Ddx: Visual system Disorders

Question 1

Ddx: Visual system disorders

Answer 1

Monocular:

Transient monoclar blindness

Optic Neuritis

Giant Cell (Temporal) Arteritis

Binocular:

Papilledema

Chiasmal Lesions

Retro chiasmal lesions

Optic radiation

Occipital Cortex

Question 2

Transient monoclar blindness

Answer 2

Transient monocular blindness (amaurosis fugax) is characterized by typically painless, unilateral transient diminution or loss of vision that develops over seconds, remains maximal for 1 to 5 minutes, and resolves over 10 to 20 minutes.

Question 3

Optic Neuritis

Answer 3

Inflammation of the optic nerve produces the syndrome of optic neuritis. The most common cause is demyelination (acute demyelinating optic neuritis). Less common causes include parameningeal, meningeal, or intraocular inflammation associated with viral infections or postviral syndromes. Rare causes include toxins (eg, methanol, ethambutol), neurosyphilis, and vitamin B12 deficiency.

Hx: Clinical presentation includes acute onset of progressive unilateral visual loss, orbital pain, worse with eye movement and central or paracentral scotoma.

Px: Examination findings include decreased visual activity, relative afferent pupillary defect (Marcus Gunn pupil), visual field deficit and impaired color perception. If the optic disc is involved, it can show swelling and blurring of the margins (papillitis). If the inflammatory process spares the optic disc, it will appear normal (retrobulbar optic neuritis).

Dx: Visual field testing demonstrates a central scotoma (blind spot) associated with decreased visual acuity. Examination of the fundus shows unilateral disk swelling
when the nerve head is involved, but is normal when the inflammatory process is posterior to the optic disk (retrobulbar neuritis), as is most common in demyelinating disease.

Diffuse gadolinium enhancement of the optic nerve on MRI is typical of acute demyelinating optic neuritis

Tx: Intravenous methylprednisolone, 1 g/d for 3 to 5 days, with or without an oral prednisone taper, from 1 mg/kg/d over 11 days, can hasten recovery but does not alter the final visual outcome or the likelihood of developing multiple sclerosis.

Question 4

Giant cell (Temporal) Arteritis

Answer 4

Arteritic infarction of the anterior portion of the optic nerve is the most devastating complication of giant cell, or temporal, arteritis.

Question 5

Papilledema

Answer 5

A diagnosis of idiopathic intracranial hypertension (pseudotumor cerebri) is established by exclusion when cerebrospinal fluid (CSF) pressure is elevated but an intracranial mass lesion and other disorders associated with intracranial hypertension. are excluded
by the history, computed tomography (CT) scanning or MRI with contrast enhancement, and meningeal inflammation is excluded by CSF examination.

Less common causes of papilledema include congenital cyanotic heart disease and disorders associated with increased CSF protein content, such as spinal cord tumor
and idiopathic inflammatory polyneuropathy (Guillain-Barré syndrome).