Neuro Flashcards
___-flow, ___ fistulas most commonly occur after severe head trauma and produce a cranial bruit.
High-flow, direct fistulas most commonly occur after severe head trauma and produce a cranial bruit.
Genetic mutation associated with oculopharyngeal muscular dystrophy
PABPN1
In general, damage to a ___ (medial or lateral) region of the brainstem disrupts the ___ (sensory or motor) pathways.
In general, damage to a lateral region of the brainstem disrupts the sensory pathways.
Therefore, Wallenberg syndrome is a type of “stroke without paralysis.”
Wallenberg syndrome
Lateral medullary infarct
Occlusion of the posterior inferior cerebellar artery or proximal vertebral artery
**Ipsilateral loss of facial P/T (descending tract of CN V)
**Contralateral loss of hemibody P/T (lateral spinothalamic tract)
- Ipsilateral cerebellar ataxia (spinocerebellar tracts)
- Ipsilateral first-order Horner syndrome (descending hypothalamic tracts)
- Ipsilateral ocular tilt reaction (head tilt toward the side of the lesion)
Also:
- Ipsilateral hearing loss (cochlear nuclei)
- Vertigo, nystagmus (vestibular nuclei)
- Dysphagia, dysarthria, dysphonia (nucleus ambiguus)
- Hiccups!
Weber syndrome
“Weak Weber”
Ipsilateral CNIII palsy
+
contralateral hemiparesis (damage to the ventral midbrain and the cerebral peduncle)
Benedikt syndrome
Ipsilateral CNIII palsy
+
contralateral ataxia or tremor (involvement of the red nucleus and substantia nigra)
Claude syndrome
Ipsilateral CNIII palsy
+
contralateral ataxia (damage to the dorsal midbrain may involve the superior cerebellar peduncle)
Nothnagel syndrome
Ipsilateral CNIII palsy (nuclear lesion)
+
contralateral ataxia, supranuclear eye movement dysfunction
(Dorsal lesion with a slightly different configuration)
Causes of skew deviation
Demyelinating lesion (young) Stroke (old)
Locations of multiple simultaneous cranial nerve palsies (4)
Orbital apex (II, III, IV, V, VI) Brainstem, e.g. midbrain (III, IV) Cavernous sinus (III, IV, V1-2, VI) Cerebellopontine angle (V, VI, VII, VIII)
The ___ system holds the image of an object on the fovea during brief head movement. The ___ system holds the image of an object on the fovea during sustained head movement.
The vestibular-ocular system holds the image of an object on the fovea during brief head movement. The optokinetic system holds the image of an object on the fovea during sustained head movement.
Anisocoria greater in light than dark
Dilated pupil = 3rd nerve palsy, Adie tonic pupil, pharmacologic dilation
Anisocoria greater in dark than light
Miosed pupil = Horner’s syndrome
Unilateral painful ophthalmoparesis without a change in visual function or orbital signs such as proptosis is most likely to occur from a ___ ___ process.
Unilateral painful ophthalmoparesis without a change in visual function or orbital signs such as proptosis is most likely to occur from a cavernous sinus process.
Differential for light-near dissociation / tonic pupil (5)
Neurosyphilis, diabetes, dorsal midbrain syndrome, chronic alcoholism, and dysautonomias, Adie tonic pupil
VF defects respecting midline correlate with lesions ___ (anterior or posterior) to the chiasm.
VF defects respecting midline correlate with lesions posterior to the chiasm.
What kind of MRI is helpful in patients with acute stroke?
Diffusion-weighted imaging (usually T1, better for anatomy)
What kind of MRI is helpful in patients with optic neuropathy?
MRI with fat suppression
How do you distinguish between autoimmune or paraneoplastic retinopathy, and optic neuropathy by history?
Presence of photopsias and nyctalopia
What kind of MRI is helpful in patients with suspected demyelinating disease?
FLAIR (always T2-weighted): attenuates bright CSF signal, which obscures periventricular white matter lesions
The ___ ___ ___ of the MLF and the ___ ___ of Cajal are located in the ___ and are involved in the generation of torsional and vertical saccades.
The rostral interstitial nucleus of the MLF and the interstitial nucleus of Cajal are located in the midbrain and are involved in the generation of torsional and vertical saccades.
