Oculomotor nerve cavernous malformation: case report and operative video.

BACKGROUND: Cavernous malformations (CMs) are clusters of thin-walled sinusoidal vessels without well-defined walls. Though they can occur anywhere in the neuroaxis, cranial nerve (CN) CMs are rare. METHOD: We report a 47-year-old male with gradual CN III palsy. Initial imaging showed no significant findings, but a follow-up MRI revealed a growing lesion along CN III. Intraoperative findings confirmed a CN III CM. Diagnosing and treating CN III CM are complex. Radiological findings lack specificity, requiring consideration of various diagnoses for patients with isolated CN III palsy and abnormal radiological findings. CONCLUSION: Surgery is the gold standard, aiming for complete lesion removal while minimizing neurological complications.

The relative sizes of nuclei in the oculomotor complex vary by order and behaviour in birds.

Eye movements are a critical component of visually guided behaviours, allowing organisms to scan the environment and bring stimuli of interest to regions of acuity in the retina. Although the control and modulation of eye movements by cranial nerve nuclei are highly conserved across vertebrates, species variation in visually guided behaviour and eye morphology could lead to variation in the size of oculomotor nuclei. Here, we test for differences in the size and neuron numbers of the oculomotor nuclei among birds that vary in behaviour and eye morphology. Using unbiased stereology, we measured the volumes and numbers of neurons of the oculomotor (nIII), trochlear (nIV), abducens (nVI), and Edinger-Westphal (EW) nuclei across 71 bird species and analysed these with phylogeny-informed statistics. Owls had relatively smaller nIII, nIV, nVI and EW nuclei than other birds, which reflects their limited degrees of eye movements. In contrast, nVI was relatively larger in falcons and hawks, likely reflecting how these predatory species must shift focus between the central and temporal foveae during foraging and prey capture. Unexpectedly, songbirds had an enlarged EW and relatively more nVI neurons, which might reflect accommodation and horizontal eye movements. Finally, the one merganser we measured also has an enlarged EW, which is associated with the high accommodative power needed for pursuit diving. Overall, these differences reflect species and clade level variation in behaviour, but more data are needed on eye movements in birds across species to better understand the relationships among behaviour, retinal anatomy, and brain anatomy.

Congenital isolated unilateral third nerve palsy in children: the diagnostic contribution of high-resolution MR imaging.

PURPOSE: To describe the neuroanatomical correlates of unilateral congenital isolated oculomotor palsy by means of high-resolution MRI. METHODS: Children with a clinical diagnosis of congenital isolated oculomotr palsy and with a high-resolution MRI acquisition targeted on the orbits and cranial nerves were selected and included in the study. An experienced pediatric neuroradiologist evaluated all the exams, assessing the integrity and morphology of extraocular muscles, oculomotor, trochlear and abducens nerves as well as optic nerves and globes. Clinical data and ophthalmologic evaluations were also collected. RESULTS: Six children (age range: 1-16 years; males: 3) were selected. All patients showed, on the affected side (left:right = 5:1), anomalies of the III nerve and extraocular muscles innervated by the pathological nerve. One patient had complete nerve agenesis, two patients showed a diffuse thinning of the nerve, from the brainstem to the orbit and 3 patients showed a distal thinning of the oculomotor nerve, starting at the level of the cavernous sinus. In all cases atrophy of corresponding muscles was noticed, but the involvement of the affected muscles varied with the nervous pattern of injury. CONCLUSIONS: High-resolution MRI represents a valuable tool for the diagnosis of III nerve anomalies in unilateral congenital IOP, showing different patterns of nerve involvement and muscular atrophy.

Meningioma originating from the oculomotor nerve without dural attachment in a child.

Meningioma originating from the oculomotor nerve without dural attachment in children has been rarely reported. A 6-year-old patient presented ptosis of the right eye for 5 years. MRI indicated an occupying lesion in the right cavernous sinus. A tumor originating from the oculomotor nerve without dural attachment was found during subsequent surgery and confirmed as meningioma by pathology. Subsequently, the tumor was removed completely, and the oculomotor nerve was reconstructed using the sural nerve. The patient's symptoms were relieved partially after 3 months. The findings of this case suggested that the mechanisms underlying meningioma involve ectopic arachnoid cap cells within the nerve sheath. Thus, the tumor should be removed completely; also, nerve reconstruction is suggested.

