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At least 19 recordsLinked to original sources
PubMed2003

Neurotization of oculomotor, trochlear and abducent nerves in skull base surgery.

OBJECTIVE: To anatomically reconstruct the oculomotor nerve, trochlear nerve, and abducent nerve by skull base surgery. METHODS: Seventeen cranial nerves (three oculomotor nerves, eight trochlear nerves and six abducent nerves) were injured and anatomically reconstructed in thirteen skull base operations during a period from 1994 to 2000. Repair techniques included end-to-end neurosuture or fibrin glue adhesion, graft neurosuture or fibrin glue adhesion. The relationships between repair techniques and functional recovery and the related factors were analyzed. RESULTS: Functional recovery began from 3 to 8 months after surgery. During a follow-up period of 4 months to 6 years, complete recovery of function was observed in 6 trochlear nerves (75%) and 4 abducent nerves (67%), while partial functional recovery was observed in the other cranial nerves including 2 trochlear nerves, 2 abducent nerves, and 3 oculomotor nerves. CONCLUSIONS: Complete or partial functional recovery could be expected after anatomical neurotization of an injured oculomotor, trochlear or abducent nerve. Our study demonstrated that, in terms of functional recovery, trochlear and abducent nerves are more responsive than oculomotor nerves, and that end-to-end reconstruction is more efficient than graft reconstruction. These results encourage us to perform reconstruction for a separated cranial nerve as often as possible during skull base surgery.

Abducens Nerve↗
PubMed1988

The central-peripheral transitional regions of cranial nerves. Trochlear and abducent nerves.

Unlike all other nerves containing somatic efferent fibres, the trochlear nerve emerges from the dorsal aspect of the brainstem. It generally emerges as a single trunk which resembles a dorsal rather than a ventral spinal nerve rootlet in terms of its size and of the morphology and position of the central tissue projection which it contains. The morphology of the central-peripheral transition of the trochlear nerve is therefore correlated with its dorsal location rather than with the nature of its constituent fibres. By contrast, abducent nerve rootlets emerge from the ventral aspect of the neuraxis, in line with other cranial and with spinal ventral nerve rootlets which also contain somatic efferent fibres. Its rootlets resemble the latter in terms of their size, being much smaller than those of dorsal rootlets or the trochlear nerve. They possess two distinct types of central-peripheral transitional zone: those of the rostral rootlets resemble zones of cervical ventral spinal rootlets. Many of these emerge through a circumscribed thickening of the astrocytic glia limitans. Caudal abducent rootlets emerge through a tongue-shaped glial elevation projecting above the level of the surrounding brainstem surface, resembling Type 1 oculomotor rootlets.

Abducens Nerve↗
PubMed1998

Unmyelinated nerve fiber analysis of the human abducent nerve.

Unmyelinated nerve fibers of the abducent nerve have occasionally been observed with electron microscopes, but, to our knowledge, they have never been evaluated from the morphometric point of view. We analyzed the aging process of the unmyelinated nerve fibers in the human abducent nerve with the help of a new staining method suitable for morphometric research on the nervous system. We studied numbers and transverse areas of unmyelinated fibers of the abducent nerve in 10 cadavers. Our findings were that (1) these fibers were distributed diffusely, (2) their number decreased with age, and (3) the mean transverse area did not change with age. Most of the unmyelinated axons were thinner than the myelinated axons. These results may be important for analysis of clinical signs in relation to aging and ophthalmologic functions.

Abducens Nerve↗
PubMed2004

Detailed MR imaging anatomy of the abducent nerve: evagination of CSF into Dorello canal.

BACKGROUND AND PURPOSE: The abducent nerve is difficult to identify reliably and consistently with conventional radiologic techniques. In this study, a 3D fast asymmetrical spin-echo MR imaging technique was used to obtain detailed images of the abducent nerve in normal volunteers. METHODS: The 3D fast asymmetrical spin-echo MR protocol was used to image the abducent nerves in 24 normal volunteers by using a 1-mm section thickness in the tilted axial and parasagittal planes. The microanatomy of the abducent nerve within Dorello's canal was also demonstrated in a cadaver study. RESULTS: In 24 normal volunteers, the anatomy of 47 abducent nerves was clearly depicted on MR images. The length of the cisternal segment of the abducent nerve, extending from the brain stem to its dural foramina, ranged from 6.7 to 19.6 mm (mean, 13.1 mm). The abducent nerves were at an angle of 5 to 90 degrees (mean, 24.5 degrees) to the clivus. CSF evagination was detected in the region of Dorello's canal in 36 (77%) of 47 abducent nerves. The length of CSF evagination varied: 0.9 mm in five nerves, 1.0 to 1.9 mm in 18 nerves, 2.0 to 2.9 mm in eight nerves, and 3.0 mm or more in five nerves. Histologic examination of serial sections of the abducent nerve revealed that the petroclival segment of the nerve was covered by an envelope composed of an arachnoid cell layer. CONCLUSION: The course of the abducent nerve was reliably identified using the 3D fast asymmetrical spin-echo MR protocol and a histologically proven arachnoid envelope around the petroclival segment of the nerve was shown as CSF evagination into Dorello's canal by MR imaging.

