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

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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

ABBREVIATIONS:

AICA, Anterior inferior cerebellar artery

ABBREVIATIONS:

BA, Basilar artery

ABBREVIATIONS:

BAEPS, Brainstem auditory evoked potentials

ABBREVIATIONS:

CI, Confidence interval

ABBREVIATIONS:

CISS, Constructive interference in steady state

ABBREVIATIONS:

EMG, Electromyography

ABBREVIATIONS:

FIESTA, Fast imaging employing steady state acquisition

ABBREVIATIONS:

K, Kappa coefficient

ABBREVIATIONS:

MVD, Microvascular decompression

ABBREVIATIONS:

PICA, Posterior inferior cerebellar artery

ABBREVIATIONS:

PPV, Positive predictive value

ABBREVIATIONS:

REZ, Root exit zone

ABBREVIATIONS:

SSFP, Steady-state free precession imaging

ABBREVIATIONS:

TOF, Time-of-flight

ABBREVIATIONS:

T2w, T2 weighted

ABBREVIATIONS:

VA, Vertebral artery

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