Pituitary adenoma with oculomotor cistern extension: membranous anatomy and clinical application.

BACKGROUND: The anatomical basis of pituitary adenomas (PAs) with oculomotor cistern (OC) extension as a growth corridor is overlooked in the literature. In this paper, the authors use the technique of epoxy sheet plastination to study the membranous structure of the OC and validate the results by retrospective analysis of patients with OC extension. METHODS: Eighteen specimens were used to study the membranous anatomy surrounding the OC using the epoxy sheet plastination technique. Thirty-four patients with OC extension were retrospectively reviewed. RESULTS: The OC consisted of two thin membranous layers. The inner layer was extended by the arachnoid layer from the posterior fossa, and the lateral layer consisted of the dura mater sinking from the roof of the cavernous sinus. The oculomotor nerve is more likely to displace with a superolateral trajectory due to the weakness of the posterior dura and the relatively large space in the medial and posterior trajectories, which is consistent with the intraoperative observations. Among the anatomical factors that affect the PA by OC extension, we found that the relative position of the internal carotid artery (ICA) and posterior clinoid process may lead to the narrowing of the OC. Of 34 cases, 28 patients achieved total resection. Among 24 preoperative patients with oculomotor nerve palsy, 16 cases were relieved to varying degrees postoperatively. There was no ICA injury or severe intracranial infection found in any of the patients. CONCLUSIONS: Extension into the OC is influenced by two anatomical factors: a weak point in the dura in the posterior OC and a potential space beyond this region of the dura. Meticulous knowledge of the membranous anatomy in endoscopic endonasal surgery is required to safely and effectively resect PA with OC extension.

Glioblastoma multiforme with oculomotor nerve involvement: case report and literature review.

Gliomas involving the cranial nerves III-XIII are rare. Even rarer are glioblastomas multiforme (GBMs) with only 10 cases previously reported. Oculomotor nerve involvement was described in only 2 patients. The mechanisms proposed so far include an origin from the nerve itself or an extension within the nerve of a midbrain tumor. We report the case of a 69-year-old man who presented with an isolated left oculomotor nerve palsy. He was found to have a left temporal GBM extended to the frontal lobe. Diagnostics and intraoperative and pathological findings clearly demonstrated a massive infiltration of the cisternal portion of the left oculomotor nerve. We suppose this could be the first case of direct oculomotor nerve invasion by exophytic spread of a supratentorial GBM or by subarachnoid seeding from a temporal tumor. Less probably, it could be the first case of an oculomotor nerve GBM with a temporal lobe invasion.

Fenestrated P1 segment of posterior cerebral artery, partly duplicated posterior communicating artery.

PURPOSE: Anatomic variations at the junction of primitive internal carotid and basilar arteries are exceedingly rare. We aimed at reporting such rare variants involving the posterior communicating artery (PComA) and the P1 segment of posterior cerebral artery (PCA). METHODS: The circle of Willis was dissected in an adult cadaver after removal of the cranial vault and cerebral hemispheres. RESULTS: The basilar end was rotated axially to the right. The P1 segment of the right PCA was fenestrated and occupied the interpeduncular fossa. The right PComA passed over the oculomotor nerve to join the anterior arm of the P1 fenestration. On the opposite side, the PComA coursed supero-medially to the oculomotor nerve and it had a partly duplicated posterior end, with two arms, medial, larger, and lateral, thinner, inserting successively into the left PCA. CONCLUSION: Extremely rare anatomic variations of the circle of Willis should not be ignored when endovascular or microneurosurgical specific approaches are intended.

Oculomotor nerve guidance and terminal branching requires interactions with differentiating extraocular muscles.

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.

Automatic oculomotor nerve identification based on data-driven fiber clustering.

