Temperature effects on feline cortical and spinal evoked potentials

Area of Science:

• Neuroscience
• Physiology
• Anesthesiology

Background:

• Somatosensory evoked potentials (SEPs) are crucial for monitoring neural pathway integrity during surgery.
• The impact of hypothermia on SEPs, particularly cortical and spinal components, requires detailed investigation.

Purpose of the Study:

• To investigate the effects of induced hypothermia on both cortical and spinal somatosensory evoked potentials.
• To assess the reversibility of these effects upon rewarming.

Main Methods:

• Baseline cortical and spinal evoked responses were recorded in five cats at normal body temperature.
• Body temperature was reduced by 5-6°C, and evoked responses were re-recorded.
• Responses were recorded again after rewarming the animals to their original normal temperatures.

Main Results:

• Cooling increased spinal evoked response latency by an average of 40%, with waveform changes in three cats.
• Cortical evoked responses also showed increased latency with greater waveform variability and slower recovery post-rewarming.
• Rewarming normalized spinal evoked response latency and waveform, but cortical responses showed slower recovery.

Conclusions:

• Hypothermia has a deleterious, yet reversible, effect on somatosensory evoked potentials.
• The findings suggest differential vulnerability of cortical and spinal pathways to hypothermia.
• Maintaining normal patient temperature during spinal surgery is recommended until the physiological effects of cooling are better understood.