The excitatory burst neurons for generating horizontal saccades are located in the ___ ___ ___ ___.
The excitatory burst neurons for generating horizontal saccades are located in the paramedian pontine reticular formation.
What are atypical features of optic neuritis that should prompt further work-up? (7)
Older age, lack of pain, peripapillary hemorrhages, ocular inflammation (uveitis or choroiditis), retinal changes, involvement of other cranial nerves, and lack of any improvement in vision after 1 month
How does a nuclear versus infranuclear CN III palsy present?
Nuclear: unilateral or bilateral ptosis, contralateral superior rectus palsy
Infranuclear: unilateral ptosis, ipsilateral superior rectus palsy
Slowly progressive facial palsies strongly suggest the diagnosis of a ___ ___.
Slowly progressive facial palsies strongly suggest the diagnosis of a brainstem mass.
Localize the lesion: CN IV palsy with RAPD
Brainstem contralateral to RAPD (more fibers cross) near CN IV nucleus and superior colliculus
RAPD is NOT associated with color vision or VF defects, unlike in optic neuropathy
What horizontal movement is preserved in one-and-a-half syndrome?
Contralateral ABduction
lesion of ipsilateral MLF and PPRF -> loss of all ipsilateral horizontal eye movement, loss of contralateral ADduction
Where do optociliary shunts come from?
Dilation of pre-existing venous shunts between the retina and choroid (because normal venous flow is obstructed)
Localize the lesion: complex, formed hallucinations, e.g. olfactory or gustatory, in the ipsilateral or contralateral visual field
Temporal lobe
Localize the lesion: formed, often constant, hallucinations associated with inverted sleep-wake cycle
Midbrain
Localize the lesion: palinopsia (persistent afterimages) that can be associated with visual hallucinations
Nondominant parieto-occipital area
Localize the lesion: unformed hallucinations, sometimes described as geometric colors or patterns
Occipital lobe
Tests that can demonstrate 20/20 vision in functional vision loss (4)
Fogging test: trial frame with plus and minus cyl over good eye, rotate while patient reading
Vertical prism dissociation test: 4PD lens placed base-down in front of “good eye” If subject has symmetric vision, 2 vertically displaced images should be seen. If able to read both images, proves normal acuity.
Duochrome test: read duochrome Snellen chart through W4D glasses
Polarized lens test: read Snellen chart through polarized filters
Tests that can demonstrate gross vision in functional vision loss (3)
Mirror test: eyes follow reflection when large mirror rotated in front of patient
OKN drum: nystagmus elicited
Base-out prism test: eye moves when place prism over “bad eye”
**Finger touching is NOT affected by vision loss! Requires proprioception, not vision
Goldmann kinetic perimetry tests the outer edge of peripheral vision: temporally to ___ degrees; superiorly, inferiorly, and nasally to ___ degrees.
Goldmann kinetic perimetry tests the outer edge of peripheral vision: temporally to 90 degrees; superiorly, inferiorly, and nasally to 60 degrees.
The anterior occipital lobe subserves the ___ ___visual field of the ___ eye.
The anterior occipital lobe subserves the far temporal visual field of the contralateral eye.
Triad of spasmus nutans
“Shimmering” nystagmus, head bobbing, torticollis
When suspecting spasmus nutans, what should be included in work-up?
Neuroimaging to exclude glioma of anterior visual pathway, parasellar or hypothalamic tumors
Transient bilateral vision loss with vertigo in an older patient should be worked up for ___ ___.
Transient bilateral vision loss with vertigo in an older patient should be worked up for vertebrobasilar insufficiency.
What is Charles Bonnet syndrome?
Severe visual impairment, e.g. advanced glaucoma, leads to hallucinations. Patients are aware the hallucinations are not real.
What is the Uhthoff phenomenon?
Worsening of vision in MS patients with history of optic neuritis when their bodies become overheated
What is Anton-Babinski syndrome?
Patients who are cortically blind do not recognize their vision loss
What occurs in aberrant regeneration of CN III? Give 2 examples.
Aberrant regeneration of CN III occurs after damage results in regrowth and misrouting of fibers with innervation of muscles not normally activated together.
Examples: eyelid retraction or pupillary miosis with supraduction, adduction, or infraduction
In what etiologies of CN III damage is aberrant regeneration seen and not seen?
