Abstract
Background: Brain tumors can cause different changes in excitation and inhibition at the neuronal network level. These changes can be generated from mechanical and cellular alterations, often manifesting clinically as seizures.Objective/Hypothesis: The effects of brain tumors on cortical excitability (CE) have not yet been well-evaluated. The aim of the current study was to further investigate cortical–cortical and cortical–spinal excitability in patients with brain tumors using a more extensive transcranial magnetic stimulation protocol.Methods: We evaluated CE on 12 consecutive patients with lesions within or close to the precentral gyrus, as well as in the subcortical white matter motor pathways. We assessed resting and active motor threshold, short-latency intracortical inhibition (SICI), intracortical facilitation (ICF), short-latency afferent inhibition (SAI), long-latency afferent inhibition, cortical silent period, and interhemispheric inhibition.Results: CE was reduced in patients with brain tumors than in healthy controls. In addition, SICI, ICF, and SAI were lower in the affected hemisphere compared to the unaffected and healthy controls.Conclusions: CE is abnormal in hemispheres affected by brain tumors. Further studies are needed to determine if CE is related with motor impairment.
Highlights
The “maximal safe resection” represents the goal standard of the modern surgical treatment of brain tumors located in eloquent areas
resting motor threshold (RMT) and active MT (AMT) were significantly higher in patients, especially in the affected hemisphere, than in healthy controls
We showed that short-latency intracortical inhibition (SICI), intracortical facilitation (ICF), and short-latency afferent inhibition (SAI) are reduced in the affected hemisphere compared to the unaffected and healthy controls
Summary
The “maximal safe resection” represents the goal standard of the modern surgical treatment of brain tumors located in eloquent areas. Rosenstock et al showed that an abnormal interhemispheric resting motor threshold (RMT) ratio was related to a higher risk for poor postoperative outcome in the 1st week, but not in the following 3 months [7]. This proposed stratification model, based on functional–anatomical and neurophysiological measures, could allow quantification of the functional impairment or recovery potential. Brain tumors can cause different changes in excitation and inhibition at the neuronal network level These changes can be generated from mechanical and cellular alterations, often manifesting clinically as seizures
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