Neuro-ophthalmology Flashcards
Lesions anterior to the lateral geniculate body produce..
Impairment of vision with impaired pupil response
Homonymous hemianopia with sensory and cognitive deficits…where’s the lesion?
Parieto-temporal lesion
Isolated homonymous hemianopia…where’s the lesion?
Occipital lobe
Bitemporal hemaniopia that involves the upper quadrants first indicates compression of the optic chiasm from below…DDx?
Pituitary adenoma, nasopharyngeal carcinoma, sphenoid sinus mucocele
Bitemporal hemaniopia that involves the lower quadrants first indicates compression of the optic chiasm from above…DDx?
Craniopharyngioma, third ventricular tumor
Causes of incongruous homonymous hemianopia (one eye affected more than the other)
Compression lesion of the optic tract near the chiasm
The ‘incongruous’ defect occurs as a result of rotation of nasal and temporal fibers
Lesion producing inferior quandrananopia
Lesion of the optic radiation in parietal fibers
Lesion producing superior quandrantanopia
Lesion of the optic radiation in temporal fibers
Lesion producing homonymous hemianopia with macular involvement
Lesion involving the pole of the calcarine cortex
Adie’s pupil
Pupil constriction to both direct and consensual light is often absent but very slow pupillary constriction occurs with accommodation
When accommodation is relaxed, slow dilatation occurs
Diagnosis of Adie’s pupil
Pupillary response to pilocarpine (the tonic pupil will constrict)
Possible causes of Horner’s syndrome
Brain stem lesions (tumor [glioma], vascular lesion, syringobulbia), cervical cord lesions (tumor [glioma], syrignomyelia), lesions to anterior roots of C8 and T1 (tumor [neurofibroma], lower brachial plexus injury), cervical sympathetic chain lesion (Pancoast tumor), lesion of ICA (trauma, occlusion/dissection), or lesion of the middle fossa (tumor, granuloma)
Distinguishing peripheral and central lesions producing Horner’s syndrome (preganglionic lesions)
Cocaine acts at the adrenergic nerve endings and, by preventing adrenaline uptake, causes pupil dilatation when the lesion is preganglionic
Distinguishing peripheral and central lesions producing Horner’s syndrome (postganglionic lesions)
When the lesion is postganglionic, cocaine has little affect because there are no nerve endings on which the drug may act
Argyll-Robertson pupils
Small pupils, irregular in shape, which do not react to light but react to accommodation
Causes of Argyll-Robertson pupils
Syphilis or any midbrain lesion (neoplastic, vascular, inflammatory, demyelination)
Muscle action of superior rectus
Looks up and out
Muscle action of inferior rectus
Looks down and out
Muscle action of inferior oblique
Looks up and in
Muscle action of superior oblique
Looks down and in
Location of oculomotor nucleus
The oculomotor nucleus lies in the ventral periaqueductal grey matter at the level of the superior colliculus
Two nuclei within oculomotor nucleus
Perlia’s nucleus (parasympathetic) and Edinger-Westphal nucleus (parasympathetic)
Action of Perlia’s nucleus
Convergence and accommodation
Action of Edinger-Westphal nucleus
Pupil constriction
Course of CN III
On leaving the brainstem the nerve passes through the interpeduncular cistern close the the PCOM and runs toward the cavernous sinus
The nerve runs within the lateral wall of the cavernous sinus and then finally through the superior orbital fissure into the orbit
Once in the orbit, it divides into the superior and inferior branches
Location of trochlear nucleus
The nucleus lies in the midbrain at the level of the inferior colliculus, near the ventral periaqueductal grey matter
Course of CN IV
The nerve passes laterally and dorsally around the central grey matter and decussates in the dorsal aspect of the brainstem in close proximity to the anterior medullary velum of the cerebellum
Emerging from the brainstem the nerve passes laterally around the cerebral peduncle and pierces the dura to lie in the lateral wall of the cavernous sinus
Finally, it passes through the superior orbital fissure into the orbit
Findings of a CN IV lesion
Defective depression of the adducted eye
Patient complains of double vision when looking downwards
Head may tilt to the side opposite the weak SO
Function of frontal eye field
Origin of fast rapid eye movement - saccadic movement, either voluntary or reflex
Activation results in jerk deviation of the eyes to the opposite side
Function of occipital cortex eye field
Origin of slow following - pursuit movement
Activation results in slow movement of the eyes to the ipsilateral side
Conjugate gaze deviation that occurs during a seizure
Eyes deviate toward the affected limbs
Indicates an epileptic focus in the frontal lobe contralateral to the direction of eye deviation
Conjugate gaze deviation that accompanies a hemiparesis (e.g. stroke) with tonic deviation of the eyes away from the hemiparetic limb
Indicates a lesion in the frontal lobe ipsilateral to the direction of eye deviation
Conjugate gaze deviation that accompanies a hemiparesis (eg. stroke) with tonic deviation of the eyes towards the hemiparetic limb
Usually indicates a lesion in the pons contralateral to the direction of eye deviation and results from damage to the paramedian pontine reticular formation (PPRF)
Lesions that produce failure of upward or downward gaze
Lesions in the midbrain or pons
Disturbed downward gaze alone can occur when…
Periaqueductal (Sylvian aqueduct) lesions
Findings of Parinaud’s syndrome
Impaired upward eye movements in association with a dorsal midbrain lesion
Upward gaze and convergence are lost, the pupils may dilate and the response to light and accommodation is impaired
Webino syndrome
Bilateral INO
Midbrain lesion characterized by bilateral exotropia and loss of convergence
One and a half syndrome
Conjugate gaze palsy to one side and impaired adduction on looking to the other side
Lesion involves the PPRF or abducens nucleus and adjacent MLF on the side of the complete palsy
Ocular apraxia
Bilateral prefrontal motor cortex damage will result in loss of voluntary eye movement to command but yet the patient will have full ROM
Characteristics of Gradenigo’s syndrome
Forehead pain is accompanied by ipsilateral lateral rectus palsy and a Horner’s syndrome if sympathetic fibers are involved
Causes of Gradenigo’s syndrome
Lesions located at the petrous-temporal bone apex (osteitis or meningitis associated with otitis media)
Lesion producing unilateral involvement of the lower face, with near normal eye closure
Indicates a contralateral supranuclear lesion
Lesion producing unilateral involvement of the entire face with defective eye closure
Indicates an ipsilateral nuclear or infranuclear lesion
