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BDNF is a neurotrophin family member implicated in many different neuronal functions, from neuronal survival during development to synaptic plasticity associated with processes of learning and memory. Its presence in the oculomotor system has previously been demonstrated, as it regulates afferent composition of extraocular motoneurons and their firing pattern. Moreover, BDNF expression increases after extraocular motoneuron partial deafferentation, in parallel with terminal axon sprouting from the remaining axons. To elucidate whether BDNF could play an active role in this process, we performed partial deafferentation of the medial rectus motoneurons through transection of one of the two main afferents, that is, the ascending tract of Deiters, and injected BDNF into the motoneuron target muscle, the medial rectus. Furthermore, to check whether BDNF could stimulate axon sprouting without lesions, we performed the same experiment without any lesions. Axon terminal sprouting was assessed by calretinin immunostaining, which specifically labels the remaining afferent system on medial rectus motoneurons, the abducens internuclear neurons. The results presented herein show that exogenous BDNF stimulated terminal axon growth, allowing the total recovery of synaptic coverage around the motoneuron somata. Moreover, calretinin staining in the neuropil exceeded that present in the control situation. Thus, BDNF could also stimulate axonal sprouting in the neuropil of intact animals. These results point to an active role of BDNF in plastic adaptations that take place after partial deafferentation.

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.

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., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Abducens nerve schwannomas are incredibly rare, with very few cases being reported previously. Our patient is the first to have been treated through use of an endoscopic endonasal approach. A 61-year-old woman presented with diplopia over a 1-year period. Magnetic resonance imaging identified a 2.8-cm lesion expanding into her right sphenoid sinus. She underwent an endoscopic endonasal approach for histological diagnosis and clearance of the lesion. Intraoperative exploration found the lesion to be originating from Dorello canal. Histological analysis confirmed a benign schwannoma. Following a multidisciplinary case review, we have followed a conservative approach and she remains well on radiological surveillance. In patients presenting with a sixth nerve palsy/paresis and a concomitant sphenoid lesion, clinicians should consider an abducens schwannoma as a possible diagnosis.

An ossified left petroclinoid ligament was found during routine dissection of the skull base in an adult male cadaver. The petroclinoid ligament is clinically and surgically important given its anatomical relationships to cranial nerves III, V, and VI, so its ossification is a risk factor for injuries due to trauma, increased intracranial pressure, and vascular and tumor compression resulting in abducens and oculomotor palsies. The causes of petroclinoid ligament ossification are yet to be completely elucidated although several reports have associated them with age-related and physiological processes. Assessing the integrity of the petroclinoid ligament is important during skull base surgical interventions to avoid postoperative complications. Therefore, this paper reviews the petroclinoid ligament and its variation, the ossified petroclinoid ligament.

Objectives: While abducens nerve palsy (ANP) is a known risk in the setting of some endoscopic endonasal skull base surgery (ESBS), frequency and prognosis of post-operative palsy remain unknown. Our goals were to determine the frequency and prognosis of ANP after high-risk ESBS, and identify factors associated with recovery., Methods: Retrospective case series of all patients with pathology at highest risk for abducens nerve injury (pituitary adenoma, chordoma, meningioma, chondrosarcoma, cholesterol granuloma) generated a list of patients with abducens nerve palsy after ESBS performed from 2011-2016. A validated ophthalmologic clinical grading scale measuring lateral rectus duction from 0 to -5 (full motion to inability to reach midline) was measured at multiple time points to assess recovery of ANP., Results: Of 655 patients who underwent ESBS with increased risk of abducens injury, 40 (6.1%) post-operative palsies were identified and 39 patients with dedicated examination at multiple time points were included in subsequent analysis. Complete resolution was noted in 25 patients (64%) within 12 months. While 19 of 23 (83%) with a partial palsy had complete resolution, only six of 16 (38%) with a complete palsy resolved entirely (P = .005; Fisher's exact test). All six patients with delayed onset of palsy resolved (P = .070; Fisher's exact test). Meningioma and chordoma had higher rates of both temporary and permanent post-operative ANP (P < .0001; Fisher's exact)., Conclusions: The frequency of post-operative ANP following ESBS is low, even in high-risk tumors. While only a minority of complete abducens nerve palsies recover, patients with partial or delayed palsy post-operatively are likely to recover function without intervention., Level of Evidence: IV Laryngoscope, 131:513-517, 2021., (© 2020 American Laryngological, Rhinological and Otological Society Inc, "The Triological Society" and American Laryngological Association (ALA).)

