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Progress in Brain Research 2022Eye movements occur when motor neurons (cranial nerves III, IV and VI) discharge and cause contractions of the extraocular muscles. Movements of the eye are influenced...
Eye movements occur when motor neurons (cranial nerves III, IV and VI) discharge and cause contractions of the extraocular muscles. Movements of the eye are influenced by several main factors: the force generated in each muscle, the inertia of the globe, the viscous and elastic properties of the muscles, and the viscoelasticity of the suspensory orbital tissues (all of which constitute the oculomotor plant). Overall, the response of the plant is sluggish, so the innervation to the muscles must have a specific time-course of activation. Otherwise, the movements of the eye would be too slow and would lead to smearing of images across the retina. Differential equations are derived that describe the activity in motoneurons and the response of the plant.
Topics: Eye Movements; Humans; Motor Neurons; Oculomotor Muscles; Oculomotor Nerve
PubMed: 35074051
DOI: 10.1016/bs.pbr.2021.10.002 -
The Journal of the Royal College of... Dec 2021
Topics: Humans; Magnetic Resonance Imaging; Oculomotor Nerve Diseases
PubMed: 34882150
DOI: 10.4997/JRCPE.2021.425 -
Developmental Biology Aug 2021Muscle function is dependent on innervation by the correct motor nerves. Motor nerves are composed of motor axons which extend through peripheral tissues as a compact...
Muscle function is dependent on innervation by the correct motor nerves. Motor nerves are composed of motor axons which extend through peripheral tissues as a compact bundle, then diverge to create terminal nerve branches to specific muscle targets. As motor nerves approach their targets, they undergo a transition where the fasciculated nerve halts further growth then after a pause, the nerve later initiates branching to muscles. This transition point is potentially an intermediate target or guidepost to present specific cellular and molecular signals for navigation. Here we describe the navigation of the oculomotor nerve and its association with developing muscles in mouse embryos. We found that the oculomotor nerve initially grew to the eye three days prior to the appearance of any extraocular muscles. The oculomotor axons spread to form a plexus within a mass of cells, which included precursors of extraocular muscles and other orbital tissues and expressed the transcription factor Pitx2. The nerve growth paused in the plexus for more than two days, persisting during primary extraocular myogenesis, with a subsequent phase in which the nerve branched out to specific muscles. To test the functional significance of the nerve contact with Pitx2+ cells in the plexus, we used two strategies to genetically ablate Pitx2+ cells or muscle precursors early in nerve development. The first strategy used Myf5-Cre-mediated expression of diphtheria toxin A to ablate muscle precursors, leading to loss of extraocular muscles. The oculomotor axons navigated to the eye to form the main nerve, but subsequently largely failed to initiate terminal branches. The second strategy studied Pitx2 homozygous mutants, which have early apoptosis of Pitx2-expressing precursor cells, including precursors for extraocular muscles and other orbital tissues. Oculomotor nerve fibers also grew to the eye, but failed to stop to form the plexus, instead grew long ectopic projections. These results show that neither Pitx2 function nor Myf5-expressing cells are required for oculomotor nerve navigation to the eye. However, Pitx2 function is required for oculomotor axons to pause growth in the plexus, while Myf5-expressing cells are required for terminal branch initiation.
Topics: Animals; Axons; Female; Gene Expression; Gene Expression Regulation; Homeodomain Proteins; Mice; Muscle Development; Myogenic Regulatory Factor 5; Oculomotor Muscles; Oculomotor Nerve; Pregnancy; Transcription Factors; Homeobox Protein PITX2
PubMed: 33905720
DOI: 10.1016/j.ydbio.2021.04.006 -
World Neurosurgery Nov 2022To evaluate the relationship between the oculomotor nerve (CNIII) and the internal carotid artery (ICA) as a new anatomic-radiologic landmark for distinguishing the...
The Intersection Between the Oculomotor Nerve and the Internal Carotid Artery to Distinguish Extracavernous and Intracavernous Paraclinoid Aneurysms Using Anatomic Dissections-A New 3T Magnetic Resonance Imaging Protocol Confirmed by Three-Dimensionally Printed Biomodels.
OBJECTIVE
To evaluate the relationship between the oculomotor nerve (CNIII) and the internal carotid artery (ICA) as a new anatomic-radiologic landmark for distinguishing the exact location of a paraclinoid intracranial aneurysm (IA).
