Transient Visual Loss

By transient visual loss we mean a drop in visual acuity or a loss of visual field, analogous to the transient ischemic attacks (TIAs) of neurological disease that last no longer than 24 h. This chapter does not discuss transient visual loss for which primary ophthalmic disorders are evident, such as intermittent angle closure glaucoma, vitreous clouding, retinal venous stasis, or the transient obscurations found in papilledema. Patients complaining of transient loss of vision frequently cause...

Dural Carotid Cavernous Fistula

Dural carotid-cavernous fistulas arise spontaneously and primarily in elderly women. Dural branches of the internal or external carotid are equally involved, and fistulas often arise spontaneously from both sources. The resulting venous congestion causes an ectasia of the orbital and conjunctival veins that are clearly differentiable from inflammatory hyperemia (large, rope-like conjunctival vessels that contrast with white scleral tissue), as well as chemosis with lid swelling, exophthalmos,...

Visual Loss of Uncertain Origin Diagnostic Strategies

Zrenner The practicing ophthalmologist faces a common challenge on a daily basis A patient's vision is worse than was expected, based on the appearances of the initial examination. Usually, a renewed and more careful examination explains the discrepancy. Often, however, additional examination finds nothing to explain the conflicting findings. Time is limited, and one is tempted to refer the patient to a neurologist or another ophthalmic service. The diagnostic...

Functional Visual Loss and Malingering

Malingering is an intentionally deceptive mimicry of a nonexistent disorder, and augmentation is an intentionally exaggerated account of an existing disorder. Functional visual loss is a subjectively described visual disorder without an objectively observed abnormality. It is an unconscious, often subconscious, simulation of a nonexistent disease. (Synonyms include psychogenic visual loss, conversion, and hysterical visual loss). The related group of psychogenic ocular disorders includes...

Hereditary Disorders of Neuro Ophthalmic Relevance

Hereditary disorders of importance for neuro-ophthalmology include genetically inherited disorders of the posterior segment and afferent visual pathway that characteristically present as visual field defects, visual acuity loss, strabismus, or even complete blindness. These disorders have significant social and economic importance with lifelong consequences for the afflicted patient. The prevalence of inherited retinal disorders is approximately 20 cases per 100,000 people. Decoding of the...

Oculomotor Pareses in Children

Monosymptomatic oculomotor paralyses during childhood are uncommon. One half of pediatric third nerve pa-reses are congenital, and are often associated with signs of aberrancy (synkinesis). In individual cases, the cause usu ally remains unknown. Frequently, a congenital oculomotor paralysis will have recurrent periods of spasms lasting about one minute, usually recurring with a regular frequency (cyclical oculomotor paralysis). The most striking sign is seen at the onset of a cycle, with a...

Subarachnoid Damage to the Oculomotor Nerve

From the ventral midbrain, through the interpeduncular fossa and to its entry into the cavernous sinus, the third nerve lies in the subarachnoid space, where it is exposed to hemorrhages from aneurysms arising from the supracli-noid carotid artery, mostly at the exit of the posterior communicating artery. Rupture of such an aneurysm produces paralysis of the third nerve, but also the dramatic symptoms of acute subarachnoid bleeds, including abrupt headache of the worst sort, reduced levels of...

Optic Atrophy after Papilledema Definition

Damage to the optic nerve caused by chronic papillede-ma. If elevated intracranial pressure goes undetected, bilateral loss of vision can develop, because chronic papilledema often leads to gliosis and atrophy of the optic nerve. The same problem can develop if the cause of the elevated pressure cannot be corrected. The pathogenic mechanism is not well understood, but ischemia is thought to play an important role. The time needed to develop this complication is variable and is not predictable...

Neuroradiologic Imaging

It is the intended purpose of this chapter to provide the practicing ophthalmologist with an understanding of the indications for neuroradiologic procedures, and to illustrate the various imaging methods with typical examples and descriptions of their findings. The use of conventional radiologic imaging in ophthalmology has been reduced to its role in the detection of metallic foreign bodies for a more detailed study of soft tissues, tomographic images have completely replaced them. Knowledge...

