What are the effects of halogenated agents on the cortical SSEP?

Halogenated agents, such as isoflurane or sevoflurane, are known to have significant effects on the central nervous system, including the cortical somatosensory evoked potentials (SSEPs). When these agents are administered, they typically result in an increase in latencies of the SSEP components alongside a decrease in amplitudes.

The increase in latencies indicates that the transmission of sensory information through the neural pathways is slowed down as a result of the anesthetic influence on neural conduction. This slowing can stem from various mechanisms, including the alteration of axonal conduction velocities due to the effects of halogenated agents on neuronal membranes.

Concurrently, the observed decrease in amplitudes reflects a reduction in the strength of the response generated by the cortical neurons in response to the sensory stimulus. This can be attributed to the overall depression of neuronal excitability and synaptic transmission that halogenated agents cause.

This information highlights the important consideration of monitoring SSEPs during surgeries utilizing halogenated anesthetics, as the changes can impact the interpretation and the clinical decision-making related to the integrity of the neural pathways being monitored.