Chiasmal Syndromes Research Articles

Visual Findings in Chiasmal Syndromes.

Visual Findings in Chiasmal Syndromes.

Imaging of Optic Neuropathy and Chiasmal Syndromes.

Optic neuropathy involves loss of visual acuity, color vision, and visual field defect with a swollen, pale, anomalous, or normal optic disc seen on fundoscopy. Chiasmal disorders classically present with gradual onset of vision loss, bitemporal hemianopsia, and occasionally, endocrinopathy if the pituitary gland and/or hypothalamus are the causes or are involved. Advance in neuroimaging, especially magnetic resonance (MR) imaging, can reveal pathologic conditions previously detected only clinically. Some entities have imaging characteristics, leading to appropriate treatment without requiring tissue biopsies. Imaging also provides disease surveillance and posttreatment assessment, with computed tomography and MR imaging being complementary to each other.

Unusual Neuro-Ophthalmologic Disturbances due to Internal Carotid Aneurysm

The majority of internal carotid aneurysm neuro-ophthalmologic disturbances are eyeball pain, complex ophthalmoplegia, pulsatile proptosis with conjunctival congestion and venous stasis retinopathy. Acute or chronic visual loss and visual field defect, clinical neuro-ophthalmological findings, resembling parasellar tumors or retrobulbar optic neuritis, are less usual in patients with aneurysms. Two cases of cerebral aneurysms with unusual neuro-ophthalmologic disturbances are presented. Case 1: Report of a 51-year-old female with left eye vision loss and inferonasal quadratanopia - a diagnosis of retrobulbar neuritis prior our neuro-ophthalmologic consultation was made. Computed tomography angiography showed right carotid artery aneurysm. Surgical treatment post cerebral angiography was suggested. Case 2: Report of a 56-year-old male with acromegaly and chiasmal neuro-ophthalmologic syndromes was described: left monocular vision loss, proptosis with third nerve palsy, dilated pupil and binasal hemianopia. MR angiography showed bilateral internal carotid artery aneurysm. No surgical treatment was performed, but endocrinological treatment was necessary. Two cases of internal carotid aneurysms were presented with unusual neuro- ophthalmologic disturbances, mimicking an optic neuritis and parasellar tumor. In conclusion the accurate differential diagnosis requires the correct neuroimaging - MRI and digital angiography, and the cooperation between the neuro-ophthalmologist, the interventional neuro-radiologist and the neurosurgeron.

Disorders of the optic chiasm

The aim of this article is to review disorders affecting the optic chiasm and develop a logical clinical approach to the diagnosis of a chiasmal syndrome. A review of recent and relevant literature was performed to highlight chiasmal syndromes and pathology, as well as to discuss current methods of diagnosis, prognosis and considerations in the treatment of a patient presenting with a chiasmal disorder.

A Mechanical Theory to Account for Bitemporal Hemianopia From Chiasmal Compression

The association between bitemporal hemianopia and chiasmal compression is well recognized. The majority of chiasmal syndromes are caused by extrinsic compression from pituitary tumors, suprasellar meningiomas, craniopharyngiomas, and aneurysms. However, it is not clear why compressive lesions of the chiasm show a predilection for damage to nasal fibers with bitemporal hemianopia. Few experimental attempts at elucidating these mysteries have been reported and none has provided an adequate explanation. The authors postulate that the susceptibility of nasal fibers to preferential damage is explained by structural collapse theories as applied to crossing and noncrossing cylinders. By constructing a simplified mathematical model, the authors demonstrate that nasal fibers are subject to relatively greater pressures for any given external compressive force acting on the chiasm.

Chiasmal syndromes.

This review of the more recent literature and testing strategies in patients with chiasmal syndromes focuses on the clinical evaluation and management of these patients. Visual loss is often the initial manifestation of disorders involving the optic chiasm. Hemianopic defects and preferential involvement of the temporal visual field are the earliest and most common visual deficits. Progression of the lesion may cause compression of adjacent structures, including the optic nerves and cavernous sinuses, and may result in more profound visual loss, ocular motor deficits, and hypopituitarism. Although a number of modalities have been used to assess visual function in patients with chiasmal disorders, perimetry remains the most effective means of detecting and following the visual deficit. Most chiasmal syndromes can be categorized as intrinsic (thickening of the chiasm itself) or extrinsic (compression of the chiasm from an adjacent structure). Magnetic resonance imaging is the best mode of neuroimaging for most chiasmal lesions and may also provide clues to the etiology of an isolated chiasmal syndrome.

Reversible visual deficit following debulking of a Rathke's cleft cyst: a tethered chiasm?

Delayed chiasmal syndromes after emptying of a Rathke's cleft cyst have not been reported previously. When these deficits occur following the treatment of parasellar lesions they are usually associated with the descent of a scarred optic system into an empty sella, and vision often improves promptly when the optic system is elevated. Two months after transsphenoidal surgery with emptying of a large intrasellar cyst, a 22-year-old man developed recurrent bitemporal visual field deficits over a 3-day period. Sagittal magnetic resonance images demonstrated an enhancing band of tissue extending anteriorly from the normally placed chiasm down to the anterior portion of the sella turcica. At craniotomy the enhancing tissue was found to be scar extending from the anterior border of the chiasm to the diaphragma sellae. The anterior portion of the diaphragm was resected as widely as possible without dissecting the scar itself from the chiasm. A membrane consistent with the wall of a Rathke's cleft cyst was found attached to the resected tissue. The patient's vision was improved 2 days after surgery. This case illustrates that traction by scar extending from the chiasm to the diaphragm, even when the chiasm is in its normal anatomical location, may cause progressive visual loss; and that untethering of the chiasm by resecting the diaphragm while leaving the scar intact can result in improved vision.

