Intraoperative Neurophysiology Monitoring for Spinal Dysraphism

J Korean Neurosurg Soc, 2021 · DOI: https://doi.org/10.3340/jkns.2020.0124 · Published: March 1, 2021

Simple Explanation

Spinal dysraphism can lead to neurological problems, often due to lesions or cord tethering, especially affecting the lower spinal cord and nerve roots. Surgery to release the tethered cord is done to prevent further nerve damage. To help guide surgeons and improve results, they use intraoperative neurophysiological monitoring (IONM). IONM involves monitoring electrical activity in nerves and muscles during surgery. Key methods include electromyography (EMG) to check muscle activity, motor evoked potentials (MEP) to test nerve pathways, and the bulbocavernosus reflex (BCR) to assess sacral nerve function. Sensory evoked potentials (SEP) can also provide extra information. Careful monitoring of the sacral nerves is crucial because tethered cord syndrome often impacts sacral function first. The BCR test is useful for this and can help predict problems after surgery. However, there's a need for more precise ways to measure and assess the sacral autonomic nervous system during these procedures.

Study Duration

Not specified

Participants

Not specified

Evidence Level

Review Article

Key Findings

1
Free-running EMG and triggered EMG are highly useful for identifying lumbosacral roots during surgery.
2
Absence of responses at higher stimulation intensities can confirm the filum terminale or non-functioning cord.
3
BCR monitoring is useful for predicting postoperative sacral dysfunction.

Research Summary

Intraoperative neurophysiological monitoring (IONM) is crucial during untethering surgery for spinal dysraphism to minimize neurological risks and maximize surgical efficacy. Key IONM modalities include EMG, MEP, and BCR, with SEP offering additional insights, particularly for sacral monitoring, as the sacral nervous system is highly vulnerable in tethered cord syndrome (TCS). Further research is needed to develop quantitative, objective evaluation methods and to directly measure the sacral autonomic nervous system, as current techniques primarily focus on the somatic nervous system.

Practical Implications

Surgical Guidance

IONM provides real-time feedback to surgeons, helping them to identify and preserve critical neural structures during untethering surgery.

Risk Reduction

The use of IONM modalities like EMG, MEP, and BCR can reduce the risk of postoperative neurological deficits, especially in the sacral region.

Improved Outcomes

Early surgical intervention guided by IONM can lead to superior long-term functional outcomes for patients with spinal dysraphism and tethered cord syndrome.

Study Limitations

1
Current IONM techniques are deficient in quantitative and objective evaluation.
2
Existing methods fail to directly measure the sacral autonomic nervous system.
3
Randomized controlled trials comparing IONM application are not available.

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