A Comparative Study On Anatomy Of The Cisternal Segment Of The Cranial Nerves And Their Related Blood Vessels With MRI And Sectional Specimen

Objective To obtain the detailed anatomical data of image through the application of 3D-CISS sequence and MPR technique in displaying the cisternal segment of the oculomotor nerve and its neurovascular relationships. Methods The optimal displaying angles and the length of intracisternal segment of the oculomotor nerve were measured on multiplanar reconstruction (MPR) images. Meanwhile, the relationship between the nerve and the basilar artery (BA), posterior cerebral artery(PCA), superior cerebellar artery(SCA), posterior communicating artery(PCoA) and pathological changes were observed from the successive multiplanar reconstruction (MPR) images, the sectional specimens, the original images and 3D-TOF images. Results Use of 3D-CISS sequence and MPR technique enable accurate result corresponding to the sectional specimens in the identification of the proximal cisternal segment of the oculomotor nerve and its neurovascular relationships. The length of the intracisternal segment of the nerve was (14.61±2.33) mm and it formed an angle of (69.56±6.74) ° with the posterior plane of the brain stem. The angle between the oculomotor nerve and the median sagittal plane was(24.48±4.57) ° on the left and (24.48±5.07) ° on the right. Shift of the BA was more likely found in aged individuals. Most of the PCA and SCA were close to the nerve and a few of them compressed it. As for the PCoA, only the embryonic type was close to or compressed the nerve.The relationships between the oculomotor nerve and pathological changes were displayed well. Conclusion Use of 3D-CISS sequence and MPR technique enable accurate identification of the proximal cisternal segment of the oculomotor nerve and its neurovascular relationships, 3D-CISS sequence and MPR technique are the optimal imaging methods for the display of thesyntopy of the oculomotor nerve to its related organization.Objective To obtain the sectional anatomical data of the proximal portion of the cisternal segment of the trochlear nerve in MRI, and to assess the anatomical features and neurovascular relationships of the trochlear nerve. Methods 40 subjects(80 nerves) and one patient with right superior oblique myokymia (SOM) were examined with 3D-CISS sequence, and then compared with the sectional specimens. The data set from each 3D-CISS sequence was reconstructed in oblique transverse, sagittal, and coronal planes with a section thickness of 0.5mm, in order to assess nerve position and any neurovascular contact at each point along the cisternal course of the trochlear nerve. The images were analyzed by two observers collaboratively. To exclude the possibility of mistaking the trochlear nerve for a vessel, we compared the structures identified as the trochlear nerve on 3D-CISS images with the corresponding structures on 3D-TOF images, and followed the vessels to their origins. Results (D3D-CISS MR imaging depicted the proximal cisternal segment of the trochlear nerve in the oblique transverse, sagittal, and coronal planes in 74 (93%), 66 (82%) , and 63 (79%) of 80 nerves, respectively. At the PE , we consistently identified a single uniform trunk of the trochlear nerve.We could not identify the trochlear nerve in its subtentorial portion. We never identified the trochlear nerve by using the 3D-TOF sequence. (2) Trochlear nerve course: We were able to identify the course of the trochlear nerve in 69 of the 74 nerves identified. In 28 cases, the trochlear nerve first coursed laterally toward the free edge of the tentorium and then turned anteriorly to run beneath the tentorium. In 41 cases the trochlear nerve followed an oblique anterolateral course to reach the free edge of the tentorium. In 7 volunteers, the bilateral trochlear nerve could not be displayed at one plane. In 5 of the 74 cases in which the trochlear nerve was identified, the cisternal course could not be defined because it was not possible to trace the entire course of the nerve throughall of the serial sections. ?The distance between the midline and the point of exit(PE) was 3-8mm, and the maximum visualized length of the trochlear nerve was l-23mm. ?Neurovascular relationships: The vessels identified as having a relation to the proximal cistemal segment of the trochlear nerve were the superior cerebellar artery (SCA) and the brachial tributaries of the precentral cerebellar vein. Nerve-vessel contacts were detected at the PE in 3 of 74 cases. In 7 of the 74 cases, nerve-vessel contacts were observed to be in direct contact with the trochlear nerve at a distance of lmm from the PE. Therefore, the nerve-vessel contacts were observed at the REZ in a total of 10 (12.5%) nerves. In 37 nerves, 43 vessels were in direct contact with the trochlear nerve, at a mean distance of 3.4mm from the PE. In 32 nerves, 38 vessels were in close relation to the trochlear nerve but not in direct contact with it, the mean distance from the PE was 3.1mm. The patient with SOM had a neurovascular contact at the REZ. (5)MRI revealed the similar result corresponding to the specimens at the PE, cistemal segment, subtentorial portion of the planes in displayng the trochlear nerve. Conclusion Use of 3D-CISS and 3D-TOF sequences enable accurate identification of the proximal cistemal segment of the trochlear nerve and its neurovascular relationships.Objective The goal of this study was to identify reliably the cisternal segment of the abducent nerve by using 3D-CISS sequence to define landmarks that assist in the identification of the abducent nerve on MR imaging and to describle mainly the nerve's relationship to the anterior inferior cerebellar artery(AICA)and the other organizations. Methods A total of 57 volunteers underwent 3D-CISS MR