Abducens Nerve↗
PubMed1998

Morphometric nerve fiber analysis and aging process of the human abducent nerve.

Myelinated nerve fibers of the human abducent nerve were analyzed with a new staining method that permits simultaneous observation of the axon and surrounding myelin sheath. The following equipment was employed for the measurements: an image-analyzing digitizer, a microscope equipped with a drawing tube (or camera lucida), and a computer for data storage and statistical analysis. The numbers, transverse areas, and circularity ratios of axons were measured in 10 human abducent nerves. The average number was 1,997 with a definite decrease with age, and the average area was 3.90 micron 2.

Abducens Nerve↗
PubMed2001

The value of the heavily T2-weighted sequence in evaluation of the cisternal and petroclival segment of the abducent nerve.

The purpose of the study was to evaluate the usefulness of magnetic resonance (MR) in imaging of the cisternal and petroclival segments of the abducent nerve. Heavily T2-weighted submillimetric 3D sequence in axial plane, T1-weighted 3D, 1.5 mm slice thickness sequence in axial plane and TOF sequence were performed on 16 volunteers. Additionally the reformatted T2-weighted images in sagittal and in oblique parasagittal plane parallel to the abducent nerve in the pontine cistern were performed. The heavily T2-weighted sequence provides high contrast between fluid and other structures. High signal intensity of the cerebrospinal fluid is a kind of background for cranial nerves, vessels, meninges as well as for bony and fibrous structures. The authors identified the abducent nerve in at least one plane of the submillimetric, heavily T2-weighted sequences in 84.4% cases (in 84.4% in axial plane, 68.8% in sagittal and 84.4% parasagittal parallel to the VI-th cranial nerve in the pontine cistern). Dorello's canal was identified in 27/32 abducent nerves (84.4%) on the submillimetric, heavily T2-weighted sequence in parasagittal parallel to the abducent nerve in the pontine cistern plane. In 71.9% (23/32) of cases, the abducent nerve was in contact with the arterial vessel in pontine cistern.

Abducens Nerve↗
PubMed1999

Detailed magnetic resonance imaging anatomy of the cisternal segment of the abducent nerve: Dorello's canal and neurovascular relationships and landmarks.

OBJECT: The goal of this study was to identify reliably the cisternal segment of the abducent nerve by using the three-dimensional Fourier transform constructive interference in steady-state (3-D CISS) magnetic resonance (MR) imaging sequence to define landmarks that assist in the identification of the abducent nerve on MR imaging and to describe the nerve's relationship to the anterior inferior cerebellar artery (AICA). METHODS: A total of 26 volunteers underwent 3-D CISS MR imaging, and 10 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. The authors identified the abducent nerve with certainty in 96% of 3-D CISS sequences obtained in the axial and sagittal planes and in 94% obtained in the coronal plane. The nerve emerged from the pontomedullary sulcus in 94% of cases. The facial colliculus could always be identified, and Dorello's canal was identified in 94% of cases. In 76.6% of cases, the abducent nerve was seen to contact the AICA, which passed inferior to the nerve in 63.8% of cases and superior to it in 29.8%. CONCLUSIONS: The anatomical course of the abducent nerve and its relationship to the AICA and other blood vessels can be reliably identified using a 3-D CISS MR sequence with the facial colliculus and Dorello's canal serving as landmarks.

Abducens Nerve↗
PubMed1989

Axon numbers in rat oculomotor, trochlear and abducent nerves.

In the rat oculomotor, trochlear and abducent nerves, large and small classes of myelinated fibres can be clearly distinguished. Small myelinated axons comprise a larger proportion of the total in the oculomotor nerve than in the other two. Mean counts enable the myelinated preganglionic parasympathetic outflow of the oculomotor nerve to be estimated at 216 fibres. Unmyelinated fibres are most frequent in the abducent nerve and least frequent in the trochlear nerve.

