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Updated: Mar 20, 2026
Intracortical Inhibition Within the Primary Motor Cortex Can Be Modulated by Changing the Focus of Attention
Published on: September 11, 2017
Intracortical inhibitory and excitatory circuits in subjects with minimal hepatic encephalopathy: a TMS study
Raffaele Nardone1,2, Pierpaolo De Blasi3, Yvonne Höller4
1Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria. raffaele.nardone@asbmeran-o.it.
Abstract:
Minimal hepatic encephalopathy (MHE) is the earliest form of hepatic encephalopathy (HE) and affects up to 80 % of patients with liver cirrhosis. By definition, MHE is characterized by psychomotor slowing and subtle cognitive deficits, but obvious clinical manifestations are lacking. Given its covert nature, MHE is often underdiagnosed. This study was aimed at detecting neurophysiological changes, as assessed by means of transcranial magnetic stimulation (TMS), involved in the early pathogenesis of the HE. We investigated motor cortex excitability in 15 patients with MHE and in 15 age-matched age-matched cirrhotic patients without MHE; the resting motor threshold, the short-interval intracortical inhibition (SICI) and the intracortical facilitation (ICF) were examined. Paired-pulse TMS revealed significant increased SICI and reduced ICF in the patients with MHE. These findings may reflect abnormalities in intrinsic brain activity and altered organization of functional connectivity networks. In particular, the results suggest a shift in the balance between intracortical inhibitory and excitatory mechanisms towards a net increase of inhibitory neurotransmission. Together with other neurophysiological (in particular EEG) and neuroimaging techniques, TMS may thus provide early markers of cerebral dysfunction in cirrhotic patients with MHE.
Insights
Minimal hepatic encephalopathy (MHE) in cirrhosis patients shows altered brain activity. Transcranial magnetic stimulation revealed increased inhibition and reduced facilitation in MHE patients, suggesting early neurophysiological changes.
Area of Science:
- Neuroscience
- Gastroenterology
- Neurology
Background:
- Minimal hepatic encephalopathy (MHE) is an early, often underdiagnosed, form of hepatic encephalopathy (HE) affecting up to 80% of liver cirrhosis patients.
- MHE is characterized by subtle cognitive deficits and psychomotor slowing, lacking obvious clinical signs.
Purpose of the Study:
- To detect neurophysiological changes using transcranial magnetic stimulation (TMS) in the early stages of HE.
- To investigate motor cortex excitability in patients with MHE compared to cirrhotic patients without MHE.
Main Methods:
- Investigated motor cortex excitability in 15 MHE patients and 15 cirrhotic patients without MHE.
- Assessed resting motor threshold, short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) using paired-pulse TMS.
Main Results:
- Patients with MHE exhibited significantly increased SICI and reduced ICF.
- These findings indicate abnormalities in intrinsic brain activity and altered functional connectivity networks.
Conclusions:
- Results suggest a shift towards increased inhibitory neurotransmission in the brain of MHE patients.
- TMS may serve as an early marker for cerebral dysfunction in cirrhotic patients with MHE, complementing EEG and neuroimaging.
