SSEP Changes Due to Implant Placement in ACDF Procedures
By Admin | September 17, 2023
In the realm of anterior cervical discectomy and fusion (ACDF) procedures, the precise placement of implants is crucial for successful outcomes. Neurophysiological monitoring plays a pivotal role in ensuring this precision. In this specific instance, somatosensory evoked potentials (SSEPs) underwent significant changes during implant placement in an ACDF procedure, emphasizing neuromonitoring’s importance in improving patient outcomes during surgery.
Our patient, a 59-year-old female with no prior relevant surgical history, presented with complaints of numbness and arm pain. Following a comprehensive evaluation, she received a diagnosis of cervical spondylosis with radiculopathy and myelopathy, spinal stenosis, along with a herniated disc in the cervical region. To alleviate her symptoms and restore her quality of life, an ACDF procedure was recommended.
During the ACDF procedure, a comprehensive array of neurophysiological monitoring techniques was employed to ensure patient safety and procedural efficacy. This included monitoring of somatosensory evoked potentials (SSEPs), motor evoked potentials (MEPs), electromyography (EMG), and train-of-four (TOF/TO4) responses.
Initially, SSEPs demonstrated stable and reliable responses. However, during the placement of the first implant at the C3-4 level, a notable observation was made. The right side SSEP exhibited a substantial decrease in amplitude, ranging between 70% and 80%. Conversely, no discernible changes were noted on the left side SSEP.
Recognizing the potential significance of SSEP changes as an indicator of impending neurological compromise, the surgical team intervened.
Because a patient's shoulders can get in the way of X-rays when performing an ACDF procedure, some surgeons will put straps on the patients wrists to tug the arms downward when taking X-rays while others will tape the shoulders down out of the way. Most of the time this is not problematic, but sometimes it can cause a compression of nerves in the shoulder. If this happens for an extended period of time it can result in temporary or permanent issues. It would be similar to when you fall asleep and wake up with the “pins and needles” sensation in your arm. But, because you are under anesthesia, you can’t adjust your arm in time before it becomes a real problem.
By monitoring this with the help of IONM, surgeons can tape a patient’s arms to get the best X-rays and enjoy more accurate procedures knowing that if something adverse is occurring, it can be reversed immediately, as was the case in this surgery.
The tape on the patient’s right shoulder was removed to eliminate any potential interference. Subsequently, the implant at the C3-4 level was replaced. However, the SSEP amplitude persisted in its diminished state.
In order to restore the SSEP signals to their baseline levels, the decision was made to remove the implant once more. This time, a smaller implant was inserted at the C3-4 level. The careful adjustment in implant size and positioning yielded a significant improvement in SSEP amplitude, ultimately restoring the signals to their baseline levels.
This case exemplifies the paramount importance of neurophysiological monitoring, specifically the monitoring of SSEPs, during ACDF procedures. Without the inclusion of neurophysiology, the changes in SSEP amplitude from the implant placement may have gone unnoticed. Consequently, the patient could have faced postoperative neurological deficits in her upper right arm.
Neurophysiological monitoring, particularly SSEPs, plays an indispensable role in ACDF procedures. The case presented underscores the vigilance required in monitoring SSEP changes during implant placement. By recognizing and addressing these changes, the surgical team successfully averted potential neurological deficits, allowing the patient to experience relief from her symptoms and attain an improved quality of life.
Axis Neuromonitoring provides high-quality intraoperative neurophysiological monitoring (IONM). For more information about neuromonitoring and how our practices create the best patient outcomes, call 888-344-2947.
