All highlighted content Flashcards
Studying for final
What can cause neural tube defects?
Lack of folic acid during pregnancy
What does the brainstem do?
Control bodily functions needed for survival ex/ **respirations, BP, HR
Lesions in what two areas cause lethargy and coma?
Upper pons and midbrain
If a patient comes in complaining of the “worst headache of my life” with sudden onset, what might be their diagnosis?
Subarachnoid hemorrhage
1) What can be described as a “balloon like outpouching” of a vessel?
2) How are these connected to the vessel?
3) What part of this “balloon” structure can rupture?
1) Berry Aneurysms
2) Typically connected to the vessel by a stalk
3) The dome can rupture.
List 3 risk factors for the rupture of aneurysms
HTN (hypertension), cigarette smoking, alcohol consumption,
What is typically caused by rupture of bridging veins?
Subdural hematoma
All information passed between what two things passes through the brainstem?
Between cerebral hemispheres and the spinal cord
What is cauda equina syndrome?
Impaired function of nerve roots below L-1, L-2
1) What are 4 potential causes of cauda equina syndrome?
2) Why does it need to be treated quickly?
1) Compression from disk herniation, tumors, trauma, epidural abscess
2) To avoid permanent effects
About_____ of fibers in corticospinal tract cross over to control movement of opposite side of body
85%
About 85% of fibers from what tract cross over to control movement of the opposite side of the body?
Corticospinal tract
What do lesions in cerebellum cause?
Movement disorders
What can cause movement disorders?
Lesions in cerebellum or basal ganglia
1) What causes hypokinetic movement disorders? Name one.
2) The same thing causes hyperkinetic movement disorders; name one
1) Lesions in the basal ganglia; Parkinsonism (slow and rigid)
2) Huntington’s disease (“dancelike” involuntary movements)
True or false: Hypokinetic and hyperkinetic movement disorders have the same cause
True
Name 8 things controlled by the hypothalamus
1) Autonomic
2) Neuroendocrine
3) Limbic and other circuits
4) Body temp
5) Hunger
6) Thirst
7) Fatigue
8) Sleep
What controls sleep?
The hypothalamus
What controls neuroendocrine functions?
Hypothalamus
What two arteries supply all blood to the brain? What part does each supply?
1) Internal carotid arteries; supply anterior
2) Vertebral arteries; supply posterior
What two arteries join to form the basilar artery at the circle of willis?
Vertebral arteries
What is the brain’s drainage system for blood?
Internal jugular vein
The ring at the base of the brain is called what?
Circle of Willis
If a patient has a gaze toward the side of the lesion, what kind of stroke may they have had?
MCA (middle cerebral artery)
What causes a watershed zone?
When the blood supply to 2 adjacent cerebral arteries is compromised
What are two causes of two adjacent cerebral arteries being compromised? [and thus causing watershed infarction]
1) Sudden occlusion of the internal carotid or
2) A drop in BP in setting of carotid stenosis
What are the 3 main somatosensory and motor pathways? List what each does
1) Lateral corticospinal tract: Motor
2) Anterolateral columns: Sensory; pain, temperature & crude touch
3) Posterolateral columns: Sensory; vibration, fine touch, proprioception
1) Where is the primary motor cortex?
2) Where is the primary somatosensory cortex?
1) Primary motor = precentral
2) Primary somatosensory = postcentral
1) What is the most important descending motor pathway of the nervous system?
2) What does it do?
1) Lateral corticospinal tract
2) Controls the movement of extremities
1) What forms the anterior spinal artery?
2) What supplies most of the cord?
3) What forms the posterior spinal artery?
1) Vertebral arteries
2) Anterior spinal artery
3) Vertebral arteries
Where is venous return for the spinal cord?
Epidural space
Where does pyramidal decussation occur?
At medulla/spinal cord junction
Where does the corticospinal tract go?
Posterior limb
Is the ANS afferent, efferent, or both?
