An alcoholic gets rapid IV fluids for electrolyte disturbance. MRI is taken after he develops acute paralysis. What disease does he have?
Central pontine myelinolysis with paralysis, dysarthria, diplopia, and loss of consciousness; caused by rapid correction of hyponatremia
Microglia originate from what embryologic layer?
The mesoderm
Except for microglia, all central and peripheral nervous system supportive cells originate from what layer?
The ectoderm
What is the function of ependymal cells?
Ependymal cells make cerebrospinal fluid
Which two types of cells of the nervous system are derived from neural crest cells?
Schwann cells and peripheral nervous system neurons
Central nervous system neurons are derived from ________ (neuroectoderm/neural crest cells) whereas peripheral nervous system neurons are derived from _________(neuroectoderm/neural crest cells).
Neuroectoderm; neural crest cells
Which four types of cells are derived from neuroectoderm?
Central nervous system neurons, ependymal cells, astrocytes, oligodendroglia
What is Nissl substance, and where is it found?
It is the rough endoplasmic reticulum in the cell body and dendrites (not axon) of a neuron
Neurons are _____ (permanent/labile) cells that _____ (do/do not) divide in adulthood.
Permanent; do not
On histopathology, what is the response of astrocytes to injury known as?
Reactive gliosis
What are the five functions of astrocytes?
Physical support, repair, potassium metabolism, removal of excess neurotransmitter, maintenance of the blood-brain barrier
Which cells comprise the blood-brain barrier?
Astrocytes
What is the molecular marker for astrocytes?
Glial fibrillary acidic protein (GFAP)
In HIV-infected patients, what cell type fuses to form multinucleated giant cells?
Microglia
In response to tissue damage, what do microglia transform into?
Large ameboid phagocytic cells
What is the histologic appearance of microglia?
They have small, irregular nuclei and relatively little cytoplasm and are not readily discernable in Nissl stains
What is the main function of microglia?
Phagocytosis (in the setting of tissue damage) in the central nervous system
Which cells in the central nervous system are destroyed in multiple sclerosis?
Oligodendrocytes are attacked in an autoimmune process leading to demyelination
What type of cell myelinates multiple (up to 30 each) central nervous system axons?
Oligodendrocyte
In Nissl stains, what types of cells appear as small nuclei with dark chromatin and little cytoplasm (like a fried egg)?
Oligodendrocytes
Oligodendrocytes are the predominant type of glial cell in _____ (gray/white) matter.
White; the white appearance is due to myelin
_____ (Oligodendrocytes/Schwann cells) are found in the central nervous system and myelinate _____ (one/up to 30) axon(s), whereas _____ (oligodendrocytes/Schwann cells) are found in the peripheral nervous system and myelinate _____ (one/up to 30) axon(s)
Oligodendrocytes; up to 30; Schwann cells; one
What type of cells promote axonal regeneration in the peripheral nervous system?
Schwann
An acoustic neuroma is a tumor derived from which cell type?
Schwann cells; it is a Schwannoma
Schwannomas often affect which cranial nerve?
Cranial nerve VIII
Schwann cells are derived from what embryonic cell population?
Neural crest cells
Which syndrome is characterized by destruction of Schwann cells?
Guillain-Barr syndrome, which involves the acute, self-limited destruction of myelin in the peripheral nervous system
What are the four sensory corpuscles?
Meissner’s corpuscles, Pacinian corpuscles, Merkel’s discs, and free nerve endings
What kind of corpuscles are involved in dynamic fine touch (eg, manipulation)?
Meissner’s corpuscles; these are quickly-adapting receptors
What kinds of corpuscles are located in glabrous (hairless) skin?
Meissner’s corpuscles; glabrous skin includes the lips and fingertips
What kind of corpuscles are located in deep skin layers?
Pacinian corpuscles
Ligaments and joint capsules contain what type of sensory corpuscles?
Pacinian corpuscles
What kind of corpuscles are responsible for sensations of vibration and pressure?
Pacinian corpuscles
What kind of sensory receptors are located in hair follicles?
Merkel’s discs
What type of touch do Merkel’s discs sense?
Static touch (eg, shapes, edges, textures); these are slowly adapting receptors
What type of sensory corpuscles can be found throughout the skin as well as some viscera?
Free nerve endings
Free nerve endings are made up of what two types of fibers? How do they differ?
C and Aδ fibers; C are slow and unmyelinated, Aδ are fast and myelinated
Pain and temperature are sensed by what type of sensory corpuscles?
Free nerve endings
In peripheral nerves, single nerve fibers are immediately contained within the _____.
