Estudio por resonancia magnética del contacto neurovascular en el espasmo hemifacial esencial: empleo de secuencia CISS y angiografía por resonancia magnética

Evaluation of pre-operative neuroimaging characteristics in patients with primary hemifacial spasm as a prognostic factor of microvascular decompression

OBJECTIVE

The aim of this study was to explore the possible pathogenesis of primary hemifacial spasm (HFS) according to the performances of preoperative high-resolution magnetic resonance (MR) sequence and investigate the correlations between the neuroimaging parameters and the prognosis of microvascular decompression (MVD).

METHODS

106 patients with HFS and 121 age-matched and gender-matched healthy controls (HCs) were included in this study. Electronic medical records and neuroimaging data were collected. The facial-nerve angle, cross-sectional area of CPA cistern and length of the cistern segment of the facial nerve were measured on affected side and unaffected as well as healthy individuals. The receiver operating characteristic curve was used for assessing the predictive performances.

RESULTS

100 patients achieved complete relief postoperatively. 13 of the 100 complete relief patients developed a relapse in the follow-up. The preoperative facial-pontine angle and cross-sectional area of the CPA cistern on the affected side was significantly smaller than the unaffected side and HC. The facial-pontine angle and the cross-sectional area of the CPA cistern was significantly smaller in recurrent group than the non-recurrent group. The AUC value of both facial-pontine angle and cross-sectional area of the CPA cistern were over 0.7.

CONCLUSION

Small facial-nerve angle and cross-sectional area of CPA cistern may be regarded as the possible pathogenesis of primary HFS. The measurement of facial-nerve angle and cross-sectional area of CPA cistern preoperatively might be used to predict the surgical effect of MVD.

Comparison of brain MRI angiography and brain MRI cisternography in patients with hemifacial spasm

OBJECTIVE

The aim of this study was to compare the ability of brain magnetic resonance imaging angiography and brain magnetic resonance imaging cisternography of showing the neurovascular contiguity of the facial nerve in patients with hemifacial spasm.

METHOD

This study included a total of 35 patients (28 females, 7 males), with an average age of 57.5 ± 13.8 years, who presented to our outpatient clinic of movement disorders. All patients were prospectively applied brain magnetic resonance imaging angiography and brain magnetic resonance imaging cisternography, and the results were evaluated by a radiologist who was blind to study protocol.

RESULTS

The study included 35 patients, of whom 28 (80 %) were female and 7 (20 %) were male. Brain magnetic resonance imaging angiography demonstrated facial nerve compression of vascular origin in 5 (14.3 %) patients presenting with the clinical presentation of hemifacial spasm. Neurovascular compression of facial nerve was shown by brain magnetic resonance imaging cisternography in 13 (37.1 %) patients.

CONCLUSION

No statistically significant difference was found between brain magnetic resonance imaging angiography and brain magnetic resonance imaging cisternography techniques in detecting a compressive interaction causing hemifacial spasm between facial nerve and adjacent vascular structures (p > 0.05).

Preoperative Evaluation of Patients with Hemifacial Spasm by Three-dimensional Time-of-Flight (3D-TOF) and Three-dimensional Constructive Interference in Steady State (3D-CISS) Sequence

PURPOSE

The purpose of this study was to investigate and evaluate the accuracy and the preoperative diagnostic value of high-resolution magnetic resonance imaging (MRI) techniques, three-dimensional time-of-flight (3D-TOF) and three-dimensional constructive interference in steady state (3D-CISS) sequence, solely or in combination for the detection of the relationship between the facial nerve and adjacent vessels in patients with hemifacial spasm (HFS).

METHODS

A total of 95 patients with primary HFS were subject to 3D-TOF and 3D-CISS MRI. The MR images were then used to evaluate the anatomical neurovascular relationships, and the results were compared with the surgical findings. We categorized the neurovascular relationship into three types: compression, contact, and neighboring or distant. Compression and/or contacts between root exit zone (REZ) and vessels were defined as positive, whereas neighboring or distant was considered to be negative.

RESULTS

3D-TOF combined with 3D-CISS assessment showed that 94 of 95 patients had artery compression or contact at REZ, whereas the remaining patient had compression at the peripheral branch of the facial nerve but not at REZ. The positive rates and the overall accuracy were 98.95 and 100 %, respectively, for the 3D-TOF combined with 3D-CISS assessment; 92.63 and 93.68 %, respectively, for the 3D-TOF assessment; and 85.26 and 86.32 %, respectively, for the 3D-CISS assessment. The positive rates and overall accuracy for the 3D-TOF combined with 3D-CISS assessment was significantly higher than those for the 3D-TOF or 3D-CISS assessment.

CONCLUSIONS

Combination of 3D-TOF with 3D-CISS imaging well delineates the relationship between the facial nerve and adjacent vessels in terms of increased positive rates and accuracy.

Value of 3-Dimensional High-Resolution Magnetic Resonance Imaging in Detecting the Offending Vessel in Hemifacial Spasm

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.