Seen: trauma, compressive lesion (parasellar lesion, e.g. meningioma or carotid aneurysm within cavernous sinus), malignancy
Not seen: ischemic or microvascular (if aberrant regeneration develops in presumed ischemic CN III palsy, scan urgently!)
Transient vision loss with eye pain that improves after lying down, dimming of vision in bright light with slow improvement after going indoors
Ocular ischemic syndrome
Difference between CN VI nuclear lesion and peripheral CN VI palsy
Nucleus lesion: horizontal gaze palsy (also affects interneurons that travel to MLF)
Peripheral lesion: isolated abduction deficit
Why do supranuclear disorders usually not cause diplopia? What are the exceptions (5)?
Most supranuclear disorders affect both eyes equally and therefore do not cause diplopia.
Supranuclear lesions with asymmetric effect:
(1) Convergence insufficiency or spasm
(2) Divergence insuffciency
(3) Ocular tilt reaction
(4) Skew deviation
(5) Thalamic esodeviation
Pupil constriction in a dark room (paradoxical pupils) is a clinical sign of ____ ____.
Pupil constriction in a dark room (paradoxical pupils) is a clinical sign of congenital and/or inherited retinal dystrophies (eg, congenital stationary night blindness).
When compression from pineal gland tumors damages the ___ (dorsal or ventral) midbrain, the parasympathetic ___ (light or near) reflex pathway is disrupted, and the pupil does not constrict to light. In contrast, the fibers in the ___ (light or near) reflex pathway approach the pretectal nucleus from the ___ (dorsal or ventral) aspect of the midbrain.
When compression from pineal gland tumors damages the dorsal midbrain, the parasympathetic light reflex pathway is disrupted, and the pupil does not constrict to light. In contrast, the fibers in the near reflex pathway approach the pretectal nucleus from the ventral aspect of the midbrain.
Therefore, in dorsal midbrain syndrome, near reflex is preserved!
What kind of VF defects are created by toxic etiologies or nutritional deficiencies, e.g. vitamin B12?
Central or cecocentral scotomas
High-flow C-C fistulas are characterized as direct, between the ___ ____ ____ and the ___ ___, or indirect, involving connections mediated by small arterial feeders off the ___ or ___ ___.
High-flow C-C fistulas are characterized as direct, between the internal carotid artery and the cavernous sinus, or indirect, involving connections mediated by small arterial feeders off the internal or external carotids.
What type of (1) CT and (2) MRI should be used to identify C-C fistula?
(1) Axial CT orbits with contrast
(2) Axial T1-weighted MRI orbits, both with and without gadolinium
Look for enlarged, dilated superior ophthalmic vein
Within the cavernous sinus, sympathetic fibers destined for the dilator muscles leave the carotid in conjunction with CN ___ posteriorly. Further anteriorly, the fibers join CN ___.
Within the cavernous sinus, sympathetic fibers destined for the dilator muscles leave the carotid in conjunction with CN VI posteriorly. Further anteriorly, the fibers join CN V1 (nasociliary branch).
The ___ ___ pathway is the “where pathway”; it is responsible for visuospatial analysis, localization of objects, and visually directed movements toward objects.
The dorsal occipitoparietal pathway is the “where pathway”; it is responsible for visuospatial analysis, localization of objects, and visually directed movements toward objects.
___ syndrome results from bilateral occipitoparietal lesions and consists of the triad of ___, ___ ___, and ___ ___ ___.
Balint syndrome results from bilateral occipitoparietal lesions and consists of the triad of simultanagnosia, optic ataxia, and ocular motor apraxia.
The ___ ___ pathway is the “what pathway”; it is responsible for color, shape, and pattern recognition. Lesions of this pathway cause ____ ___ and ___ ___ visual field defects.
The ventral occipitotemporal pathway is the “what pathway”; it is responsible for color, shape, and pattern recognition. Lesions of this pathway cause object agnosia (e.g. prosopagnosia) and superior homonymous visual field defects.
Lesions of the optic tract cause complete or incomplete ___ ___.
Lesions of the optic tract cause complete or incomplete homonymous hemianopia.
Calcified plaques are typically caused by ___ ___ or ___ calcification.
Calcified plaques are typically caused by heart valve or aorta calcification.
