Introduction: To test the hypothesis of impaired cholinergic activity in amyotrophic lateral sclerosis (ALS), we studied short‐ and long‐latency afferent inhibition (SAI and LAI). Methods: The ulnar nerve was stimulated at the wrist preceding transcranial magnetic stimulation (TMS), 21 ms for SAI and 200 ms for LAI, in 21 patients and 17 control subjects. Short‐interval intracortical inhibition (SICI) and cognitive function was assessed in ALS patients using automatic threshold tracking and the Montreal Cognitive Assessment (MoCA). Results: The SAI paradigm resulted in inhibition in all control subjects, whereas inhibition was observed in 13 of 21 (62%) patients. Mean SAI and LAI values were significantly reduced in ALS. No significant correlation existed between afferent inhibition and other neurophysiological data. The MoCA was normal in all but 1 patient. Discussion: LAI and SAI are both impaired in ALS, probably unrelated to increased cortical excitability or cognitive dysfunction. Muscle Nerve 59:699–704, 2019
Purpose: In addition to motor cortex involvement, sensory abnormalities have been demonstrated in amyotrophic lateral sclerosis (ALS), including structural and metabolic alterations in the occipital cortex. The aim of this study was to examine occipital excitability changes in ALS. Methods: Twenty-one patients with ALS and 16 healthy subjects were enrolled into the study. Phosphene experience and phosphene threshold were studied to assess occipital excitability. Cognitive function was evaluated in both groups by means of Montreal Cognitive Assessment and Addenbrooke's Cognitive Examination-Revised visuospatial score tests. Results: Phosphene was experienced in 13 (81.3%) healthy subjects and 9 (42.9%) patients with ALS (P ¼ 0.04). The mean phosphene threshold was not significantly different between the two groups. No correlation existed between phosphene threshold and motor cortical excitability parameters, ALS Functional Rating Scale Revised, Montreal Cognitive Assessment, and Addenbrooke's Cognitive Examination-Revised scores.Conclusions: Visual cortex is affected, and the occipital excitability is reduced in ALS, without any relation to motor cortical excitability changes, providing another clue suggestive of sensory involvement in ALS.
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