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Current Opinion in Ophthalmology Sep 2019Optic pathway gliomas are low-grade neoplasms that affect the precortical visual pathway of children and adolescents. They can affect the optic nerve, optic chiasm,... (Review)
Review
PURPOSE OF REVIEW
Optic pathway gliomas are low-grade neoplasms that affect the precortical visual pathway of children and adolescents. They can affect the optic nerve, optic chiasm, optic tracts and radiations and can either be sporadic or associated with neurofibromatosis type one. Gliomas isolated to the optic nerve (ONG) represent a subgroup of optic pathway gliomas, and their treatment remains controversial. New developments in ONG treatment have emerged in recent years, and it is necessary for clinicians to have a current understanding of available therapies.
RECENT FINDINGS
The current review of the literature covers the background of and recent developments in ONG treatment, with a focus on standard chemotherapy, new molecularly targeted therapies, radiation therapy and surgical resection and debulking.
SUMMARY
Although standard chemotherapy remains the mainstay of ONG treatment, newer molecularly targeted therapies such as mitogen-activated protein kinase kinase inhibitors and bevacizumab represent a promising new treatment modality, and clinical studies are ongoing.
Topics: Adolescent; Antineoplastic Agents; Child; Female; Humans; Male; Molecular Targeted Therapy; Ophthalmologic Surgical Procedures; Optic Chiasm; Optic Nerve Glioma; Optic Nerve Neoplasms; Optic Tract; Radiotherapy
PubMed: 31246635
DOI: 10.1097/ICU.0000000000000587 -
International Journal of Radiation... May 2021Dosimetric and clinical predictors of radiation-induced optic nerve/chiasm neuropathy (RION) after single-fraction stereotactic radiosurgery (SRS) or hypofractionated... (Review)
Review
PURPOSE
Dosimetric and clinical predictors of radiation-induced optic nerve/chiasm neuropathy (RION) after single-fraction stereotactic radiosurgery (SRS) or hypofractionated (2-5 fractions) radiosurgery (fSRS) were analyzed from pooled data that were extracted from published reports (PubMed indexed from 1990 to June 2015). This study was undertaken as part of the American Association of Physicists in Medicine Working Group on Stereotactic Body Radiotherapy, investigating normal tissue complication probability (NTCP) after hypofractionated radiation.
METHODS AND MATERIALS
Eligible studies described dose delivered to optic nerve/chiasm and provided crude or actuarial toxicity risks, with visual endpoints (ie, loss of visual acuity, alterations in visual fields, and/or blindness/complete vision loss). Studies of patients with optic nerve sheath tumors, optic nerve gliomas, or ocular/uveal melanoma were excluded to obviate direct tumor effects on visual outcomes, as were studies not specifying causes of vision loss (ie, tumor progression vs RION).
RESULTS
Thirty-four studies (1578 patients) were analyzed. Histologies included pituitary adenoma, cavernous sinus meningioma, craniopharyngioma, and malignant skull base tumors. Prior resection (76% of patients) did not correlate with RION risk (P = .66). Prior irradiation (6% of patients) was associated with a crude 10-fold increased RION risk versus no prior radiation therapy. In patients with no prior radiation therapy receiving SRS/fSRS in 1-5 fractions, optic apparatus maximum point doses resulting in <1% RION risks include 12 Gy in 1 fraction (which is greater than our recommendation of 10 Gy in 1 fraction), 20 Gy in 3 fractions, and 25 Gy in 5 fractions. Omitting multi-fraction data (and thereby eliminating uncertainties associated with dose conversions), a single-fraction dose of 10 Gy was associated with a 1% RION risk. Insufficient details precluded modeling of NTCP risks after prior radiation therapy.
CONCLUSIONS
Optic apparatus NTCP and tolerance doses after single- and multi-fraction stereotactic radiosurgery are presented. Additional standardized dosimetric and toxicity reporting is needed to facilitate future pooled analyses and better define RION NTCP after SRS/fSRS.
