Aplasia and hypoplasia of the optic nerve. Comparison of 2 cases

Hypoplasia and aplasia of the optic nerve are congenital anomalies characterized respectively by a marked volume reduction (very small papilla, often identifiable only as a rosy-yellowish area from which the retinal vessels emerge) and by the absence of the optic disk (absence of the nerve and mainly of its vessels) and of the visual functions. These anomalies are often associated with malformations of the central nervous system and of the ocular structures. The defects originate in the embryonal period due to the arrested development of the mesodermal component towards the head of the optic nerve. The aim of this study is to try to interpret the different clinical manifestations of the disease by observing two cases (a female and a male) with a clinical picture of aplasia and hypoplasia of the optic nerve respectively. Both cases presented the following clinical characteristics: developmental defects of the optic nerve, severe microcephaly, positive IgG antibodies against CMV. The association of the optic nerve defect with microcephaly is due to the embryogenic origin of the optic vescicle by prosencephalon. The resulting clinical picture is probably the outcome of an interfering process that the authors have presumed in CMV intrauterine infection, after having excluded the most frequent teratogenic agents (maternal diabetes, tabagism, intake of alcohol ad drugs). Moreover, the different degree of ocular involvement and the different time of onset of the intrauterine pathogenic insult in the two cases could account for the different clinical pictures.     

High-resolution magnetic resonance imaging of the intraorbital optic nerve and subarachnoid space in patients with papilledema and optic atrophy

OBJECTIVE: To evaluate the orbital portion of the optic nerve and the subarachnoid space using fast spin-echo magnetic resonance imaging in normal subjects and in patients with papilledema or optic atrophy. DESIGN: Measurements of the optic nerve complex on coronal images were made using high-resolution magnetic resonance imaging with fast spin-echo sequences. PATIENTS: Twenty-one patients, including 5 patients with papilledema due to congenital hydrocephalus, intracranial tumors, or meningitis, as well as 16 patients with optic atrophy, were studied. Sixteen healthy volunteers served as controls. MAIN OUTCOME MEASURES: The longitudinal diameter of the optic nerve, the longitudinal outer diameter of the subarachnoid space, the diameter ratio, and the area of the subarachnoid space were determined. RESULTS: In normal subjects, the ring-shaped area of high signal intensity that represented the subarachnoid space was widest behind the globe, then narrowed toward the orbital apex. In patients with papilledema, the area of the subarachnoid space was markedly dilated, the optic nerve was compressed, and the nerve sheath was widened, resulting in a small diameter ratio compared with that of controls. Patients with pallor of the temporal aspect of the optic disc appeared to exhibit dilation of the subarachnoid space; the size of the optic nerve was decreased more than that of the nerve sheath, resulting in a small diameter ratio compared with controls. Patients with complete pallor of the disc, however, exhibited hyperintense optic nerve complexes without a ring-shaped appearance toward the orbital apex. CONCLUSION: Fast spin-echo magnetic resonance imaging appears useful for objectively evaluating the optic nerve and surrounding subarachnoid space in patients with papilledema and optic atrophy.     

Confocal tomographic angiography of the optic nerve head in patients with glaucoma

