Early Detection of Contrast-Induced Encephalopathy Using Somatosensory Evoked Potential Monitoring during Coil Embolization of an Intracranial Aneurysm.

Objective: Contrast-induced encephalopathy (CIE) is a rare complication of endovascular procedures with an incompletely understood pathophysiology. Its intraoperative detection under general anesthesia can be challenging. We present a case of CIE occurring during aneurysm embolization, demonstrating varying severity across procedures and suggesting that somatosensory evoked potentials (SEPs) may help in early recognition.

Case presentation: A 63-year-old woman underwent endovascular coil embolization for a ruptured distal anterior cerebral artery aneurysm under general anesthesia, with intraoperative transcranial SEP monitoring. Contrast injection from the cervical internal carotid artery (ICA) during the procedure caused transient SEP attenuation, leading to mild post-procedural paresis and sensory impairment in the patient, both of which resolved within days. Six months later, DSA from the common carotid artery confirmed coil compaction. The patient underwent the examination and showed no signs of developing neurological symptoms. Repeat embolization was performed in the following month. During the 2nd procedure, contrast injection from the C1 segment of the ICA resulted in complete loss of left lower limb SEP. Immediately after the procedure, she exhibited mild left lower limb paresis and sensory impairment. Immediate postoperative cone-beam CT revealed contrast enhancement in the right hemisphere, leading to a diagnosis of CIE. On the following day, she developed left hemispatial neglect, along with worsening left hemiparesis and sensory impairment, despite no apparent abnormalities on MRI. The deficits improved with steroid therapy and were resolved by day 6.

Conclusion: Intraoperative SEP monitoring may be useful for the early detection of CIE during aneurysm embolization.