Correction: clinical utility and limitations of intraoperative monitoring of visual evoked potentials

This corrects the article DOI: 10.1371/journal.pone.0120525

Clinical Utility and Limitations of Intraoperative Monitoring of Visual Evoked Potentials

Objectives: During surgeries that put the visual pathway at risk of injury, continuous monitoring of the visual function is desirable. However, the intraoperative monitoring of the visual evoked potential (VEP) is not yet widely used. We evaluate here the clinical utility of intraoperative VEP monitoring. Methods: We analyzed retrospectively 46 consecutive surgeries in 2011-2013. High luminance stimulating devices delivered flash stimuli on the closed eyelid during intravenous anesthesia. We monitored VEP features N75 and P100 and took patients' preoperative and postoperative visual function from patient charts. Postoperative ophthalmologic workup was performed in 25 (54%) patients and preoperatively in 28 (61%) patients. Results: VEP recordings were feasible in 62 of 85 eyes (73%) in 46 patients. All 23 eyes without VEP had impaired vision. During surgery, VEPs remained stable throughout surgery in 50 eyes. In 44 of these, visual function did not deteriorate and three patients (6 eyes) developed hemianopia. VEP decreased transiently in 10 eyes and visual function of all was preserved. VEPs were lost permanently in 2 eyes in two patients without new postoperative visual impairment. Conclusions: Satisfactory intraoperative VEP monitoring was feasible in all patients except in those with severe visual impairment. Preservation of VEPs predicted preserved visual function. During resection of lesions in the visual cortex, VEP monitoring could not detect new major visual field defects due to injury in the posterior visual pathway. Intraoperative VEPs were sensitive enough to detect vascular damage during aneurysm clipping and mechanical manipulation of the anterior visual pathway in an early reversible stage. Intraoperative VEP monitoring influenced surgical decisions in selected patients and proved to be a useful supplement to the toolbox of intraoperative neurophysiological monitoring

Clinical utility and limitations of intraoperative monitoring of visual evoked potentials

OBJECTIVES During surgeries that put the visual pathway at risk of injury, continuous monitoring of the visual function is desirable. However, the intraoperative monitoring of the visual evoked potential (VEP) is not yet widely used. We evaluate here the clinical utility of intraoperative VEP monitoring. METHODS We analyzed retrospectively 46 consecutive surgeries in 2011-2013. High luminance stimulating devices delivered flash stimuli on the closed eyelid during intravenous anesthesia. We monitored VEP features N75 and P100 and took patients' preoperative and postoperative visual function from patient charts. Postoperative ophthalmologic workup was performed in 25 (54%) patients and preoperatively in 28 (61%) patients. RESULTS VEP recordings were feasible in 62 of 85 eyes (73%) in 46 patients. All 23 eyes without VEP had impaired vision. During surgery, VEPs remained stable throughout surgery in 50 eyes. In 44 of these, visual function did not deteriorate and three patients (6 eyes) developed hemianopia. VEP decreased transiently in 10 eyes and visual function of all was preserved. VEPs were lost permanently in 2 eyes in two patients without new postoperative visual impairment. CONCLUSIONS Satisfactory intraoperative VEP monitoring was feasible in all patients except in those with severe visual impairment. Preservation of VEPs predicted preserved visual function. During resection of lesions in the visual cortex, VEP monitoring could not detect new major visual field defects due to injury in the posterior visual pathway. Intraoperative VEPs were sensitive enough to detect vascular damage during aneurysm clipping and mechanical manipulation of the anterior visual pathway in an early reversible stage. Intraoperative VEP monitoring influenced surgical decisions in selected patients and proved to be a useful supplement to the toolbox of intraoperative neurophysiological monitoring

Clinical Utility and Limitations of Intraoperative Monitoring of Visual Evoked Potentials

