Electromyography (EMG) neuromonitoring is a specialized technique used during various surgical procedures. It involves the continuous observation of nerve function in real-time. This method enhances patient safety during delicate operations where nerves are at risk.
Purpose of Neuromonitoring
The main reason for using EMG neuromonitoring is to detect and help prevent potential nerve damage during surgery. It functions as an early warning system, providing immediate feedback to surgeons if nerve irritation or injury occurs. This allows the surgical team to adjust their approach, potentially avoiding permanent neurological deficits.
This real-time information helps surgeons work with greater precision near important neural pathways. By reducing the risk of accidental nerve damage, it aims to improve patient outcomes and minimize postoperative complications.
How Neuromonitoring Works
EMG neuromonitoring operates by measuring the electrical activity produced by muscles. This electrical activity reflects the health and function of the motor nerves that supply those specific muscles. When a motor nerve is stimulated, it sends an electrical signal, causing the muscle to contract and generate a measurable electrical response.
To capture these signals, specialized electrodes are placed on or under the skin, along nerve pathways or directly into muscle tissue. These can be surface electrodes or subdermal needle electrodes for precise signal detection. The signals are transmitted to a computer system for analysis. Trained professionals monitor these signals for changes from baseline activity, which may indicate nerve compromise. The system can also trigger the stimulation of specific muscles or nerves to assess their response.
Surgical Applications
EMG neuromonitoring is used in a range of surgical procedures where nerves are vulnerable to injury. In spinal surgeries, such as those for scoliosis correction or disc herniation repair, it helps protect spinal cord pathways and individual nerve roots. For instance, during pedicle screw placement in spinal fusion surgeries, EMG can monitor nerve roots to ensure accurate screw positioning.
Brain surgeries, particularly those involving tumor removal near motor pathways, also benefit from EMG neuromonitoring. This allows surgeons to identify and preserve motor nerves within the brain, preventing postoperative weakness or paralysis. The monitoring provides feedback on the functional integrity of these pathways as the surgeon operates.
Certain Ear, Nose, and Throat (ENT) procedures, like thyroidectomy, commonly use EMG to monitor the recurrent laryngeal nerve. This nerve is responsible for vocal cord movement and is at risk during thyroid surgery due to its close anatomical proximity to the thyroid gland. Continuous monitoring alerts the surgeon to potential irritation or injury, to prevent voice changes after surgery. EMG is also used in surgeries involving the brachial or lumbosacral plexuses, which are networks of nerves in the shoulder/arm and lower back/leg regions. It is applied in procedures to resect skull base tumors or cranial nerve neuromas, where precise nerve identification and preservation are important.
Patient Experience and Safety
Before surgery involving EMG neuromonitoring, patients discuss the procedure with their surgical team. This includes an explanation of why neuromonitoring is being used and what to expect. This pre-operative communication addresses any patient concerns and ensures understanding of the process.
During the procedure, electrodes are carefully placed on the patient. Depending on the specific nerves being monitored and the type of surgery, these electrodes may be applied to the skin’s surface or inserted as fine needles into specific muscles. The placement is non-invasive or minimally invasive and ensures good contact for accurate signal detection.
A specialized monitoring team, often including a neurophysiologist or trained technologist, oversees the EMG signals throughout the surgery. They work closely with the surgeon and anesthesia team, providing real-time updates on nerve function. If significant changes in nerve activity are detected, the monitoring team alerts the surgeon, allowing for immediate adjustments to the surgical approach. Neuromonitoring is considered a safe procedure with minimal associated risks. While no surgical monitoring technique can eliminate all risks, the benefits of nerve protection outweigh minor discomfort from electrode placement. Studies suggest that intraoperative neuromonitoring can decrease neurological complication rates.