Metrizamide computed tomographic cisternography: A high-yield diagnostic procedure for chiasmal syndromes with equivocal computed tomographic or magnetic resonance scans

Eight patients with chiasmal syndromes that could not be characterized despite high-resolution computed tomographic (CT) evaluation of the chiasm and suprasellar cistern were evaluated by metrizamide computed tomographic cisternography (MCTC). In all cases, the MCTC was essential in establishing the presence or absence of a structural chiasmal lesion. Although Magnetic Resonance Imaging (MRI) has largely supplanted MCTC as the procedure of choice in CT-negative chiasmal syndromes, the utility of intrathecal contrast computed tomography with cerebrospinal fluid analysis in evaluating chiasmal involvement in pituitary adenomas, craniopharyngiomas, gliomas, and particularly in unusual inflammatory lesions of the chiasm, make it a useful procedure to retain in one's diagnostic armamentarium.

The ocular presentation of intracranial epidermoid tumors: A review of 37 cases from the literature with personal observations on one new patient

A review of 37 cases from the literature with personal observations on one new patient with intracranial epidermoid tumor is given. The tumor presents as a suprasellar or intracerebral lesion in young adults of either sex and manifests ocular symptoms in about 50% of the cases. The common ocular presentation is of an isolated optic nerve dysfunction or a chiasmal syndrome which is frequently associated with epileptic manifestations. Computerized tomography typically demonstrates a low density, irregularly-shaped but well-circumscribed lesion occupying the suprasellar cistern or the bases of the frontotemporal lobes and frequently involving the lateral or third ventricles. Occasionally the tumor may be isodense to contiguous brain tissue and cerebrospinal fluid. Recognition may then demand neuroradiologic persistence. The tumor should be considered in the differential diagnosis of chiasmal syndromes.

VER analysis of the chiasmal syndrome.

In the evaluation of chiasmal syndromes the efficiency of VER analysis could be enhanced by separate stimulation of the temporal and nasal half of the visual field. The report is based on data of 27 patients with compressive chiasmal lesions. VER findings have been correlated with the visual fields meticulously plotted with a Tuebingen perimeter and/or an Octopus computer perimeter. Alterations in both parameters have been graded in three groups. The degree of alteration correlated fairly well for both test procedures. Not only was a reduction of VER amplitude observed for the affected hemifield, but a latency delay as well. A discrete damage in the nasal hemifield may be detected even earlier by means of VER half field analysis than by conventional subjective perimetry.

Radiological findings in neurosarcoidosis.

The radiological investigation of neurosarcoidosis is discussed in relation to a series of 32 patients presenting to a neurological hospital. Cranial computed axial tomography, performed in 13 of these cases, was the most frequently positive procedure (77%). The indications for air studies are now limited but in cases with nerve or chiasmal syndromes and negative CAT they may show small mass lesions, or incomplete filling of basal cisterns due to granulomatous infiltration or fibrosis. Sarcoid masses are avascular and angiography is only useful for exclusion of incidental tumours with pathological circulation. Cord syndromes were present in eight cases, but myelography was only indicated in five of these and was normal in three. The cord may be involved by intra-medullary granulomas or meningeal infiltration causing arachnoiditis, both of which cause myelographic abnormalities though these are not specific for sarcoidosis.

Symposium on Neuro-Ophthalmology

Essentials of Clinical Neuro-Ophthalmology, by Arthur H. Wolintz, 198 pp, with illus, $12.50, Boston, Little, Brown, 1976. This symposium-type book of the 1975 New Orleans Academy of Ophthalmology belongs about midway between useful reference and "filler" for collectors of the unbroken series. It is almost a verbatim transcript of lectures by experts in neuro-ophthalmologic diagnosis and management. Over 100 pages record round-table discussions and comments on instructive clinical cases and other problems. Some of the conversational language is so informal that forest conservationists might complain about using such high quality paper for such purposes! Any trainee in ophthalmology or practicing eye specialist will appreciate the excellent chapter on assessment of vision in optic nerve and chiasmal disease, as long as they are not intimidated by seeing the author's face staring out at them in eight of the illustrations. There are summary chapters on various optic nerve diseases, chiasmal syndromes, and

The Neurosurgical Evaluation of the Chiasmal Syndromes

The Neurosurgical Evaluation of the Chiasmal Syndromes

DERMOID TUMOR IN THE FORAMEN MAGNUM, WITH ASTEREOGNOSIS AND DISSOCIATED SENSORY LOSS

Tumeurs perlees, as described by Cruveilhier1in 1829, are among the more rare intracranial neoplasms, comprising less than 1 per cent of the total number of the latter. The use of the term dermoid or epidermoid2is preferable to that of cholesteatoma, as it indicates the epithelial nature of the tumors and distinguishes them from the cholesteatomas of middle ear origin. Their lustrous mother-of-pearl appearance makes them easy to recognize. Not infrequently they are cystic. Epidermoids differ from dermoids in that they contain only squamous or basal epithelium, while dermoids also have epithelial appendages, such as hair and sebaceous glands. Approximately 150 cases of pearly tumors have been reported in the literature; the location was chiefly in the pia mater at the base of the brain. Chiasmal syndromes occur; the tumor may extend into the cerebellopontile angle, or, as in 2 of Cushing's cases reported by Bailey,3