METHODS
Microanatomic dissections were performed in 20 cavernous sinuses to evaluate the ICA paraclinoid region. Based on anatomic observations, a new magnetic resonance (MRI) protocol to classify paraclinoid aneurysms was proposed. MRI of 42 IAs from 34 patients was independently analyzed and classified as intracavernous, extracavernous, or transitional by 2 neuroradiologists. To validate the proposed MRI protocol, each IA was classified by a three-dimensionally (3D) printed biomodel and agreement with the radiologic classifications was evaluated. Of 42 IAs, 23 undergoing microsurgeries were also classified by direct visualization.
RESULTS
We observed that the true cavernous sinus roof is defined by the carotid-oculomotor membrane, which has an intimate relationship with the intersection between the superior limit of the CNIII and the ICA. Based on this intersection, all 42 IAs were radiologically classified and agreement with the 3D printed biomodels was observed in 95% IAs. Concordance tests showed a statistically significant (P < 0.05) agreement between the classifications. All 23 IAs treated had the radiologic and 3D biomodel classification confirmed.
CONCLUSIONS
The intersection between the ICA and the CNIII, which crosses it transversely in its entire diameter, is a reliable anatomic-radiologic landmark to correctly classify paraclinoid aneurysms. Through a new MRI protocol, it is possible to radiologically identify this intersection and to easily distinguish the intracavernous and extracavernous ICA paraclinoid aneurysms.
Topics: Humans; Carotid Artery, Internal; Oculomotor Nerve; Intracranial Aneurysm; Magnetic Resonance Imaging; Carotid Artery Diseases; Printing, Three-Dimensional
PubMed: 35970294
DOI: 10.1016/j.wneu.2022.08.030 -
American Journal of Physical Medicine &... May 2020Isolated oculomotor nerve palsy is rarely encountered after mild traumatic brain injury. It is difficult to offer patients accurate management strategies or prognostic... (Review)
Review
BACKGROUND
Isolated oculomotor nerve palsy is rarely encountered after mild traumatic brain injury. It is difficult to offer patients accurate management strategies or prognostic assessments because only a few reports have described the management of oculomotor nerve palsy.
METHODS
We performed a search for all clinical studies of isolated oculomotor nerve palsy after mild traumatic brain injury published up to July 9, 2019. We placed no restrictions on language or year of publication in our search, and we searched the following key words: traumatic brain injury, isolated oculomotor nerve palsy, mild head trauma, management, and prognosis.
RESULTS
We identified 14 cases of isolated oculomotor nerve palsy after mild traumatic brain injury. In three cases, steroids were used to manage the oculomotor nerve palsy. Five patients who had underlying brain lesions underwent surgery, and seven patients were observed and followed up. The time to partial or complete resolution was 6.0 ± 5.3 mos with a range of 0.5-18 mos.
CONCLUSIONS
This review includes a survey of surgical treatment for the management of traumatic brain injury that underlies oculomotor nerve palsies, steroid therapy to reduce related brain edema, and oculomotor rehabilitation with training eye movement behavior.
Topics: Brain Injuries, Traumatic; Humans; Oculomotor Nerve Diseases; Prognosis; Risk Factors
PubMed: 31609729
DOI: 10.1097/PHM.0000000000001316 -
Neurosurgical Focus: Video Apr 2022Petroclival meningiomas are surgically challenging due to the surrounding neurovascular structures. Petroclival meningiomas located inferior to the oculomotor nerve and...
Petroclival meningiomas are surgically challenging due to the surrounding neurovascular structures. Petroclival meningiomas located inferior to the oculomotor nerve and superior or medial to the abducens nerve are ideal for an endoscopic endonasal transclival approach because this prevents the need to work across cranial nerves, limiting operative risk. The authors present a case of a 45-year-old woman with a growing petroclival meningioma that was distorting the pons. In the video they demonstrate the technique and discuss nuances of petroclival meningioma resection via an endoscopic endonasal transclival approach with posterior clinoidectomy. The video can be found here: https://stream.cadmore.media/r10.3171/2022.1.FOCVID21209.
PubMed: 36285000
DOI: 10.3171/2022.1.FOCVID21209 -
Neuro-Chirurgie Jan 2022Posterior communicating artery aneurysms (PCoAA) usually present with brain hemorrhage, but they might present with oculomotor nerve palsy (ONP) in about one out of five... (Review)
Review
OBJECTIVE
Posterior communicating artery aneurysms (PCoAA) usually present with brain hemorrhage, but they might present with oculomotor nerve palsy (ONP) in about one out of five patients. Treatment options include endovascular coiling and surgical clipping. The present analysis aims to compare the two treatment options for ONP due to PCoAA in terms of complete recovery and related parameters.
