Optic Nerve Disease

Page Quick Links Papilledema Papillitis Optic Atrophy	Optic Nerve Disease
		Compressive Optic Neuropathy
		Optic Neuritis
		Acute Ischemic Optic Neuropathy
		Temporal Arteritis

Papilledema

Epidemiology

The epidemiology of papilledema reflects the etiology of increased intracranial pressure (ICP). Increased ICP may result from brain tumor at any age and in either gender. Intracranial masses that obstruct CSF outflow may be relatively small and still result in dramatic increased ICP and papilledema.

Pseudotumor cerebri (also known as idiopathic or benign intracranial hypertension) characteristically presents in obese women of childbearing age. In contrast, infection can result in meningeal infiltration and meningitis at any age and in any gender. Inflammation due to sarcoidosis is more common in African Americans and Scandinavians.

Predisposing factors of papilledema include a history of carcinoma or lymphoma, and recent viral, bacterial, or tuberculous infection. Risk factors for increased ICP include recent weight gain, use of exogenous estrogen or vitamin A, and intake of certain drugs (antibiotics, corticosteroids, isotretinoin).

Ocular symptoms and signs

Symptoms of increased ICP include headache, transient visual obscurations, intracranial noises (humming or ringing), decreased vision, and double vision.41-44

The most common presenting ocular symptom of papilledema is transient visual obscurations that are described as graying or blacking out of vision that lasts only for seconds and can be precipitated by moving from a lying to a sitting or standing position. Many patients notice a whooshing sound in one or both ears when lying down. Less frequently, horizontal diplopia that is most prominent at a distance is the first symptom of a sixth nerve palsy associated with the increased intracranial pressure. Retroorbital ache is sometimes present and may be worse with eye movement.

Headache is a common presenting symptom; it is typically present upon awakening and associated with nausea and emesis, but may be nonspecific in character. A peripheral constriction of the visual fields, especially in the nasal quadrant, can eventually progress to central visual loss in some cases.
Early papilledema is associated with bilateral, although frequently asymmetric, opacification of the bilateral nerve fiber layer, lack of spontaneous venous pulsation, and obliteration of the central cup. Hemorrhages and exudates may also occur. In chronic papilledema, small telangiectatic vessels and white concretions on the disc surface may be present, and afferent function may be abnormal (central visual acuity, color, pupils, and visual fields)41, 42, 44, 45 With chronic papilledema, choroidal folds (Paton lines) or optic atrophy may result (Fig. 26-10). Rarely, subretinal neovascularization develops due to fracture of Bruch’s membrane in the retina and the growth of new vessels through this layer with subsequent leakage of blood and fluid.

Diagnosis

Bilateral disc edema is a clinical diagnosis that is not appropriately termed papilledema until increased intracranial pressure is diagnosed. The differential diagnosis of bilateral disc swelling includes malignant hypertension, central retinal vein occlusions, anterior ischemic optic neuropathy, papillitis or optic nerve involvement by inflammation, infection, or neoplasia (Table 6); none of these entities disrupt spontaneous venous pulsations. Occasionally, a patient will present with headaches and atypical appearing optic nerves. “Pseudo-papilledema” may be diagnosed due to optic nerve head drusen, anomalous optic nerves, hyperopic nerves, or tilted discs.
             
If there is doubt as to whether disc edema is truly present, several diagnostic testing techniques are available. Ultrasound (B-mode) is used to detect buried drusen. Fluorescein angiogram is used to identify early vessel dilatation and leakage. (Sanders, 1969) In uncooperative children or adults, fundus photos are invaluable to document the features of the optic nerve heads.

Management

Although afferent function may be normal in the early stages of papilledema, formal visual field testing is key to management at all stages. Neuroimaging, preferably MRI, is performed to look for an intracranial mass. In patients with persistent papilledema or who are unusual or unresponsive to medication, magnetic resonance venography should be considered as a diagnostic tool to exclude venous thrombosis. When the lumbar puncture is performed, opening pressure should be documented and the CSF should be analyzed for cells, glucose, and protein content.46, 47

Management is of the underlying disorder and is considered in standard textbooks of neurology. If a tumor is present, surgical intervention is necessary. If pseudotumor cerebri is diagnosed, weight loss should be encouraged and the patient followed very closely with visual field testing. Failure to monitor visual fields can result in permanent visual loss and even blindness. If visual field defects are present the patient should be placed on a minimum of 1 g acetazolamide. The sustained action capsules are superior to the tablets and result in less gastric disturbance. If medical therapy fails to relieve the headache or visual loss progresses, surgical options should be discussed. Optic nerve sheath fenestration is indicated if a shunt fails to normalize the visual field or there is catastrophic visual loss with mild or absent headache.

