Ординатура / Офтальмология / Английские материалы / Primary Care Ophthalmology_Palay, Krachmer_2005

202 CHAPTER 12 • Neuro-ophthalmology

A B

C

FIGURE 12–2 Nonarteritic anterior ischemic optic neuropathy in a 49-year-old man with diabetes. The patient initially presented with sudden, painless vision loss in his right eye. Approximately 2 years before, he had experienced a similar event in the left eye. A, Right eye shows optic disc edema, flame-shaped hemorrhage, and cotton-wool spot concentrated on upper half of the disc. B, Left, previously affected eye shows pallor of upper disc (sectoral pallor), with some pink still present inferiorly. C, Bilateral inferior altitudinal visual field defects were present (corresponding to superior optic disc events).

Etiology and Associated Factors and Diseases

•Vision loss results from hypoperfusion of the optic disc.

•Hypoperfusion may result from atherosclerotic or thrombotic processes affecting the arteries supplying the optic disc.

•Hemodynamic compromise is a potential cause, occurring in patients with hypotension or blood loss.

•The disorder is associated with hypertension, diabetes, coronary artery disease, and other vasculopathic conditions.

•Patients typically have a “crowded” optic disc configuration, with a small or absent physiologic cup.

Differential Diagnosis

Other optic neuropathies that need to be considered include the following:

•Arteritic anterior ischemic optic neuropathy (giant cell arteritis)

•Optic neuritis

•Infiltrative optic neuropathy

•Asymmetrical papilledema

•Compressive optic neuropathy

Workup

•Westergren erythrocyte sedimentation rate testing should be performed to look for evidence of giant cell arteritis.

•Medical evaluation for hypertension, diabetes, and anemia is indicated.

•Neuroimaging may be required in uncertain or progressive cases.

Treatment

•No treatment has been proved effective; intravenous and oral steroids are of uncertain help but are a consideration in patients with progressing vision loss or NAION in the better eye

•Daily aspirin may reduce the incidence of an episode in the fellow eye.

Follow-up

•Visual field testing should be performed at approximately 2 weeks and at 2 months to see if the clinical course is stable, as expected.

•Progression of visual deficits may require more extensive investigation such as neuroimaging.

•Mild improvement in the central vision may occur in about 50% of patients.

•Simultaneous or rapidly sequential anterior ischemic optic neuropathy (involvement of both eyes within a few months) suggests giant cell arteritis.

Giant Cell Arteritis: Arteritic Anterior Ischemic Optic

Neuropathy (AAION)

Symptoms

•A sudden vision loss occurs in one or both eyes.

•Vision loss frequently is extreme.

•Systemic symptoms include headache, scalp and temple tenderness, myalgia, arthralgia, low-grade fever, anemia, malaise, weight loss, and anorexia. Jaw and tongue claudication are particularly suggestive of giant cell arteritis.

•Polymyalgia rheumatica may accompany or precede giant cell arteritis. Symptoms are morning stiffness and muscle aches, particularly in the neck and shoulders.

204 CHAPTER 12 • Neuro-ophthalmology

Signs

•The frequency of the disorder increases with each successive decade of life: Before the age of 50 years, it is very rare; at ages 50 to 59 years, it occurs occasionally. Most cases occur in patients 60 years of age or older.

•Optic disc pallor and swelling may be present on examination, or only minimal optic disc changes that do not reflect the profound vision loss may be noted (Fig. 12–3A).

•Temporal arteries often are firm, tender, or pulseless (Fig. 12–3B).

•The erythrocyte sedimentation rate is generally greater than 50 mm/hr but can occasionally be normal.

•Mild anemia commonly occurs.

•A third, fourth, or sixth cranial nerve palsy also may occur, as can vision loss from a central retinal artery occlusion.

•A relative afferent pupillary defect is present in unilateral cases.

Etiology

• Vision loss is caused by vasculitic occlusion of arteries to the optic disc.

