Electrophysiological evaluations, including nerve conduction studies and needle electromyography (EMG), remain the most critical tools for the diagnosis of motor neuron diseases (MND). This article provides an overview of our current diagnostic strategies focusing on ALS and related MNDs. The recently proposed Gold Coast criteria for ALS allow diagnosis even in cases lacking upper motor neuron signs. Detection and distribution assessment of denervation potentials—such as fibrillation potentials and fasciculation potentials—on EMG, alongside consistency with clinical progression, still form the core of a conclusive diagnosis. Diagnostic workflows incorporate multimodal approaches, including nerve conduction studies (preservation of sensory nerve potentials), repetitive nerve stimulation tests (decremental responses), and ultrasonography (fasciculation survey and lack of nerve enlargement). Tailored, patient-specific test protocols integrating these modalities improve diagnostic accuracy in ALS.

YOUSI

In the past 50 years, near-infrared spectroscopy (NIRS) has developed into a tissue oximetry and neuroimaging technique. However, since it is difficult for NIRS to selectively and quantitatively measure tissue hemoglobin (Hb), its clinical applications are limited and it is almost exclusively used as a research tool. Since the early stages of development, various approaches have been proposed to overcome its limitations. Thanks to recent advances in technology, time-domain NIRS (TD-NRS) is being reevaluated. Furthermore, near-infrared optical tomography (NIROT), which reconstructs two- or three-dimensional distribution images of Hb concentrations, is the most promising technique. This paper outlines TD-NIRS and NIROT, and evaluates the potential of optical diagnosis.

At the end of October 2024, a committee symposium titled “Toward Appropriate Utilization of Neurophysiological Methods in Psychiatry” was held. In this symposium, the author presented the clinical usefulness and potential of the transcranial magnetic stimulation/high-precision electroencephalography simultaneous recording method (TMS-EEG method) within the context of overcoming current limitations and establishing biological markers to support psychiatric diagnosis, under the premise that no established biomarkers currently exist in the psychiatric field (excluding dementia and epilepsy). In this article, within the scope permitted by space, I will provide an overview of the TMS-EEG method, from its fundamentals to its clinical application in the psychiatric field.