Dyschromatopsias Associated with Neuro Ophthalmic Disease

Krastel, and W. Hart People with congenital dyschromatopsias are frequently not aware that their color perception differs from those with normal, trichromatic color vision. Others have learned to adapt to their limited perception of certain colors. Thus, a person with faulty red green color discrimination will often describe a dark green color as red. Some of these people know that they cannot properly identify colors accurately in certain ranges of hue and luminance....

Spasm of the Near Reflex

Spasms of accommodation and convergence are usually functional in nature, but are occasionally the result of a severe head injury or part of a dorsal midbrain syndrome. A highly variable (moment-to-moment) esotropia is accompanied by pupillary miosis and accommodative myopia. When binocular horizontal pursuit movements are tested, the adducting eye takes up fixation in either direction. This pseudo-abducens palsy is usually enhanced during cover uncover testing ( Fig. 10.8). The spasms can last...

Neurosurgery of the Visual Pathway

Tatagiba The visual pathways take an extraordinary and extensive intraorbital and intracranial course from the globe to the visual cortex within the occipital lobes. Hence, a large number of orbital and intracranial pathologies interfere with the optic pathways. The diagnosis and treatment of these pathologies demands an interdisciplinary team with ophthalmologists, neuroradiologists, neurosurgeons, and radiation therapists. The management algorithm takes into...

Toxic Optic Neuropathies Definition

A toxic optic neuropathy is a bilateral optic neuropathy caused by the neurotoxic effects of medications (usually chronic) or environmental toxins (acute or chronic). Ethambutol and other antitubercular drugs, cytostatic agents, heavy metals, hexachlorophene, and methanol can all cause a toxic optic neuropathy (also see Chap. 17). The first priority is to identify the offending agent and then to block further exposure. Specific measures that follow are determined by the nature of the toxin. The...

Lebers Hereditary Optic Neuropathy Definition

Leber's hereditary optic neuropathy (LHON) is a mito-chondrially inherited, severe, initially monocular but within weeks binocular visual loss, most commonly in young men. The visual acuity in LHON is reduced to 20 200 or worse. The visual field shows a large, central or cecocentral sco-toma, and color perception is badly damaged. The acute phase is marked by a peripapillary microangiopathy with irregular areas of microvascular dilation, tortuosity, and variations in caliber sometimes described...

Of Neuro Ophthalmic Emergencies

Ninety percent of clinical neuro-ophthalmology is in the taking of a history (after W.F. Hoyt). Attentive listening, specific questioning and careful evaluation of the information gained make up the foundation of what is primarily a diagnostic subspecialty. The effort invested in gathering this information saves time and avoids unnecessary, potentially dangerous and or expensive diagnostic procedures. When possible, the previous records of the patient's care should be reviewed prior to...

Info

PASPara-aminosalicylic acid, MAO monoamine oxidase PASPara-aminosalicylic acid, MAO monoamine oxidase Disturbances of the phototransduction processes and or of the synaptic processing in the retinal neuronal network are easily detectable by ERG testing. Changes in the ERG often allow a distinction between rod- and cone-dominated damage caused by toxic exposures. Reduced amplitude and prolonged latency of ERG responses are typical signs of retinal toxicity and can be used to evaluate known or...

It Note

The diagnosis of ophthalmoplegic migraine requires the urgent exclusion of an aneurysm at the origin of the posterior communicating artery. In purely retinal migraine, ischemia of the retina or the anterior optic nerve can produce monocular visual field defects of varying severity, up to periods of transient amaurosis. The differential diagnosis includes amaurosis fugax, caused by retinal emboli arising from an atheromatous plaque in the carotid artery or from a valve in the heart. There are a...

Of the Human Visual Pathway

Nearly a half of all cortical neurons are devoted to the processing of visual information. The afferent visual pathway from the retina to the primary visual cortex has four neuronal elements ( Fig. 3.1). First neuron photoreceptors Second neuron bipolar cells Third neuron retinal ganglion cells (and their axonal processes, including the chiasm and optic tracts) Fourth neuron geniculocalcarine neurons Surface area of the cerebral retina is about 30 cm2 Fig. 3.1. Schematic diagram of the human...

With cogwheel phenomenon

Fig. 21.5 a Testing of the muscle tone around the elbow joint by passive manipulation during maximal relaxation of the muscles. b Diagram of important pathological findings the pocketknife phenomenon (fading of resistance when under steady pressure), and cogwheeling (joint rigidity with repeated, brief, and uniform increases in tonus over the entire range of motion of the joint) in case of muscle rigidity in Parkinson's disease Table 21.10. The differential diagnosis of central and peripheral...

