What is a post Chiasmal lesion?
Posterior chiasmal syndrome, the lesions affecting the caudal fibres in chiasma produce paracentral bitemporal field defects. Homonymous hemianopia on the contralateral side may occur when posterior chiasmal lesions involve the optic tract. Lateral chiasmal lesions may produce binasal hemianopia.
What can cause quadrantanopia?
Etiology
- Stroke (ischemic or hemorrhagic)
- Tumor causing damage to the posterior visual pathways (intra-axial primary or metastatic)
- Aneurysm.
- Demyelinating disease.
- Trauma.
- Abscess.
- Arachnoid cyst.
What is Superotemporal defect?
As opposed to the defect described by Traquair, some authors have used the term to refer to an ipsilateral optic neuropathy with a contralateral superotemporal visual field defect. This superotemporal defect is caused by compression of the inferonasal fibers from the contralateral eye traveling in Wilbrand’s knee.
What causes optic chiasm lesion?
The usual suspects are pituitary adenomas, craniopharyngiomas, and meningiomas. Pituitary tumors are the most common cause of chiasmal syndromes. Visual field defects may be one of the first signs of non-functional pituitary tumor.
How do you get quadrantanopia?
A superior quadrantanopia results from an insult to the optic radiation inferiorly in the temporal lobe, resulting in a ‘pie in the sky’ type of visual field defect (Figure 1d), while an inferior quadrantanopia is caused by damage to the parietal lobe optic radiation (Figure 1e).
Can quadrantanopia be cured?
Any field loss present after this time may be permanent. You may however feel that your sight improves as you adapt to the defect over time. Visual field loss cannot be cured if it does not spontaneously recover.
What is pie on the floor defect?
Homonymous incongruous quadrantanopia (“pie in the floor”) defects localize post-chiasmally along the visual pathway and are generally found in the superior optic radiations of the parietal lobe. The more congruous the defects in the visual fields, the closer the lesions are located to the occipital lobe.
What is red desaturation?
The red desaturation test involves the patient monocularly comparing the intensity of a standard red color, such as the red cap of a medication bottle, to evaluate for subjective interocular differences in red color perception.
What type of imaging is best for the diagnosis of chiasmal lesions?
Magnetic resonance imaging is the best mode of neuroimaging for most chiasmal lesions and may also provide clues to the etiology of an isolated chiasmal syndrome. Hemianopsia / etiology Humans
What are common neoplasms that affect the chiasm?
Less common neoplasms that affect the chiasm include chordoma (a type of tumor that arises from the remnants of notochord cells that become sequestered during development), germinoma, endodermal sinus tumor, leukemia, Hodgkin’s and non-Hodgkin’s lymphoma, nasopharyngeal carcinoma, and metastatic carcinomas.
What are intrinsic and extrinsic chiasmal lesions?
Summary: Most chiasmal syndromes can be categorized as intrinsic (thickening of the chiasm itself) or extrinsic (compression of the chiasm from an adjacent structure). Magnetic resonance imaging is the best mode of neuroimaging for most chiasmal lesions and may also provide clues to the etiology of an isolated chiasmal syndrome.
What is a benign kidney lesion on a CT scan?
If a kidney lesion is a solid mass, particularly one that picks up blood and thus “enhances” on contrast CT, it is considered malignant until proven otherwise. In the era of CT scan however, masses are found at a much smaller size than ever before. Now, if a mass is small, less than 2 cm, up to 20-25% of such lesions may be benign.