Abducens Nerve↗
PubMed1994

The neurovascular relationships and the blood supply of the abducent nerve: surgical anatomy of its cisternal segment.

Twenty-eight abducent nerves were examined after injecting india ink and gelatin into the vertebrobasilar arterial system. All the abducent nerves were found to be crossed and/or penetrated by the surrounding vessels. The ventral surface of the nerves was crossed by the anterior inferior cerebellar artery (AICA) (75.0%), the posterior inferior cerebellar artery (17.85%), the common trunk of the AICA and posterior inferior cerebellar artery (7.14%), the internal auditory artery (14.28%), the anterolateral artery (46.43%), the pontomedullary artery (92.86%), and the corresponding veins (46.43%). The dorsal surface of the cisternal segment was crossed by the AICA (35.71%), the inferolateral pontine artery (10.71%), the anterolateral artery (82.14%), and the certain veins (46.43%). Sixty-four percent of the cisternal segments were penetrated by one or more of the following vessels: the AICA (25.0%), the anterolateral artery (17.86%), the pontomedullary artery (3.57%), and/or by the corresponding veins (42.86%). The majority of the cisternal segments of the abducent nerves were supplied by the anterolateral arteries (85.71%), and only some of them by the AICA (14.29%) or the pontomedullary artery (7.14%). The authors discuss the possible clinical significance of the anatomical data.

Abducens Nerve↗
PubMed2005

Isolated abducent nerve palsy after microvascular decompression for trigeminal neuralgia: case report.

OBJECTIVE AND IMPORTANCE: Microvascular decompression (MVD) is a safe and effective treatment for trigeminal neuralgia. Isolated postoperative ipsilateral abducent nerve palsy is an extremely rare complication of this procedure and has not been reported before. The author wishes to report this rare complication, discuss its aetio-pathogenesis and the natural course. CLINICAL PRESENTATION: A 57-year-old man underwent MVD for right sided medically refractory trigeminal neuralgia based on the MRI finding of ectatic basilar artery compression at its root entry zone. The procedure was uneventful with complete relief of pain. However, he developed isolated ipsilateral sixth nerve palsy following surgery that lasted for six weeks. INTERVENTION: Anterior displacement of tortuous and dilated basilar artery to create space between the artery and the nerve during MVD operation probably resulted in inadvertent neuropraxia to the abducent nerve that was located immediately anterior to the artery but was not in the surgical field. Immediate sixth nerve palsy resulted post-operatively. A conservative route was adopted with spontaneous improvement of the extraocular eye movements after six weeks. CONCLUSION: Isolated abducent nerve damage is a rare complication of the MVD procedure. Surgical manipulation of the dilated and tortuous vessels located anterior to the trigeminal nerve may cause indirect stretching of the delicate abducent nerve with resultant neuropraxia. This complication is difficult to recognize and prevent intra-operatively as the nerve lies on the far side of the artery. Fortunately, spontaneous recovery of the neural function seems to be the most likely outcome.

Abducens Nerve Diseases↗
PubMedDate not supplied

Cisternal segment of the normal abducent nerve: MR imaging with 3D fast asymmetric spin echo sequence.

PURPOSE: The aim of this study was to reveal the techniques and findings of the 3D fast asymmetric spin echo (3D FASE) sequence for imaging the cisternal segment of the normal abducent nerve. METHODS: Ten healthy volunteers were examined using the 3D FASE sequence, and oblique coronal and oblique sagittal images were reconstructed according to the specific course of the abducent nerve. RESULTS: The abducent nerve was identified with certainty and displayed on the oblique coronal and oblique sagittal reconstructed images in 80% of cases using Dorello's canal as landmark. The bilateral nerve of one case and unilateral nerve of two cases could not be identified and displayed. The mean diameter of the cisternal segment was 1.39 mm on 3D FASE image. CONCLUSIONS: The 3D FASE sequence can be used to image the cisternal segment of the abducent nerve with Dorello's canal as a landmark.

Abducens Nerve↗
PubMed2001

Duplicated abducent nerve and its course: microanatomical study and surgery-related considerations.

