-
Current Opinion in Neurology Feb 2021Negative findings on neuroimaging are part of the diagnostic criteria for idiopathic intracranial hypertension (IIH), a syndrome characterized by increased intracranial... (Review)
Review
PURPOSE OF REVIEW
Negative findings on neuroimaging are part of the diagnostic criteria for idiopathic intracranial hypertension (IIH), a syndrome characterized by increased intracranial pressure (ICP). Some positive neuroimaging findings are associated with increased ICP, but their role in diagnosis of IIH has not been established. We provide an overview of these findings and their relevance for diagnosis of raised intracranial pressure.
RECENT FINDINGS
MRI acquisition techniques have significantly improved in the last few decades leading to better characterization of the intracranial changes associated with IIH, including empty sella turcica, optic nerve tortuosity, distension of the optic nerve sheath, posterior globe flattening, slit-like ventricles, and venous sinus stenosis. These may be MRI biomarkers of increased ICP. Prevalence difference between people with and without increased ICP, and reversibility of these MRI findings following treatment of increased ICP inform evaluation of their diagnostic potential.
SUMMARY
MRI and magnetic resonance venography findings are important tools in the diagnosis of IIH. Empty sella turcica, optic nerve protrusion, distension of the optic nerve sheath, optic nerve tortuosity, posterior globe flattening, and transverse sinus stenosis have been found to be the most promising diagnostic markers for IIH, although absence of these findings does not rule out the diagnosis.
Topics: Biomarkers; Constriction, Pathologic; Humans; Intracranial Hypertension; Magnetic Resonance Imaging; Neuroimaging; Optic Nerve; Pseudotumor Cerebri
PubMed: 33230036
DOI: 10.1097/WCO.0000000000000885 -
Ophthalmology Feb 2021The spaceflight-associated neuro-ocular syndrome (SANS) affects astronauts on missions to the International Space Station (ISS). The SANS has blurred vision and ocular...
PURPOSE
The spaceflight-associated neuro-ocular syndrome (SANS) affects astronauts on missions to the International Space Station (ISS). The SANS has blurred vision and ocular changes as typical features. The objective of this study was to investigate if microgravity can create deformations or movements of the eye or optic nerve, and if such changes could be linked to SANS.
DESIGN
Cohort study.
PARTICIPANTS
Twenty-two astronauts (age 48 ± 4 years).
METHODS
The intervention consisted of time in microgravity at the ISS. We co-registered pre- and postspaceflight magnetic resonance imaging (MRI) scans and generated centerline representations of the optic nerve. The coordinates for the optic nerve head (ONH) and optic chiasm (OC) ends of the optic nerve were recorded along with the entire centerline path.
MAIN OUTCOME MEASURES
Optic nerve length, ONH movement, and OC movement after time in microgravity.
RESULTS
Optic nerve length increased (0.80 ± 0.74 mm, P < 0.001), primarily reflecting forward ONH displacement (0.63 ± 0.53 mm, P < 0.001). The forward displacement was positively related to mission duration, preflight body weight, and clinical manifestations of SANS. We also detected upward displacement of the OC (0.39 ± 0.50 mm, P = 0.002), indicative of brain movement, but this observation could not be linked to SANS.
CONCLUSIONS
The spaceflight-induced optic nerve lengthening and anterior movement of the ONH support that SANS is caused by an altered pressure difference between the brain and the eye, leading to a forward push on the posterior of the eye. Body weight is a potential contributing risk factor. Direct assessment of intracranial pressure in space is required to verify the implicated mechanism behind the ocular findings in SANS.
Topics: Astronauts; Cohort Studies; Extraterrestrial Environment; Female; Humans; Intracranial Pressure; Magnetic Resonance Imaging; Male; Middle Aged; Optic Disk; Optic Nerve; Papilledema; Space Flight; Syndrome; Time Factors; Vision Disorders; Weightlessness
PubMed: 32659310
DOI: 10.1016/j.ophtha.2020.07.007 -
Biomedical Papers of the Medical... Sep 2023A case report of a 40-year-old patient with tuberculosis treated with ethambutol is described. Within six months of starting treatment, there was a painless sudden...
PURPOSE
A case report of a 40-year-old patient with tuberculosis treated with ethambutol is described. Within six months of starting treatment, there was a painless sudden decline in visual function. Despite the known complications of ethambutol treatment, it was discontinued after another three months.