A B

FIGURE 12–3 Arteritic anterior ischemic optic neuropathy (giant cell arteritis). The patient was a 73-year-old man who noted the progressive decline of vision in his right eye to no light perception over 2 days. He had experienced headaches and malaise for several weeks previously. Although his erythrocyte sedimentation rate was only 33 mm/hr, he was immediately hospitalized for high-dose intravenous corticosteroids for suspected giant cell arteritis. A, Pale swelling of the right optic disc, characteristic of arteritic anterior ischemic optic neuropathy. The left optic disc (not shown) is normal. B, The temporal artery was firm, pulseless, and tender. A temporal artery biopsy confirmed the diagnosis of giant cell arteritis.

Differential Diagnosis

Other diagnostic considerations in this setting include the following:

•NAION (when optic disc edema is present)

•Compressive optic neuropathy (especially with minimal optic disc signs)

Workup

•Measurement of the erythrocyte sedimentation rate should be performed immediately. Assay for C-reactive protein also is helpful.

•A temporal artery biopsy should be performed but is not required before institution of corticosteroid therapy (best if performed within 2 weeks of initiating corticosteroids).

•Neuroimaging may be needed if the diagnosis is uncertain.

•An ophthalmologic consultation should be obtained to aid in the diagnosis and management of vision loss.

•Chest x-ray imaging and determination of electrolyte and blood glucose levels are needed to evaluate existing medical problems that may be exacerbated by corticosteroid administration, such as tuberculosis, diabetes, and hypertension.

Treatment

•Corticosteroids are administered immediately: intravenous methylprednisolone 250 mg every 6 hours for 3 days with acute vision loss (followed by oral, daily prednisone) or prednisone 80 to 100 mg orally if giant cell arteritis is suspected but no vision loss has occurred.

Follow-up

•A second biopsy of the contralateral temporal artery or other tender scalp artery is recommended if the first biopsy results are negative but clinical suspicion remains strong.

•Long-term corticosteroid use (with slow taper, with periodic determinations of erythrocyte sedimentation rate) requires careful medical support to monitor the potentially serious side effects.

Optic Neuritis

Symptoms

•Vision loss in one eye occurs over several days.

•Pain with eye movement is common.

•Spontaneous recovery occurs over months.

•Patients may relate a history of transient neurologic disturbances.

Signs

•Patients usually are 15 to 45 years of age.

•Two thirds of patients initially have normal-appearing discs (with retrobulbar optic neuritis); one third have optic disc edema.

206CHAPTER 12 • Neuro-ophthalmology

•Central visual field loss is common, but any disc-related visual field defect (such as altitudinal losses) may be present (Fig. 12–4).

•A relative afferent pupillary defect usually is present in the affected eye but may be absent if a previous event occurred in the fellow eye.

•Spontaneous, near-complete recovery from the visual deficit occurs within months in most cases.

Etiology

•Optic neuritis results from demyelination of the optic nerve, either with an idiopathic origin or occurring in association with multiple sclerosis.

•In some cases, the disorder is presumed to be of postviral origin.

Differential Diagnosis

With Normal Optic Discs

Other disorders that can cause poor vision, initially with relatively normal optic discs, include the following:

•Compressive optic neuropathy

•Vasculitis

•Carcinomatous meningitis

•Trauma

•Radiation-induced optic neuropathy

•Toxic or nutritional optic neuropathy (bilateral)

With Swollen Discs

In patients with swollen discs, the following possibilities should be considered:

•Anterior ischemic optic neuropathy

•Leber’s optic neuropathy

•Hypertensive optic neuropathy

•Infiltrative or compressive optic neuropathy

Workup

•Ophthalmologic evaluation is required to rule out other ocular disease and to perform formal visual field testing.

•Magnetic resonance imaging (MRI) of the brain and orbits with contrast is needed to assist in determining treatment options (see Fig. 12–4B).

•Complete blood count (CBC), determination of electrolyte levels, and chest x-ray imaging should be performed if corticosteroid treatment is anticipated.

