M-waves are more effectively stimulated by which type of stimulation?

M-waves, or muscle action potentials, are best stimulated by anodal stimulation. Anodal stimulation involves placing a positive electrode (anode) in close proximity to the target nerve or muscle tissue, which is important for effectively activating the underlying muscle fibers. This technique enhances depolarization of the nerve membranes, making it easier to elicit a robust response.

In contrast, cathodal stimulation, which uses a negative electrode, can sometimes lead to the activation of adjacent or deeper structures rather than the targeted muscle fibers. Direct stimulation typically refers to the direct application of electrical impulses to the muscle or nerve, which may not always yield as clear or focused results as anodal stimulation specifically does. Indirect stimulation often involves pathways or additional networks, which may dilute the effectiveness of the stimulation on the muscle being tested.

Thus, the preference for anodal stimulation in eliciting M-waves can be attributed to its ability to provide a more efficient and direct approach to activating the motors neurons and achieving clearer muscle responses during intraoperative monitoring. This understanding is crucial for optimizing neuromonitoring techniques in a surgical context.