Normal Retina

Papilledema

Papillitis

Epidemiology

Papillitis is term used for disc edema of uncertain etiology. As such, there are no specifics to the race, gender or age of those affected. Papillitis may be unilateral or bilateral and in some cases, such as inflammation or neoplasia, occurs recurrently. Bilateral disc edema of uncertain etiology, even if associated with a headache, should be referred to as bilateral papillitis.

Ocular Symptoms and Signs

In contrast to disc edema secondary to increased intracranial pressure, papillitis is associated with acute onset of visual loss. An afferent pupillary defect, color desaturation and central visual field defect is present. Of note, in contrast to papilledema typically has normal optic nerve function early on. Papilledema does not typically present with decreased vision, an afferent pupillary defect, color desaturation or significant visual field defects. The most common visual field defect in papillitis is a central scotoma; early papilledema produces only an enlarged blind spot (which may be missed with the new automated fields).

Diagnosis

Papillitis may represent optic neuritis, which is often associated with the development of or co-existent, multiple sclerosis (MS). In contrast to the symptoms and signs of papilledema, optic neuritis is typically acute in onset and is associated with retrobulbar pain that is worse with eye movement; it is not accompanied by headache. Transient visual obscurations are not typical, more commonly optic neuritis is retrobulbar (behind the globe) and the optic nerve is entirely normal in appearance. In addition, spontaneous venous pulsations are present, the veins are of normal appearance, and hemorrhages and exudates are absent.

If macular edema is present and the exudates form a macular star as it recedes, the diagnosis is more likely infectious (e.g., cat scratch disease) rather than optic neuritis associated with MS. If microinfarcts (cotton wool spots) are present, the diagnosis is either malignant hypertension or vasculitis such as Lupus Erythematosis or Temporal Arteritis.

Papillitis may be idiopathic, infectious, due to ischemia  (acute ischemic optic neuropathy or AION) or a tumor (optic nerve or sphenoid wing meningioma; glioma, or parasellar process).

Compressive lesions can also cause cavitation (optic nerve cupping) or shunt vessels on the surface of the disc. Temporal arteritis should be considered in all patients over the age of 50 years with a headache, especially when visual symptoms are present. In that disorder, transient visual obscurations may precede visual loss; vision may be poor (less than 20/400) unlike in patients with papilledema, in whom vision is typically good unless the papilledema is longstanding. Diplopia due to cranial nerve impairment may also occur. The ocular signs may include optic nerve pallor, swelling, or cavitation. A branch or central retinal artery occlusion may also occur. Occasionally, both optic nerves become swollen in rapid succession and are inappropriately designated papilledema.

Management

The management depends on the cause. Oral or intravenous corticosteroids are indicated in inflammatory papillitis, but oral corticosteroids are contraindicated as the initial treatment for optic neuritis.

If temporal arteritis is suspected, a sedimentation rate (ESR), C reactive protein (CRP) and complete blood count should be obtained. Elevation of the ESR and CRP along with anemia and thrombocytosis is characteristic. An oral corticosteroid dose of at least 1 mg/kg is initiated and tapered slowly over at least six months.

Optic Atrophy

Epidemiology

Optic Atrophy is the non-specific end product of all optic neuropathies, so there is no specific age, gender or race predilection. End-stage glaucoma is associated with optic atrophy and pallor; conversely cavitation of the optic nerve without pallor can be the only evidence of an intracranial tumor or temporal arteritis.

Ocular Symptoms and Signs

Visual loss may be acute, subacute, chronic or unrecognized. It is not unusual to identify optic atrophy with the associated optic nerve pallor, nerve fiber loss and visual field defects in patients with multiple sclerosis and no specific memory of an acute event. Chronic compression from Graves’ ophthalmopathy, optic nerve tumors, hyperostosis of the optic canal or other intracranial processes is characteristically slowly progressive and with an onset that is not easily identified by the patient.

Diagnosis

Optic atrophy is NOT a diagnosis; the cause of the pallor and/or cavitation (cupping) must be sought.
Posterior ischemic optic neuropathy is defined as an optic neuropathy without optic disc swelling that evolves into optic nerve pallor over 3-4 weeks. The differential diagnosis includes temporal arteritis, traumatic optic neuropathy or optic nerve stroke due to coma and hypotension.
Retrobulbar neuritis is multiple sclerosis until proven otherwise. A complete work-up should include neuro-imaging, labs for temporal arteritis if the patient is at least 50 years old, infectious work-up to include syphilis, tuberculosis and Lyme disease. The inflammatory work-up should include cAnca, pAnca, ACE, lysozyme, calcium. Rarely, hereditary conditions such as Leber’s optic neuropathy, nutritional neglect or toxic etiologies are present.

Management

The management depends on the cause.

Normal Retina

Optic Atrophy