___ ___ typically predisposes patients to Hollenhorst plaques. ___ ___ ___ can lead to Hollenhorst plaques or platelet-fibrin plaques.
Carotid stenosis typically predisposes patients to Hollenhorst plaques. Aortic arch atheroma can lead to Hollenhorst plaques or platelet-fibrin plaques.
What is the pathogenesis of hemifacial spasm? (3)
Most common: compression of the seventh nerve root exit zone by an aberrant vessel
Less common: CPA tumors, previous CN VII injury
What condition should be considered in a patient with altered mental status and a hemianopic visual field defect?
Progressive multifocal leukoencephalopathy
What treatment for MS patients has been associated with progressive multifocal leukoencephalopathy?
Natalizumab (PML occurs in patients who are JC-virus positive)
What ocular motility issues can occur in Whipple disease? (2)
Oculomasticatory myorhythmia: mastication causes ocular oscillation
Vertical saccadic deficiencies
What ocular motility issues can occur with midbrain degeneration? (2)
Progressive supranuclear palsy
Vertical gaze deficiencies
What ocular motility issue can occur with chronic alcoholism?
Ophthalmoparesis (Wernicke encephalopathy)
What do the “decibels” mean in automated static perimetry?
Decibels indicate a logarithmic scale of intensity, measuring attenuation from the maximum stimulus of the perimeter. For example, a 35 dB stimulus is 10 times dimmer than a 25 dB stimulus.
How do you perform a photostress recovery test? How do you interpret the findings?
The patient gazes into a light held 2-3 cm from the eye for 10 seconds. Immediately after the light is removed, the patient attempts to read the next largest VA line above the previously measured corrected VA.
Normal photostress recovery time is <30 seconds. Patients with optic neuropathy have normal photostress recovery times. Patients with maculopathy or severe carotid artery stenosis have prolonged recovery times (≥ 90-180 seconds).
What is ocular neuromyotonia? In what clinical setting is this observed?
Episodic diplopia lasting 30–60 seconds after sustained activation of a cranial ocular motor nerve (e.g. transient RXT after maintaining eyes in extreme right gaze)
Associated with a history of radiation therapy for a skull-based neoplasm
How do bilateral fourth nerve palsies present?
(1) ___ hypertropia
(2) Excyclotorsion of __ degrees
(3) Large (≥__ prism diopters) __ pattern strabismus
(4) Habitual ___ ___ position
(1) Crossed hypertropia (ie, the right eye is higher on left gaze, and the left eye is higher on right gaze)
(2) Excyclotorsion of 10 degrees or greater
(3) Large (≥25 prism diopters) V pattern strabismus (ET)
(4) Habitual chin down position (due to V-pattern ET being worse with chin up)
Most common location of lesion causing downbeat nystagmus? And what is the most common lesion?
Cervicomedullary junction (lesions cause defects in holding vertical gaze)
Arnold-Chiari I malformation
What is ocular tilt reaction?
Combination of skew deviation with binocular torsion, torticollis, and a subjective vertical tilt
Adie tonic pupil, when associated with decreased ___ ___ ___, is called ___-Adie syndrome.
Adie tonic pupil, when associated with decreased deep tendon reflexes, is called Holmes-Adie syndrome.
Ocular motor apraxia is characterized by increased ___ and intermittent failure of ___ ___ initiation. ___ eye movements are normal.
Ocular motor apraxia is characterized by increased latency and intermittent failure of horizontal saccadic initiation. Vertical eye movements are normal.
Saccadic eye movements are generated by the ___ eye fields. Each frontal eye field initiates saccades to the ___ side. Smooth pursuit eye movements are generated by the ___ lobe, and each area generates smooth pursuit eye movements to the ___ side.
Saccadic eye movements are generated by the frontal eye fields. Each frontal eye field initiates saccades to the contralateral side. Smooth pursuit eye movements are generated by the parietal lobe, and each area generates smooth pursuit eye movements to the ipsilateral side.
The cardinal sign of a unilateral INO is slowed ___ ___ velocity in one eye, usually associated with ___ ___ in the fellow eye. The INO is named for the side with ___ ___.
