title: Intraoperative neurophysiological monitoring during resection of infratentorial lesions: the surgeon's view.
abstract: OBJECTIVE Methods of choice for neurophysiological intraoperative monitoring (IOM) within the infratentorial compartment mostly include early brainstem auditory evoked potentials, free-running electromyography, and direct cranial nerve (CN) stimulation. Long-tract monitoring with somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) is rarely used. This study investigated the incidence of IOM alterations during posterior fossa surgery stratified for lesion location. METHODS Standardized CN and SEP/MEP IOM was performed in 305 patients being treated for various posterior fossa pathologies. The IOM data were correlated with lesion locations and histopathological types as well as other possible confounding factors. RESULTS Alterations in IOM were observed in 158 of 305 cases (51.8%) (CN IOM alterations in 130 of 305 [42.6%], SEP/MEP IOM alterations in 43 of 305 [14.0%]). In 15 cases (4.9%), simultaneous changes in long tracts and CNs were observed. The IOM alterations were followed by neurological sequelae in 98 of 305 cases (32.1%); 62% of IOM alterations resulted in neurological deficits. Sensitivity and specificity for detection of CN deficits were 98% and 77%, respectively, and 95% and 85%, respectively, for long-tract deficits. Regarding location, brainstem and petroclival lesions were closely associated with concurrent CN IOM and SEP/MEP alterations. CONCLUSIONS The incidence of IOM alterations during surgery in the posterior fossa varied widely between different lesion locations and histopathological types. This analysis provides crucial information on the necessity of IOM in different surgical settings. Because MEP/SEP and CN IOM alterations were commonly observed during posterior fossa surgery, the authors recommend the simultaneous use of both modalities based on lesion location.
authors.affiliation: Neurochirurgische Klinik, Universitätsklinikum Düsseldorf.
authors.forename: Philipp J
authors.initials: PJ
authors.lastname: Slotty
authors.affiliation: Neurochirurgische Klinik, Universitätsklinikum Düsseldorf.
authors.forename: Amr
authors.initials: A
authors.lastname: Abdulazim
authors.affiliation: Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Kodama
authors.affiliation: Klinik für Neurochirurgie, Universitätsklinikum Frankfurt am Main, Germany; and.
authors.forename: Mani
authors.initials: M
authors.lastname: Javadi
authors.affiliation: Neurochirurgische Klinik, Universitätsklinikum Düsseldorf.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hänggi
authors.affiliation: Klinik für Neurochirurgie, Universitätsklinikum Frankfurt am Main, Germany; and.
authors.forename: Volker
authors.initials: V
authors.lastname: Seifert
authors.affiliation: Neurochirurgische Klinik, Universitätsklinikum Düsseldorf.|Klinik für Neurochirurgie, Universitätsklinikum Frankfurt am Main, Germany; and.
authors.forename: Andrea
authors.initials: A
authors.lastname: Szelényi
mesh_terms: D000368:Aged; D004558:Electric Stimulation; D004569:Electroencephalography; D004576:Electromyography; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D015994:Incidence; D015192:Infratentorial Neoplasms / Q000453:epidemiology / Q000503:physiopathology / Q000601:surgery*; D007431:Intraoperative Complications / Q000453:epidemiology / Q000503:physiopathology; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
keywords: BAEP = brainstem auditory evoked potential; CN = cranial nerve; CPA = cerebellopontine angle; DNS = direct nerve stimulation; EMG = electromyography; IOM = intraoperative monitoring; MEP = motor evoked potential; NPV = negative predictive value; PPV = positive predictive value; SEP = somatosensory evoked potential; brainstem cavernoma; diagnostic and operative techniques; infratentorial neoplasms; intraoperative neuromonitoring; motor evoked potential; somatosensory evoked potential