The complete features of the neurological complications of coronavirus disease 2019 (COVID-19) still need to be elucidated, including associated cranial nerve involvement. In the present study we describe cranial nerve lesions seen in magnetic resonance imaging (MRI) of six cases of confirmed COVID-19, involving the olfactory bulb, optic nerve, abducens nerve, and facial nerve. Cranial nerve involvement was associated with COVID-19, but whether by direct viral invasion or autoimmunity needs to be clarified. The development of neurological symptoms after initial respiratory symptoms and the absence of the virus in the cerebrospinal fluid (CSF) suggest the possibility of autoimmunity.

Competing Interests: The authors declare that there are no conflict of interest.

Background: Ocular motor dysfunction is one of the most common postoperative complications of petroclival meningioma. However, its incidence, recovery rate, and independent risk factors remain poorly explored., Methods: A prospective analysis of 31 petroclival meningiomas was performed. Operative approaches were selected by utilizing a new 6-region classification of petroclival meningiomas we proposed. Two scores were used to evaluate the functions of the oculomotor and abducens nerves. Pearson correlation analysis and binary logistic regression analysis were used to identify independent risk factors for intraoperative oculomotor and abducens nerve injury., Results: Postoperative new-onset dysfunctions in the pupillary light reflex and eye/eyelid movements as well as abducens paralysis were detected in eight (25.8%), ten (32.3%) and twelve (38.7%) cases, respectively. Their corresponding recovery rates after 6 months of follow-up were 75% (6/8), 80% (8/10), and 83.3% (10/12), respectively, and their mean times to start recovery were 4.03, 2.43, and 2.5 months, respectively. Tumor invasion into the suprasellar region/sphenoid sinus was the only risk factor for dysfunctions in both the pupillary light reflex (p = 0.001) and eye/eyelid movements (p = 0.002). Intraoperative utilization of the infratrigeminal interspace was the only risk factor for dysfunction in eyeball abduction movement (p = 0.004)., Conclusions: Dysfunctions of the oculomotor and abducens nerves recovered within 6 months postoperatively. Tumor extension into the suprasellar region/sphenoid sinus was the only risk factor for oculomotor nerve paralysis. Eye/eyelid movements were more sensitive than the pupillary light reflex in reflecting nerve dysfunctions. Intraoperative utilization of the infratrigeminal interspace was the only risk factor for abducens nerve paralysis.

Aims: To elucidate the intramuscular distribution and branching patterns of the abducens nerve in the lateral rectus (LR) muscle so as to provide anatomical confirmation of the presence of compartmentalization, including for use in clinical applications such as botulinum toxin injections., Methods: Thirty whole-mount human cadaver specimens were dissected and then Sihler's stain was applied. The basic dimensions of the LR and its intramuscular nerve distribution were investigated. The distances from the muscle insertion to the point at which the abducens nerve enters the LR and to the terminal nerve plexus were also measured., Results: The LR was 46.0 mm long. The abducens nerve enters the muscle on the posterior one-third of the LR and then typically divides into a few branches (average of 1.8). This supports a segregated abducens nerve selectively innervating compartments of the LR. The intramuscular nerve distribution showed a Y-shaped ramification with root-like arborization. The intramuscular nerve course finished around the middle of the LR (24.8 mm posterior to the insertion point) to form the terminal nerve plexus. This region should be considered the optimal target site for botulinum toxin injections. We have also identified the presence of an overlapping zone and communicating nerve branches between the neighboring LR compartments., Conclusion: Sihler's staining is a useful technique for visualizing the entire nerve network of the LR. Improving the knowledge of the nerve distribution patterns is important not only for researchers but also clinicians to understand the functions of the LR and the diverse pathophysiology of strabismus.

Introduction: Schwannomas involving the occulomotor cranial nerves  (CNs; III, IV and VI), can be disabling, due to the associated diplopia and decreased quality of life and are extremely rare. We evaluated the role of Gamma Knife surgery (GKS) in these cases., Methods: Five patients with CN IV and VI schwannomas (three and two, respectively) were treated in Lausanne University Hospital between 2010 and 2015. Four benefitted from upfront GKS and one from a combined approach (planned subtotal resection followed by GKS), due to a large preoperative tumour volume (size, 3 × 2 × 2.5 cm; volume, 7.9 ml), with symptomatic mass effect and oedema, as well as an entrapement cyst at the brainstem interface, in a young patient. Neuro-ophtalmological evaluation was performed at baseline and during each follow-up time-point. A systematic literature review is presented and compared to the present report., Results: The mean follow-up was 44.4 months (12-54). Initial clinical presentation was diplopia in four cases and cavernous sinus syndrome in one. The marginal dose was 12 Gy in all cases. The mean target volume was 1.51 cm 3 (0.086-5.8). The mean prescription isodose volume (PIV) was 1.71 cm 3 (0.131-6.7). At last follow-up, all patients presented with disappearance of the baseline symptoms. Tumour control was achieved in 100%, with decrease in volume in all cases. The systematic review analysed 11 peer-reviewed studies, with a total of 35 patients. For uniformly reported CN VI, the mean marginal radiation dose ranged between 12 and 12.5 Gy, with disappearance of symptoms in 12.5%, improvement in 31.25%, stabilisation in 6.25%, worsening in 12.5%. Tumour volume decreased in all cases., Conclusions: Our data suggest that first intention GKS is a safe and effective option for patients with small to medium size oculomotor schwannomas, providing a high rate of clinical alleviation and tumour control. When the initial tumour volume is too large for first intention GKS, a combined approach with planned subtotal resection followed by GKS can be performed, with favourable and comparable outcomes as in upfront GKS.