The oculomotor nerve (OCN) is the main motor nerve innervating eye muscles and can be involved in multiple flammatory, compressive, or pathologies. The diffusion magnetic resonance imaging (dMRI) tractography is now widely used to describe the trajectory of the OCN. However, the complex cranial structure leads to difficulties in fiber orientation distribution (FOD) modeling, fiber tracking, and region of interest (ROI) selection. Currently, the identification of OCN relies on expert manual operation, resulting in challenges, such as the carries high clinical, time-consuming, and labor costs. Thus, we propose a method that can automatically identify OCN from dMRI tractography. First, we choose the multi-shell multi-tissue constraint spherical deconvolution (MSMT-CSD) FOD estimation model and deterministic tractography to describe the 3D trajectory of the OCN. Then, we rely on the well-established computational pipeline and anatomical expertise to create a data-driven OCN tractography atlas from 40 HCP data. We identify six clusters belonging to the OCN from the atlas, including the structures of three kinds of positional relationships (pass between, pass through, and go around) with the red nuclei and two kinds of positional relationships with medial longitudinal fasciculus. Finally, we apply the proposed OCN atlas to identify the OCN automatically from 40 new HCP subjects and two patients with brainstem cavernous malformation. In terms of spatial overlap and visualization, experiment results show that the automatically and manually identified OCN fibers are consistent. Our proposed OCN atlas provides an effective tool for identifying OCN by avoiding the traditional selection strategy of ROIs.

Malignant nerve sheath tumor of oculomotor nerve in a pediatric patient.

Malignant nerve sheath tumors are extremely rare pathologies. They tend to occur within peripheral nerves and have close association of neurofibromatosis disease. Here, we present the second case of MNST of oculomotor nerve in literature. The patient was a 2-year-old girl with left sided oculomotor nerve palsy. After resection, the patient immediately had chemotherapy and radiotherapy. One year after surgery disease progressed with extensive intracranial seedings, and she passed away.

Oculomotor nerve segment between proximal posterior and superior cerebellar arteries: an MRI study.

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.

Hyperintense areas in the cisternal segments of the cranial nerves: a magnetic resonance imaging study.

PURPOSE: The study aimed to explore hyperintense areas in the cisternal segments of the cranial nerves using magnetic resonance imaging (MRI). METHODS: Seventy outpatients underwent thin-sliced, coronal constructive interference steady-state (CISS) sequence and sagittal T2-weighted MRI following conventional MRI examination. RESULTS: With the coronal CISS sequence, hyperintense areas were located in the central parts of the olfactory bulbs in 65.7% of patients. For the intracranial optic nerve and optic chiasm, hyperintense areas were detected in 98.6% of the CISS sequences and 100% of the T2-weighted images. In the optic tract, hyperintense areas were detected in 51.4% of cases. In 35% of the patients who underwent the CISS sequence, the intracranial optic nerves were considerably compressed by the internal carotid and anterior cerebral arteries, with hyperintense areas similar to those in patients without vascular compression. Hyperintense areas of the cisternal segments of the oculomotor nerve and trigeminal root were identified in 52.9% and 87.1% of the patients, respectively. CONCLUSIONS: The hyperintense areas found within the cisternal segments of the cranial nerves delineated on the coronal CISS sequence and sagittal T2-weighted imaging may indicate the intracranial part of the glymphatic pathway through the cranial nerves. The cranial nerves may function as part of the glymphatic pathway.

Oculomotor nerve root split: incidental finding on MRI-case report and literature review.