The cardinal sign of a unilateral INO is slowed adducting saccadic velocity in one eye, usually associated with abducting nystagmus in the fellow eye. The INO is named for the side with slowed adduction (i.e., a right INO refers to slowed adduction of the right eye secondary to a MLF lesion on the right side of the brainstem).
What is the most common hereditary optic neuropathy? What is the causative gene, and how is it inherited?
Dominant optic atrophy
OPA1 gene, most commonly on chromosome 3
Autosomal dominant
What clinical feature best distinguishes a parietal lobe lesion from an occipital lobe lesion?
Abnormal OKN response with parietal lobe lesion (initiation of pursuit affected)
Differential for extremely small pupils (3)
Pontine hemorrhage, narcotic intoxication, pilocarpine use
___ intraocular pressures can lead to larger pupils.
Elevated intraocular pressures can lead to larger pupils.
Management of IIH unresponsive to medical therapy with progressive vision loss
Surgical intervention is warranted:
If HA is significant, VP shunt
If a patient did not have HA, optic nerve sheath fenestration
What is the phenomenon of visual snow, and who gets it?
Visual snow is also often seen in patients with migraine and is described as snowy, pixelated vision, similar to television static
___ ___ may occur in Guillain-Barré syndrome, especially in the variant known as Miller Fisher syndrome when ___, ___, and ___ are also present.
Facial diplegia may occur in Guillain-Barré syndrome, especially in the variant known as Miller Fisher syndrome when ophthalmoplegia, ataxia, and areflexia are also present.
Clinically what distinguishes first/second order from third order Horner syndrome?
First/second order: anhidrosis of the ipsilateral head, face, and neck
Third order: anhidrosis limited to the ipsilateral forehead (lesion at or distal to the superior cervical ganglion)
Medications that can cause, unmask, or worsen myasthenia gravis (10)
Antiarrhythmics, statins, antibiotics, chemotherapeutic drugs, antiepileptic drugs, quinolones, penicillamine, corticosteroids, beta-blockers, calcium channel blockers
Patients with an optic tract lesion develop a contralateral ___ ___ and contralateral ___.
Patients with an optic tract lesion develop a contralateral homonymous hemianopia and contralateral RAPD.
Paradoxical inversion of the optokinetic nystagmus (OKN) response is associated with ___ ___ ___. (E.g. Right-jerk nystagmus worsens with OKN drum to the ___)
Also associated with pattern in which the velocity of ___-phase movement ___ exponentially with distance from fixation
Paradoxical inversion of the optokinetic nystagmus (OKN) response is associated with infantile or congenital motor nystagmus (E.g. Right-jerk nystagmus worsens with OKN drum to the left)
Also associated with pattern in which the velocity of slow-phase movement increases exponentially with distance from fixation
What test is the most sensitive means of detecting abnormal visual function in a patient with papilledema?
Visual field testing
Acquired cases of prosopagnosia typically result from stroke affecting what region(s) of the brain? (2)
Bilateral inferior occipitotemporal lobes (ventral occipitotemporal pathway, aka WHAT pathway) or right inferior occipital lobe
Gaze-evoked nystagmus with rebound nystagmus in primary gaze is frequently due to ___ disease.
Gaze-evoked nystagmus with rebound nystagmus in primary gaze is frequently due to cerebellar disease.
Gaze preference is an acute inability to produce gaze ___ to the side of a cerebral (supranuclear) lesion.
Gaze preference is an acute inability to produce gaze contralateral to the side of a cerebral (supranuclear) lesion
The ___ optic nerve is most sensitive to trauma and sinus surgery.
The intracanalicular optic nerve is most sensitive to trauma and sinus surgery.
Facial myokymia is usually the result of a ___ ___ or ___.
Facial myokymia is usually the result of a pontine glioma or demyelination. It is characterized by continuous unilateral contraction of facial muscle bundles and typically signifies intramedullary disease of the pons involving the CN VII nucleus or fascicle.
Damage to area __ within the lingual and fusiform gyrus is probably responsible for most cases of cerebral achromatopsia.
Damage to area V4 within the lingual and fusiform gyrus is probably responsible for most cases of cerebral achromatopsia.
Functional neuroimaging suggests that benign essential blepharospasm occurs due to dysfunction of the ___ ___.
Functional neuroimaging suggests that benign essential blepharospasm occurs due to dysfunction of the basal ganglia.