Endoneurium; the prefix endo- means inner
Each fascicle of peripheral nerve fibers is surrounded by a permeability barrier called the _____.
Perineurium (remember: Perineurium and Permeability barrier)
What dense connective tissue surrounds the entire nerve, including the fascicles and the blood vessels?
The epineurium; the prefix epi- means ‘outer’
During a limb reattachment, what nerve layer must be rejoined for the surgery to be successful?
The perineurium; the prefix peri- means around; some axons will regrow if there is an intact perineurium
Where in the brain is norepinephrine synthesized?
The locus ceruleus
Where in the brain is dopamine synthesized?
The ventral tegmentum and the substantia nigra pars compacta
Where in the brain is serotonin synthesized?
The raphe nucleus
Where in the brain is acetylcholine synthesized?
The basal nucleus of Meynert
How do neurotransmitter levels change with anxiety?
Anxiety increases norepinephrine, decreases serotonin and γ-aminobutyric acid, and does not affect dopamine or acetylcholine
How do neurotransmitter levels change with depression?
Norepinephrine, dopamine, and serotonin all decrease
In which psychiatric condition are central nervous system dopamine levels increased?
Schizophrenia
In Alzheimer’s and Huntington’s diseases, central nervous system levels of which neurotransmitter is decreased?
Acetylcholine
Which neurotransmitter is involved in the pathogenesis of Parkinson’s disease?
Dopamine activity is decreased
The locus ceruleus is a nucleus in the brain stem involved with physiologic responses to which two emotions?
Stress and panic
Which brain region, found in the striatum, plays an important role in laughter, fear, reward, and addiction
The nucleus accumbens
The blood-brain barrier is formed by what three structures?
Capillary endothelial tight junctions, basement membranes, and astrocyte foot processes
What two substances cross the blood-brain barrier slowly by a carrier-mediated transport mechanism?
Glucose and amino acids
What properties of a molecule allow it to diffuse across the blood-brain barrier?
Nonpolar and lipid-soluble substances
Name the three blood-tissue barriers found in the body.
The blood-brain barrier, the blood-testis barrier, and the maternal-fetal blood barrier of the placenta
Name three specialized brain regions with fenestrated capillaries and no blood-brain barrier.
The area postrema (responsible for vomiting with chemotherapy), the organum vasculosum of the lamina terminalis (osmotic sensing), and the neurohypophysis (responsible for antidiuretic hormone release)
Infarction destroys endothelial cell tight junctions in the blood-brain barrier, leading to leakage of fluid into the brain from damaged blood vessels, causing _____ _____.
Vasogenic edema
Central control for thirst and water balance is found in what part of the brain?
The hypothalamus (the supraoptic nucleus)
Destruction of the lateral nucleus of the hypothalamus would produce what disorder?
Anorexia (remember: if you zap your lateral nucleus, you shrink laterally)
A patient presents with hyperphagia and obesity after a localized injury to the hypothalamus. What part of the hypothalamus has been injured?
The ventromedial nucleus (remember: if you zap your ventromedial nucleus, you grow ventrally and medially)
Parasympathetic activity is regulated by the _____ (anterior/posterior) hypothalamus.
Anterior (remember: pArasympathetic, Anterior; A/C = anterior cooling)
Sympathetic activity is regulated by the _____ (anterior/posterior) hypothalamus.
Posterior
Circadian rhythms are predominantly regulated by which part of the hypothalamus?
The suprachiasmatic nucleus (remember: you need sleep to be charismatic [chiasmatic])
A patient presents with the inability to regulate heat conservation and production. What part of the brain is injured?
The posterior hypothalamus (remember: if you zap your Posterior hypothalamus, you become a Poikilotherm [cool, like a snake])
What area of the brain coordinates the cooling of the body in hot temperatures?
The anterior hypothalamus
What region of the brain regulates sexual urges and emotions?
The septal nucleus
How does the mnemonic TAN HATS describe the functions of the hypothalamus?
TAN HATS: Thirst and water balance, Adenohypophysis control, Neurohypophysis releases hormones from hypothalamus, Hunger, Autonomic regulation, Temperature regulation, Sexual urges
Which area of the hypothalamus responds to emetics?
The area postrema (responsible for vomiting with chemotherapy)
Leptin stimulates the _____ (ventromedial/lateral) area, leading to _____ (hunger/satiety) and inhibits the _____ (ventromedial/lateral) area, leading to _____ (hunger/satiety).
Ventromedial; satiety; lateral; satiety
The posterior pituitary receives axonal projections from the _____ and _____ nuclei.
Supraoptic and paraventricular
The posterior pituitary secretes which two hormones?
