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Hae-Won Koo, Wonhyoung Park, Kuhyun Yang, Jung Cheol Park, Jae Sung Ahn, Sun Uck Kwon, Changmo Hwang and Deok Hee Lee

Although extremely rare, retention of foreign bodies such as microcatheters or micro guidewires can occur during various neurovascular procedures due to gluing of the microcatheter tip or entanglement of the micro guidewire tip with intravascular devices. The authors have experienced 2 cases of irresolvable wire retention, one after flow diverter placement for a left cavernous internal carotid artery aneurysm and the other after intracranial stenting for acute basilar artery occlusion. The first patient presented 6 weeks after her procedure with right lung parenchymal hemorrhage due to direct piercing of the lung parenchyma after the retained wire fractured and migrated out of the aortic arch. The second patient presented 4 years after his procedure with pneumothorax due to migration of the fractured guidewire segment into the right thoracic cavity. In this report, the authors discuss the possible mechanisms of these unusual complications and how to prevent delayed consequences from a retained intravascular metallic wire.

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Jaewoo Chung, Wonhyoung Park, Seok Ho Hong, Jung Cheol Park, Jae Sung Ahn, Byung Duk Kwun, Sang-Ahm Lee, Sung-Hoon Kim and Ji-Ye Jeon

OBJECTIVE

Somatosensory and motor evoked potentials (SEPs and MEPs) are often used to prevent ischemic complications during aneurysm surgeries. However, surgeons often encounter cases with suspicious false-positive and false-negative results from intraoperative evoked potential (EP) monitoring, but the incidence and possible causes for these results are not well established. The aim of this study was to investigate the efficacy and reliability of EP monitoring in the microsurgical treatment of intracranial aneurysms by evaluating false-positive and false-negative cases.

METHODS

From January 2012 to April 2016, 1514 patients underwent surgery for unruptured intracranial aneurysms (UIAs) with EP monitoring at the authors’ institution. An EP amplitude decrease of 50% or greater compared with the baseline amplitude was defined as a significant EP change. Correlations between immediate postoperative motor weakness and EP monitoring results were retrospectively reviewed. The authors calculated the sensitivity, specificity, and positive and negative predictive values of intraoperative MEP monitoring, as well as the incidence of false-positive and false-negative results.

RESULTS

Eighteen (1.19%) of the 1514 patients had a symptomatic infarction, and 4 (0.26%) had a symptomatic hemorrhage. A total of 15 patients showed motor weakness, with the weakness detected on the immediate postoperative motor function test in 10 of these cases. Fifteen false-positive cases (0.99%) and 8 false-negative cases (0.53%) were reported. Therefore, MEP during UIA surgery resulted in a sensitivity of 0.10, specificity of 0.94, positive predictive value of 0.01, and negative predictive value of 0.99.

CONCLUSIONS

Intraoperative EP monitoring has high specificity and negative predictive value. Both false-positive and false-negative findings were present. However, it is likely that a more meticulously designed protocol will make EP monitoring a better surrogate indicator of possible ischemic neurological deficits.