Diplopia is defined as "double vision" when looking at a single object. Monocular diplopia is related to an ocular disorder and must be differentiated from binocular diplopia which is secondary to ocular misalignment. The examination of the patient with binocular diplopia is often challenging for non-specialists. However, a careful and systematic clinical examination followed by targeted ancillary testing allows the clinician to localize the lesion along the oculomotor pathways. The lesion may involve the brainstem, the ocular motor nerves III, IV or VI, the neuromuscular junction, the extraocular ocular muscles, or the orbit. Causes of binocular diplopia are numerous and often include disorders typically managed by internal medicine such as inflammatory, infectious, neoplastic, endocrine, and metabolic disorders. In addition to treating the underlying disease, it is important not to leave diplopia uncorrected. Temporary occlusion of one eye by applying tape on one lens or patching one eye relieves the diplopia until more specific treatments are offered should the diplopia not fully resolve., (Copyright © 2017 Société Nationale Française de Médecine Interne (SNFMI). Published by Elsevier SAS. All rights reserved.)

Endothelin-converting enzyme-like 1 (ECEL1, also termed DINE in rodents), a membrane-bound metalloprotease, has been identified as a gene responsible for distal arthrogryposis (DA). ECEL1-mutated DA is generally characterized by ocular phenotypes in addition to the congenital limb contractures that are common to all DA subtypes. Until now, the consequences of the identified pathogenic mutations have remained incompletely understood because of a lack of detailed phenotypic analyses in relevant mouse models. In this study, we generated a new knock-in mouse strain that carries an ECEL1/DINE pathogenic G607S missense mutation, based on a previous study reporting atypical DA hindlimb phenotypes in two siblings with the mutation. We compared the morphological phenotypes of G607S knock-in mice with C760R knock-in mice that we previously established. Both C760R and G607S knock-in mouse embryos showed similar axonal arborization defects with normal trajectory patterns from the spinal cord to the target hindlimb muscles, as well as axon guidance defects of the abducens nerves. Intriguingly, distinct phenotypes in DINE protein localization and mRNA expression were identified in these knock-in mouse lines. For G607S, DINE mRNA and protein expression was decreased or almost absent in motor neurons. In the C760R mutant mice DINE was expressed and localized in the somata of motor neurons but not in axons. Our mutant mouse data suggest that ECEL1/DINE G607S and C760R mutations both lead to motor innervation defects as primary causes in ECEL1-mutated congenital contracture disorders. However, the functional consequences of the two mutations are distinct, with loss of axonal transport of ECEL1/DINE in C760R mutants and mRNA expression deficits in G607S mutants.