Only efferent pathways
What are the two ANS divisions?
Sympathetic and parasympathetic divisions
1) What do sympathetic neurons release to end organs?
2) What about parasympathetic?
1) Sympathetic: norepinephrine to the end organs
2) Parasympathetic: acetylcholine
What 3 things control the ANS?
Hypothalamus, brainstem nuclei, and the amygdala
What are the 3 long tracts of the spinal cord?
1) Posterior column-medial leminiscal system
2) Anterolateral systems
3) Corticospinal tract
1) What does the Posterior column-medial leminiscal pathway convey?
2) Where does it decussate?
1) Proprioception, vibration sense, and fine touch
2) In lower medulla
What pathway’s nerves cross over at the same level?
Anterolateral pathway **
What can vitamin B12 deficiency affect in the CNS?
Posterior cord
Anterior cord syndrome damage causes what?
Loss of pain and temperature sensation below the level of the lesion
**anterior spinal artery infarct is a common cause
What are the 4 dermatomes we need to know?
T4 – nipple line
T10 – umbilicus
C6 – thumb (6 shooter)
S5 - perianal
What is the biggest cause of radiculopathy?
Diabetes
1) What can cauda equina syndrome cause?
2) What can this then cause?
1) Saddle anesthesia (sensory loss in S2-5, numbness in inguinal area)
2) Bladder disfunction, constipation, fecal incontinence and loss of erections
Almost all pathways projecting into the cerebral cortex, relay through the thalamus; which one doesn’t?
Olfactory
1) What supply anterior hemispheres?
2) What about posterior hemispheres?
3) What forms the basilar artery?
4) What forms the Circle of Willis?
1) Internal carotid arteries
2) Vertebral arteries
3) Vertebral arteries
4) The anterior and posterior blood supplies form the anastomotic ring
1) What come off the aorta?
2) What does the common carotid arteries split into?
3) List the arteries that supply the cerebral hemispheres
1) Common carotid arteries
2) Internal and external carotid arteries
3) Anterior, middle and posterior cerebral arteries (ACA, MCA, PCA)
What are the anterior and middle cerebral arteries (ACA & MCA)?
The termination of the internal carotids
What supply the Wernicke’s and Broca’s areas?
Middle cerebral artery
What supply the basal ganglia and the internal capsule?
Branches of the MCA
What can cause lacunar infarctions?
HTN
What are watershed infarcts?
2 adjacent cerebral arteries are compromised
What is the watershed?
The region in-between the 2 adjacent compromised vessels
1) What type of stroke is caused by lack of adequate blood supply to the brain for long enough to cause cell death?
2) What can cause it?
1) Ischemic stroke
2) Can be caused by embolus or thrombus
1) What links the anterior cerebral arteries together?
2) What do the posterior communicating arteries do? Be specific
1) The anterior communicating artery
2) Link anterior and posterior circulations; specifically they join the internal carotids and the posterior cerebrals
1) Where does the anterior cerebral artery (ACA) go?
2) What does it supply?
1) Travels forward, splits into 2 main branches, then turns back over the corpus collosum
2) The cortex on the anterior medial surface of the brain from frontal to anterior parietal lobe.
-Includes the medial sensorimotor cortex.
1) Where does the middle cerebral artery (MCA) go?
2) What does it supply?
1) Enters Sylvian Fissure and then splits into 2-4 main branches, which form loops.
2) The cortex above and below the Sylvian Fissure; including the lateral temporal lobe and parts of the parietal lobe.
-Also includes thalamus and posterior limb of the internal capsule
1) Where does the posterior cerebral artery (PCA) go?
2) What does it supply?
1) Curves back off the basilar artery
2) Through its many branches supplies: the inferior and medial temporal lobes and the medial occipital cortex.
1) What artery supplies the medial sensorimotor cortex?
2) What supplies the the inferior and medial temporal lobes?
