Vitamin, Water Soluble
Class Summary
Essential to normal metabolism and DNA synthesis.
Cyanocobalamin (Nascobal)
Deoxyadenosylcobalamin and hydroxocobalamin are active forms of vitamin B-12 in humans. Vitamin B-12 synthesized by microbes but not by humans or plants. Deficiency may result from intrinsic factor deficiency (pernicious anemia), partial or total gastrectomy, or distal ileum diseases. Deficiency initially and typically manifests as macrocytic anemia, although neurologic symptoms may be present. Can also cause confusion or delirium in elderly patients.
Essential for normal erythropoiesis. Required for healthy neuronal functions and normal functions of rapidly growing cells.
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Normal optic nerve histopathology.
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Glaucomatous optic atrophy histopathology.
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Healthy optic disc.
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Nonarteritic anterior ischemic optic neuropathy.
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Arteritic anterior ischemic optic neuropathy, cilioretinal artery occlusion.
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Primary optic atrophy.
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Optic atrophy following papilledema (secondary).
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Glaucomatous optic atrophy.
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Juvenile open-angle glaucoma (JOAG) with optic pallor.
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Consecutive optic atrophy following panretinal photocoagulation (PRP).
Tables
|
Postneuritis |
Ischemic Arteritic |
Ischemic Nonarteritic |
Compressive |
Age |
15-50 y |
Approximately 70 y |
Sixth decade |
Varies based on cause |
Sex |
Multiple sclerosis F>M |
F>M |
F=M |
Varies based on cause |
Visual acuity |
Varies from mild blurring (34%) and moderate loss of acuity (12%) to severe or total loss of light perception (complete blindness) in 54% of cases, to no light perception. The loss of vision is acute and progressive.--Vision usually recovers within 2 mo |
< 20/200 (6/60) |
>20/200 (6/60) |
Varies from mild blurring to no light perception |
Color vision |
Color vision > vision loss |
Color vision loss = vision loss |
Color vision loss = vision loss |
Color vision = vision loss |
RAPD* |
+ |
+ |
+ |
+ |
Motility |
Painful movement in cases of retrobulbar neuritis |
Normal |
Normal |
Depends on the site of compression |
Nystagmus |
In multiple sclerosis, vertical nystagmus (upbeating or downbeating) may be seen |
No |
No |
See-saw nystagmus in optic chiasm compression |
Optic disc |
Temporal pallor |
Pallid disc edema |
Segmental disc edema |
Bow-tie pallor seen in optic chiasm compression; varies in other instances |
Electrophysiologic study |
VEP-increased latency < †> |
VEP-reduced amplitude |
VEP-reduced amplitude |
Reduced VEP amplitude |
Neuroimaging (CT, MRI) |
In multiple sclerosis, hyperechoic lesions are seen in the brain on MRI |
- |
- |
For exact location of compression |
Other associations |
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Headache, scalp tenderness, jaw claudication |
Hypertension and diabetes |
Headache, vomiting, and focal neurologic deficits |
*RAPD - Relative afferent pupil defect < †>VEP - Visual-evoked potential |
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