BACKGROUND: Essential hypertension is characterized by an impairment of endothelium-dependent vasodilatation. OBJECTIVE: To test whether antihypertensive treatment with the angiotensin converting enzyme inhibitor lisinopril can improve vasodilatation in response to endothelium-dependent agonists in essential hypertensive patients. DESIGN AND METHODS: We studied the effect of acute (6-8 h after dosing), prolonged (1 month) and chronic (12 months) lisinopril treatment on forearm blood flow response (strain-gauge plethysmography) induced in 10 hypertensive patients (aged 43.6 +/- 8.1 years, blood pressure 151.4 +/- 6.8/99.8 +/- 3.3 mmHg) by intrabrachial infusions of 0.15, 0.45, 1.5, 4.5, and 15 microg/100 ml per min acetylcholine and 5, 15, and 50 ng/100 ml per min bradykinin, two endothelium-dependent vasodilators, and 1, 2, and 4 microg/100 ml per min sodium nitroprusside, an endothelium-independent vasodilator. At baseline, vascular response was compared with that of 10 normotensive subjects (aged 42.4 +/- 6.6 years, blood pressure 118.4 +/- 6.1/77.8 +/- 3.4 mmHg). RESULTS: Hypertensive patients had blunted (P < 0.01 or less) vasodilatations in response to infusions of acetylcholine (from 3.7 +/- 0.3 to 18.3 +/- 4.9 ml/100 ml per min) and bradykinin (from 3.7 +/- 0.4 to 15.8 +/- 2.6 ml/100 ml per min) compared with those of controls (from 3.6 +/- 0.3 to 25.3 +/- 5.2 ml/100 ml per min for acetylcholine and from 3.7 +/- 0.3 to 26.9 +/- 4.9 ml/100 ml per min for bradykinin) whereas the responses to infusion of sodium nitroprusside were similar (from 3.6 +/- 0.3 to 18.5 +/- 3.9 and from 3.6 +/- 0.3 to 16.4 +/- 1.8 ml/100 ml per min, respectively). Acute and prolonged lisinopril treatments significantly (P < 0.05 or less) improved vasodilatation in response to infusion of bradykinin (from 3.7 +/- 0.4 to 24.5 +/- 4.9 and from 3.7 +/- 0.3 to 22.1 +/- 4.9 ml/100 ml per min, respectively), but not in response to infusions of acetylcholine and of sodium nitroprusside. Chronic lisinopril treatment increased (P < 0.05) the response to infusions of not only bradykinin (from 3.5 +/- 0.5 to 27.6 +/- 5.3 ml/100 ml per min), but also of acetylcholine (from 3.5 +/- 0.5 to 27.8 +/- 8.0 ml/100 ml per min) and sodium nitroprusside (from 3.4 +/- 0.6 to 25.9 +/- 8.5 ml/100 ml per min). However, when the responses to infusions of acetylcholine and bradykinin were normalized with respect to that to infusion of sodium nitroprusside, only the vasodilatation in response to infusion of bradykinin was shown to have been increased by lisinopril treatment. CONCLUSIONS: Administration of lisinopril to patients with essential hypertension can selectively increase vasodilatation in response to infusion of bradykinin.     

Modality specific naming and gesture disturbances: a case with optic aphasia, bilateral tactile aphasia, optic apraxia and tactile apraxia

As life expectancy increases and members of the postwar generation settle into their fifth decade of life, hormone replacement therapy--estrogen or an estrogen-progestin combination--has become a major research interest. An extensive, but often confusing and even contradictory, literature exists on the uses of hormone replacement for the treatment and prevention of a multitude of difficulties that may be associated with the perimenopausal and postmenopausal periods. These include hot flushes, vaginal changes, urinary tract changes, changes in sexuality, affective or emotional symptoms, changes in the oral mucosa and skin, loss of memory and Alzheimer's disease, bone loss and osteoporosis, and cardiovascular disease. This article reviews the literature in each of these areas. It also reviews studies relating to possible side effects of hormone therapy, including endometrial cancer, gall bladder disease, and breast cancer. The article outlines principles for practitioners to follow in assisting women to make informed and individualized decisions about this therapy. Part II of this article, which will appear in the May/June 1996 issue of the Journal of Nurse-Midwifery, will cover specific therapeutic regimens and their management, as well as alternative therapies and preventive measures.     

Adrenoleukodystrophy with disease of the eye and optic nerve

Adrenoleukodystrophy is an X-chromosome-linked recessive disease characterized by primary atrophy of the adrenal glands with or without Addison's disease and low plasma cortisol levels, and a degeneration of white matter of the central nervous system with blindness. In suspected cases of adrenoleukodystrophy an impaired rise in plasma cortisol levels after adrenocorticotrophin stimulation may be diagnostic. With the electron microscope, pathognomonic intracytoplasmic lamellar inclusions have been seen in adrenal cortical cells, peripheral nerve Schwann's cells, testicular interstitial cells, and in macrophages of the brain. Adrenoleukodystrophy appears to be a genetically determined lipid storage disease with an error in membrane sterol metabolism. A 10-year-old boy with adrenoleukodystrophy had visual loss, a prominent early symptom. The ocular abnormality consisted of a disproportionate loss of nerve fibers from the macular region. No intracytoplasmic lamellar inclusions were identified in cells representing macrophages within the optic nerve. They contained myelin debris suggestive of end-stage disease.     

Open foramen ovale in patients with arterial vascular occlusions of the retina and optic nerve

BACKGROUND: We examined the frequency and significance of persistent foramen ovale (PFO) in patients with ocular circulatory disturbance. PATIENTS AND METHODS: Forty patients with acute arterial occlusions of the posterior bulb segment were investigated by means of transthoracic and transesophageal echocardiography (TEE). The parallel presence of cerebral ischemia was clarified on the basis of existing CCT findings and by additional HMPAO-SPECT investigation. RESULTS: PFO was identified in nine of the patients investigated. The probability of paradoxical embolism arises from further findings: eight of those with PFO (89%) showed echocardiographic signs of right heart strain, indicating previous pulmonary embolism, compared with only three of those without PFO (10%). Five of those with PFO showed a potential source of embolism, two of them with phlebothromboses in their clinical history and three with additional atrial septal aneurysm. Cardiovascular risk factors were prevalent in the group without PFO. Both groups had a mean age of approximately 60 years. Signs of cerebral ischemia were present in the SPECT or CT findings for four of the patients with PFO and nine of those without. CONCLUSIONS: From our findings, it appears highly probable that ocular arterial occlusion is caused by paradoxical embolism. PFO should be taken into account in establishing a diagnosis, including diagnosis in elderly patients.     