METHODS
In the case report, we highlight the damage to the dominantly peripheral visual pathways. Using electrophysiological examinations, we showed a significant alteration in the optic nerves. Optical Coherence Tomography (OCT) showed progressive loss of vessel density and nerve fibre layer of retinal ganglion cells. Perimetric examination showed both a central decrease in sensitivity and mainly scotomas in the temporal parts of the visual fields. Although there was improvement in visual fields over time, OCT findings indicated progression of ethambutol-induced optic neuropathy (EON). Magnetic Resonance Imaging confirmed the alteration in the peripheral part of the visual pathway (intraorbital, intracranial parts of optic nerves, chiasma, and optic tracts).
CONCLUSION
Even though EON is not an unknown complication, new cases still occur and, unfortunately, with an irreversible course. Therefore, it is important to draw attention constantly to this complication and to consider it not only in ophthalmologists' surgeries.
Topics: Humans; Adult; Ethambutol; Antitubercular Agents; Optic Nerve Diseases; Optic Nerve; Tuberculosis; Tomography, Optical Coherence
PubMed: 35582729
DOI: 10.5507/bp.2022.022 -
Archives of Pathology & Laboratory... Jan 2017Ischemic optic neuropathy (ION) describes a state of hypoxic injury of the optic nerve. Clinically, ION is divided into anterior and posterior forms defined by the... (Review)
Review
Ischemic optic neuropathy (ION) describes a state of hypoxic injury of the optic nerve. Clinically, ION is divided into anterior and posterior forms defined by the presence or absence of optic disc swelling, respectively. It is further classified as arteritic when secondary to vasculitis, and nonarteritic when not. The site of vascular occlusion for anterior ION from giant cell arteritis is the short posterior ciliary arteries, but mechanical vascular obstruction does not play a role in most nonarteritic cases. Histologically, ION is characterized by axon and glial necrosis, edema, and a sparse mononuclear response. Like other ischemic injuries, the morphologic alternations in the nerve are time dependent. A variant of ION called cavernous degeneration (of Schnabel) features large cystic spaces filled with mucin. Several conditions can histologically mimic cavernous degeneration of the optic nerve. The scarcity of cases of ION examined histologically has contributed to an incomplete understanding of its pathogenesis.
Topics: Arteritis; Diagnosis, Differential; Humans; Optic Disk; Optic Nerve; Optic Neuropathy, Ischemic
PubMed: 28029908
DOI: 10.5858/arpa.2016-0027-RS -
PloS One 2022Diffusion-weighted magnetic resonance imaging of the human optic nerve and tract is technically difficult because of its small size, the inherent strong signal generated...
Diffusion-weighted magnetic resonance imaging of the human optic nerve and tract is technically difficult because of its small size, the inherent strong signal generated by the surrounding fat and the cerebrospinal fluid, and due to eddy current-induced distortions and subject movement artifacts. The effects of the bone canal through which the optic nerve passes, and the proximity of blood vessels, muscles and tendons are generally unknown. Also, the limited technical capabilities of the scanners and the minimization of acquisition times result in poor quality diffusion-weighted images. It is challenging for current tractography methods to accurately track optic pathway fibers that correspond to known anatomy. Despite these technical limitations and low image resolution, here we show how to visualize the optic nerve and tract and quantify nerve atrophy. Our visualization method based on the analysis of the diffusion tensor shows marked differences between a healthy male subject and a male subject with progressive optic nerve neuropathy. These differences coincide with diffusion scalar metrics and are not visible on standard morphological images. A quantification of the degree of optic nerve atrophy in a systematic way is provided and it is tested on 9 subjects from the Human Connectome Project.
Topics: Humans; Male; Diffusion Tensor Imaging; Optic Nerve; Diffusion Magnetic Resonance Imaging; Connectome; Peripheral Nervous System Diseases; Atrophy
PubMed: 36508429
DOI: 10.1371/journal.pone.0278987 -
PloS One 2020Several studies have shown an association between intracranial pressure and the diameter of the optic nerve sheath measured by transbulbar ultrasonography. To understand...
OBJECTIVE
Several studies have shown an association between intracranial pressure and the diameter of the optic nerve sheath measured by transbulbar ultrasonography. To understand the pathophysiology of this phenomenon, we aimed to measure the changes of the optic nerve, optic nerve sheath and perineural space separately with increasing intracranial pressure in a porcine model.
METHODS
An external ventricular drain was placed into the third ventricle through a right paramedian burrhole in eight anesthesized pigs. The diameters of the optic nerve and the optic nerve sheath were measured while the intracranial pressure (ICP) was increased in steps of 10mmHg from baseline up to 60 mmHg.