Isolated unilateral abducens nerve palsy is usually due to ischemia, trauma or neoplasm. Dorello's canal is the space between the petrous apex and superolateral portion of the clivus, bound superiorly by Gruber's ligament. The abducens nerve travels with inferior petrosal sinus (IPS) though the Dorello's canal before entering the cavernous sinus. A 31-year-old man presented with neck pain, and binocular horizontal diplopia, worse looking towards left and at distance. He had a history of intravenous drug abuse but no history of hypertension or diabetes. On examination, he had complete left 6th nerve palsy with normal fundi, pupils, and other cranial nerves. Methicillin-resistant Staphylococcus aureus bacteremia was detected with naïve tricuspid valve endocarditis and multiple septic emboli to lungs with infarcts. His cerebrospinal fluid was normal. MRI of the brain was normal. MRV of head and neck showed thrombosis of the left internal jugular vein, left sigmoid sinus and left inferior petrosal sinus with normal cavernous sinus and no evidence of mastoiditis. He was treated with broad spectrum antibiotics. He was not anticoagulated for fear of pulmonary hemorrhage from pulmonary infarcts. Although cerebral venous sinus thrombosis commonly presents with elevated intracranial pressure, isolated ipsilateral 6th nerve palsy from its compression in Dorello's canal due to thrombosis of the ipsilateral inferior petrosal sinus is extremely rare. To our knowledge, only two patients have been reported with isolated abducens palsy due to IPS thrombosis; one caused by septic emboli and the other developed it during IPS cortisol level sampling., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objectives: Sixth cranial nerve (SCN) palsy is an uncommon but important neurological problem in patients admitted to pediatric emergency department. The underlying etiology of SCN palsy has a wide range from viral infections to intracranial tumors; therefore, a careful and systematic approach is necessary while examining these patients., Methods: Fourteen patients who presented with acute SCN paralysis to pediatric emergency department during the last 10 years were examined., Results: The age at the time of admission ranged between 14 months and 16 years (median, 9.5 years). Of the 14 patients, 5 were girls and 9 were boys. A total of 3 of the 14 patients had bilateral cranial nerve VI paralysis, and 9 patients had additional abnormal findings on neurological examination. Neuroimaging studies included cranial tomography (n = 3) and brain magnetic resonance imaging in all patients. The underlying etiology was malignancy (n = 3); glioma, medulloblastoma, acute lymphoblastic leukemia, and dural sinus thrombosis (n = 2); as well as Guillain-Barre syndrome (n = 2), multiple sclerosis (n = 1), pseudotumor cerebri (n = 1), and meningitis (n = 1). The remaining 4 patients had miscellaneous benign etiologies., Conclusions: Other lesions of primary brain tumors causing increased intracranial pressure constitute 50% of the underlying etiology, followed by Guillain-Barre syndrome (14.2%). However, these patients had neurological symptoms signs, in addition to diplopia or SCN paralysis. Patients admitted to pediatric emergency department with acute SCN paralysis should be examined in detail to disclose the underlying etiology especially if they present with additional clinical signs or symptoms.

A century ago an ambitious young anatomist in Rome, Primo Dorello, who sought to understand the cause of abducent nerve palsy that often occurred in patients with severe middle ear infections, conducted intricate studies on the intracranial course of the nerve. In his findings, he identified that the abducent nerve passes through a narrow sinus near the apex of the petrous bone, which formed an osteofibrous canal. Dorello suggested that in this enclosed region the abducent nerve may be particularly vulnerable to compression due to the vascular edema accompanying the infection. Although his work was widely appreciated, it was not well received by all. Interestingly, Giuseppe Gradenigo, one of the most prominent Italian otologists of the early 20th century, who was known for his work on a triad of symptoms (Gradenigo's syndrome) that accompanies petrous apicitis, a result of severe middle ear infections, was obstinate in his criticism of Dorello's findings. Thus a scientific duel began, with a series of correspondence between these two academics-one who was relatively new to the otological community (Dorello) and one who was well reputed in that community (Gradenigo). The disagreement ultimately ebbed in 1909, when Dorello published a report in response to Gradenigo's criticisms and convinced Gradenigo to change his views. Today Dorello's canal is widely recognized as a key landmark in skull base surgery of the petroclival region and holds clinical significance due to its relation to the abducent nerve and surrounding vascular structures. Yet, although academics such as Dorello and Gradenigo are recognized for their work on the canal, it is important not to forget the others throughout history who have contributed to the modern-day understanding of this anatomical structure. In fact, although the level of anatomical detail found in Dorello's work was previously unmatched, the first description of the canal was made by the experienced Austrian anatomist Wenzel Leopold Gruber in 1859, almost 50 years prior to Dorello's landmark publication. Another critical figure in building the understanding of Dorello's canal was Harris Holmes Vail, a young otolaryngologist from Harvard Medical School, who in 1922 became the first person to describe Dorello's canal in the English language. Vail conducted his own detailed anatomical studies on cadavers, and his publication not only reaffirmed Dorello's findings but also immortalized the eponym used today-"Dorello's canal." In this article the authors review the life and contributions of Gruber, Dorello, Gradenigo, and Vail, four men who played a critical role in the discovery of Dorello's canal and paved the way toward the current understanding of the canal as a key clinical and surgical entity.

A 22-year-old man was referred for horizontal diplopia that worsened on left gaze. He had been admitted for a head trauma caused by a traffic accident. Brain CT scan showed a longitudinal fracture of the left temporal bone with extension to the left carotid canal and central skull base, including sphenoid lateral wall and roof, and left orbit medial wall non-displaced fracture. Prism cover test revealed 20 prism diopters of esotropia and abduction limitation in the left eye. Hess screening test results were compatible with left abducens nerve paralysis. Symptoms suggesting complete lower motor neuron palsy of the left facial nerve, such as unilateral facial drooping, inability to raise the eyebrow and difficulty closing the eye, were present. As there was no improvement in facial paralysis, the patient received surgical intervention using a transmastoidal approach. Three months postoperatively, prism cover test showed orthotropia, however, the facial nerve palsy persisted., (2015 BMJ Publishing Group Ltd.)