Aplasia and hypoplasia of the vestibulocochlear nerve: diagnosis with MR imaging

PURPOSE: To introduce aplasia or hypoplasia of the vestibulocochlear nerve (VCN) as a possible cause of hearing loss and to identify the magnetic resonance (MR) imaging characteristics of this entity. MATERIALS AND METHODS: In seven patients with congenital deafness or unexplained sensorineural hearing loss, MR imaging enabled diagnosis of aplasia or hypoplasia of the VCN. Axial (0.7-mm) three-dimensional Fourier transformation-constructive interference in steady state (3DFT-CISS) images and parasagittal reconstruction images perpendicular on the course of the VCN were obtained. Twenty normal inner ears were also studied; their findings were compared with those of the patients. RESULTS: The facial nerve and inferior and superior vestibular and cochlear branches of the VCN were identified on the MR images in the 20 normal inner ears. Aplasia of the VCN was detected in two patients with normal labyrinths but with a severe stenosis of the internal auditory canal. A common VCN with absence of the cochlear branch was found bilaterally in two patients with a congenital malformation of the labyrinth. A common VCN with absence or hypoplasia of the cochlear branch was found in three patients with normal internal auditory canals and labyrinths. CONCLUSION: Submillimetric gradient-echo images (eg, 3DFT-CISS) should always be used to exclude aplasia or hypoplasia of the cochlear branch of the VCN in all cochlear implant candidates and patients with congenital deafness. This entity, which can occur with or without associated labyrinthine malformation, should be confirmed in two planes.     

Hypoplasia of the optic nerve in association with porencephaly

Two cases of hypoplasia of the optic nerve associated with porencephaly are described. The clinicopathological correlation of the double ring sign is presented and the possible mechanism of optic nerve hypoplasia being a secondary degeneration is discussed.     

The cat optic nerve: fibre total count and diameter spectrum

Seventy-two aged Blacks, equally divided between those residing in a high-rise public housing project and those living in the community awaiting admission were interviewed to test the theory that differences in community security would predict differences in coping reactions. Data on perceived community security and reported medical, social and mental coping reactions were colleted, using a simply and directly worded, precoded, stimulus-response instrument developed by the author. Respondents were assigned to either a high or to a low community security group by two methods: first, they were assigned a place of residence; next, they were assigned according to their obtained community security score. Results in general supported the theory. Of the two empirical indicators of community security, however, larger differences in coping reaction scores were found in the high scoring and low scoring community security groups than in the high-rise and community groups.     

Regulation of retinal and optic nerve blood flow

Blood flow to the retina and optic nerve remains constant over a range of elevated intraocular pressure or mean arterial pressure, independent of sympathetic activation (pressure autoregulation). In addition, increased metabolic activity in these tissues proportionally increases blood flow (metabolic autoregulation). At constant metabolic rate, altered arterial oxygen content reciprocally alters blood flow, leaving total oxygen delivery constant, while blood flow rises and falls with the arterial carbon dioxide tension. These responses are similar to those of the cerebral circulation. However, while aging, atherosclerosis, arterial hypotension, and individual variation may profoundly alter blood flow regulation and predispose to the development of illness, these factors remain largely unexplored.     

Evaluation of coexisting optic nerve head drusen and glaucoma with optical coherence tomography

OBJECTIVE: Optic nerve head drusen often make evaluation of the nerve head difficult to interpret. In addition, visual field defects are known to occur in patients with optic disk drusen, resembling glaucomatous damage. The authors report two cases of coincident optic nerve head drusen and glaucoma, in which the use of optical coherence tomography (OCT) in evaluating the nerve fiber layer was beneficial. PARTICIPANTS: Two patients with both optic nerve head drusen and glaucoma, one with primary open angle glaucoma, the other with pseudoexfoliation glaucoma were evaluated. Both patients had asymmetric optic disk drusen, with clinically visible drusen only in one eye. INTERVENTION: Ophthalmologic examination, color and red-free photography, automated Humphrey visual field testing and OCT were performed. RESULTS: Nerve fiber layer loss as measured by OCT was found to be greater than expected by the appearance of the optic nerve head and red-free photography, with visual fields consistent with findings in case 1. In case 2, visual fields were full, despite nerve fiber layer thinning seen by OCT and red-free photography. CONCLUSIONS: There can be significant nerve fiber layer thinning in patients with both glaucoma and optic disk drusen, despite the appearance of the optic nerve head in these patients. The cup margin may be obscured by the drusen, giving rise to a falsely full-appearing disk. In such cases, OCT may provide a useful means to quantitatively measure the nerve fiber layer thickness and to aid in the management of these patients by detecting nerve fiber layer thinning earlier than would otherwise be possible.     

