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Seminars in Ultrasound, CT, and MR Oct 2022The abducens, or the sixth cranial nerve, is purely motor and runs a long course from the brainstem to the lateral rectus. Travels with the inferior petrosal sinus...
The abducens, or the sixth cranial nerve, is purely motor and runs a long course from the brainstem to the lateral rectus. Travels with the inferior petrosal sinus through the Dorello's canal before entering the cavernous sinus. Based on the location of an abnormality, other neurologic structures may be involved with the disturbs related to this nerve. This article aims to review the abducens nerve anatomy and demonstrates the imaging aspect of the diseases that most commonly affect it.
Topics: Abducens Nerve; Cavernous Sinus; Humans
PubMed: 36116854
DOI: 10.1053/j.sult.2022.04.008 -
World Neurosurgery May 2019Abducens nerve function seldom shows complete recovery after removal of abducens nerve schwannoma. No cases with unclear course of the abducens nerve during surgery have... (Review)
Review
BACKGROUND
Abducens nerve function seldom shows complete recovery after removal of abducens nerve schwannoma. No cases with unclear course of the abducens nerve during surgery have been reported to achieve complete recovery of nerve function.
CASE DESCRIPTION
We report the case of a 44-year-old woman who presented with occasional dysgeusia without abducens nerve paresis. Magnetic resonance imaging showed a solid tumor about 2 cm in diameter at the left cerebellopontine cistern. Cranial nerves except the abducens nerve appeared intact. The tumor was removed via suboccipital craniotomy. The abducens nerve was totally invisible on the surface of the tumor throughout the procedure. Only short segments of abducens nerve were identifiable at around Dorello's canal and the root exit zone. The tumor was resected by subcapsular dissection, and part of the tumor capsule was preserved as a scaffold for nerve generation, although whether any abducens nerve was included remained uncertain. Histopathologic examination confirmed World Health Organization grade I schwannoma. Postoperatively, the patient presented with complete left abducens nerve paresis and diplopia, but abducens nerve function began to improve 3 months later and had completely recovered within 16 months after surgery.
CONCLUSIONS
This represents the first description of abducens nerve schwannoma in which the course of the abducens nerve was intraoperatively unclear but complete recovery was achieved. In such cases, intentional subcapsular dissection may potentiate functional recovery.
Topics: Abducens Nerve; Abducens Nerve Diseases; Adult; Cranial Nerve Neoplasms; Female; Humans; Neurilemmoma; Recovery of Function
PubMed: 30716483
DOI: 10.1016/j.wneu.2019.01.123 -
Disease-a-month : DM May 2021
Topics: Abducens Nerve; Abducens Nerve Diseases; Adult; Aged; Child; Child, Preschool; Humans; Middle Aged; Paralysis
PubMed: 33546871
DOI: 10.1016/j.disamonth.2021.101133 -
Neurosurgery Sep 2007Only a few anatomic studies concerning the intra- or extracranial course of the abducens nerve (Cranial Nerve VI) have been reported. This is likely because the nerve... (Review)
Review
OBJECTIVE
Only a few anatomic studies concerning the intra- or extracranial course of the abducens nerve (Cranial Nerve VI) have been reported. This is likely because the nerve passes through anatomically intricate areas, making its neurovascular relationships complex. Here we provide an anatomically and surgically oriented classification of the abducens nerve, analyze the microanatomy of the nerve and the surrounding connective and/or neurovascular structures, and provide measurements and anatomic topography.
PATIENTS AND METHODS
A microsurgical anatomic dissection of 55 cadaveric human heads was performed using different skull base approaches to explore the entire course of the VIth cranial nerve, from its origin at the pontomedullary sulcus to the lateral rectus muscle. We then approached the same areas via an endoscopic endonasal transsphenoidal route, analyzed the neurovascular relationships from an anteromedial perspective, and made comparisons with the microsurgical views.
RESULTS
The abducens nerve is divided into five segments, of which three are intracranial (cisternal, gulfar, and cavernous) and two are orbital (fissural and intraconal). Using two opposing surgical routes (microsurgical transcranial and endoscopic endonasal approaches) allows us to clearly reveal the spatial relationships of the abducens nerve with other neurovascular structures on the different nerve segments.
CONCLUSION
The classification of five segments for the abducens nerve seems anatomically valid and is surgically oriented with respect to both the microscopic and endonasal endoscopic approaches. It would be useful to explain, segment by segment, the pathogenic mechanism(s) for nerve injuries that are evidenced by lesions that exist along the entire intra- and extracranial course.
Topics: Abducens Nerve; Cadaver; Cerebral Aqueduct; Humans; Models, Anatomic; Neuroendoscopy
PubMed: 17876228
DOI: 10.1227/01.neu.0000289706.42061.19 -
Journal of Pediatric Ophthalmology and... 2021
Topics: Abducens Nerve; Abducens Nerve Diseases; Cadaver; Humans
PubMed: 34038276
DOI: 10.3928/01913913-20210209-01 -
Clinical & Experimental Optometry May 2022
Topics: Abducens Nerve; Humans; Paresis; Pons
PubMed: 34151746
DOI: 10.1080/08164622.2021.1924630 -
Acta Neurochirurgica Oct 2009Schwannomas of the abducens nerve are extremely rare tumors affecting cavernous, cisternal or both segments of sixth cranial nerve. Clinical features and... (Review)
Review
Schwannomas of the abducens nerve are extremely rare tumors affecting cavernous, cisternal or both segments of sixth cranial nerve. Clinical features and neuroradiological imagery are frequently insufficient to reach an accurate pre-operative diagnosis. We report a patient with a cystic tumor with ring-like contrast enhancement at the right anterior pontomesencephalic junction. Radical excision was performed via anterior transpetrosal approach and showed an extrinsic tumor originating from the sixth nerve. A postoperative sixth nerve palsy had disappeared completely 9 months after the surgery. The correct diagnosis of an abducens nerve schwannoma is established by the intraoperative finding of a tumor attachment to the sixth nerve and by histopathological analysis. The various differential diagnoses, the clinical and radiological features of this diagnosis and management are issues discussed in this illustrated review.
