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