Topics: Adenoma; Blindness; Cavernous Sinus; Craniopharyngioma; Humans; Maximum Tolerated Dose; Meningeal Neoplasms; Meningioma; Models, Biological; Models, Theoretical; Optic Chiasm; Optic Nerve; Organs at Risk; Pituitary Neoplasms; Radiation Dose Hypofractionation; Radiation Tolerance; Radiosurgery; Radiotherapy Dosage; Re-Irradiation; Skull Base Neoplasms; Visual Acuity; Visual Fields
PubMed: 29534899
DOI: 10.1016/j.ijrobp.2018.01.053 -
Journal of the College of Physicians... Jun 2018Tuberculosis rarely involves the hypothalamo-pituitary region and constitutes only 1% of the lesions involving the sellar and/or suprasellar region. Coleman and Meredith...
Tuberculosis rarely involves the hypothalamo-pituitary region and constitutes only 1% of the lesions involving the sellar and/or suprasellar region. Coleman and Meredith first reported pituitary tuberculosis in 1940, and only a handful of cases have been reported ever since. It may manifest as a chiasmal syndrome due to compression of the optic chiasm or as hypopituitarism due to pituitary destruction. It has a characteristic radiological appearance and can mimic a pituitary adenoma. Diagnostic procedures, such as trans-sphenoidal biopsy, are crucial for accurate diagnosis. We report a case of a 32-year male, who presented with complaints of headache and decreased visual acuity for the past 6 months. Eye examination revealed bitemporal hemianopsia. Brain MRI scan showed a mass in the sella with features suggestive of pituitary adenoma. Transcranial resection of the mass was performed; histopathology of the excised mass proved it to be a pituitary tuberculoma.
Topics: Adult; Antitubercular Agents; Craniotomy; Headache; Hormone Replacement Therapy; Humans; Hypopituitarism; Magnetic Resonance Imaging; Male; Optic Chiasm; Pituitary Diseases; Pituitary Gland; Tuberculoma; Vision Disorders
PubMed: 29866234
DOI: 10.29271/jcpsp.2018.06.S97 -
Journal Francais D'ophtalmologie Jan 2021The optic chiasm is an essential anatomical structure in neuro-ophthalmology. The systematization of the visual pathways results from the arrangement of the retinal... (Review)
Review
The optic chiasm is an essential anatomical structure in neuro-ophthalmology. The systematization of the visual pathways results from the arrangement of the retinal ganglion cell fibers. It explains the signs of chiasmal syndrome. A good knowledge of the anatomy permits to correlate visual field defects with imaging results. It is now possible to map the organization of the ganglion cell fibers within the chiasm. Their hemidecussation allows for stereoscopic vision in humans. The causes of chiasmal syndrome are multiple, but tumors and compressive causes predominate. The proximity of the pituitary region to the chiasm accounts for the frequency of chiasmal syndrome, which involves ophthalmologists not only through dysfunction of the visual pathway, which may be the presenting sign, but also through possible complications throughout the course of the disease. This review aims to synthesize the embryology, anatomy and principles of work-up for chiasmal syndrome as well as its many possible causes.
Topics: Cranial Nerve Diseases; Humans; Magnetic Resonance Imaging; Neoplasms; Optic Chiasm; Vision Disorders; Visual Field Tests
PubMed: 33183775
DOI: 10.1016/j.jfo.2020.07.004 -
Journal of the Neurological Sciences Apr 2017Vision loss is a disabling complication of tuberculous meningitis. Approximately, 15% of survivors are either completely or partially blind. All structures of the visual... (Review)
Review
Vision loss is a disabling complication of tuberculous meningitis. Approximately, 15% of survivors are either completely or partially blind. All structures of the visual pathway may be affected in tuberculous meningitis. Optic nerve and optic chiasma are most frequently and dominantly affected. Thick-gelatinous exudates lying over the base of brain, are the pathological hallmark of tuberculous meningitis and are responsible for almost all of its major complications, including vision loss. Strangulation of optic nerves and optic chiasma by the exudates, compression over optic chiasma by the dilated third ventricle, raised intracranial pressure, endarteritis, shunt failure, bacterial invasion of optic nerves and drug-induced optic nerve damage are important reasons that are considered responsible for vision loss. Prompt antituberculosis treatment is the best management option available. Immunomodulatory drugs and cerebrospinal fluid diversion procedures are of limited help. Early recognition and treatment of tuberculous meningitis is the only way forward to tackle this problem.