Topics: Abducens Nerve; Abducens Nerve Diseases; Brain Stem; Brain Stem Neoplasms; Cranial Nerve Neoplasms; Craniotomy; Diagnosis, Differential; Diagnostic Errors; Facial Nerve Diseases; Hearing Loss; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Neurilemmoma; Neurosurgical Procedures; Tomography, X-Ray Computed; Treatment Outcome
PubMed: 19357806
DOI: 10.1007/s00701-009-0302-9 -
Journal of Clinical Neurophysiology :... Jan 2018The utility of extraocular cranial nerve electrophysiologic recordings lies primarily in the operating room during skull base surgeries. Surgical manipulation during... (Review)
Review
The utility of extraocular cranial nerve electrophysiologic recordings lies primarily in the operating room during skull base surgeries. Surgical manipulation during skull base surgeries poses a risk of injury to multiple cranial nerves, including those innervating extraocular muscles. Because tumors distort normal anatomic relationships, it becomes particularly challenging to identify cranial nerve structures. Studies have reported the benefits of using intraoperative spontaneous electromyographic recordings and compound muscle action potentials evoked by electrical stimulation in preventing postoperative neurologic deficits. Apart from surgical applications, electromyography of extraocular muscles has also been used to guide botulinum toxin injections in patients with strabismus and as an adjuvant diagnostic test in myasthenia gravis. In this article, we briefly review the rationale, current available techniques to monitor extraocular cranial nerves, technical difficulties, clinical and surgical applications, as well as future directions for research.
Topics: Abducens Nerve; Electromyography; Humans; Neurosurgical Procedures; Oculomotor Muscles; Oculomotor Nerve; Trochlear Nerve
PubMed: 29298208
DOI: 10.1097/WNP.0000000000000417 -
PloS One 2016We have previously reported that the presence of the abducens nerve was variable in patients with type 3 Duane's retraction syndrome (DRS), being present in 2 of 5 eyes...
BACKGROUND
We have previously reported that the presence of the abducens nerve was variable in patients with type 3 Duane's retraction syndrome (DRS), being present in 2 of 5 eyes (40%) and absent in 3 (60%) on magnetic resonance imaging (MRI). The previous study included only 5 eyes with unilateral DRS type 3.
OBJECTIVES
To supplement existing scarce pathologic information by evaluating the presence of the abducens nerve using high resolution thin-section MRI system in a larger number of patients with DRS type 3, thus to provide further insight into the pathogenesis of DRS.
DATA EXTRACTION
A retrospective review of medical records on ophthalmologic examination and high resolution thin-section MRI at the brainstem level and orbit was performed. A total of 31 patients who showed the typical signs of DRS type 3, including abduction and adduction deficit, globe retraction, narrowing of fissure on adduction and upshoot and/or downshoot, were included. The abducens nerve and any other extraocular muscle abnormalities discovered by MRI were noted.
RESULTS
DRS was unilateral in 26 patients (84%) and bilateral in 5 patients (16%). Two out of 5 bilateral patients had DRS type 3 in the right eye and DRS type 1 in the left eye. Of the 34 affected orbits with DRS type 3 in 31 patients, the abducens nerve was absent or hypoplastic in 31 eyes (91%) and present in 3 eyes (9%). Patients with a present abducens nerve showed more limitation in adduction compared to patients with an absent abducens nerve (P = 0.030).
CONCLUSIONS
The abducens nerve is absent or hypoplastic in 91% of DRS type 3. Patients with a present abducens nerve showed more prominent limitation of adduction. As DRS type 3 partly share the same pathophysiology with type 1 and 2 DRS, the classification of DRS may have to be revised according to MRI findings.
Topics: Abducens Nerve; Adolescent; Adult; Aged; Child; Child, Preschool; Duane Retraction Syndrome; Female; Humans; Infant; Magnetic Resonance Imaging; Male; Middle Aged
PubMed: 27352171
DOI: 10.1371/journal.pone.0150670 -
Internal Medicine (Tokyo, Japan) Oct 2022The most common neurological symptom of spontaneous intracranial hypotension (SIH) is abducens nerve paresis, and the precise pathophysiology is unclear. The accepted...
The most common neurological symptom of spontaneous intracranial hypotension (SIH) is abducens nerve paresis, and the precise pathophysiology is unclear. The accepted explanation is traction on the cranial nerves caused by the downward displacement of the cranial content. We herein report magnetic resonance imaging of SIH that can explain the mechanism underlying abducens nerve paresis. The cavernous sinuses were particularly thickened compared with the surrounding dura. This phenomenon can be explained by venous swelling, which can occur after leakage of cerebrospinal fluid in a closed cavity. This swelling pushes the abducens nerve up, which then causes abducens nerve paresis.
Topics: Abducens Nerve; Abducens Nerve Diseases; Cavernous Sinus; Edema; Humans; Intracranial Hypotension; Magnetic Resonance Imaging; Paresis
PubMed: 35342130
DOI: 10.2169/internalmedicine.8488-21