3) What supplies the lateral temporal lobes?
1) ACA
2) PCA
3) MCA
1) What supplies blood to the thalamus and posterior limb of the internal capsule?
2) What could a lacunar infarction in this area cause?
1) Small branches of the MCA
2) Contralateral hemiparesis
1) What is lacunar infarct syndrome?
2) What is it characterized by?
3) Give examples
1) The clinical manifestations of a lacunar infarct
2) Pure motor hemiparesis.
3) Contra/Unilateral face, arm and leg weakness.
-Location ex/posterior limb of internal capsule.
1) What strokes are most common, MCA, ACA, or PCA?
2) What is its unique symptom?
1) MCA
2) Patients often have a gaze toward the side of the lesion
What two things can watershed infarctions cause?
1) Sudden occlusion of the internal carotid
2) Drop in BP in setting of carotid stenosis
1) How long does a TIA last?
2) Give 4 common causes
1) <24 hours (usually closer to 10 minutes)
2) Migraines, seizures, arrhythmias and hypoglycemia
_____% of patients with TIAs with have a stroke within ___ months and most of those within the next _____ hours
10%; 3 months; 48 hours
What is leading cause of significant disability?
Strokes
1) What are the two main types of strokes?
2) What type of stroke is caused by a thrombus or embolus?
1) Ischemic and hemorrhagic
2) Ischemic
What is the biggest difference between a thrombus and embolus?
1) Embolus: travels
2) Thrombus: doesn’t travel
1) What type of stroke is usually caused by an embolus: large vessel, or small vessel?
2) What are small vessel strokes also called?
1) Large vessel
2) Lacunar infarcts
1) What are emboli most often made of?
2) Where do they commonly come from?
1) Most often blood clots.
2) The heart
Define dissection [in the context of strokes]
Tear on the inner surface of an artery
1) What do cortical signs come from?
2) What are they?
1) Lobar strokes
2) Aphasia, neglect, homonymous visual field defects, apraxia, hemiparesis, and sensory loss
What sometimes causes headaches with ischemic strokes?
Innervation of the blood vessels and meninges
What is usually the cause of strokes in younger patients?
Dissection/trauma
What do the internal jugular veins do?
Drain the dural sinuses (which is where the veins that drain the brain go)
A tumor on the pituitary can press on the optic chiasm and cause what kind of field defects?
Bilateral temporal (aka bitemporal hemianopia)
A tumor on the what part of the brain can press on the optic chiasm?
Pituitary
How would you describe the orientation of the image on the retina?
Inverted and reversed
Information from the lower visual field is projected on the ___________ retina
upper
Why are images reversed on the retina?
The right visual field projects onto the left retina (and vice versa) of each eye
Why are images inverted on the retina?
Information from the upper visual field is projected onto the lower retina, and vice versa
The central fixation point for each eye is what?
The fovea
Where do fibers that carry visual information cross?
Optic chiasm
True or false: There is a total crossing of fibers in the optic chiasm
False; it’s a partial crossing of fibers
Lesions anterior to the [optic] chiasm produce what kind of visual field defects?
monocular
Lesions of the optic chiasm produce what kind of visual field defects?
bilateral lateral
The medial (nasal) fibers from both eyes do what in the optic chiasm?
Cross over
The optic tract wraps around the midbrain, then to where?
The lateral geniculate nuclei (LGN) of the thalamus
Where does the optic tract go after the optic chiasm?
The LGN of the thalamus
What can result in bitemporal hemianopia from compression of the optic chiasm?
Pituitary adenomas
Why do pituitary adenomas cause the visual effect they do?
They press on the optic chiasm, compressing the medial fibers, which convey the outer half of vision for both eyes
What is the superior colliculus important in?
Directing visual attention and eye movements towards visual stimuli
1) The superior colliculus and pretectal areas project where for visual attention?
2) How?
