Neuro-opthalmology Flashcards
What are the five most important things to test for ophthalmic exam?
- Measure visual acuity
- Examine pupillary reactions
- Test the function of EOM
- Evaluate the visual fields
- Inspect the optic nerve head
____% of sensory fibers in brain are from the optic nerves
_____% of intracranial disease has ophthalmic manifestations (demonstrate neuro-ophthalmic signs or symptoms)
- 35
- 65
Causes of dilated pupils (3)
- Efferent defect
- Trauma
- Third nerve with aneurysm (dilated &fixed)
Adie’s Pupil aka Tonic Pupil presentation
- Larger than normal with vermiform movement (worm-like)
- Decrease patellar reflexes
(typically young women)
What is the pathway for a pupillary reflex?
Optic nerve → optic chiasm → pretechtal nucleus → Edinger Westphal nucleus (both sides receive input, sits on CN 3 nucleus) → pre-gangliononic parasympathetic fibers travels w/the third cranial nerve→ciliary ganglion→post-ganglionic parasympathetic fibers from short ciliary n. innervate constrictor pupillae muscles.
_____ defect causes of efferent pupillary defect
CN III (parasympathetic)
Causes of afferent defect
- Optic nerve (CN II)
- Retinal detachment or defect
- Macular Degeneration
(abnormal eye will dilate when light is shown in it during swinging flashlight test)
How do you differentiate between afferent and efferent defect with a penlight?
- Afferent: Abnormal eye will dilate when light is shown in it during swinging flashlight test (they perceive less light, so it dilates)
- Efferent: pupil is fixed and dilated with and w/o light shown into it
(TQ!!!)
Pathway of the sympathetic nervous system to the eye
Patient presents with ptosis, elevated lower eyelid, miosis in the right eye and pain near her right clavicle. Dx? Special test?
- small cell carinoma in apex of lung (disrupting the SNS) → Horner’s
(confirm by dragging metal spoon across forehead (moves faster over the affected side bc there is no sweat there))
3rd Nerve Palsy symptoms (4)
- horizontal and vertical diplopia
- severe ptosis (controls lateral palpebral m.)
- Inability to move the eye inwards, upwards, or downward
- Dilated fixed pupil - emergency (possible stroke; aneurysm of posterior communicating artery)
Causes of 3rd nerve palsy (5)
- Intracranial aneurysm
- Microvascular infarct of the nerve
- Trauma
- Brain tumor
- Cerebral herniation
(3rd nerve palsy and fixed pupil on one side is an intracranial aneurysm until proven otherwise→refer to stroke center)
4th Nerve Palsy symptoms (3)
- Paralysis of the superior oblique muscle
- Vertical diplopia that causes issues w/ downgaze and contralateral side gaze
- Head tilt toward opposite shoulder to reduce diplopia (reduces vertical diplopia)
(SO4 = superior oblique = shoulder opposite)
Causes of 4th nerve palsy
(allows for down & in eye movement)
- Closed head trauma
- Caused by microvascular disease
- common congenital abnormalities
(CN IV is the only nerve that comes out posteriorly & has the longest run to its target. most sensitive to head trauma)
6th Nerve Palsy symptoms (3)
- loss of abduction
- horizontal diplopia
- They will turn their head the opposite direction to eliminate diplopia
(esotrophia in straight position)
Causes of 6th nerve palsy
Tumor is possible, but microvascular disease is the most common reason
(Should relieve in 3-4 months)
Symptoms of a pupil-sparring 3rd nerve palsy (2)?
- ptosis
- cannot adduct or depress eye
Internuclear ophthalmoplegia
Lesions of the MLF (medial longitudinal fasciculus) that cause connections between motor nuclei to be destructed
What is the function of the medial longitudinal fasciculus in regard to eye function?
Is a tract of internuclear neurons within the brain stem which carries output from the sixth nerve nuclei to the contralateral third nerve nuclei to coordinate horizontal eye movements
Internuclear ophthalmoplegia symptoms
- Slow or weak adduction of one eye
- Nystagmus of the abducting fellow eye and lateral gaze
(when they look left, the right eye can’t move past midline )
Causes of internuclear ophthalmoplegia (4)
- Demyelinating disease
- Microvascular disease in the brain stem
- Hemorrhage
- Trauma
(when they look left, the right eye can’t move past midline )
MRI should be done to find the lesion in internuclear ophthalmoplegia. What else should be suspected?
myasthenia gravis of eyes: present w/slurred speech
(much worse after hot shower. Tensilon test)
Causes of nystagmus (upbeat or downbeat) that are benign (4)
(rythmic to-and-fro movements of the eye)
- Medication (upbeating)
- Tumor (downbeating)
- Congenital
- Extreme lateral gaze (end-point)
Causes of nystagmus that may be malignant: dysfunction of ________ (3)
- Vestibular
- cerebellar
- brainstem