Objectives During surgeries that put the visual pathway at risk of injury, continuous monitoring of the visual function is desirable. However, the intraoperative monitoring of the visual evoked potential (VEP) is not yet widely used. We evaluate here the clinical utility of intraoperative VEP monitoring. Methods We analyzed retrospectively 46 consecutive surgeries in 2011-2013. High luminance stimulating devices delivered flash stimuli on the closed eyelid during intravenous anesthesia. We monitored VEP features N75 and P100 and took patients' preoperative and postoperative visual function from patient charts. Postoperative ophthalmologic workup was performed in 25 (54%) patients and preoperatively in 28 (61%) patients. Results VEP recordings were feasible in 62 of 85 eyes (73%) in 46 patients. All 23 eyes without VEP had impaired vision. During surgery, VEPs remained stable throughout surgery in 50 eyes. In 44 of these, visual function did not deteriorate and three patients (6 eyes) developed hemianopia. VEP decreased transiently in 10 eyes and visual function of all was preserved. VEPs were lost permanently in 2 eyes in two patients without new postoperative visual impairment. Conclusions Satisfactory intraoperative VEP monitoring was feasible in all patients except in those with severe visual impairment. Preservation of VEPs predicted preserved visual function. During resection of lesions in the visual cortex, VEP monitoring could not detect new major visual field defects due to injury in the posterior visual pathway. Intraoperative VEPs were sensitive enough to detect vascular damage during aneurysm clipping and mechanical manipulation of the anterior visual pathway in an early reversible stage. Intraoperative VEP monitoring influenced surgical decisions in selected patients and proved to be a useful supplement to the toolbox of intraoperative neurophysiological monitoring.ISSN:1932-620

Correction: Clinical Utility and Limitations of Intraoperative Monitoring of Visual Evoked Potentials.

[This corrects the article DOI: 10.1371/journal.pone.0120525.]

Surgical management of isolated orbital floor and zygomaticomaxillary complex fractures with focus on surgical approaches and complications

Zygomaticomaxillary complex (ZMC) and orbital blow out fractures are commonly encountered midfacial fractures that may result in aesthetic and functional impairment. This retrospective study reports on the surgical treatment and associated postoperative complications in our patient collective. We evaluated 100 patients who underwent open reduction and internal fixation of midfacial fractures between 2010 and 2015. Preoperative clinical features, surgical technique and postoperative complications were analyzed. Surgery was performed with a mean latency of 7 days after trauma. We used titanium mesh and polydioxanone sheets to reconstruct the orbital floor. Most ZMC fractures were stabilized with two point fixation with titanium plates. Preoperative symptoms were present in 70 patients (70%). Infraorbital hypesthesia occurred in 49 patients, diplopia in 41 patients and ocular motility impairment in 24 patients. Postoperative symptoms persisted during a mean follow-up time of 4.5 months in 47 patients (47%) showing infraorbital hypesthesia in 24%, diplopia in 17%, ectropion in 7% and ocular motility impairment in 4%. Complications requiring revision were retrobulbar hematoma 3% (n = 3), ectropion 3% (n = 3), diplopia 1% (n = 1), exophthalmos 1% (n = 1), implant dislocation 1% (n = 1), implant discomfort 2% (n = 2), persisting fracture dislocation 1% (n = 1). All patients recovered without significant impairment. Surgery is required in the majority of the patients with midfacial fractures. Among others ectropion is challenging due to its aesthetic and functional impact on patients. To prevent ectropion, additional canthopexy or the transconjunctival surgical approach are reasonable options in selected cases. Level of Evidence: Level V, descriptive study. AbbreviationsCTcomputed tomographyOForbital floorPDSpolydioxanoneORIFopen reduction and internal fixationZMCzygomaticomaxillary complex

Utility of VEP recording channels.

<p>Utility of VEP recording channels.</p

Impaired vision is associated with reduced N75 amplitude.

<p>Box plot showing the distribution of the N75 amplitude in eyes with intact and impaired preoperative visual function. The median N75 amplitude for the intact vision group (3.92±4.09 μV, range 1.78 to 19.39 μV) was higher than that of the impaired vision group (2.03±1.16 μV, range 0.68 to 5.03 μV). Mann-Whitney <i>P</i> < 0.001.</p

Patient characteristics.

<p>Patient characteristics.</p