Treatment

•For patients with white matter plaques found on MRI, intravenous methylprednisolone (250 mg) every 6 hours for 3 days (with an optional 10-day oral corticosteroid taper) should be considered. This treatment has been shown to reduce future multiple sclerosis–related neurologic events, but only for the following 2 years. Intravenous methylprednisolone may hasten visual recovery but has not been shown to affect final visual outcome.

1

1

30˚

A B

30˚

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FIGURE 12–4 Optic neuritis. The patient was a 32-year-old woman who noted progressive decline in the vision of her right eye over 5 days, as well as pain with eye movement. The optic discs and fundus were normal, but a large relative afferent pupillary defect was present in the right eye. A, Initial visual field testing demonstrated significant visual field loss and a visual acuity of counting fingers only. B, MRI revealed periventricular white matter plaques (1) characteristic of multiple sclerosis. The patient was given high-dose intravenous corticosteroids. C, Results of visual field testing 3 months later were normal, and the visual acuity had improved to 20/20. Within 2 years, she experienced additional neurologic events consistent with multiple sclerosis.

208CHAPTER 12 • Neuro-ophthalmology

•For patients without white matter changes found on MRI, intravenous corticosteroid treatment has no proven long-term advantage, but this treatment often is used to hasten recovery in “one-eyed” patients or those with severe vision loss.

•Oral corticosteroids must not be used alone, because they increase the incidence of recurrence of optic neuritis.

Follow-up

•Neurologic evaluation is needed to investigate the possibility of underlying multiple sclerosis and to assess subsequent treatment.

•Visual field testing is repeated at intervals to ensure that the course of the disease is consistent with optic neuritis. Failure of the patient to improve as expected necessitates additional workup.

Papilledema

The term papilledema refers to bilateral optic disc edema from elevated intracranial pressure but does not identify the underlying etiologic process. Both brain tumors and pseudotumor cerebri (idiopathic intracranial hypertension) produce papilledema in affected patients.

Symptoms

•Headache is common; nausea and vomiting also can occur.

•Brief, transient episodes of vision loss may occur with postural changes.

•Pulsatile tinnitus is common.

•Horizontal diplopia occasionally is present, resulting from paresis of one or both sixth cranial nerves.

•Other neurologic dysfunction may be present with an intracranial mass.

Signs

•Patients with pseudotumor cerebri are often obese females aged 12 to 40 years.

•Optic disc edema typically is present in both eyes (Fig. 12–5A and B).

•Patients initially may have relatively normal visual fields. Over time, chronic papilledema causes peripheral visual field loss (Fig. 12–5C).

•Visual acuity typically is not affected until very late in progressive cases.

•Unilateral or bilateral sixth cranial nerve paresis may occur.

Etiology

Elevated intracranial pressure is caused by the following:

•Intracranial mass

•Impediment to cerebrospinal fluid flow or absorption, as from dural sinus thrombosis, arteriovenous malformation, aqueductal stenosis, meningitis, and trauma (e.g., intracranial hematoma, subarachnoid hemorrhage)

•Idiopathic intracranial hypertension (pseudotumor cerebri) associated with obesity and some medications (vitamin A, some antibiotics such as tetracycline, and others)

Papilledema 209

A B

C

FIGURE 12–5 Idiopathic intracranial hypertension (pseudotumor cerebri). The patient was a 39-year-old woman who had experienced brief episodes of vision loss in both eyes, lasting seconds, and headache. MRI findings were normal, and lumbar puncture revealed an opening pressure of 400 mm of water. Right eye (A) and left eye (B) show papilledema (bilateral optic disc swelling from elevated intracranial pressure). C, Visual acuity was 20/20 in each eye, but visual field testing demonstrated enlargement of the blind spots bilaterally, and a visual field defect was evident in the left eye. This type of visual field defect (“nasal step”) is characteristic of optic disc disease; it follows the nerve fiber layer pattern and respects the horizontal meridian.