Duane retraction syndrome consists of abduction deficit and palpebral fissure narrowing, upshoots, or downshoots on adduction. Infants with abduction deficit should be considered to have Duane retraction syndrome until disproven, because congenital abducens nerve palsy is extremely rare. The abducens nerve on the affected side is absent in type 1 Duane retraction syndrome and in some type 3 patients. The authors present a 7-month-old girl who showed limitation of abduction simulating Duane retraction syndrome. High-resolution magnetic resonance imaging (MRI) revealed atrophic lateral rectus and present abducens nerve. This report is important because this case showed that congenital abducens nerve palsy exists, although it is extremely rare, and high-resolution MRI could be pivotal for the differentiation of Duane retraction syndrome and congenital abducens nerve palsy in infancy., (© The Author(s) 2014.)

There is increasing evidence that neuronal cell death occurs via extrinsic (death receptors) and intrinsic (mitochondria) pathways. Radiation induces caspase activation fundamentally via the mitochondrial pathway. Caspases are the key regulators of apoptosis. Healthy male Sprague‑Dawley rats were used in the present study to examine the radioprotective effect of a type of pan-caspase inhibitor, z-VAD-fmk, following radiation, to investigate the effects of caspase blockade in a model of the nucleus of the abducens nerve. z-VAD-fmk was injected intracerebroventricularly as a bolus injection (0.2 µg/h for 1 h) into rats prior to exposure to radiation. Irradiation was conducted at room temperature at a dose of radiation of 4 Gy. The present study performed immunohistochemistry, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and western blot analysis and identified no significant changes in the expression of the X-linked inhibitor of apoptosis protein (XIAP) following radiation (P>0.05). As compared with the radiation alone group, the quantification of TUNEL-positive neurons was reduced in z-VAD‑fmk-treated animals following radiation (P<0.01). Inhibition of caspase induced by z-VAD‑fmk reduced the expression and activation of caspase-3, -8 and -9 (P<0.01). z-VAD-fmk effectively prevented radiation-induced apoptosis and this caspase inhibitor may be a potential therapeutic target in the treatment of brain radiation injury. The nucleus of the abducens nerve may be used as a radiation injury model, providing visual information and data on the apoptotic morphology of the abducens nucleus.

Purpose of Review: Determining which cranial nerve(s) is (are) involved is a critical step in appropriately evaluating a patient with diplopia., Recent Findings: New studies have looked at the various etiologies of cranial nerve palsies in the modern imaging era. The importance of the C-reactive protein test in evaluating the possibility of giant cell arteritis has recently been emphasized., Summary: Dysfunction of the oculomotor (third), trochlear (fourth), or abducens (sixth) cranial nerve will produce ocular misalignment and resultant binocular diplopia or binocular blur. A misalignment in the vertical plane of as small as 200 μm is enough to produce diplopia. Diagnosing diplopia from a cranial nerve abnormality requires an understanding of structure (the anatomy of the cranial nerves from nucleus to muscle), function (the movements controlled by the cranial nerves), possible etiologies, and exceptions to the rules.

Aim: To investigate the innervation pattern of extra-ocular muscles in patients with clinically diagnosed Duane's ocular retraction syndrome (DRS) using magnetic resonance imaging (MRI)., Materials and Methods: The study population consisted of 11 patients. Six patients had type I DRS (eight eyes), four patients had type II DRS (five eyes) and one patient had inverse DRS. Images were acquired using a Siemens 3 T MRI system. The type of DRS, corresponding innervation findings, and condition of the affected muscles were evaluated by two experienced neuroradiologists in consensus., Results: All patients with clinically diagnosed DRS type I showed absence of the abducens nerve (CN6), hypoplasia of the superior oblique muscle (SOM), and aberrant innervation of lateral rectus muscle (LRM) by an extra branch of oculomotor nerve (CN3). All patients with type II DRS show dual-innervation of the LRM (by CN6 and an aberrant CN3 branch) and hypoplasia of SOM. The single patient with inverse DRS showed hypoplasia of CN3, the medial rectus muscle (MRM), the inferior rectus muscle (IRM), and the inferior oblique muscle (IOM)., Conclusion: Each type of DRS has characteristic MRI appearances. Therefore, MRI is a useful diagnostic tool for the confirmation and classification of suspected cases of DRS., (Copyright © 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Variable bony anatomy at the skull base may result in compression or entrapment of exiting cranial nerves. The authors present an unusual variation of bilateral ossification of the roof of Dorello's canal and review the germane literature. Clinicians might consider ossification of the petrosphenoidal ligament (also called Gruber's ligament) in patients with unexplained cases of abducens nerve palsy.