What other names does the primary visual cortex go by? (2)
Striate cortex, Brodmann area 17
Area __, which lies primarily in the posterior parietal lobe, receives direct input from V1 and is involved in visual integration.
Area V3, which lies primarily in the posterior parietal lobe, receives direct input from V1 and is involved in visual integration.
Area __, within the medial temporal region, holds neurons that encode the speed and direction of moving stimuli. This sensory area is likely the origin of pursuit movements and thus connects the afferent and efferent pathways.
Area V5, within the medial temporal region, holds neurons that encode the speed and direction of moving stimuli. This sensory area is likely the origin of pursuit movements and thus connects the afferent and efferent pathways.
Sensory nystagmus is associated with conditions that cause bilateral ___ vision loss in children younger than 2 years. In the absence of obvious ocular causes such as cataract, the patient should be evaluated for ___ ___, ___ ___, and ___ ___.
Sensory nystagmus is associated with conditions that cause bilateral pregeniculate vision loss in children younger than 2 years. In the absence of obvious ocular causes such as cataract, the patient should be evaluated for optic neuropathy, foveal hypoplasia, and retinal dystrophy.
Divergence insufficiency results from involution of the connective tissue band between the ___ and ___ rectus muscles. This causes ___ displacement of the ___ rectus muscles, i.e. ___ ___ ___.
Divergence insufficiency results from involution of the connective tissue band between the superior and lateral rectus muscles. This causes inferior displacement of the lateral rectus muscles, i.e. sagging eye syndrome -> esotropia, difficulty with upgaze.
Sequelae of optic disc drusen:
- ___ ___ vision loss
- Peripapillary ___
- ___ optic neuropathy
- Retinal ___ ___
Sequelae of optic disc drusen:
- Transient monocular vision loss (similar to papilledema)
- Peripapillary hemorrhages
- Ischemic optic neuropathy
- Retinal vascular occlusions
Classic presentation of NAION: ___ disc edema with ___ altitudinal visual field defects and peripapillary ___
Classic presentation of NAION: superior disc edema with inferior altitudinal visual field defects and peripapillary hemorrhages
Alexia without agraphia (patient cannot read but can write) results from damage to the ___ ___ and the ___ ___ ___.
Alexia without agraphia (patient cannot read but can write) results from damage to the corpus callosum and the left occipital lobe.
Findings in Parinaud syndrome (7)
- Upgaze palsy
- Convergence-retraction nystagmus on attempted upgaze
- Mid-dilated pupils with light-near dissociation
- Eyelid retraction
- Skew deviation
- Disruption of convergence
- Increased square-wave jerks
Pituitary apoplexy is acute ___/___ of the pituitary gland, and presents with severe headache, nausea, altered consciousness, and diplopia, decreased visual acuity, or visual field loss. Sudden expansion into the cavernous sinuses may cause dysfunction of CN III-VI.
Pituitary apoplexy is acute haemorrhage/infarct of the pituitary gland, and presents with severe headache, nausea, altered consciousness, and diplopia, decreased visual acuity, or visual field loss. Sudden expansion into the cavernous sinuses may cause dysfunction of CN III-VI.
Adie tonic pupil results from damage to either the __ ___ or the ipsilateral __ ___.
Adie tonic pupil results from damage to either the iris sphincter or the ipsilateral ciliary ganglion. (Inability to constrict to light results in dilated pupil)
An abducens nucleus lesion causes an ___ ___ gaze palsy, and often ___ ___ weakness.
An abducens nucleus lesion causes an ipsilateral horizontal gaze palsy (contains neurons that both innervate ipsilateral lateral rectus and travel to MLF), and often ipsilateral facial weakness (involvement of CNVII that wraps around abducens nucleus).
The lacrimal pump is driven by the ___ ___ muscle, which is innervated by the ___ ___.
The lacrimal pump is driven by the orbicularis oculi muscle, which is innervated by the facial nerve.