A case of crushing head injury with bilateral abducens and facial nerve palsies

A 20-year-old male was admitted to our hospital suffering from a crushing head injury. At accident, his head had been compressed by the printing machine on both temporal regions. He remained at dull conscious. On admission one hour after the injury, he showed bilateral sixth-nerve and seventh nerve palsies and bleeding from the nose. CT scan showed marked pneumocephalus, traumatic subarachnoid hemorrhage, fluid collections in the bilateral sphenoid sinuses and right mastoid air cells. Bone CT disclosed bilateral temporal bone fractures. MRI did not show cerebral parenchymal damage. He recovered fully conscious at four hours after the injury, but cranial nerve palsies sustained over 30 days after the injury. Bilateral decompression of the facial canal were performed at day 31. At one year after the injury, bilateral abducens nerve palsies and facial nerve palsies recovered incompletely (grade III). The case report and the mechanism of such cranial nerve injuries by low-velocity crushing head injury is described.     

Platelet-derived growth factor B-chain expression in the rat retina and optic nerve: distribution and changes after transection of the optic nerve

To test the possible involvement of platelet-derived growth factor B-chain (PDGF-B) in anterograde and retrograde degenerations of the CNS neurons, we studied the changes of PDGF-B localization and its mRNA expression in the rat retina and optic nerve (ON) after unilateral ON transection, using immunohistochemistry and in situ hybridization. In the control retinas immunoreactivity for PDGF-B and its mRNA expression were localized in the retinal ganglion cells (RGCs) and the nerve fiber layer. After ON transection PDGF-B immunoreactivity in the nerve fiber layer started to decrease on post-injury day 3 or 4. Atrophic changes in the RGCs started on day 5 just after the decrease of PDGF expression, and thereafter the RGC number decreased. In the longitudinal section of the ON rostral to the transected site, swollen axons showed intense PDGF-B immunoreactivity and macrophages, and some glial cells revealed a significant increase in both immunoreactivity and hybridization signals. Based on these findings, we hypothesized that the decrease in PDGF-B in RGCs after axotomy causes the loss of RGCs, and that increased PDGF-B expression in the ON plays a role in the cascade of tissue reactions following ON transection.     

Organization of retinal axons within the optic nerve, optic chiasm, and the innervation of multiple central nervous system targets Rana pipiens

Light microscopic analysis of the optic nerve, chiasm, and optic tracts of Rana pipiens after the anterograde and retrograde transport of horseradish peroxidase has shown that retinal ganglion-cell axons reach the optic nerve head in chronotopically organized fascicles that form bands across the intraocular optic nerve. These bands of fascicles are divided along the midline in a "zone of reorganization" to create two full maps of the retinal surface; however, this map is discontinuous in that nasal and temporal quadrants are adjacent to one another. In the intracranial portion of the optic nerve, axons undergo another reorganization such that peripheral retinal axons shift position and become localized laterally and ventrally, whereas centrally placed axons become localized dorsally. Within this reorganization, the nerve is reconfigured into laminae of axons, and each lamina consists of age-related axons organized into two retinal maps. In the ipsilateral chiasm, axons diverge to form three central, optic tracts: the medial optic tract, the projection to the corpus geniculatum, and the basal optic root. Ipsilateral axons leave the chiasm at the same level of the chiasm as do their contralateral counterparts. The remaining axons converge in the lateral diencephalon to form a fourth fascicle, the marginal optic tract. Thus, within the optic chiasm, a sequence of positional transformations occur that result in the formation of multiple optic pathways. The various changes in axonal trajectory always coincide with changes in the orientation of cell groups that lie within the nerve and optic chiasm.     

Motor neuropathy, putamen necrosis and optic nerve atrophy after acute methanol poisoning

Optic neuropathy and putaminal necrosis are the most common sequellae of methanol poisoning. We report a case in a patient with a chronic motor neuro(no)pathy in addition to these neurological complications. Peripheral nerve and spinal cord disorders, related to methanol poisoning, are uncommon and probably underestimated.