BACKGROUND: The oculomotor nerve (OMN) innervates the pupil, ciliary body, upper eyelid, and extraocular muscles through two divisions: a superior division that innervates the levator palpebrae superioris (LPS) and superior rectus (SR), and an inferior division that supplies the medial rectus (MR), inferior rectus (IR), inferior oblique (IO), and parasympathetic fibers to the pupil and ciliary body. We present a case of complete splitting of the cisternal segment of bilateral OMNs that was discovered incidentally on magnetic resonance imaging (MRI) in a patient who had no ocular complaints. CASE REPORT: A 69-year-old patient was found to have bilateral splitting of the cisternal segments of OMNs during an MRI for trigeminal neuralgia workup. Both nerves sprang from the midbrain as distinct roots. They were symmetric on the right and minimally asymmetric on the left. On both sides, the medial root was slightly inferiorly situated. The patient had no visual problems and continued to function normally. A review of the literature for similar cases identified no such variants; however, it did identify eight examples of OMN fenestrations produced by aneurysms (AN), six of which had no OMN palsy symptoms. CONCLUSION: An anatomic variant of split bilateral OMN cisternal segments is described. The superior and inferior divisions may have different brainstem origins. Although this variant is an anatomic curiosity, it may have clinical significance and explain the various presentation of compressive OMN palsies.

[Schwannoma originating from the branch of the inferior oblique muscle innervated by the oculomotor nerve: a report of two cases].

Patient 1 was a 44-year-old female with a progressively enlarging orbital mass on the right side for 2 years, while patient 2 was a 25-year-old female who complained of protrusion of the right eye for 2 months. Both patients presented with exophthalmos and a palpable infraorbital mass without vision loss. Magnetic resonance imaging examination showed a well circumscribed circular orbital lesion, with hypointensity on T1 weighted image and heterogeneous hyperintensity on T2 weighted image, which could be significantly enhanced, in either eye. Both eyes were diagnosed as begin orbital tumor and received resection under general anesthesia. Intraoperatively, the distal end of the tumors was found to transmigrate to normal nerves and insert into the inferior oblique muscle. Combined with the pathological diagnosis of schwannoma and postoperative occurrence of mydriasis and inferior oblique muscle paralysis in both patients, it was confirmed that the two lesions were schwannomas originating from the branch of the inferior oblique muscle innervated by the oculomotor nerve.

The trajectory of the medial longitudinal fasciculus in the human brain: A diffusion imaging-based tractography study.

The aim of this study is to investigate the trajectory of medial longitudinal fasciculus (MLF) and explore its anatomical relationship with the oculomotor nerve using tractography technique. The MLF and oculomotor nerve were reconstructed at the same time with preset three region of interests (ROIs): one set at the area of rostral midbrain, one placed on the MLF area at the upper pons, and one placed at the cisternal part of the oculomotor nerve. This mapping protocol was tested in an HCP-1065 template, 35 health subjects from Massachusetts General Hospital (MGH), 20 healthy adults and 6 brainstem cavernous malformation (BCM) patients with generalized q-sampling imaging (GQI)-based tractography. Finally, the 200 µm brainstem template from Center for In Vivo Microscopy, Duke University (Duke CIVM), was used to validate the trajectory of reconstructed MLF. The MLF and oculomotor nerve were reconstructed in the HCP-1065 template, 35 MGH health subjects, 20 healthy adults and 6 BCM patients. The MLF was in conjunction with the ipsilateral mesencephalic part of the oculomotor nerve. The displacement of MLF was identified in all BCM patients. Decreased QA, RDI and FA were found in the MLF of lesion side, indicating axonal loss and/or edema of displaced MLF. The reconstructed MLF in Duke CIVM brainstem 200 µm template corresponded well with histological anatomy. The MLF and oculomotor nerve were visualized accurately with our protocol using GQI-based fiber tracking. This GQI-based tractography is an important tool in the reconstruction and evaluation of MLF.

GCA: Better ✓check for third cranial nerve involvement!

KEY POINTS: • The intriguing "Check Mark Sign" suggests 3rd cranial nerve involvement in GCA.

Diabetic Oculomotor Nerve Palsy Displaying Enhancement of the Oculomotor Nerve in the Orbit and Cavernous Sinus on MRI.

