Measurement of Active Motor Threshold Using a Dynamometer During Navigated Transcranial Magnetic Stimulation in a...

Area of Science:

• Neurosurgery
• Neurology
• Neurophysiology

Background:

• Navigated transcranial magnetic stimulation (nTMS) is crucial for brain tumor patients, often requiring electrophysiological responses.
• Active motor threshold (AMT) measurement is vital for nTMS, but patient-related factors like sustained muscle contraction can impede accuracy.
• Standard AMT measurement techniques may fail when patients cannot maintain steady muscle contractions, necessitating alternative methods.

Observation:

• A case study involving a 68-year-old woman with recurrent oligodendroglioma demonstrated challenges in standard AMT measurement due to paresis.
• The patient's inability to sustain muscle contraction hindered conventional AMT assessment during nTMS.
• A hand dynamometer was successfully employed to facilitate sustained muscle contraction for AMT measurement in this patient.

Findings:

• The hand dynamometer provided counter force and stabilization, enabling consistent muscle contraction for accurate AMT assessment.
• Real-time numerical feedback on the device aided both the patient and examiner in achieving the required sustained contraction.
• This method proved effective in obtaining necessary electrophysiological data for nTMS in a challenging clinical scenario.

Implications:

• The hand dynamometer offers a practical solution for obtaining AMT measures in nTMS when patients struggle with sustained muscle contractions.
• This technique can enhance the reliability of nTMS for brain tumor patients with motor deficits.
• Further validation studies are recommended to integrate this simple device into routine nTMS protocols.