Topics: Blindness; Humans; Optic Chiasm; Optic Nerve; Tuberculosis, Meningeal
PubMed: 28320145
DOI: 10.1016/j.jns.2017.01.031 -
International Journal of Molecular... Jul 2019Retinal ganglion cells (RGCs) extend axons out of the retina to transmit visual information to the brain. These connections are established during development through... (Review)
Review
Retinal ganglion cells (RGCs) extend axons out of the retina to transmit visual information to the brain. These connections are established during development through the navigation of RGC axons along a relatively long, stereotypical pathway. RGC axons exit the eye at the optic disc and extend along the optic nerves to the ventral midline of the brain, where the two nerves meet to form the optic chiasm. In animals with binocular vision, the axons face a choice at the optic chiasm-to cross the midline and project to targets on the contralateral side of the brain, or avoid crossing the midline and project to ipsilateral brain targets. Ipsilaterally and contralaterally projecting RGCs originate in disparate regions of the retina that relate to the extent of binocular overlap in the visual field. In humans virtually all RGC axons originating in temporal retina project ipsilaterally, whereas in mice, ipsilaterally projecting RGCs are confined to the peripheral ventrotemporal retina. This review will discuss recent advances in our understanding of the mechanisms regulating specification of ipsilateral versus contralateral RGCs, and the differential guidance of their axons at the optic chiasm. Recent insights into the establishment of congruent topographic maps in both brain hemispheres also will be discussed.
Topics: Animals; Axons; Brain; Cell Lineage; Humans; Retinal Ganglion Cells; Vision, Binocular; Visual Pathways
PubMed: 31277365
DOI: 10.3390/ijms20133282 -
Continuum (Minneapolis, Minn.) Oct 2019This article reviews the anatomy, symptoms, examination findings, and causes of diseases affecting the optic chiasm, optic tracts, optic radiations, and occipital lobes. (Review)
Review
PURPOSE OF REVIEW
This article reviews the anatomy, symptoms, examination findings, and causes of diseases affecting the optic chiasm, optic tracts, optic radiations, and occipital lobes.
RECENT FINDINGS
Modern ophthalmic imaging can be used to monitor the effects of diseases of the optic chiasm and tract on the retinal ganglion cells. It can also be used to visualize transsynaptic degeneration of the anterior visual pathway in the setting of acquired retrogeniculate lesions. Visual prostheses that directly stimulate the occipital lobe are a potential strategy for rehabilitation that is in active clinical trials.
SUMMARY
Detecting and characterizing visual deficits due to optic chiasm and retrochiasmal disease are important for the diagnosis, localization, and monitoring of neurologic disease; identifying patient disability; and guiding rehabilitation.
Topics: Adult; Brain Diseases; Female; Humans; Middle Aged; Occipital Lobe; Optic Chiasm; Optic Nerve Diseases; Vision Disorders; Visual Pathways
PubMed: 31584539
DOI: 10.1212/CON.0000000000000785 -
Radiotherapy and Oncology : Journal of... Feb 2015Accurate organs at risk definition is essential for radiation treatment of brain tumors. The aim of this study is to provide a stepwise and simplified contouring guide...
PURPOSE
Accurate organs at risk definition is essential for radiation treatment of brain tumors. The aim of this study is to provide a stepwise and simplified contouring guide to delineate the OARs in the brain as it would be done in the everyday practice of planning radiotherapy for brain cancer treatment.
METHODS
Anatomical descriptions and neuroimaging atlases of the brain were studied. The dosimetric constraints used in literature were reviewed.
RESULTS
A Computed Tomography and Magnetic Resonance Imaging based detailed atlas was developed jointly by radiation oncologists, a neuroradiologist and a neurosurgeon. For each organ brief anatomical notion, main radiological reference points and useful considerations are provided. Recommended dose-constraints both for adult and pediatric patients were also provided.
CONCLUSIONS
This report provides guidelines for OARs delineation and their dose-constraints for the treatment planning of patients with brain tumors.
Topics: Adult; Brain; Brain Neoplasms; Child; Cochlea; Female; Humans; Magnetic Resonance Imaging; Male; Neuroimaging; Optic Chiasm; Organs at Risk; Pituitary Gland; Radiation Dosage; Radiometry; Radiotherapy Planning, Computer-Assisted; Tomography, X-Ray Computed
PubMed: 25701297
DOI: 10.1016/j.radonc.2015.01.016