imaging, and 20 of these volunteers also underwent MR angiography in which a time-of-flight sequence was used to identify the facial colliculus, the abducent nerve and its apparent origin, Dorello's canal, and the AICA, et al. Results (T)The abducent nerve were identified with certainty in 97% obtained in the axial, sagittal planes and in 95% obtained in the coronal plane. On the contrary, we were never able to identify the abducent nerve by using the TOF sequence in 20 volunteers. ?The nerve emerged from the pontomedullary sulcus in 103(93%) of cases, and 7 cases emerged from an area superior to the sulcus .It never originated inferior to the sulcus. We consistently identified only one nerve root and never detected a doubling of the nerve. (3)We were always able to identify the facial colliculus at the floor of the fourth ventricle on transverse MR slices. Dorello's canal was identified in 96% of cases. ?The blood vessels we could identify on MR images obtained using 3D-CISS sequences included the vertebral artery(VA), the basilar artery(BA), the posterior inferior cerebellar artery(PICA), the AICA, the superior cerebellar artery, and the petrosal vein. The AICA was the blood vessel most often identified. When the AICA was identified, it was noted to be in contact with the abducent nerve in 71 (74.7% )of 95 nerves, and not in contact in 24 (25.3%) of the 95 nerves. ? MRI revealed the similar result corresponding to the slices and 3D-CISS MPR images of the specimens in displayng the abducent nerve. ?The reason caused by the compression were all found in 7 patients with the abnormal symptom of palsy in the abducent nerve. It was identifiedthat 3D-CISS sequences and MPR techniques play a great role in the clinical application. Conclusion The anatomical course of the abducent nerve and its relationship to the AICA, the other blood-vessels, masses can be reliably identified using a 3D-CISS MR sequence with the facial colliculus and Dorello's canal serving as landmarks.Objective To display the trigeminal nerve and evaluate neurovascular anatomical relationships in patients with trigeminal neuralgia caused by neurovascular compression. Methods MR manifestations in 50 volunteers , 56 patients (49 patients caused by the neurovascular compression, 7 patients caused by the masses) with neuralgia and partial operative results of 49 patients with neuralgia were reviewed retrospectively at 3D-CISS and 3D-TOF imaging with MPR techniques. For the patients with neurovascular compression! conventional MR imaging was used to conform that patients had neither multiple sclerosis nor a brain tumor. For the patients with neurovascular compression, compression was diagnosed when contact of the blood vessel and the nerve at the REZ was clearly detected in two or more sections of the transverse images. For the image analysis, the transverse original images, the coronal and sagittal reformatted images, and the other reformatted images obtained parallel and perpendicular to the trigeminal nerve at the REZ were used. The position of the blood vessel compressing the nerve was classified into one of the following four sites: cranial, caudal, medial, or lateral. When compression was detected in two or more sites, it was defined as a compression of two or more sites. Results ? The trigeminal nerve were identified with certainty in 100% at the axial , sagittal and coronal planes. The trigeminal nerve root, motor root, sensitive root, trigeminal nerve ganglion, ophthalmic nerve, maxillary nerve and mandibular nerve were displayd at the 3D-CISS imaging. MRI revealed the similar result corresponding to the slices and MPR imagings of the specimens in displayng the trigeminal nerve. ?In 10 of 13 patients who underwent surgery, the artery that was considered a responsible vessel at 3D-CISS and 3D-TOF imaging was confirmed as such, the vein was the responsible vessels only detected by 3D-CISS sequence in the other three patients. (3) Eighteen(90% ) of 20 patients related to the maxillary division had neurovascular compression at the medial site of the root entry zone, while 15 (79%) of 19 patients related to the mandibular division had compression at the lateral site (P<0.001, jf test) . @MR angiographic image could not depict the compressing vein, and the ability of displaying the trigemianl nerve, the degree of compression is poor. Conclusion 3D-CISS MR imaging is useful in the detection of trigeminal nerve, neurovascular relationship and correlation between the region of neuralgic manifestation and the compressed site of trigeminal nerve.Objective The aim of study is to evaluate the efficacy of 3D-CISS on image quality of the nerves surrounded by CSF when compared with that of 3D-TSE. Methods The cranial nerves (VD-XD) were examined using 3D-CISS and 3D-TSE sequences respectively, and displayed to the full at the reformatted images. The nerve identification and image quality were graded for the cranial nerves (VII-XII). Statistical analysis was performed using the Wilcoxin test. p<0.05 was considered significant. Results The cisternal and canalicular segment of the facial and vestibulocochlear nerves were identified 100% by both sequences. The identification rates for the cisternal segment of the other neural structures were as follows: the glossopharyngeal nerve(95.3% in 3D-CISS and 57.1% in 3D-TSE), the vagus nerve(90.9% in 3D-CISS and 52.3% in 3D-TSE), the accessory nerve(86.3% in 3D-CISS and 41.1% in 3D-TSE), the hypoglossal nerves(95.1% in 3D-CISS and 59.3% in 3D-TSE). 3D-CISS images were significantly better for the glossopharyngeal, vagus, accessory nerve and the hypoglossal nerve; and slightly better for the cisternal and canalicular segment of the facial and vestibulocochlear nerves. Conclusion 3D-CISS sequence is preferable when imaging the cranial nerves surrounded by the CSF.