Neuro-Ophthalmology

Matthew J. Thurtell, MBBS, FRACP, Assistant Professor of Ophthalmology and Neurology, Department of Ophthalmology and Visual Sciences, University of Iowa Iowa City, IA. Robert L. Tomsak, MD, PhD, Professor of Ophthalmology and Neurology, Kresge Eye Institute, Wayne State University, Detroit, MI. Robert B. Daroff, MD, Professor of Neurology, Associate Dean for Development, School of Medicine, Case Western Reserve University, Cleveland, OH.

1. Optic Neuritis ; Optic neuritis is the most frequent cause of optic neuropathy in young adults and is often encountered in clinical practice. In this chapter, we summarize the cardinal signs of optic neuropathy and discuss the diagnostic evaluation and management of idiopathic optic neuritis. ; 2. Arteritic Anterior Ischemic Optic Neuropathy ; Arteritic anterior ischemic optic neuropathy occurs in the setting of giant cell arteritis and is a medical emergency, as there is a high risk of fellow eye involvement if corticosteroid treatment is not initiated in a timely fashion. In this chapter, we review the clinical features of arteritic anterior ischemic optic neuropathy. We also discuss the evaluation and treatment of patients with suspected giant cell arteritis. ; 3. Non-Arteritic Anterior Ischemic Optic Neuropathy ; Non-arteritic anterior ischemic optic neuropathy is the most frequent cause of optic neuropathy in older adults. Its pathogenesis remains uncertain, although it often occurs in patients with small structurally-congested optic discs. We summarize the symptoms, signs, possible precipitating factors, and management of this common optic neuropathy. ; 4. Compressive Optic Neuropathy ; Optic nerve compression results in progressive, and often painless, monocular vision loss. In this chapter, we review the clinical signs and common causes of compressive optic neuropathy. We discuss in more detail the imaging characteristics and management of optic nerve sheath meningioma. ; 5. Hereditary Optic Neuropathy ; Monocular and binocular vision loss can occasionally be caused by hereditary optic neuropathy. While progressive painless binocular central vision loss is characteristic of dominant optic atrophy, acute painless monocular vision loss is characteristic of Leber's hereditary optic neuropathy. We discuss the clinical features and evaluation of Leber's hereditary optic neuropathy, and briefly mention promising treatment options. ; 6. Idiopathic Intracranial Hypertension ; Idiopathic intracranial hypertension is a syndrome of raised intracranial pressure of unknown cause that most often occurs in obese young women. Bilateral papilledema is usually present and can cause severe irreversible vision loss if left untreated. In this chapter, we review the symptoms, signs, evaluation, and management of idiopathic intracranial hypertension. ; 7. Pseudopapilledema ; A diagnostic dilemma often arises when a patient with headaches is found to have optic nerve head elevation. Anomalous optic nerve head elevation often mimics papilledema and is therefore known as pseudopapilledema. In this chapter, we review the features that help to distinguish pseudopapilledema from papilledema and we discuss common causes of pseudopapilledema, such as optic nerve head drusen. ; 8. Chiasmal Syndromes ; Dysfunction of the optic chiasm typically produces bitemporal visual field defects. Chiasmal dysfunction most frequently results from compression by extrinsic lesions, such as pituitary macroadenomas and suprasellar meningiomas. We describe the clinical signs of chiasmal dysfunction in this chapter. We also discuss the evaluation and management of pituitary apoplexy. ; 9. Homonymous Hemianopia ; Homonymous hemianopia is caused by lesions involving the retrochiasmal visual pathways or primary visual cortex. The most common cause of homonymous hemianopia is stroke. We discuss the approach to the patient with homonymous hemianopia, with specific reference to prognosis, implications for driving, and rehabilitation. ; 10. Higher Visual Function Disorders ; A disorder of higher visual function should be considered when visual complaints are out of proportion to examination findings. Such disorders can remain undiagnosed until other cognitive deficits develop. In this chapter, we review common higher visual function disorders, with specific reference to the visual (posterior) variant of Alzheimer's disease. ; 11. Transient Visual Loss ; Transient visual loss is common and often due to a transient loss of blood supply to the afferent