During a posterior fossa approach for acoustic neuroma removal, what most likely causes an increase in the latency of wave V?

An increase in the latency of wave V during auditory evoked potentials can be attributed to retraction of the cerebellum. This surgical maneuver can lead to tension or stretching of the auditory pathways, particularly in relation to the brainstem where wave V is generated. The retraction can affect the neural conduction velocity by imposing physical stress on the surrounding nervous tissue and potentially altering the physiological response time.

In contrast, while fluid in the ear canal might affect auditory transmission in a clinical setting, it does not specifically interfere with wave V latency during surgical procedures, as wave V is primarily assessed from central auditory pathways and not from peripheral structures. Failure to stimulate would lead to a lack of response entirely rather than an increase in latency, which is not the same as a change in timing when stimulation is successful. Similarly, loss of blood supply to the cochlea would likely affect cochlear function and potentially lead to loss of auditory nerve response, but it wouldn't specifically increase the latency of wave V during head surgery focused on neural pathways in the posterior fossa. Thus, retraction of the cerebellum is indeed the most relevant factor impacting latency in this scenario.