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Neurosurgery:
doi: 10.1227/01.neu.0000429838.38342.e2
Research-Human-Clinical Studies

Value of 3-Dimensional High-Resolution Magnetic Resonance Imaging in Detecting the Offending Vessel in Hemifacial Spasm: Comparison With Intraoperative High Definition Endoscopic Visualization

El Refaee, Ehab MDNS, MSc*,‡; Langner, Soenke MD§; Baldauf, Joerg MD*; Matthes, Marc MSc*; Kirsch, Michael MD§; Schroeder, Henry W.S. MD, PhD*

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Abstract

BACKGROUND: High-resolution 3-dimensional (3-D) magnetic resonance imaging (MRI) is widely used to predict the neurovascular anatomy within the cerebellopontine angle.

OBJECTIVE: To assess the value of 3-D steady-state free precession imaging (SSFP) and time-of-flight magnetic resonance angiography (TOF MRA) in detecting the offending vessels in hemifacial spasm in comparison to intraoperative endoscopic visualization.

METHODS: 42 patients underwent endoscope-assisted microvascular decompression (MVD). All available preoperative 3-D SSFP and TOF MRA images were checked. Intraoperative videos were captured by a high-definition endoscopic camera attached to endoscopes while exploring the area of facial nerve root exit zone (REZ). Evaluation of the 3-D images was performed by 2 independent groups of observers and compared with the operative findings.

RESULTS: Three-D MRI had an average positive predictive value (PPV) of 89.1% in differentiating between simple and complex compression. Mean accuracy of the images in detection of the offending vessels was 83.3% and 77% according to the first and second groups of observers, respectively. Averaged inter-observer agreement between the 2 groups of observers was substantial, with an averaged Kappa coefficient (K) of 0.56. In the simple compression group, mean accuracy was 97% and 89.4% according to the first and second groups of observers, respectively. Averaged K for agreement was substantial (K = 0.65).

CONCLUSION: According to endoscopic visualization, 3-D SSFP and TOF MRA images are accurate in detecting the offending vessels in simple compression of the facial nerve, and in predicting presence of a complex compression with variable sensitivity in identifying all offending vessels.

ABBREVIATIONS: 3-D, 3-dimensional

AICA, Anterior inferior cerebellar artery

BA, Basilar artery

BAEPS, Brainstem auditory evoked potentials

CI, Confidence interval

CISS, Constructive interference in steady state

EMG, Electromyography

FIESTA, Fast imaging employing steady state acquisition

K, Kappa coefficient

MVD, Microvascular decompression

PICA, Posterior inferior cerebellar artery

PPV, Positive predictive value

REZ, Root exit zone

SSFP, Steady-state free precession imaging

TOF, Time-of-flight

T2w, T2 weighted

VA, Vertebral artery

Copyright © by the Congress of Neurological Surgeons

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