RESULTS
The median diameters of the optic nerve (ON) increased from 0.36 cm (baseline- 95% confidence interval (CI) 0.33 cm to 0.45 cm) to 0.68 cm (95% CI 0.57 cm to 0.82 cm) at ICP of 60 mmHg (p<0.0001) and optic nerve sheath (ONS) from 0.88 cm (95% CI 0.79 cm to 0.98 cm) to 1.24 cm (95% CI 1.02 cm to 1.38 cm) (p< 0.002) while the median diameter of the perineural space (PNS) (baseline diameter 95% CI 0.40 cm to 0.59 cm to diameters at ICP 60 95% CI 0.38 cm to 0.62 cm) did not change significantly (p = 0.399). Multiple comparisons allowed differentiation between baseline and values ≥40 mmHg for ON (p = 0.017) and between baseline and values ≥ 50mmHg for ONS (p = 0.006). A linear correlation between ON (R2 = 0.513, p<0.0001) and ONS (R2 = 0.364, p<0.0001) with ICP was found. The median coefficient of variation for intra- and inter-investigator variability was 8% respectively 2.3%.
CONCLUSION
Unexpectedly, the increase in ONS diameter with increasing ICP is exclusively related to the increase of the diameter of the ON. Further studies should explore the reasons for this behaviour.
Topics: Animals; Hemodynamics; Intracranial Pressure; Optic Nerve; Swine; Ultrasonography
PubMed: 32017786
DOI: 10.1371/journal.pone.0228242 -
Anatomical Record (Hoboken, N.J. : 2007) Mar 2019The optic nerves (ONs), one of the 12 pairs of cranial nerves (Pair II), together with the olfactory and the cochlear nerves, are devoted to transmit sensory inputs. In... (Review)
Review
The optic nerves (ONs), one of the 12 pairs of cranial nerves (Pair II), together with the olfactory and the cochlear nerves, are devoted to transmit sensory inputs. In particular, ONs convey visual information from the retina to the brain. In mammals, the ONs are bilateral structures that extend from the optic disc to the optic chiasm containing glial cells and retinal ganglion cells (RGCs) axons. RGCs are the only retinal neurons able to collect visual information and transmit it to the visual centers in the brain for its processing and integration with the rest of sensory inputs. During embryonic development, RGCs born in the retina extend their axons to exit the eye and follow a stereotypic path outlined by the transient expression of a wide set of guidance molecules. As the rest of central nervous system structures, the ONs are covered with myelin produced by oligodendrocytes and wrapped by the meninges. ON injuries or RGCs degenerative conditions may provoke partial or complete blindness because they are incapable of spontaneous regeneration. Here, we first review major advances on the current knowledge about the mechanisms underlying the formation of the ONs in mammals. Then, we discuss some of the human disorders and pathologies affecting the development and function of the ONs and finally we comment on the existing view about ON regeneration possibilities. Anat Rec, 302:428-445, 2019. © 2018 Wiley Periodicals, Inc.
Topics: Animals; Axons; Cranial Nerves; Humans; Nerve Regeneration; Optic Nerve; Retinal Ganglion Cells
PubMed: 30306726
DOI: 10.1002/ar.23922 -
Thoracic Cancer Aug 2022With the development of imaging, the etiology of ocular lesions caused by lung cancer was not found only intraocular. Neuro-ophthalmological imaging has been found to be...
BACKGROUND
With the development of imaging, the etiology of ocular lesions caused by lung cancer was not found only intraocular. Neuro-ophthalmological imaging has been found to be useful for the diagnosis of meningeal carcinomatosis, although few studies have previously been published. Our study used magnetic resonance imaging (MRI) to determine if there was a the relationship between ocular symptoms and lung cancer metastasis.
METHODS
We carried out a retrospective analysis which included patients with ocular lesions and lung cancer on which orbit MRI was performed together with ocular examination during January 2014 to January 2022. Here, we describe the characteristics of intraocular metastasis and optic nerve sheath lesions.
RESULTS
A total of 21 lung cancer patients had ocular lesions, of which eight cases had choroidal metastasis; a further eight patients had optic nerve sheath lesions. There was one case (12.5%) of choroidal metastasis with brain or meningeal metastasis, and eight cases (100%) with optic nerve sheath lesions with brain or meningeal metastasis. A total of 75.0% patients with choroidal metastasis did not have any history of known lung cancer, and 25.0% of optic nerve sheath lesions in patients were found before a meningeal metastasis diagnosis. The features of optic nerve sheath lesions included thickening and strengthening of the long segment of the orbital optic nerve sheath with a clear boundary.