visual system, although there are many other potential causes. We review the approach to the patient with transient visual loss in this chapter, with special attention to vascular causes. ; 12. Migraine Aura ; Migraine aura is a common cause of transient positive and negative visual phenomena. Similar symptoms can occasionally occur with occipital lesions or as a manifestation of occipital seizures. In this chapter, we review the clinical features of migraine aura, with specific reference to those features that help distinguish it from occipital seizures. ; 13. Non-Organic Vision Loss ; Non-organic vision loss is common, but can be challenging to diagnose and treat. We discuss the approach to the patient with suspected non-organic vision loss in this chapter, and we describe the maneuvers that can be used to demonstrate intact visual function. ; SECTION II EFFERENT DISORDERS ; 14. Third Nerve Palsy ; Acute painful pupil-involving third nerve palsy requires urgent investigation, since it can be due to third nerve compression by a rapidly enlarging posterior communicating artery aneurysm. We summarize the approach to the patient with a third nerve palsy in this chapter, with emphasis on the imaging evaluation of acute pupil-involving third nerve palsy. ; 15. Fourth Nerve Palsy ; Fourth nerve palsy is a common cause of binocular vertical diplopia, but can be difficult to diagnose, since examination findings are often subtle. In this chapter, we review the symptoms, signs, causes, differential diagnosis, and evaluation of fourth nerve palsy. ; 16. Sixth Nerve Palsy ; Binocular horizontal diplopia is often due to sixth nerve palsy, but can be caused by other conditions, such as medial rectus muscle restriction in thyroid eye disease. We review the approach to the patient with sixth nerve palsy in this chapter. We briefly discuss the role of imaging in patients with sixth nerve palsy, as this remains a controversial topic. ; 17. Ocular Myasthenia ; Ocular myasthenia typically causes intermittent or fluctuating ptosis and diplopia, but is often difficult to diagnose definitively. We discuss the approach to the patient with suspected ocular myasthenia, but no acetylcholine receptor antibodies, and review the treatment options for ocular myasthenia. ; 18. Complete Bilateral External Ophthalmoplegia ; Complete bilateral external ophthalmoplegia is characterized by global weakness of the extraocular ocular and levator muscles. It has a broad differential diagnosis, which varies depending on the tempo of onset. In this chapter, we review the approach to the patient with complete bilateral external ophthalmoplegia and discuss the common causes. ; 19. Superior Oblique Myokymia ; Monocular oscillopsia is an uncommon symptom that is often due to superior oblique myokymia. Since the eye oscillations in this condition are intermittent and often subtle, the diagnosis is frequently missed. We discuss the evaluation and management of patients with suspected superior oblique myokymia in this chapter. ; 20. Internuclear Ophthalmoplegia ; Internuclear ophthalmoplegia is a classic ocular motor syndrome that is caused by a lesion affecting the medial longitudinal fasciculus in the brainstem. In this chapter, we review the signs, causes, and differential diagnosis of internuclear ophthalmoplegia. ; 21. Progressive Supranuclear Palsy ; Patients with progressive supranuclear palsy, a sporadic akinetic-rigid syndrome, often have visual complaints and abnormal eye movements. We review the neuro-ophthalmic signs of progressive supranuclear palsy and present a practical approach to the management of common visual symptoms, such as reading difficulty. ; 22. Gaze-Evoked Nystagmus ; Gaze-evoked nystagmus is the most common type of nystagmus encountered in clinical practice, but is poorly localizing. It is often confused with physiologic <"end-point>" nystagmus, which occurs in normal humans and is of no concern. In this chapter, we discuss the approach to the patient with gaze-evoked nystagmus. ; 23. Downbeat Nystagmus ; Downbeat nystagmus is a common type of central vestibular nystagmus that often produces oscillopsia or blurred vision. We review the signs, causes, and investigation of downbeat nystagmus. We also discuss currently-available treatment options. ; 24. Upbeat Nystagmus ; Upbeat nystagmus is a less common type of central vestibular nystagmus that is often transient, but can be persistent and responsible for visual symptoms. We review the characteristics and causes of upbeat nystagmus