Most characteristic ocular finding of Takayasu arteritis
Retinal arteriovenous anastomoses, best seen on FA
Can have microaneurysms, peripheral nonperfusion, retinal NV, VH, OIS, optic atrophy
Systemic sequelae of Takayasu arteritis (4)
Large-vessel granulomatous inflammation -> ischemic stroke, carotid and vertebral artery stenosis, systemic hypertension, diminished radial pulses
Of the 3 motor cranial nerves, the ___ is the most robust and has the most direct route from the brainstem to the orbit. It is therefore least likely to be injured in a noncontact trauma. Traumatic CN ___ paresis or palsy typically requires severe head trauma and is usually associated with basal skull fractures and intracranial bleeding.
Of the 3 motor cranial nerves, the oculomotor is the most robust and has the most direct route from the brainstem to the orbit. It is therefore least likely to be injured in a noncontact trauma. Traumatic CN III paresis or palsy typically requires severe head trauma and is usually associated with basal skull fractures and intracranial bleeding.
Causes of opsoclonus (6)
- Paraneoplastic syndromes (neuroblastoma in children; small-cell lung, breast, and ovarian cancer in adults)
- Encephalitis
- Drug intoxication
- Multiple sclerosis
- Environmental toxins
- Hyperosmolar coma
Reversible cerebral vasoconstriction syndrome
Middle-aged women with severe recurrent headaches +/- focal neurologic deficits, seizures, constriction of cerebral arteries that resolve within 3 months
Half occur during postpartum period or exposure to vasoactive substances, e.g. SSRIs
MRA may show “string-of-beads” appearance of cerebral arteries
Poor visual prognosis in IIH is associated with ___ gender, ___ ___ race, ___ ___, anemia, and severe papilledema.
Poor visual prognosis in IIH is associated with male gender, African American race, morbid obesity, anemia, and severe papilledema.
How does dominant optic atrophy present? What is its most characteristic optic nerve finding?
Presents before age 10 with VA 20/40 to 20/100, central/cecocentral scotoma, blue dyschromatopsia/tritanopia
Most characteristic: Wedge-shaped optic nerve pallor
Most common visual field defect associated with cancer-associated retinopathy
Ring scotoma
Electrophysiology differences between retinopathy and optic neuropathy
Retinopathy: abnormal ERG AND VEP
Optic neuropathy: normal ERG, abnormal VEP
Optic neuritis is a presenting symptom in __% of MS patients. __% of patients with optic neuritis develop clinically definite MS over the next 15 years.
Optic neuritis is a presenting symptom in 25% of MS patients. 50% of patients with optic neuritis develop clinically definite MS over the next 15 years (25% of those without MRI lesions, 75% of those with lesions).
Most specific serum test for GCA
CRP
__% of optic neuritis is retrobulbar, remaining __% is anterior papillitis.
65% of optic neuritis is retrobulbar, remaining 35% is anterior papillitis.
Presentation and examples (3) of trigeminal autonomic cephalgias
Unilateral headache, eye redness, tearing; may have autonomic dysfunction, Horner syndrome-like findings (1-2mm ptosis, miosis)
E.g. cluster headache, paroxysmal hemicrania, SUNCT (short unilateral neuralgiform HA with conjunctival injection and tearing)
Presentation and MRI findings of posterior reversible encephalopathy syndrome
Headache, altered mental status, seizures, visual disturbances (TVO, scotomata, photopsias, dimming of vision)
MRI shows edema (hyperintense on T2) of white matter of posterior cerebral areas, especially parieto-occipital lobes
Presentation and surgical correction for heavy eye syndrome
Presents in patients with high myopia -> superotemporal prolapse of posterior globe, which displaces superior rectus medially and lateral rectus inferiorly
Correct with bilateral loop myopexy between superior and lateral rectus muscles
Branch of posterior cerebral artery that supplies primary visual cortex
Calcarine branch
What causes crocodile tears?
Aberrant facial nerve regeneration (fibres originally supplying mandibular and sublingual glands reinnervate lacrimal gland)
Pulfrich phenomenon
Illusion that object is moving in elliptical path rather than straight line; occurs in patients with demyelinating optic neuritis
Riddoch phenomenon
Patient with cortical blindness can see moving objects, but not static objects
Distinguish between illusory and hallucinatory palinopsia (environmental triggers, location of image relative to stimuli, causes)
Illusory: afterimage triggered by contrast and/or motion, appears in same location as stimulus; caused by migraine, drugs, and some medications
Hallucinatory: no triggers, appear in different location from stimulus; associated with homonymous visual field loss because caused by cortical lesions
What cause of anisocoria is not affected by full strength pilocarpine 1% or more?
