Evidence map›Paper›PMID 41820716›Full record

Observational studyNeurosurgical review2026

Free-hand electrode placement for intraoperative monitoring of extraocular cranial nerves in skull base surgery: preliminary experience and feasibility assessment.

Giuseppe Corazzelli, Viviana Baiano, Salvatore Marino, Ilaria Mastroianni, Arianna Fava, Schiano Di Cola Mario, Fabio Di Rienzo, Nicola Gorgoglione, Sebastien Froelich, Vincenzo Esposito and 1 more

Abstract readObservational Study
PubMed Publisher
In one paragraph

Observational study in Neurosurgical review, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

11 authors.

Giuseppe CorazzelliNeurosurgery Department, Santa Maria delle Grazie Hospital, ASL Napoli 2 Nord, Naples, Italy. GiuCoraz@gmail.com.ORCID http://orcid.org/0000-0002-8536-6962
Viviana BaianoDepartment of Neurosurgery, IRCCS Neuromed, Pozzilli, Italy.
Salvatore MarinoDepartment of Neurosurgery, IRCCS Neuromed, Pozzilli, Italy.
Ilaria MastroianniDepartment of Neurosurgery, IRCCS Neuromed, Pozzilli, Italy.
Arianna FavaDepartment of Neurosurgery, IRCCS Neuromed, Pozzilli, Italy.
Schiano Di Cola MarioDepartment of Neurosurgery, IRCCS Neuromed, Pozzilli, Italy.
Fabio Di RienzoDepartment of Neurosurgery, IRCCS Neuromed, Pozzilli, Italy.
Nicola GorgoglioneDepartment of Neurosurgery, IRCCS Neuromed, Pozzilli, Italy.
Sebastien FroelichDepartment of Neurosurgery, Lariboisière Hospital, Assistance Publique-Hopitaux de Paris, Paris, France.
Vincenzo EspositoDepartment of Human Neurosciences, Sapienza University of Rome, Rome, Italy.
Paolo Di RussoDepartment of Neurosurgery, IRCCS Neuromed, Pozzilli, Italy.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Postoperative dysfunction of the oculomotor (CN III) and abducens (CN VI) nerves remains a major determinant of disability after skull base surgery for tumors. This study assessed the feasibility, safety, and diagnostic performance of a surgeon-controlled, free-hand extraocular muscle electrode placement for corticobulbar motor evoked potentials (cb-MEPs) and direct nerve stimulation (DNS). This monocentric, observational, retrospective study enrolled 40 patients scheduled for skull base tumor surgery, with planned intraoperative monitoring of CN III and/or VI. Curved needle electrodes were placed free-hand by the neurosurgeon at the scleral–muscular junction of the medial and/or lateral rectus, and cb-MEPs and DNS were recorded; evaluability required reproducible baselines. Primary endpoint was 3-month cranial nerve palsy. Diagnostic accuracy was calculated, and Spearman correlations tested the relationship between intraoperative percentage amplitude change and postoperative deficit severity. Placement succeeded in all cases (mean 10 min) with one transient conjunctivitis (2.5%). Stable baseline cb-MEPs occurred in 20/37 (CN III) and 18/31 (CN VI). For CN III, cb-MEPs showed sensitivity 66.7% and specificity 100%; amplitude reduction correlated with postoperative severity (ρ = 0.94, p < 0.001). DNS was evaluable in 22/26, with sensitivity 83.3% and specificity 100%. For CN VI, cb-MEPs showed sensitivity 75.0% and specificity 96.8%, with correlation to severity (ρ = 0.88, p < 0.001). DNS elicited responses in 15/22, with sensitivity 75.0% and specificity 100%. This neurosurgeon-performed, free-hand technique enabled rapid, safe, and reproducible electrode placement for extraocular cranial nerve monitoring during skull base surgery. When baselines are obtainable, cb-MEPs and DNS provide highly specific, actionable feedback aligned with postoperative outcomes. These findings support pragmatic adoption and prospective multicenter validation.

Indexed as

Cranial NervesIntraoperative Neurophysiological MonitoringMonitoring, IntraoperativeNeurosurgical ProceduresOculomotor NerveSkull BaseSkull Base NeoplasmsAbducens NerveAdolescentAdultAgedElectrodesEvoked Potentials, MotorFeasibility StudiesFemaleHumansAbducens nerveDirect nerve stimulationIntraoperative neurophysiological monitoringMotor evoked potentialsOculomotor nerveSkull base surgery

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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.