Purpose: To employ magnetic resonance imaging (MRI) to seek evidence of compartmental lateral rectus atrophy consistent with a lesion involving selective denervation of only 1 of the 2 neuromuscular compartments of the lateral rectus., Design: Prospective observational case-control series., Methods: At a single institution, surface coil coronal MRI was obtained at 312 μm resolution in quasi-coronal planes 2 mm thick throughout the orbit in 20 normal volunteers and 18 patients with unilateral lateral rectus palsy fixated monocularly on a target placed in central gaze. Maximum cross sections and posterior volumes of the superior and inferior lateral rectus compartments were computed and correlated with clinical findings., Results: Twelve patients with lateral rectus palsy demonstrated symmetric, highly significant 40% reductions in maximum cross sections and 50% reductions in posterior volumes from normal for both compartments (P < 10(-6) for all comparisons). Six patients with lateral rectus palsy had similar significant but asymmetric reductions in those measures only for the superior compartment of the affected lateral rectus (P < 10(-4) for all comparisons), with insignificant 20%-30% reductions for the inferior compartment (P > 0.2 for all comparisons)., Conclusions: A subset of patients with clinical lateral rectus palsy may have palsy limited to the superior compartment. Paralytic esotropia may be caused by lateral rectus superior compartment palsy despite an intact lateral rectus inferior compartment. This finding is consistent with evidence supporting independent innervation of the 2 lateral rectus neuromuscular compartments., (Copyright © 2014. Published by Elsevier Inc.)

We describe the case of a 13-year-old boy who presented to the emergency department with an acute onset paresis of the left abducens, facial and vagus nerves. Bilateral papilledema was seen on fundoscopy. Blood tests and brain magnetic resonance imaging and angiography showed no abnormalities. A lumbar puncture revealed an elevated intracranial pressure (575mmH2O) and clear cerebrospinal fluid. The diagnosis of pseudotumor cerebri (PTC) associated with multiple cranial nerve palsies was made. Treatment with acetazolamide was initiated, resulting in progressive improvement with no sequelae and no clinical recurrence over an 8-month follow-up period. PTC in children can present with a wide spectrum of neurological signs, especially cranial nerve palsies which are most likely related to a pressure-dependent stretching mechanism. In 2007, distinctive diagnostic criteria for pediatric PTC were established, including the presence of any cranial nerve palsy in the absence of an identifiable etiology., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

The study of the ocular-motor nerves must be exhaustive from their source (nuclei in the brainstem) down to the effector muscles (orbit). Visual disturbances have to be analysed by differentiating between a decrease in visual acuity and ocular-motor disorders. Imaging tests are dominated by MRI, including fine slices and gadolinium injection. A study of the Circle of Willis vessels is often useful, and essential in the case of type III impairment. A further CT scan is essential for analysis of the foramina, base of the skull and orbital walls. Impairment of CN VI requires a CT scan of the apex of petrous. The study of the cavernous sinuses must be in-depth (T2 and T1 after gadolinium and elimination of fats) and always comparative. Impairment of CN III is often complex, difficult to identify precisely (complete or partial, with or without a pupil impairment, associated with other neurological signs) and requires a reasoned study based on anatomical, semiological and pathological knowledge. Other than tumour diseases, it is necessary to consider less well known malformative, ischemic and inflammatory aetiology., (Copyright © 2013. Published by Elsevier Masson SAS.)

A 49-year-old female presented with bilateral abducens nerve palsies. She had 75 prism diopter esotropia. The extraocular movement of the lateral rectus was -1 limitation for the right eye and -4 limitations for the left. After performing orbital magnetic resonance imaging (MRI), 2 mL of bupivacain (5 mg/mL) was injected into the left lateral rectus (LR). One month after injection, a further orbital MRI was performed. Subsequently, recession of both medial rectus (6 mm) and resection of the left LR (9 mm) were performed. After one month, bupivacaine had no hypertrophic effects. There was little change in angle of deviation. The orbital MRI scan showed a 1.91% increase in volume compared to the muscle prior to the injection. Histological findings showed no muscle fibers of the left LR muscle, only the fiber nucleus and the collagen that replaced the fibers. We report on the changes in stiffness and muscle volume and on the histology of the muscle one month after injecting bupivacaine into the paralyzed left LR muscle combined with standard surgical treatment.

