined 26 ALS patients and 18 healthy controls. Motor cortex excitability was assessed using transcranial magnetic stimulation to measure the motor evoked potential (MEP) suppression ratio. Somatosensory cortex excitability was evaluated through upper-limb somatosensory evoked potentials (SEPs) with conventional and paired-pulse techniques. Statistical analyses included parametric/non-parametric tests, correlation analyses, and χ2 tests. ROC analysis was used to assess diagnostic performance. Significance threshold was p < 0.05.
Results:
ALS patients showed a significantly reduced MEP suppression ratio (p < 0.001) with excellent discriminative power (100 % accuracy). SEP suppression ratio was significantly lower in ALS (p < 0.001), with sensitivity 76.3 %, specificity 91.7 %, and accuracy 84 %. In patients with giant SEPs, a strong inverse correlation was observed between MEP and SEP suppression ratios (r = - 0.70, p < 0.001).
Conclusions:
MEP and SEP suppression ratio are robust biomarkers of motor cortical dysfunction in ALS patients with a highlighting cortical heterogeneity between sub-groups, suggesting cortical interconnection.
Significance:
Alongside confirming motor and sensory cortical hyperexcitability as ALS hallmarks, this study reveals subgroup-specific patterns suggesting a compensatory interplay between sensory and motor cortex.