OBJECT: The anatomy of the abducent nerve is well known; its duplication (ranging from 5 to 28.6%), however, has rarely been reported in the literature. The authors performed a microanatomical study in 100 cadaveric specimens (50 heads) to evaluate the prevalence of this phenomenon and to provide a clear anatomical description of the course and relationships of the nerve. The surgery-related implications of this rare anatomical variant will be highlighted. METHODS: The 50 human cadaveric heads (100 specimens) were embalmed in a 10% formalin solution for 3 weeks. Fifteen of them were injected with colored neoprene latex. A duplicated abducent nerve was found in eight specimens (8%). In two (25%) of these eight specimens the nerve originated at the pontomedullary sulcus as two independent trunks: in one case the superior trunk was thicker than the inferior and in the other it was thinner. In the other six cases (75%) the nerve originated as a single trunk, splitting in two trunks into the cisternal segment: in two of them the trunks ran below the Gruber ligament, whereas in four specimens one trunk ran below and one above it. In all the specimens, the duplicated nerves fused again into the cavernous sinus, just after the posterior genu of the internal carotid artery. CONCLUSIONS: Although the presence of a duplicated abducent nerve is a rare finding, preoperative magnetic resonance imaging should be performed to rule out this possibility, thus tailoring the operation to avoid postoperative deficits.

Abducens Nerve↗
PubMed2006

Structural and ultrastructural study of the intracranial portion of the oculomotor, trochlear and abducent nerves in dog.

The right intracranial portion of the oculomotor, trochlear and abducent nerves were removed from six adult German shepherd dogs and analysed by light and electron microscopy. In all cases the nerve sectional area was calculated. Unmyelinated and myelinated fibres were analysed and number, diameter and cross-sectional area were calculated. In myelinated fibres, also calculated were the corresponding axon area and diameter, and myelin sheath thickness. The mean number of myelinated fibres was 8543.50 +/- 1231.85 being the unmyelinated 1402 +/- 241.58 in the oculomotor nerve; 1509 +/- 223.17 and 287.67 +/- 72.28 in the trochlear nerve and 2473.00 +/- 211.41 and 231.25 +/- 92.67 respectively in the abducent. The mean diameter was 10.23 +/- 0.68 microm in myelinated and 0.43 +/- 0.21 for unmyelinated in oculomotor nerve, 10.53 +/- 0.55 microm and 0.33 +/- 0.04 for the trochlear, and 10.45 +/- 1.27 microm and 0.47 +/- 0.09 in the abducent nerve respectively. This study reveals that oculomotor, trochlear and abducent nerves of the dog show structural and ultra-structural features similar to the same nerves in other species.

Abducens Nerve↗
PubMed1995

Abducent nerve palsy following dental local analgesia.

A case of temporary abducent nerve palsy, following posterior superior alveolar nerve block during removal of an upper third molar tooth is presented. The relevant anatomy and other causes of sixth nerve palsy are considered, together with guidelines for the management of such an occurrence.

Abducens Nerve↗
PubMed1994

Abducent nerve paralysis during interferon alpha-2a therapy in a case of chronic active hepatitis C.

A 59-year-old woman with chronic active hepatitis C was treated with recombinant human interferon alpha-2a. After three days of administration, the patient complained of diplopia with dizziness and head heaviness. Ophthalmic examinations revealed a disturbance of the movement of left eye ball to the outer side without any other neurological signs. The diplopia, which was diagnosed as abducent nerve paralysis, improved rapidly and reversed at about 6 weeks after discontinuation of interferon and during infusion of hydrocortisone. To our knowledge, this is the first report of abducent nerve paralysis associated with alpha-2a interferon.

Abducens Nerve↗
PubMedDate not supplied

Anatomical variations of the abducent nerve in humans.

Anatomical variation of the nervus abducens in human encephali were found and described. They consisted of (1) an unusual trifurcation of the abducent nerve, limited to the extradural portion of the neural trunk (1.4% of the cases) and (2) the duplicity (11.1%) of the neural trunk, starting before reaching the orbit and ending before reaching the m. rectus lateralis. The possibility of correlating these variations with clinical aspects and forensic interpretations is mentioned.

Abducens Nerve↗
PubMed1996

Abnormality of the labyrinthine artery and its topographical relation to the abducent nerve.

A case of duplication of the labyrinthine artery arising from the basilar artery is described. The more slender branch takes a dorsal course and penetrates the abducent nerve in its uppermost fibres, while the thicker branch passes by the nerve on the ventral side. The two branches of the labyrinthine artery run separately to the internal auditory meatus. This variant was found only in one brain and only on the left side. The clinical relevance of this finding is discussed.

Abducens Nerve↗