The diagnosis of Moebius syndrome, a rare congenital disorder, is primarily based on congenital facial and abducent nerve palsy. Involvement of other cranial nerves is also common. Occasionally the V, X, XI, and XII cranial nerves are involved, resulting in a difficulty to chew, swallow, and cough, which often leads to respiratory complications. Mental retardation and autism have been reported in some cases. Moebius syndrome can be associated with orofacial anomalies and limb malformations. The authors describe a patient with a confirmed diagnosis of Moebius syndrome associated with hydrosyringomyelia. No case of Moebius syndrome involving primarily the spinal cord has been reported so far. This patient did not present with other factors directly linked to syringomyelia.

Leprosy is a devastating disease caused by Mycobacterium leprae. It includes a spectrum of clinicopathological lesions. Neuritic leprosy with caseation necrosis (abscess) manifesting as a soft tissue mass is a relatively rare presentation of leprosy. Here, the authors report their experience with three patients with neuritic leprosy. The patients presented with swellings in the right ulnar nerve, the right great auricular nerve, and the temporal branch of the right sixth cranial nerve. The clinical impression was that of tumorous masses. Gross examination of the biopsy specimens revealed caseous necrotic materials. Further histological evaluation disclosed tuberculoid granulomas with extensive caseation necrosis. Stains for acid-fast bacilli were positive in the third case. A comparison between the caseation encountered in the tuberculoid neurotic leprosy and the neurolysis of lepromatous neurotic leprosy has been also discussed. The findings here emphasize "mass lesion with necrosis" as a possible clinical presentation of the neuritic leprosies. The clinicopathologic features were addressed and the relevant literature was reviewed.

The interdependence of the development of the eye and oculomotor system during embryogenesis is currently unclear. The occurrence of clinical anophthalmia, where the globe fails to develop, permits us to study the effects this has on the development of the complex neuromuscular system controlling eye movements. In this study, we use very high-resolution T2-weighted imaging in five anophthalmic subjects to visualize the extraocular muscles and the cranial nerves that innervate them. The subjects differed in the presence or absence of the optic nerve, the abducens nerve, and the extraocular muscles, reflecting differences in the underlying disruption to the eye's morphogenetic pathway. The oculomotor nerve was present in all anophthalmic subjects and only slightly reduced in size compared to measurements in sighted controls. As might be expected, the presence of rudimentary eye-like structures in the socket appeared to correlate with development and persistence of the extraocular muscles in some cases. Our study supports in part the concept of an initial independence of muscle development, with its maintenance subject to the presence of these eye-like structures.

Objective: To determine whether the abducens nerve is present in patients with type 2 Duane's retraction syndrome (DRS)., Design: Retrospective, observational case series., Participants: Twelve consecutive patients diagnosed with type 2 DRS., Methods: A retrospective review of medical records of ophthalmologic examination and thin-sectioned magnetic resonance imaging (MRI) at the brainstem level and the orbit was performed on 12 patients who showed the typical signs of type 2 DRS, including adduction deficit; globe retraction; narrowing of fissure on adduction; and upshoot, downshoot, or both., Main Outcome Measures: Presence of the abducens nerve and any other extraocular muscle abnormalities discovered by MRI scan., Results: Magnetic resonance imaging revealed the presence of the abducens nerve in all the affected eyes (n = 13) of 12 patients with type 2 DRS., Conclusions: The abducens nerve is present on the affected side in type 2 Duane's retraction syndrome., (Copyright © 2012 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

We present a patient with a Rathke's cleft cyst who presented with rapidly progressive bilateral 6th nerve palsy. A 20-year-old woman with a history of cleft palate, hypertension, and hydronephrotic kidneys presented with a one month history of headache, associated with dizziness and diplopia on horizontal gaze. Examination was significant for profound bilateral 6th nerve palsies. Magnetic resonance imaging showed a hypodense mass that filled the sella and compressed the right cavernous sinus without contacting the optic chiasm. Pituitary function was normal. An endoscopic, transnasal transsphenoidal resection of the lesion was performed; microscopic examination revealed a Rathke's cleft cyst. Surgical excision resulted in near complete resolution of the bilateral 6th nerve palsy. Rathke's cleft cysts are an unusual cause of bilateral sixth nerve palsy and represent a potential cause of cranial neuropathy.

Recurrent sixth nerve palsies are usually idiopathic, although they have been postulated to be caused by a postinflammatory insult or abnormal cerebral circulation. We report the case a 9-month-old boy who had 2 episodes of a left abduction deficit that resolved spontaneously. A 3-dimensional high-resolution T2-weighted sequence magnetic resonance imaging scan of the head revealed a hypoplastic left 6th nerve and a small left Dorello's canal., (Copyright © 2011 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.)