METHODS
A comprehensive literature search was performed for studies published between 2000 and 2019 on ONP due to PCoAA. The included studies were divided into two categories-surgical clipping (group A) and endovascular coiling (group B). The collected data were statistically processed with SPSS version 25.
RESULTS
There was a significant difference between the two treatment groups regarding complete recovery of ONP (P<0.001), suggesting superiority of the surgical clipping. The correlation analysis showed no correlations for group A. Group B had negative and positive correlations, showing that endovascular coiling results in higher rates of complete ONP recovery for elderly patients.
CONCLUSION
Surgical clipping is superior to endovascular coiling in terms of complete recovery among patients with ONP due to PCoAAs. Endovascular coiling seems to benefit older patients. While no recommendations exist for the treatment of ONP due to intracranial aneurysms, an increasing number of studies imply the superiority of operative clipping.
Topics: Aged; Aneurysm, Ruptured; Embolization, Therapeutic; Endovascular Procedures; Humans; Intracranial Aneurysm; Intracranial Hemorrhages; Neurosurgical Procedures; Oculomotor Nerve Diseases; Retrospective Studies; Treatment Outcome
PubMed: 33845117
DOI: 10.1016/j.neuchi.2021.03.012 -
World Neurosurgery Apr 2023The oculomotor cistern (OMC) is a cerebrospinal fluid space bound by meningeal layers that surrounds the oculomotor nerve as it crosses the oculomotor triangle to reach... (Review)
Review
BACKGROUND
The oculomotor cistern (OMC) is a cerebrospinal fluid space bound by meningeal layers that surrounds the oculomotor nerve as it crosses the oculomotor triangle to reach the lateral wall of the cavernous sinus at the level of the anterior clinoid process. Although several anatomical and radiological studies are available, its anatomy and relationship with pituitary adenomas (PAs) are still matter of discussion.
OBJECTIVE
The aim of the study is to provide an updated and focused overview of the OMC, highlighting the different perspectives and descriptions from anatomical, radiological, and clinical points of view.
METHODS
A scoping review was conducted up to 29 October 2022, according to PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) criteria. PubMed, Web of Science, Scopus databases, and correlated citations were investigated.
RESULTS
Of the 562 records identified, 22 were included in the present analysis. There were 13, 5, and 4 anatomo-surgical, radiological, and clinical studies, respectively. Though there is general consensus on its definition, data are variable on different features of OMC. Defects or absence of dural layers adjacent to the oculomotor nerve were described in only 4 papers. The transition from meningeal to neural layers is still unclear. PAs with OMC involvement are poorly studied and have unique clinical characteristics. To date, 21 patients have been described; the reported prevalence of OMC involvement by PAs ranges from 4.1% to 14.6%.
CONCLUSIONS
Clarifying the OMC features with further systematic studies may not only broaden theoretical knowledge but also have implications on endoscopic transnasal pituitary surgery.
Topics: Humans; Adenoma; Endoscopy; Oculomotor Nerve; Pituitary Gland; Pituitary Neoplasms
PubMed: 36657712
DOI: 10.1016/j.wneu.2023.01.048 -
Surgical and Radiologic Anatomy : SRA Nov 2022No study has documented the oculomotor nerve (OMN) segment lying between the posterior cerebral (PCA) and superior cerebellar (SCA) arteries adjacent to the brainstem....
PURPOSE
No study has documented the oculomotor nerve (OMN) segment lying between the posterior cerebral (PCA) and superior cerebellar (SCA) arteries adjacent to the brainstem. The present study aimed to characterize it.
METHODS
A total of 71 patients underwent thin-sliced, sagittal T2-weighted magnetic resonance imaging for analysis.
RESULTS
The OMN segments lying between the PCA and SCA were identified in all patients. The OMN segment in relation to the PCA and SCA was classified into five types. Of them, the PCA-OMN contact type was the most frequent and found in 35.2% of 71 sides on the right and 39.4% on the left. Also, the PCA-OMN compression type was identified in 12.7% on the right and 15.5% on the left. In these types, the mean distance between the brainstem and contact/compression sites were measured 4.4 ± 2.3 mm on the right and 4.4 ± 1.6 mm on the left. In more than forty percent, the sites were located at the level of the pontomesencephalic junction.
CONCLUSIONS
The OMN may be frequently in contact with the PCA near the brainstem. The site located more distal than the central-peripheral myelin junction of the OMN can attribute to a low frequency of neurovascular compression syndrome of the nerve.
Topics: Humans; Oculomotor Nerve; Basilar Artery; Magnetic Resonance Imaging
PubMed: 36241748
DOI: 10.1007/s00276-022-03033-3