210 CHAPTER 12 • Neuro-ophthalmology

Differential Diagnosis

Other disorders that can cause bilateral optic disc elevation include the following:

•Pseudopapilledema (anomalous optic discs)

•Bilateral optic neuritis

•Bilateral anterior ischemic optic neuropathy

•Amiodarone toxicity

•Bilateral infiltrative optic neuropathy (e.g., sarcoidosis, tuberculosis, metastatic cancer)

•Hypertensive retinopathy (“malignant” hypertension)

Workup

•Measuring the blood pressure is required, because severe hypertension can manifest with bilateral optic disc edema.

•Neuroimaging (MRI with contrast preferred) is performed immediately to look for a mass or dural sinus thrombosis.

•A lumbar puncture is needed to measure the opening pressure and to obtain cerebrospinal fluid for analysis if findings on neuroimaging are normal.

•Neurosurgery and neurology consultations are necessary for identified causes.

•Ophthalmology and neurology consultations are needed to confirm a diagnosis of pseudotumor cerebri, to monitor the clinical course, and for formal visual field testing.

Treatment

•Treatment of idiopathic intracranial hypertension (pseudotumor cerebri) includes the following:

Weight loss is very effective.

Acetazolamide (Diamox) is effective.

Topiramate (Topamax) is effective, especially in combination with acetazolamide.

Furosemide (Lasix) is less effective.

Neurosurgical shunting or optic nerve sheath fenestration may be needed in cases of visual field deterioration despite medical therapy.

•For other conditions such as a mass or dural sinus thrombosis, the etiologic process determines the treatment.

Follow-up

•Frequent, formal visual field testing is required in patients with chronic papilledema, because their visual acuity may remain 20/20 despite progressive peripheral visual field loss.

Other Optic Neuropathies

Infiltrative Disorders

•Lymphoproliferative cells (as in lymphoma and leukemia), infectious agents (as in tuberculosis), or inflammatory granulomas (as in sarcoidosis) may invade the optic nerve, resulting in an elevated, swollen appearance of the optic disc.

•Leukemic infiltration of the optic disc with visual loss constitutes a true oncologic emergency; prompt radiation treatment may preserve vision.

Toxic and Nutritional Disorders

•A slow, bilateral loss of central vision is characteristic, with mild pallor of the temporal aspect of the optic nerve.

•Alcohol abuse and a poor diet are common causes, suggesting nutritional and substance abuse consultation; folic acid and thiamine supplementation may improve vision.

•Other causes include pernicious anemia and heavy metal (lead) toxicity.

•Medications (e.g., ethambutol, isoniazid, streptomycin, digitalis) are sometimes implicated.

Leber’s Optic Neuropathy

•A rapid, sequential bilateral loss of central vision occurs in young men and rarely in women.

•Mild disc swelling may occur acutely, with disc pallor developing over time.

•Mitochondrial DNA mutations in asymptomatic women are inherited by their children; however, usually the disorder manifests in males.

Optic Nerve Trauma

•Traumatic optic nerve injury may be caused by direct trauma from foreign bodies or bone fragments or indirect trauma from a blunt injury to the brow or cranium, even without fractures.

•The optic disc may appear normal at first, but pallor develops in 4 to 8 weeks.

•High-dose intravenous corticosteroids may be of benefit during the acute phase.

•Decompression of the bony optic canal has been advocated by some clinicians.

•In all cases the presence of associated ocular trauma (e.g., retinal detachment, penetrating injuries) must be determined.

Optic Disc Pallor

•Optic disc pallor is the final common pathway of almost all optic nerve insults.

•If the etiologic process is unknown, neuroimaging is required to look for compressive etiology (e.g., tumor).

Optic Nerve Head Drusen

•Hyaline material is present in the substance of the optic disc (in 1% of the general population).

•This rocklike yellow material forms irregularly shaped excrescences, which may be exposed on the disc surface in older patients (Fig. 12–6A).

•Peripheral visual field defects may occur; however, visual acuity is almost never affected (Fig. 12–6B).

•The occurrence is bilateral in 70% of patients.

•The drusen often are “buried” in young patients, making it difficult for clinicians to distinguish these elevated discs from discs with true edema (Fig. 12–7).