In SSEPs during spinal cord ischemia, how is the waveform affected?

In SSEPs during spinal cord ischemia, how is the waveform affected?

• A. Increased amplitude and increased latency
• B. Decreased amplitude and increased latency
• C. Decreased amplitude and decreased latency
• D. Increased amplitude and decreased latency

Answer: (B)

Spinal cord ischemia slows conduction through the somatosensory pathways and reduces the number of functioning fibers, so SSEPs become smaller and occur later. Ischemia causes metabolic failure and demyelination/axonal injury in the dorsal columns, which lengthens the time it takes for the signal to reach the cortex (latency increases) and diminishes the synchronized, total neural input reaching the cortex (amplitude decreases). If the ischemia is severe, the waveform can even disappear. This combination—decreased amplitude with increased latency—is the hallmark of spinal cord ischemia on SSEPs.

Spinal cord ischemia slows conduction through the somatosensory pathways and reduces the number of functioning fibers, so SSEPs become smaller and occur later. Ischemia causes metabolic failure and demyelination/axonal injury in the dorsal columns, which lengthens the time it takes for the signal to reach the cortex (latency increases) and diminishes the synchronized, total neural input reaching the cortex (amplitude decreases). If the ischemia is severe, the waveform can even disappear. This combination—decreased amplitude with increased latency—is the hallmark of spinal cord ischemia on SSEPs.