CONCLUSIONS
The pathway of choroidal and optic nerve sheath lesions was different. Optic nerve sheath lesions were associated with brain and meningeal metastasis. When lung cancer-induced meningeal metastasis is suspected, orbital MRI is recommended to assist in the diagnosis.
Topics: Brain; Humans; Lung; Lung Neoplasms; Meningeal Carcinomatosis; Optic Nerve; Retrospective Studies
PubMed: 35702825
DOI: 10.1111/1759-7714.14538 -
Anatomical Record (Hoboken, N.J. : 2007) Dec 2022Unlike the usual peripheral nerve, the optic nerve accompanies a thick "dural sheath," a thin "sheath of pia mater" (SPM), and multiple "septa," which divides the nerve...
Unlike the usual peripheral nerve, the optic nerve accompanies a thick "dural sheath," a thin "sheath of pia mater" (SPM), and multiple "septa," which divides the nerve fibers into fascicles. We collected specimens from 25 adult cadavers and 15 fetuses and revisited the histological architecture of the optic and oculomotor nerves. In the optic chiasma, the meningeal layer of the dura joins the pia to form a thick SPM, and the periosteum of the sphenoid is continuous with the dural sheath at the orbital exit of the bony optic canal. The septa appeared as a cluster of irregularly arrayed fibrous plates in the intracranial course near the chiasma. Thus, the septa were not derived from either the SPM or the dural sheath. In the orbit, the central artery of the retina accompanies collagenous fibers from the dural sheath and the SPM to provide the vascular sheath in the optic nerve. These connective tissue configurations were the same between adult and fetal specimens. At the optic disk, the dural sheath and SPM merged with the sclera, whereas the septa appeared to end at the lamina cribrosa. However, in fetuses without lamina cribrosa, the septa extend into the nerve fiber layer of the retina. The SPM and septa showed strong elastin immunoreactivity, in contrast to the absence of reactivity in the sheaths of the oculomotor nerve. Each S100 protein-positive Schwann sheath of the oculomotor nerve was surrounded by collagenous endoneurium. Glial fibrillary acidic protein-positive astrocytes showed a linear arrangement along the septa.
Topics: Adult; Humans; Optic Nerve; Optic Disk; Connective Tissue; Cadaver; Fetus
PubMed: 35358354
DOI: 10.1002/ar.24925 -
Transactions of the American... 1983The pathophysiologic events in optic nerve axons have recently been recognized as crucial to an understanding of clinically significant acquired alterations in the... (Review)
Review
The pathophysiologic events in optic nerve axons have recently been recognized as crucial to an understanding of clinically significant acquired alterations in the ophthalmoscopic appearance of the optic disc. Stasis and related abnormalities of axonal transport appear to explain most aspects of optic nerve head swelling, including optic disc drusen and retinal cottonwool spots. Loss of axoplasm and axonal death can be invoked to interpret optic disc pallor, thinning and narrowing of rim tissue, changes in the size and outline of the optic cup, laminar dots, atrophy of the retinal nerve fiber layer, and acquired demyelination and myelination of the retinal nerve fiber layer. It is speculated that the axons may also play a role in the mechanical support of the lamina cribrosa in resisting the pressure gradient across the pars scleralis of the optic nerve head. Axons and their associated glial cells may be involved in those cases where "reversibility" of cupping of the optic disc has been reported. The structure, physiology, and experimental pathologic findings of the optic nerve head have been reviewed. Many aspects concerning the final anatomic appearance of the optic nerve head have been explained. However, many questions remain concerning the intermediate mechanisms by which increased intracranial pressure retards the various components of axonal transport in papilledema and by which increased IOP causes axonal loss in glaucoma. Investigation of the molecular biology of axonal constituents and their responses to abnormalities in their physical and chemical milieu could extend our understanding of the events that result from mechanical compression and local ischemia. Moreover, we have identified a need to further explore the role of axons in the pathophysiology of optic disc cupping.
Topics: Animals; Autoradiography; Axonal Transport; Axons; Disease Models, Animal; Fluorescein Angiography; Humans; Intracranial Pressure; Macaca mulatta; Ocular Hypertension; Ophthalmoscopy; Optic Atrophy; Optic Disk; Optic Nerve; Optic Nerve Diseases
PubMed: 6203209
DOI: No ID Found