1) To the brainstem and association cortex
2) Via relays in other thalamic nuclei
What are the functions of the other thalamic nuclei that project the superior colliculus to the brainstem?
Visual attention/orientation/discrimination/perception (i.e. help us direct our attention to something seen or heard)
What do the neurons of the LGN participate in? (3 things)
Motion, spatial awareness, and color vision.
What fans out over a wide area to form the optic radiations?
The superior colliculi
What pathway is likely defective if color vision isn’t working?
The LGN
Central __________________ occlusion can cause infarction of the entire retina
retinal artery
Define Amaurosis Fugax
Transient occlusion of the retinal artery
1) What causes Amaurosis Fugax?
2) What is a common cause of that?
1) Emboli [occluding the retinal artery]
2) Ipsilateral carotid artery stenosis
If a patient describes having the visual of a window shade going up or down in one eye, what might they be having?
Amaurosis Fugax
What are the two main symptoms of Amaurosis Fugax?
1) A “window shade going up or down” on ONE eye
2) Loss of vision in one eye for roughly 10 min.
What can Amaurosis Fugax be a signal of?
Impending retinal or cerebral infarct.
1) What is optic neuritis?
2) What does it cause?
1) A demyelinating disorder of the optic nerve related to MS
2) Eye pain with movement (among other things) of one eye
_____ or more of patients with a clinically isolated episode of optic neuritis will eventually develop MS
50%
If a patient complains of pain in one eye that’s worse with movement, what may they have?
Optic neuritis
What is the vestibular system? What does it do?
Sensory system that senses balance and spatial orientation coordinating movement with balance
What are the two parts of the labyrinth of the inner ear?
1) Bony labyrinth
2) Membranous labyrinth.
The bony labyrinth is filled with ________ called ______
fluid; perilymph
1) What makes up the membranous labyrinth?
2) Where is it?
3) What is the membranous labyrinth filled with?
1) The cochlear duct, utricle, saccule and semicircular canals
2) Suspended in the perilymph.
3) Filled with endolymph.
The maculae consist of ___________ called ________ sitting in a gelatinous layer where mechanoreceptor hair cells are embedded
calcified crystals; otoliths
Primary vestibular neurons in the vestibular ganglia convey information about what?
Angular and linear acceleration
1) The lateral vestibular nucleus gives rise to what?
2) What two things is this important in?
1) The lateral vestibulospinal tract
2) Maintaining balance and extensor tone.
1) Where is the MVT (medial vestibulospinal tract) found?
2) What is it important in?
1) Extends only to the cervical spine
2) Important in controlling head and neck position
What is an important job of the medial longitudinal fasciculus (MLF)?
Conjugates the gaze
Define vertigo
Spinning sensation
1) Most vertigo cases are caused by what?
2) What is a less common cause of vertigo?
1) Peripheral disorders involving the inner ear (usually benign.)
2) Central disorders of the brainstem or cerebellum are less common (usually urgent.)
Dix-Hallpike testing can help differentiate between what?
Central or peripheral causes of vertigo
1) What does the Dix-Hallpike test look like if the patient has peripheral lesions of the inner ear?
2) What does the nystagmus look like?
1) 2-5 second delay [in vertigo and nystagmus]
2) The nystagmus is horizontal or rotary and does not change directions
1) What does the Dix-Hallpike test look like if the patient has central lesions of the inner ear?
2) What does the nystagmus look like?
3) Is there adaptation if it’s repeated?
1) Nystagmus and vertigo may begin immediately in supine position
2) Vertical nystagmus, nystagmus that changes directions while the patient is in the same position or prominent nystagmus in the absence of vertigo are only seen with central lesions.
3) No adaptation
1) What is the most common cause of vertigo?
2) How long does it last?
3) When does it happen?
1) Benign paroxysmal positional vertigo (BPPV)
2) Brief episodes of vertigo lasting for a few seconds
3) Occur with change of position
1) With Benign paroxysmal positional vertigo (BPPV), what helps the dizziness?