Aim: We aimed to show the significance of the anterior pontine membrane as a determining structure between the subdural and subarachnoid space in the clival region., Material and Methods: Five adult cadaver heads and five cerebral hemispheres were used. The skull vault and hemipheres were removed by sectioning through the pontomesencephalic junction. Five other heads hemispheres were removed but the arachnoid membrane was protected and the cerebral side of the clival dura mater was dissected. In another specimen, the dural porus of the abducens nerve was sectioned for histological evaluation. Three cases of hematoma at the clivus were presented to support our findings., Results: The anterior pontine membrane is the arachnoid membrane forming the anterior wall of the prepontine cistern with its lateral extension at the skull base. This membrane forms the subdural and subarachnoid spaces by forming a barrier between the clival dura mater and neurovascular structures of the brainstem. There were rigid fibrous trabeculations between both cerebral and periosteal dural layers forming the basilar plexus as the interdural space in the clivus., Conclusion: The anterior pontine membrane separates the subdural and subarachnoid spaces at the clival region. The hematomas of the clival region require to be evaluated with consideration given to the existance of the subdural space.

Purpose: Orbital magnetic resonance imaging (MRI) was used to investigate the structural basis of motility abnormalities in congenital fibrosis of the extraocular muscles type 3 (CFEOM3), a disorder resulting from missense mutations in TUBB3, which encodes neuron-specific beta-tubulin isotype III., Methods: Ophthalmic examinations in 13 volunteers from four CFEOM3 pedigrees and normal control subjects, were correlated with TUBB3 mutation and MRI findings that demonstrated extraocular muscle (EOM) size, location, contractility, and innervation., Results: Volunteers included clinically affected and clinically unaffected carriers of R262C and D417N TUBB3 amino acid substitutions and one unaffected, mutation-negative family member. Subjects with CFEOM3 frequently had asymmetrical blepharoptosis, limited vertical duction, variable ophthalmoplegia, exotropia, and paradoxical abduction in infraduction. MRI demonstrated variable, asymmetrical levator palpebrae superioris and superior rectus EOM atrophy that correlated with blepharoptosis, deficient supraduction, and small orbital motor nerves. Additional EOMs exhibited variable hypoplasia that correlated with duction deficit, but the superior oblique muscle was spared. Ophthalmoplegia occurred only when the subarachnoid width of CN3 was <1.9 mm. A-pattern exotropia was frequent, correlating with apparent lateral rectus (LR) muscle misinnervation by CN3. Optic nerve (ON) cross sections were subnormal, but rectus pulley locations were normal., Conclusions: CFEOM3 caused by TUBB3 R262C and D417N amino acid substitutions features abnormalities of EOM innervation and function that correlate with subarachnoid CN3 hypoplasia, occasional abducens nerve hypoplasia, and subclinical ON hypoplasia that can resemble CFEOM1. Clinical and MRI findings in CFEOM3 are more variable than those in CFEOM1 and are often asymmetrical. Apparent LR innervation by the inferior rectus motor nerve is an overlapping feature of Duane retraction syndrome and CFEOM1. These findings suggest that CFEOM3 is an asymmetrical, variably penetrant, congenital cranial dysinnervation disorder leading to secondary EOM atrophy.

Background: Aim of the study was to evaluate effectiveness of intraoperative identification of oculomotor nerves (OMN) in resection of skull base tumors invading superior orbital fissure and cavernous sinus., Materials and Methods: 69 patients with cranioorbital tumors operated in Burdenko Neurosurgical Institute (Moscow, Russia) since 2000 until 2005 were included in the study. They were divided into 2 groups: 19 patients treated with intraoperative identification of OMN and 50 patients in the control group. Craniorbital meningiomas were in the majority among all cases. Intraoperative identification of OMN was performed using coaxial electrode while muscular response was registered through electrodes inserted in m. levator palpebrae superioris, m. obliquus superior and m. rectus lateralis (for III, IV and VI cranial nerves, respectively). Identification of IMN trunci was repeated throughout the whole stage of tumor resection for their preservation., Results: comparison of dynamics of oculomotor dysfunction in early postoperative period in patients of both groups demonstrated that intraoperative identification of OMN allowed to decrease the frequency of oculomotor deficit. The rates in main and control groups were: for III and IV nerves--37% and 68% (p < 0.05), for VI nerve--47% and 54% (p > 0.05), respectively., Conclusion: application of intraoperative identification of OMN allows to decrease the risk of oculomotor deterioration due to III and IV nerve dysfunction by 1.8 times. Technically the method is quite simple and not time-consuming procedure.