INTRODUCTION: Imaging data were scarce on diabetic oculomotor nerve palsy (ONP). Our study explored the MRI features and their clinical implications for diabetic ONP. METHODS: Fifty-nine patients with a clinical diagnosis of diabetic ONP were recruited from our department between January 2015 and December 2019. Orbital MRI was retrospectively analyzed, and follow-up scans were obtained for 5 patients. Based on the ocular motor nerve palsy scale, the difference in the scores on the first and last hospital days was defined as the improvement score and was used to assess the treatment effects in all. RESULTS: Thirty-eight (64.41%) patients presented thickening and enhancement of the cavernous segment and inferior division of the intraorbital segment of the ipsilateral oculomotor nerve, with the cisternal segment spared in all. After complete resolution of symptoms, follow-up MRI in 5 patients revealed that the enhancement was less obvious compared with the previous images. 6 patients in the enhancement group and 4 patients in the nonenhancement group were treated with 80 mg of methylprednisolone. Significant differences were not detected in the median improvement scores between patients with and those without corticosteroid use (p = 0.240). CONCLUSION: Thickening and enhancement of the unilateral oculomotor nerve were common imaging findings in diabetic ONP, and they persisted after complete resolution of symptoms in some patients. The cavernous segment and the inferior division of the intraorbital segment were simultaneously involved, and the cisternal segment was often spared. Refraining from corticosteroids was recommended even with nerve enhancement.

Pediatric intracranial neurenteric cyst of the oculomotor nerve: a case-based review.

BACKGROUND: Neurenteric cysts (NECs) of the central nervous system (CNS) are uncommon congenital entities arising from embryonal elements. Intracranial NECs in the pediatric population are rare. METHODS: The authors describe the presentation, radiographic imaging, and pathologic findings of an 11-year-old boy with a right oculomotor nerve NEC. A literature review was performed to identify additional cases of pediatric intracranial NECs published in the English language, over the past 30 years (1990-2020). The authors discuss the presentation, investigations, management, and prognosis of this interesting entity. RESULTS: We describe an 11-year-old boy who presented to neurosurgical attention with disconjugate gaze, anisocoria, and ptosis. Magnetic resonance imaging (MRI) demonstrated a lobulated, cystic, and peripherally enhancing mass involving the right oculomotor nerve. The patient underwent pterional craniotomy for drainage of the cyst and subtotal resection of the cyst wall. The tan-colored mass was displacing the basilar artery, compressing the cerebral peduncle, and adherent to the inferior surface of the tentorium. The lesion was within the oculomotor nerve and splitting the fibers, and the cystic contents were thick and mucinous. Histopathological examination of the specimen demonstrated a thin fibrous cyst wall with scattered inflammatory cells and lined by simple columnar epithelium containing mucin. The lining cells were immunoreactive with epithelial membrane antigen (EMA) and pan-keratin AE1/AE3. The diagnosis of a NEC was rendered. A comprehensive literature review of pediatric intracranial NECs yielded 46 additional lesions published in the literature, involving the skull base, posterior fossa, cerebral convexity, and cranial nerves. NECs present with local mass effect and less commonly, with aseptic meningitis or intracystic hemorrhage. Maximal safe GTR remains the mainstay management, although cyst drainage and marsupialization, cyst shunting, and fenestration of cystic contents into the ventricle or basal cisterns have been reported with variable success. CONCLUSION: CNS NECs are rare congenital entities; although they occur less frequently in the intracranial components compared to the spine, their diagnosis and management should be considered for intracranial cystic lesions. Maximal safe GTR is the mainstay treatment and frequently yields favorable outcomes.

Acute Complete Oculomotor Nerve Palsy in a Young Male Due to a Skull Base Myofibroma.

ABSTRACT: A 25-year-old male patient visited the ophthalmology clinic because of upper eye lid ptosis in the right eye, binocular double vision, and light sensitivity. He was diagnosed with a complete third nerve palsy caused by a skull base myofibroma, a rare clinical entity that has not been described before in oculomotor nerve palsy.

Isolated Oculomotor Neuritis After Dengue Fever.

ABSTRACT: We report a rare case of isolated partial left III cranial nerve palsy due to inflammatory oculomotor neuritis after dengue fever with unique neuro-imaging findings of enhancement seen along the entire course of the oculomotor nerve.