2) What is usually the cause?
1) If the patient remains still, the dizziness usually abates.
2) Otolithic debris in the semicircular canals
1) What characterizes Meniere’s disease?
2) What is the etiology?
1) Recurrent episodes of vertigo with progressive hearing loss and tinnitus
2) Excess fluid (and pressure in endolymphatic system)
1) Besides Meniere’s, what can cause cause hearing loss and tinnitus with associated dizziness?
2) How is it different? (3 things)
1) Acoustic neuroma
2) Causes unsteadiness, it’s not true vertigo, and does not have discrete episodes.
Name two common causes of central vertigo
1) Vertebrobasilar ischemia or infarct
2) Small hemorrhage in cerebellum or brainstem
What can gentamicin cause?
Bilateral vestibular dysfunction (and dizziness)
1) What is the second most common cause of vertigo?
2) What is its suspected origin?
3) Who does it affect?
4) Is hearing impaired?
1) Vestibular neuritis
2) Viral origin
3) 30 to 50 years of age; men and women are affected equally
4) Not impaired
What are the 3 angular axes that semicircular canals use to detect angular acceleration?
1) Anterior
2) Posterior
3) Horizontal (lateral)
Name 3 essential roles of the vestibular nuclei
1) Adjustment of posture
2) Muscle tone
3) Eye position in response to movements of the head in space.
Where are vestibular nuclei found?
Brainstem
Semicircular canals convey information about ______ acceleration, while otolith organs convey information about ________ acceleration.
Angular; linear
What tract is important in maintaining balance and extensor tone, and extends the entire length of the spinal cord?
Lateral vestibulospinal tract
What nuclei contribute to the medial vestibulospinal tract, that is important in controlling head and neck position and extends only to the cervical spine?
Medial vestibulospinal nucleus and Inferior vestibulospinal nucleus
What part of the vestibular system conjugates the gaze?
Medial longitudinal fasciculus (MLF)
Name a positive sign that could mean that a patient possibly has a problem outside of their vestibular system
Orthostatic hypotension
An adaptable horizontal or rotary nystagmus is indicative of what?
Peripheral lesions of the inner ear
In which vestibular condition does a change in position cause vertigo due to otolithic debris in the semicircular canals?
Benign paroxysmal positional vertigo
A patient complaining of a full feeling in the ear, ringing of the ears and hearing loss over time that accompanies recurrent episodes of vertigo. What would be your diagnosis?
Meniere’s disease
True or false: acoustic neuromas cause true vertigo
False
Vestibular neuritis is the ____most common cause of vertigo while Benign paroxysmal positional vertigo is the ____ most common cause of vertigo.
2nd; 1st
Name 2 common causes of central vertigo
1) Vertebrobasilar ischemia or infarct
2) Small hemorrhage in cerebellum or brainstem
Gentamicin is ototoxic and causes ____________ vestibular dysfunction
bilateral
What is the vestibular system? What does it do?
Sensory system that senses balance and spatial orientation coordinating movement with balance
What are the two parts of the labyrinth of the inner ear?
1) Bony labyrinth
2) Membranous labyrinth.
The bony labyrinth is filled with ________ called ______
fluid; perilymph
1) What makes up the membranous labyrinth?
2) Where is it?
3) What is the membranous labyrinth filled with?
1) The cochlear duct, utricle, saccule and semicircular canals
2) Suspended in the perilymph.
3) Filled with endolymph.
The maculae consist of ___________ called ________ sitting in a gelatinous layer where mechanoreceptor hair cells are embedded
calcified crystals; otoliths
Primary vestibular neurons in the vestibular ganglia convey information about what?
Angular and linear acceleration
1) The lateral vestibular nucleus gives rise to what?
2) What two things is this important in?
1) The lateral vestibulospinal tract
2) Maintaining balance and extensor tone.