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Opt 7730 Chiasmal Syndrome, Neuro-ocular exam
Terms in this set (35)
Is the chiasm a common place for a brain tumor to form?
Yes! Roughly 25% of all brain tumors occur here.
What structures are typically beneath the optic chiasm?
Pituitary gland in 80% of people, tuberculum sellae (prefixed) in 9%, and dorsum sellae (postfixed) in 11%
Will a pituitary tumor compress the chiasm from the top or from the bottom?
From the bottom. This means that the fibers coming from the inferior retina, corresponding to the superior visual field, are most likely to be affected.
What are the three ways that vision loss typically presents in chiasmal syndrome?
1) Incidental: patient did not notice anything, found on screener.
2) Slow progressive VF or VA loss
3) Acute loss of vision (this is the most rare)
What is the typical presentation of chiasmal field loss?
Bitemporal, asymmetric, and incomplete. Note that if it is complete, it is less likely to be from a pituitary tumor.
What are some typical signs that are NOT usually caused by chiasmal syndrome?
+RAPD, blurred vision, color vision loss, pallor of the disc, dense inferior visual field loss
Besides field loss, what are some other signs of chiasmal syndrome?
Diplopia (from CN compression in cavernous sinus or hemi-field slide), HA, symptoms secondary to endocrine abnormalities, near vision complaints (post-fixational blindness caused by overlapping blind temporal fields)
When you see a bowtie band pattern of optic atrophy, what is likely the cause?
Chiasmal compression of crossing nasal fibers.
If you see a patient with suspected chiasmal syndrome, how should they be managed?
of brain with contrast. Referral to endocrinology when appropriate. These patients should have regular ophthalmic examination with careful visual field testing.
List the most common causes of chiasmal syndrome in order of most to least prevalent.
Pituitary adenoma (50-55%), Craniopharyngioma (20-25%), Meningioma (10%), Glioma (7%).
What is the typical age range for developing a pituitary adenoma?
What is pituitary apoplexy?
A rapid expansion of a tumor secondary to infarction or hemorrhage in the tumor.
What are the most common symptoms of pituitary apoplexy?
Severe HA, vomiting, double vision, loss of vision, significant disturbances of consciousness, hemiparesis, or oculomotor palsy.
What are the treatment options for pituitary ademoma?
Transsphenoidal Sx for nonfunctioning tumors.
Radiation therapy for recurrent or residual tumors.
Medical therapy for hypersecreting tumors.
What is a cranipharyngioma and how is it treated?
An expansion of squamous cells that are remnants of Rathke's pouch, which gives rise to the anterior pituitary during development. Typically occur within the first 2 decades of life but can occur into adulthood. Treatment is Sx, or radiation and partial excision.
How will the VF typically appear with a craniopharyngioma?
Will have a partial superior and a complete inferior temporal bilateral hemianopsia.
Describe the VF appearance with a suprasellar or parasellar meningioma.
Typically presents with a junctional scotoma. Can also cause Foster Kennedy syndrome (unilateral papilledema b/c of optic atrophy in one eye).
What are some non-tumor causes of chiasmal syndrome?
Aneurysm, infection, frontal head trauma, meningitis, sarcoidosis.
What are some good prognostic signs for visual recovery after chiasmal syndrome?
Normal looking optic nerves w/o atrophy, smaller tumor as causative agent, preserved RNFL on OCT.
What are some clinical tests we can use to measure afferent visual function?
Visual acuity, contrast sensitivity, color vision, Amsler grid, confrontations, photostress test, pupils, eyelid symmetry
List 3 kinds of charts that can be used to assess contrast sensitivity.
Pelli-Robson, Mars, and Ridgevue (iPad app)
What does Kollner's rule of acquired dyschromatopsia state?
Outer retina conditions will cause B/Y defects.
Inner retina, optic nerve, and visual pathway defects will cause R/G defects.
If an individual has an increased photostress recovery time in their right eye as compared to their left, is this more suggestive of macular disease or optic nerve disease?
Macular. Optic nerve disease is less likely to impair glare recovery time.
If a patient's anisocoria is greater in bright light than in dim light, what does this suggest?
Suggests a parasympathetic defect in the eye with the larger pupil.
If a patient's anisocoria is greater in dim light than in bright light, what does this suggest?
Suggests a sympathetic defect in the eye with the smaller pupil (potentially Horner's)
If a patient's anisocoria is the same in dim and bright light, what does this suggest?
Tht the anisocoria is physiologic.
If your patient has an RAPD, what locations could be the cause of the problem?
The optic nerve, the optic tract, or the retina. Note that severe amblyopia can also rarely cause an RAPD.
If your patient has a fixed left pupil, can you still perform a swinging flashlight test to look for an RAPD?
Yes! When performing the test, you would expect to see the normal right eye constrict with direct illumination. When swinging, if the right pupil does NOT remain the same size (i.e. gets larger and then constricts on each swing) there is also an APD in the fixed pupil eye.
Describing the number-plus grading system for APDs.
1+ : initial constriction, but early redilation
2+: no initial movement of the pupil, then dilation
3+: immediate redilation
4+: amaurotic pupil
Outline the neutral density filter grading scale for APDs and how they are measured using this method.
A ND filter is placed over the
, and the swinging flashlight test is performed with increasing density until RAPD goes away. G1: ND 0.4 G2: ND 0.7
G3: ND 1.1
G4: ND 2.0
If your patient has an RAPD, but does not have a reduction in VA, where do you expect the lesion might be?
Between the optic tract and the pretectal area.
When measuring LPS function, what is a normal change in upper lid position from downgaze to upgaze?
12mm or more. Less than this suggests that LPS function is reduced. Suspect Myasthenia gravis, myopathies, III palsy, or congenital ptosis.
What should you look for when assessing the function of CN VII?
Look for facial asymmetry, blink pattern, forehead wrinkling, lagophthalmos, and facial emotional response and response to command. Can also assess orbicularis strength by attempting to pull open a patient's eyes while they are trying to keep them closed.
What are three potential clinical tests of cerebellar function?
Romberg test, finger-nose-finger test, heel-to-shin test.
What is a positive Romberg test?
You ask the patient to stand with their feet together, eyes closed, and arms at their side. If they lose their balance this is a positive Romberg.
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