Antidiuretic hormone and oxytocin
The supraoptic nucleus produces which hormone?
Antidiuretic hormone
Oxytocin is produced in the _____ nucleus of the posterior pituitary.
Paraventricular
What structure is the major relay for sensory information ascending to the cortex?
The thalamus
The ablation of the lateral geniculate nucleus would produce what kind of deficits?
Visual
The medial geniculate nucleus is responsible for the relay of what type of stimuli to the cortex?
Auditory
A patient with a thalamic defect presents with a lack of proprioception. What part of the thalamus has the defect?
The lateral part of the ventral posterior nucleus
Sensory stimuli from the spinothalamic tract are relayed to the cortex via what part of the thalamus?
The lateral part of the ventral posterior nucleus
Sensory stimuli from cranial nerve V reaches the cortex via relay through what part of the thalamus?
The medial part of the ventral posterior nucleus (remember: you put Makeup on your face and the sensory information is relayed through the VPM)
The ventral anterior/lateral nuclei are responsible for the relay of what kind of information?
Motor plans; they interact with the motor cortex, basal ganglia, and cerebellum
The blood supply to the thalamus comes from which arteries?
The posterior communicating, posterior cerebral, and anterior choroidal arteries
Motor information is relayed through which two nuclei in the thalamus?
The ventral anterior and ventral lateral nuclei
Tactile sensation - including touch, pressure, pain, and proprioception - is relayed through which area in the thalamus?
The ventral posterior nucleus
What are the four components of the limbic system?
The cingulate gyrus, hippocampus, fornix, and mammillary bodies
What are the five functions of the limbic system?
Feeding, Fighting, Fleeing, Feeling, and sex (remember: the 5 Fs)
What are the output neurons of the cerebellum?
Purkinje fibers
What are two types of neurons provide input to the cerebellum?
Climbing and mossy fibers
From lateral to medial, name the four deep nuclei of the cerebellum.
Dentate, Emboliform, Globose, Fastigial (remember: Don’t Eat Greasy Foods)
What is the role of the lateral cerebellum?
Voluntary movement of the extremities
What function does the medial cerebellum serve?
Balance and truncal coordination
The cerebellum provides stimulatory feedback to the _____ (contralateral/ipsilateral) cortex.
Contralateral; modulates movement via the Purkinje fibers in the superior cerebellar peduncle
The cerebellum receives _____ (contralateral/ipsilateral) input from the cortex via the middle cerebellar peduncle.
Contralateral
Ipsilateral proprioceptive information from the body reaches the cerebellum via the _____ (inferior/middle) cerebellar peduncle.
Inferior
Which supratentorial brain region is most involved in voluntary movements and postural adjustments?
The basal ganglia
A patient presents with cog-wheel rigidity. This symptom is likely the result of decreased input from what structure?
The dopaminergic neurons of the substantia nigra
Decreasing dopaminergic output from the substantia nigra leads to _____ (increased/decreased) stimulation of the direct (excitatory) pathway and _____ (increased/decreased) inhibition of the indirect (inhibitory) pathway.
Decreased; decreased; resulting in decreased motor activity overall
Inadequate function of the substantia nigra occurs in what disease?
Parkinson’s disease
The globus pallidus externus receives input from the putamen via what pathway of the basal ganglia?
The indirect pathway
The putamen receives regulatory input from what basal ganglia structure?
The substantia nigra pars compacta
The subthalamic nucleus is in the _____ (direct/indirect) pathway.
Indirect/inhibitory pathway
D1 dopamine receptors are _____ (inhibitory/excitatory); D2 dopamine receptors are _____ (inhibitory/excitatory).
Excitatory; inhibitory
When active, the direct pathway of the basal ganglia _____ (facilitates/inhibits) movement, and the indirect pathway _____ (facilitates/inhibits) movement.
Facilitates; inhibits
How does the mnemonic TRAP help to remember the signs of Parkinson’s disease?
TRAP: Tremor (at rest), cogwheel Rigidity, Akinesia, Postural instability (a patient with Parkinson;s is TRAPped in his/her body)
Parkinson’s disease is associated with depigmentation of which region of the brain?
Substantia nigra pars compacta
What are Lewy bodies?
Intranuclear inclusions composed of -synuclein seen in Parkinson’s disease
Illicit street drugs contaminated with _____ have been linked to development of Parkinson’s disease.
MPTP
Neurons using which neurotransmitter are affected in Parkinson’s disease?
Dopamine
What is hemiballismus? A lesion of which brain region can cause it?
The sudden, wild flailing of one arm and/or leg; caused by a lesion to the contralateral subthalamic nucleus
Hemiballismus is the result of loss of inhibition of which part of the brain?
