Bitemporal hemianopia
Template:DiseaseDisorder infobox
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-In-Chief:Aditya Govindavarjhulla, M.B.B.S. [2]
Synonyms and keywords: Bitemporal hemianopsia
Overview
Bitemporal hemianopia is a specific type of visual disturbance in which sight in the outer half of the visual field of each eye is lost. As a result, the patient retains central vision but loses sight at the edges of his or her vision. This is not always obvious to a patient because one tends to focus conscious attention more on objects in the center of the visual field.
Hemianopia signifies a loss of half of the visual field, and bitemporal denotes the two lateral, or temporal, sides of the head. By contrast, homonymous hemianopia signifies that the same half of each visual field is lost, ie all vision on the left, or on the right, of the midline. Such a pattern of visual loss is caused by damage to the more distal part of the optic radiation, most commonly by a stroke.
Etymology
"Bitemporal hemianopia" can be broken down as follows:
- bi-: involves both left and right visual fields
- temporal: involves the temporal visual field
- hemi-: involves half of each visual field
- anopsia: blindness (formed by a(n) no + opsis vision + ia)
Pathophysiology
Hemianopia results from a lesion of the optic chiasm. This is the area where optic nerves from the right side of the brain cross over to the left and vice versa. Visual information from the temporal visual field is transmitted by the nasal retina and information from the nasal field is transmitted by the temporal retina. At the optic chiasm, nasal fibers of the retina cross over to other side of the brain and carry information to the higher visual brain centers. Thus, a lesion in the optic chiasm affects the nasal fibers of both retinas. It is when this disruption in the circuitry occurs that there is a loss of information from both of the outer visual fields.
Causes
Most of the causes of bitemporal hemianopia are due to disorders of the pituitary gland and its surrounding structures.
Common Causes
Causes by Organ System
| Cardiovascular | No underlying causes |
| Chemical / poisoning | No underlying causes |
| Dermatologic | Dermatochalasis |
| Drug Side Effect | Chloroquine retinopathy |
| Ear Nose Throat | No underlying causes |
| Endocrine | Pituatary macroadenoma, Prolactinoma |
| Environmental | No underlying causes |
| Gastroenterologic | No underlying causes |
| Genetic | No underlying causes |
| Hematologic | No underlying causes |
| Iatrogenic | No underlying causes |
| Infectious Disease | No underlying causes |
| Musculoskeletal / Ortho | No underlying causes |
| Neurologic | Chloroquine retinopathy, Pituitary macroadenoma, Prolactinoma, Craniopharyngioma, Aneurysm of anterior communicating artery, Intracranial vascular loop, Meningioma, Enlarged third ventricle, Glioma of third ventricle, Chronic chiasmal arachnoiditis, Suprasellar tumors, Adamantinoma of sella turcica, Optic neuropathy, Optic chiasmal syndrome, Obstructive hydrocephalus, Traumatic chiasmal syndrome, Dolichoectasia of internal carotid arteries |
| Nutritional / Metabolic | No underlying causes |
| Obstetric/Gynecologic | Hypophyseal hypertrophy in pregnancy |
| Oncologic | Adamantinoma of sella turcica, Craniopharyngioma, Glioma of third ventricle, Pituitary macroadenoma, Prolactinoma, Meningioma, Suprasellar tumors |
| Opthalmologic | Dermatochalasis, Optic neuropathy, Optic chiasmal syndrome, Bilateral blepharoptosis, Traumatic chiasmal syndrome |
| Overdose / Toxicity | No underlying causes |
| Psychiatric | No underlying causes |
| Pulmonary | No underlying causes |
| Renal / Electrolyte | No underlying causes |
| Rheum / Immune / Allergy | No underlying causes |
| Sexual | No underlying causes |
| Trauma | Traumatic chiasmal syndrome |
| Urologic | No underlying causes |
| Dental | No underlying causes |
| Miscellaneous | No underlying causes |
Causes in Alphabetical Order
- Adamantinoma of sella turcica[1]
- Aneurysm of anterior communicating artery
- Bilateral blepharoptosis[2]
- Chloroquine retinopathy[3]
- Chronic chiasmal arachnoiditis[4]
- Craniopharyngioma
- Dermatochalasis[5]
- Dolichoectasia of internal carotid arteries[6]
- Enlarged third ventricle[7]
- Glioma of third ventricle
- Hypophyseal hypertrophy in pregnancy[8]
- Intracranial vascular loop
- Meningioma
- Obstructive hydrocephalus
- Optic chiasmal syndrome
- Optic neuropathy
- Pituitary macroadenoma
- Prolactinoma
- Suprasellar tumors
- Traumatic chiasmal syndrome
Related Chapters
References
- ↑ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC510604/?pa
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/21158577
- ↑ http://www.neurology.org/content/24/12/1135.abstract
- ↑ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC512211/
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/12644764
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/2139057
- ↑ http://bjo.bmj.com/content/62/8/536.full.pdf
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/14082282