Pharmacologic (CN III palsy and Adie pupil will constrict with pilocarpine)
Most common cancer associated with cancer-associated retinopathy
Small cell lung carcinoma
Large-vessel vasculitis
Giant cell arteritis, Takayasu arteritis
Medium-vessel vasculitis
Polyarteritis nodosa, Kawasaki disease
Small-vessel vasculitis
Granulomatosis with polyangiitis
Vasculitis of all vessels
Behcet disease
Acute onset bilateral papilledema + dorsal midbrain syndrome points to pathology from?
Cerebral aqueduct stenosis (mass or hydrocephalus compressing dorsal midbrain at level of pineal gland)
Etiologies of dorsal midbrain syndrome
Compression of posterior commissure at level of pineal gland (mass, hydrocephalus, cerebral aqueduct stenosis), occlusion of vertebrobasilar artery that supplies pretectum, haemorrhage, infarction, demyelination, inflammation, infection, trauma
VEP testing abnormalities in patients with history of optic neuritis/demyelinating disease
Delayed P100 latency
Subacute or long-standing ___ ___ may lead to sound-induced photisms (sensations of color or light induced by loud noise).
Subacute or long-standing optic neuropathy may lead to sound-induced photisms (sensations of color or light induced by loud noise) due to discharges from the lateral geniculate nucleus.
How does ischemic CN III palsy present differently from compressive?
Ischemia causes pain but minimal pupil involvement because not compressive
Foville syndrome
- Lesions of dorsal pons -> CN VI fascicles injure CN VII fascicles, tractus solitarius, descending tract of CN V
- CN V, VI, VII without body weakness
Millard-Gubler syndrome
- Lesions of ventral pons -> damage to CN VI and VII, corticospinal tract
- Contralateral hemiplegia, ipsilateral facial weakness, abduction deficit
How does Parkinson disease cause difficulty reading?
Convergence insufficiency
Intracranial finding of tuberous sclerosis
Calcified astrocytic hamartomas
Intracranial finding of Sturge-Weber syndrome
Leptomeningeal vascular malformations
Intracranial finding of von Hippel-Lindau syndrome
Cerebellar hemangioblastomas
Intracranial finding of neurofibromatosis 2
Acoustic neuromas
Location of CN VI nucleus
Dorsal base of pons
Why is CN VI prone to compression due to high or low intracranial pressure?
Makes a 90 degree turn over tip of clivus and passes below petroclinoid ligament to enter cavernous sinus
Location of CN III nucleus
Superior colliculus in midbrain
Location of CN IV nucleus
Between superior and inferior colliculus in midbrain
What is the only cranial nerve that exits dorsally from the brainstem?
Trochlear nerve
Raymond syndrome
CN VI palsy with contralateral weakness (CN VI exits ventrally from pons and passes adjacent to corticospinal tract)
Most common visual field defect caused by optic disc drusen
Arcuate (nerve fiber bundle) defects
Inheritance pattern of congenital motor nystagmus
X-linked, mutation in FRMD7 (FERM domain containing 7) gene
How is tangent screen testing performed? What finding is expected?
Patient is tested with a 9mm white stimulus at 1m, then repeated with 18mm white stimulus and patient moved back to 2m -> field should expand to twice original size
If field does not expand, indicates nonorganic vision loss
What visual field defects are most commonly seen with tilted disc syndrome? (2)
Superotemporal defects or bitemporal hemianopia that does not respect the midline
Presentation of diabetic papillopathy
Asymptomatic unilateral painless hyperaemic optic disc edema, dilation of disc vasculature/telangiectasias
Eye movement abnormalities associated with paraneoplastic syndromes
Opsoclonus (multidirectional, high frequency and amplitude without intersaccadic intervals), ocular flutter (fast horizontal movements)
Alexia with agraphia (patient cannot read orwrite) results from damage to the ___ ___ ___.
Alexia with agraphia (patient cannot read orwrite) results from damage to the left angular gyrus.
Hemispatial neglect results from damage to the ___ ___.
Hemispatial neglect results from damage to the cingulate gyrus.
Pattern of demyelinating optic neuritis on pattern-reversal VEP testing
Delayed pattern-reversal VEP