Loss of inhibition of the thalamus leads to excess motor stimulation of contralateral arm
What is the mode of inheritance for Huntington’s disease?
Autosomal dominant
In Huntington’s disease, which type of neurons are lost secondary to atrophy of the caudate nucleus?
Caudate loses ACHergic and GABAergic neurons due to CAG repeats in Huntington’s
What are the computed tomography findings of Huntington’s disease?
Enlarged lateral ventricles, atrophy of putamen, defined sulci
A mutation on which chromosome is associated with Huntington’s disease? What specific mutation is it?
Chromosome 4; a trinucleotide repeat of CAG
What three symptoms are associated with Huntington’s disease?
Chorea, depression, progressive dementia
Between what ages does Huntington’s disease manifest?
Between 20 and 50 years of age; patients often present at a younger age than affected parents did because of anticipation
Sudden, jerky, purposeless movements are characteristic of lesions in which part of the brain?
Basal ganglia
What is chorea?
Sudden, jerky, purposeless movements
What is athetosis?
Slow, writhing movements, especially of fingers
Athetosis is characteristic of lesions in which part of the brain?
Basal ganglia
What is myoclonus?
Sudden, brief, involuntary muscle contraction
What is dystonia?
Involuntary sustained muscle contraction
What effect does alcohol have on essential tremor?
Decreases tremor
What is an intention tremor? With which brain region is it associated?
A slow, zigzag motion when pointing; caused by cerebellar dysfunction
How is essential tremor treated?
-blockers
Pill-rolling tremor is a _____ (resting/intention) tremor associated with Parkinson’s disease.
Resting
What is the mode of inheritance for essential/postural tremor?
Autosomal dominant
Essential tremor is a _____ (action/intention/resting) tremor.
Action
What are the four lobes of the brain?
Parietal lobe, occipital lobe, temporal lobe, and frontal lobe
A patient presents with unintelligible yet fluid speech. This patient most likely has a defect in which area of the brain?
Wernicke’s area in the temporal lobe of the dominant hemisphere (remember: Wernicke’s is Wordy but makes no sense)
In which lobe is the primary visual cortex found?
The occipital lobe
In which lobe is Broca’s area found? What is its function?
The frontal lobe of the dominant hemisphere; speech (motor) (remember: damage to BROca’s causes BROken speech)
In what gyrus is Wernicke’s area found?
The superior gyrus of the temporal lobe (superior temporal gyrus)
The central sulcus divides which two lobes?
Parietal and frontal
Broca’s and Wernicke’s areas are located in the _____ hemisphere.
Dominant
In which lobe are the principal sensory areas located?
Parietal
The associative auditory cortex is also known as _____ (Broca;s/Wernicke;s area).
Wernicke;s area
Which fissure divides the temporal from the frontal lobe?
Sylvian fissure (lateral sulcus)
The principal motor area is next to which sulcus?
It is anterior to the central sulcus
A child presents with difficulty planning, concentrating, and inhibiting impulses. The origin of these deficits may be attributed to what lobe of the brain?
The frontal lobe
A patient with Pick’s disease presents with a lack of social judgment. The function of which lobe has been affected?
The frontal lobe
Motor input to which part of the body originates from the cortex within the Sylvian fissure (lateral sulcus)?
Tongue and throat
Motor input to which part of the body originates from the cortex within the longitudinal cerebral fissure?
Foot and ankle
A lesion in what area of the brain may result in a conduction aphasia, poor repetition with good comprehension, and fluent speech?
The arcuate fasciculus
A lesion in what area of the brain may result in hyperorality, hypersexuality, and disinhibited behavior?
Lesions in the amygdala cause Klüver-Bucy syndrome, characterized by hyperorality, hypersexuality and disinhibited behavior)
A lesion in what area of the brain may cause personality changes and deficits in concentration, orientation, and judgment?
The frontal lobe
A lesion in what area of the brain may result in spatial neglect syndrome (agnosia of the contralateral side of the world)?
The right parietal lobe
A lesion in what area of the brain may result in reduced levels of arousal and wakefulness (eg, coma)?
The reticular activating system
A patient with Wernicke-Korsakoff syndrome likely has a lesion in what area of the brain?
The mammillary bodies
Intention tremor and limb ataxia may indicate a lesion in what area of the brain?
The cerebellar hemisphere (remember: cerebellar hemispheres are laterally located and affect lateral limbs)
Damage to the cerebellum results in _____ (ipsilateral/contralateral) deficits.
Ipsilateral
Truncal ataxia may indicate a lesion in what area of the brain?
