Flashcards in Neuro6 Deck (45):
What do we see histopathologically/grossly in Huntington Disease? (3)
--Degeneration of the GABAergic neurons of the caudate nucleus --> expansion of lateral ventricles
--Also degenerative changes in the putamen and cortex
--decreased levels of GABA and ACh in the brain
What are the clinical characteristics of Huntington Disease?
--writhing movement (athetoid)
**sometimes Huntington disease is initially mistaken for substance abuse
60% of abscesses in the brain are caused by what primary disease process?
otitis media (middle ear infection)
cerebellar and temporal lobe abscesses are associated with otitis media
Cerebellar abscesses are specifically associated with what disease?
otitis media (middle ear infection)
What bacteria are most commonly responsible for otitis media?
What is a subdural empyema?
A collection of pus between the dura and the arachnoid. This is usually a complication of bacterial meningitis.
Where in the brain would sinusitis cause abcesses?
frontal and temporal lobe
What is a ring-enhancing lesion in the brain on CT indicative of?
a brain abscess
Unlike injury to the lateral geniculate nucleus or optic radiations, why do we observe macular sparing with a lesion to the occipital cortex?
This is because the most posterior region of the occipital cortex, which is where the macula is represented, has a bilaterally redundant blood supply. It is supplied by the PCA (posterior cerebral artery) and a branch of the middle cerebral artery.
What blood vessel pathology would lead to a bitemporal hemianopia?
The anterior communicating artery is located in the vicinity of the optic chiasm. Aneurysm of the anterior communicating artery can therefore compress the optic chiasm, producing a bitemportal hemianopia.
What artery gives rise to the ophthalmic artery?
Internal carotid artery
How would occlusion of the ophthalmic artery manifest clinically?
This artery perfuses the optic nerve and the retina. Occlusion of this artery would lead to monocular blindness in the affected eye.
What would be the ophthalmologic deficit that results from aneurysm of the posterior communicating artery?
The posterior communicating arteries overlie CN III. Aneurysm of these arteries can lead to a CN III palsy. Because the parasympathetic fibers of CN III are located peripherally, the first sign of compression of this nerve would manifest as mydriasis (pupil dilation) on the affected side. If the aneurysm grows to impinge the centrally located motor fibers, extraocular eye movement will be impaired: lateral strabismus, with the affected eye pointing down and out on primary gaze.
What blood vessel pathology would lead to a binasal hemianopia?
The internal carotid arteries also run next to the chiasm on their outside; calcification of these vessels could compress the non-decussating fibers of the chiasm, leading to a binasal hemianopia. (The nasal visual field projects to the temporal retina; the optic nerve fibers of the temporal retina do not decussate.)
What is PrP sc?
PrP sc is a prion protein that is responsible for the spongiform changes seen in Creutzfeldt-Jakob Disease (CJD)
What is mutation in zinc-copper superoxide dismutase associated with?
It is associated with some hereditary forms of Amyotrophic Lateral Sclerosis (ALS)
What are neurofibrillary tangles composed of?
Hyperphosphorylated tau proteins. Tau proteins are microtubule-associated proteins that normally bind to and stabilize microtubules.
The hyperphosphorylated tau proteins form insoluble paired helical filaments (PHF)
Where is the facial nucleus located?
The lower pons
What cranial nerve nuclei are located in the medulla?
the motor nuclei for CNs 9, 10, 11, and 12
What cranial nerve nuclei are located in the midbrain?
3 and 4
What type of information does each branch of the trigeminal nerve carry?
ophthalmic - sensory
maxillary - sensory
mandibular - motor and sensory
Where is the motor nucleus of the trigeminal nerve located?
In the mid-pons
What is apraxia?
An inability to perform a task or a movement when asked, even though the command was understood
Where is the hippocampus located?
In the medial temporal lobe
What brain structure is exquisitely sensitive to anoxic injury, and can be selectively affected by anoxic injury?
The hippocampus. This would result in anterograde amnesio--an inability to acquire new information (form new memories).
With what disorder do we see violent flinging of the proximal limb muscles?
What nerve lies in the tonsillar fossa?
the glossopharyngeal nerve
What information is carried by the glossopharyngeal nerve?
The glossopharyngeal nerve carries general sensory information from the mucosa of the pharynx, and general sensory and taste sensation from the posterior 1/3 of the tongue.
This nerve also innervates the stylopharyngeus muscle, which helps to elevate the palate. However, this innervation occurs proximal to the point at which the nerve crosses the tonsillar fossa
What nerve innervates the constrictor muscles of the pharynx?
What nerve innervates the muscles of the soft palate?
Most are innervated by the vagus nerve.
The tensor palati is innervated by the mandibular branch of the trigeminal nerve
What nerve innervates the muscles of the tongue?
The hypoglossal nerve innervates the hypoglossus, geniooglossus, and styloglossus.
The only tongue muscle not innervated by CN12 is the palatoglossus, which is innervated by the vagus
What is the order of layers through which a needle passes for a lumbar puncture (LP)?
Where would you administer local anesthetic in an epidural?
in the epidural space
Where would you administer local anesthetic in spinal anesthesia?
into the CSF in the subarachnoid space
Between which vertebra is a needle typically inserted for an LP?
Between L4 and L5
What are the characteristics of a subdural hematoma on imaging?
--cross suture lines
--don't cross the midline
What is the Cushing reflex?
Hypertension and bradycardia in response to increased intracranial pressure (ICP).
Explain why we see hypertension in the Cushing reflex
--This reflex is triggered in response to a decrease in cerebral perfusion pressure (CPP), which is the difference between MAP and ICP, when that change is due to significantly increased ICP.
--Initially when ICP increases, cerebral arteries will dilate maximally to decreased cerebral vascular resistance and therefore maintain cerebral vascular pressure. However, if the increase in ICP overwhelms this response, the hypothalamus will activate the sympathetic nervous system, which will increase cardiac output and stimulate peripheral vasoconstriction in an attempt to increase MAP.
Why do we paradoxically observe bradycardia in the Cushing reflex?
The hypothalamus activates the sympathetic nervous system, which will increase cardiac output and stimulate peripheral vasoconstriction, leading to increased MAP.
However, this increased MAP will be sensed by the baroreceptors in the carotid and aortic arches, leading to a vagal response that leads to a reduction in heart rate, often to the point of bradycardia.
Sensory innervation of the laryngeal mucosa above the vocal folds
Internal branch of the superior laryngeal nerve
Sensory innervation of the laryngeal mucosa below the vocal folds?
Recurrent laryngeal nerve
Sensory innervation of the pharyngeal mucosa?
Motor innervation of the cricothyroid muscle
External branch of the superior laryngeal nerve
Motor innervation of the lateral cricoarytenoid muscle
recurrent laryngeal nerve