Absolute Visual Field

One examined retinal location with two threshold reversals DLS Differential luminance sensitivity (decibel) Several presentations only for assessment of depth Fig. 4.8. Testing strategies used with automated static perimetry. Left The principle of threshold static perimetry, in which the threshold for perception of a stimulus is determined by sequentially presenting test objects with stimulus values that lie just above or below a putative value at a given location, and threshold is defined as a...

Traumatic Optic Neuropathy Definition

A traumatic optic neuropathy is one caused by trauma to the optic nerve, most frequently in the setting of a traffic accident with cranial and or midface fractures. Traumatic optic neuropathy results primarily from indirect injury, rather than by direct crushing or tearing mechanisms. A direct blow to the eye can cause an avulsion of the optic nerve more properly called an expulsion . The mechanism appears to be one of a sudden, explosive increase in intraocular pressure with rupture of the...

Microvascular Oculomotor Pareses

Microvascular ischemia of the oculomotor nerve arises from small-vessel disease of the vasa vasorum supplying the third nerve. It is the most common cause of oculomotor paresis in most ophthalmic practices. Though not specific, the presentation is characteristic, including acute onset of diplopia, complete or partial palsies of the muscles supplied by the third nerve, sparing of the pupillary sphincter, and ipsilateral retrobulbar and or temporal pain. The pain is thought to stem from the acute...

Fascicular Paralysis of the Oculomotor Nerve

Due to the separation of the third nerve fascicles as they leave their nuclear complex, pass through the red nucleus, substantia nigra, and the pyramidal tracts to exit the brain-stem into the interpeduncular fossa, damage in this region often results in incomplete paralysis. The pupil may be spared, or an isolated paralysis of elevation may be found. Even patterns of isolated superior or inferior divisional palsies of the third nerve can arise from disease located within the midbrain....

Functional Loss of Both Vestibular Organs

Caloric testing of vestibular function. Fixation is excluded, e.g., by means of Frenzel glasses. With the head reclined, the external auditory canal on one side is irrigated with water at 44 C. This warms the endolymph in the lateral sector of the horizontal canal, whereas the endolymph in the medial sector of the horizontal canal remains unaffected. The warmer fluid in the lateral sector tends to rise, setting up a weak circulation within the canal. This tiny circulation suffices...

Central Vestibular Nystagmus

Central vestibular nystagmus is caused by damage to the vestibular nuclei or to their connections with the ocular motor nuclei. Since the vestibular, optokinetic, and pursuit systems all converge on a common final pathway through the vestibular nuclei, they are all impaired. Due to the loss of the optokinetic and pursuit systems, the sufferer is unable to stop the nystagmus-driven movement of images across the retina. Consequently, central vestibular nystagmus in contradistinction to peripheral...

T Pearl

Recovery of the optic disc appearance after correction of the elevated intracranial pressure can take many weeks. A child with hydrocephalus - of whatever cause - is threatened with blindness if chronic papilledema develops. All such children require regular ophthalmic follow-up examinations to monitor their fundus appearance. Unique Nature of Pseudotumor Cerebri Benign Intracranial Hypertension Each of these names is misleading at best. The term pseudotumor originated at a time when...

Clinical Features of Graves Disease

Graves' disease also called thyroid ophthalmopathy, dys-thyroid ophthalmopathy, or endocrine orbitopathy is an autoimmune disease that commonly, though not always, is associated with hyperthyroidism. It is accompanied by a broad spectrum of signs and symptoms of orbital inflammation. Chief among these is exophthalmos. Graves' disease is the most common cause of exophthalmos among Fig. 9.5. A patient with Graves' disease. Striking proptosis, left more than right, with bilateral retraction of...

Oculomotor Apraxia Definition

Oculomotor apraxia describes an eye movement disorder characterized by loss of or severely diminished volitional saccades with retention of the fast phases of vestibular nystagmus. Reflexive saccades stimulated by objects of interest in the peripheral visual field may be disordered or normal. Congenital oculomotor apraxia Cogan's syndrome manifests in newborn infants. During the first 3 months of life, affected infants are unable to look toward objects held out to them, and may be mistakenly...