While sudden bilateral painless visual disturbances can, on very rare occasions, be caused by a transient ischemic attack to the occipital visual cortex¹²⁹ or transient vertebrobasilar insufficiency, the etiology to an acute painless visual disturbance affecting both eyes is likely to be from physiological, metabolic, toxic, or pharmacologic etiologies. Acute methanol toxicity may present with ocular manifestations of blurred vision, photophobia, painful eye movements, and reduced visual acuity. On examination, the patient may have optic disc edema with engorged retinal veins.¹³⁰

Idiopathic Intracranial Hypertension (Pseudotumor Cerebri)

Presentation And Examination Findings

Patients with idiopathic intracranial hypertension (IIH) typically present with chronic daily headaches (the major cause of morbidity)⁴⁰ and visual abnormalities – either monocular or binocular transitory visual obscurations varying from slight blurring to total loss of light perception - which are seen in up to 72% of the patients.¹³¹The headache, sometimes associated with nausea and pulsatile tinnitus, is generally worse in the morning and worsened by valsalva.⁴¹On examination, papilledema with blurring of the optic disc border, absent spontaneous venous pulsations, distention of the retinal veins, visual field deficits, and possibly even protrusion of the optic disc with hemorrhages and exudates may be present; a horizontal diplopia from an associated sixth nerve palsy may rarely be present.⁴¹

Diagnostic Workup And Management

IIH should be strongly suspected in any young obese female presenting with chronic headaches, blurred vision or visual disturbance, and papilledema on examination. The diagnosis of IIH requires four diagnostic criteria:

1. Increased ICP
2. Normal ventricles on neuroimaging
3. No intracranial mass
4. Normal CSF

A lumbar puncture with measurement of opening pressure, CSF analysis, and head CT are indicated to establish the diagnosis and rule out intracranial mass, hydrocephalus, or other etiologies of headache and papilledema.^40-41 The CSF pressure will usuallybe elevated above the normal value of 20 cm H₂O but is prone to natural variations and even transient normalcy.^41,132 A pressure of 20 cm H₂O or below isconsidered normal, a value between 20 and 25 cm H₂O is non-diagnostic, and a pressure of over 25 cm H₂O is diagnostic of IIH.^133-134A young female presenting with headache and papilledema may raise the specter of sagittal sinus thrombosis; an MRI and MRV can be used to evaluate for this and may reveal additional signs of elevated CSF pressure related to IIH, such as a partially empty sella, dilation or tortuosity of the optic nerve sheet, or gadolinium enhancement of the optic disc.¹³⁵

A variety of treatments for IIH have been described in the literature, including repeated lumbar punctures, weight loss, a variety of drugs (such as acetazolamide, diuretics, oral glycerol, corticosteroids, and cardiac glycosides), hyperbaric oxygen, vasopressin, and a variety of CSF shunting approaches. A 2005 Cochrane Database review of the available literature found no evidence that any of these work in a sustained fashion.⁴⁰ In the ED, the crux of management revolves around symptomatic relief and appropriate referral.

<< Previous | Topic Table of Contents | Next >>