in this chapter. We also discuss the management of upbeat nystagmus occurring in the setting of Wernicke's encephalopathy. ; 25. Acquired Pendular Nystagmus ; Acquired pendular nystagmus often occurs in the setting of multiple sclerosis, but can also occur in the syndrome of oculopalatal tremor. It can cause disabling oscillopsia and, thus, many affected patients request treatment. In this chapter, we discuss the clinical features and treatment of acquired pendular nystagmus. ; 26. Infantile Nystagmus Syndrome ; Formerly known as congenital nystagmus, this form of nystagmus can occur in isolation or in association with other ophthalmic, neurologic, or endocrine abnormalities. While it does not usually cause oscillopsia, it can cause blurred vision and, thus, affected patients sometimes request treatment. We review the clinical features of infantile nystagmus syndrome and present a contemporary approach to treatment. ; 27. Saccadic Intrusions and Dysmetria ; Saccadic intrusions and dysmetria are often encountered in association with certain cerebellar and neurodegenerative diseases. When severe, they can give rise to difficulty reading or oscillopsia. In this chapter, we review the approach to the patient with saccadic intrusions and dysmetria. We also briefly discuss proposed medical treatments. ; SECTION III EYELID DISORDERS ; 28. Eyelid Ptosis ; Upper eyelid ptosis is frequently encountered in clinical practice, but has a broad differential diagnosis. We discuss the approach to the patient with upper eyelid ptosis in this chapter, with special attention to levator dehiscence. ; 29. Benign Essential Blepharospasm ; Blepharospasm is an involuntary closure of the eyes that is caused by spasm of the orbicularis oculi. It can be isolated or occur in association with certain ophthalmic and neurologic disorders. We review the approach to the patient with blepharospasm in this chapter, with emphasis on treatment strategies. ; SECTION IV PUPIL DISORDERS ; 30. Physiologic Anisocoria ; A difference in the size of the pupils (anisocoria) is a frequent finding on physical examination. While often a cause for alarm, it is not uncommonly physiologic and of no concern. In this chapter, we summarize the approach to the patient with anisocoria. ; 31. Horner's Syndrome ; Horner's syndrome can be caused by a lesion anywhere along the oculosympathetic pathway. While there may be other signs might that help with localization of the lesion, the syndrome often occurs in isolation. We review the approach to the patient with suspected Horner's syndrome, with special attention to the role of investigations such as pharmacologic pupil testing and imaging. ; 32. Tonic Pupil ; A tonic pupil is caused by a lesion affecting the post-ganglionic parasympathetic innervation of the pupil. It can be an incidental finding on examination or associated with visual symptoms, such as photophobia or blurred vision at near. We discuss the common causes and diagnostic evaluation of a tonic pupil in this chapter. ; 33. Pharmacologic Mydriasis ; A dilated unreactive pupil is a dramatic clinical finding. While it can be seen in the setting of compressive third nerve palsy, it can also be due to pharmacologic mydriasis. We discuss the approach to the patient with suspected pharmacologic mydriasis, with an emphasis on the role of pharmacologic pupil testing. ; SECTION V COMBINATION SYNDROMES ; 34. Orbital Apex, Superior Orbital Fissure, and Cavernous Sinus Syndromes ; Lesions in the orbital apex, superior orbital fissure, and cavernous sinus can give rise to characteristic combinations of cranial nerve palsies. In this chapter, we briefly review the possible causes of these syndromes. We discuss rhino-orbital mucormycosis in detail, since it has a grave prognosis if it is not diagnosed and treated in timely fashion. ; 35. Dorsal Midbrain Syndrome ; Lesions of the dorsal midbrain give rise to a characteristic and highly localizing constellation of neuro-ophthalmic signs. We review the clinical features and common causes of the dorsal midbrain syndrome in this chapter, with special reference to the clinical features and management of ventriculo-peritoneal shunt malfunction. ; 36. Thyroid Eye Disease ; Thyroid eye disease is the most common cause of orbital disease encountered in clinical practice. It often occurs in patients with Graves' disease, but it is not always associated with abnormal thyroid function. In this chapter, we review the clinical signs, investigation, and treatment of thyroid eye disease.