The cerebellar vermis (remember: vermis is centrally located–affects central body)
Anterograde amnesia (the inability to make new memories) may indicate a lesion of what area of the brain?
The hippocampus
In a lesion of the paramedian pontine reticular formation, the eyes look _____ (away from/toward) the side of the lesion. In a lesion of the frontal eye fields, the eyes look _____ (away from/toward) the lesion.
Away from; toward
Dysarthria may be indicative of a lesion in which part of the cerebellum?
Cerebellar vermis
What are the symptoms of central pontine myelinosis?
Dysarthria, acute paralysis, dysphagia, diplopia, loss of consciousness
What is a common iatrogenic cause of central pontine myelinosis?
Correcting hyponatremia too rapidly
Name a symptom of recurrent laryngeal nerve injury.
Hoarseness
What is Broca’s aphasia?
Nonfluent aphasia with intact comprehension
A patient with aphasia indicates that he can comprehend what the physician is saying but is unable to respond in spoken words. In what part of the brain is this lesion likely located (location and name)?
The inferior frontal gyrus (Broca’s area)
What is Wernicke’s aphasia?
Fluent aphasia with impaired comprehension
What is dysarthria?
Motor inability to speak
What is the difference between aphasia and dysarthria?
Aphasia is a higher-order inability to speak whereas dysarthria is a motor inability to speak
Which areas are affected in global aphasia?
Both Wernicke’s and Broca’s areas are affected, resulting in nonfluent aphasia and impaired comprehension.
Poor repetition but fluent speech with intact comprehension is characteristic of _____ (global/conduction) aphasia.
Conduction aphasia
Which artery supplies the anteromedial surface of the brain?
Anterior cerebral artery
The middle cerebral artery supplies which surface of the brain?
Lateral surface
The posterior cerebral artery supplies the _____ and _____ surfaces of the brain.
Posterior and inferior
A patient presents with symptoms consistent with those of an acute stroke: he is unable to move his leg or foot. What artery in the brain may be occluded?
The anterior cerebral artery; the contralateral medial surface of the frontal cortex is infarcted
A patient presents with symptoms that are consistent with those of an acute stroke: he is unable to feel or move one arm and half of his face. What artery in the brain may be occluded?
The middle cerebral artery
What artery supplies both Wernicke;s and Broca;s speech areas?
The middle cerebral artery
What is the most common site for an aneurysm of the circle of Willis? What type of sign or symptom is this most likely to cause?
An aneurysm in the anterior communicating artery; visual field deficits
An aneurysm in what artery of the Circle of Willis may cause cranial nerve III palsy?
The posterior communicating artery
What arteries supply the internal capsule, the caudate, the putamen, and the globus pallidus?
The lateral striate
The divisions of which artery make up the lateral striate?
The middle cerebral artery
What are the symptoms of an isolated stroke of the posterior limb of the internal capsule?
Contralateral hemiparesis
What symptoms are expected in a patient who suffered a watershed infarct?
Upper leg and upper arm weakness; defects in higher-order visual processing
A patient presents with acute motor and sensory deficits of the lower leg and foot. Which cerebral artery could be blocked?
The anterior cerebral artery
What are the symptoms of an anterior spinal artery stroke?
Contralateral hemiparesis of the lower extremities, decreased contralateral proprioception (medial lemniscus), ipsilateral paralysis of the hypoglossal nerve
What are the symptoms of an anterior inferior cerebellar artery stroke?
Ipsilateral facial paralysis, ipsislateral facial pain and temperature sense dysfunction, ipsilateral cochlear nucleus dysfunction, nystagmus, ipsilateral dystaxia
What are the symptoms of a posterior cerebral artery stroke?
Contralateral homonymous hemianopia with macular sparing (supplies occipital cortex)
A patient presents to the emergency room with contralateral loss of pain and temperature, ipsilateral dysphagia, hoarseness, decreased gag reflex, vertigo, diplopia, nystagmus, vomiting, ipsilateral Horner’s syndrome, ipsilateral ataxia, and ipsilateral loss of facial pain and temperature sense. You immediately recognize this as _____syndrome, which is caused by a stroke in which artery?
Wallenberg’s; posterior inferior cerebellar artery
A stroke patient with aphasia, sensory and/or motor dysfunction likely has a stroke affecting an artery of the _____ (anterior/posterior) circle of Willis.
The anterior circle
A stroke patient with coma, vertigo, visual field deficits, and/or ataxia likely has a stroke affecting an artery of the _____ (anterior/posterior) circle of Willis.
The posterior circle
Stroke involving the posterior inferior cerebellar artery results in which syndrome, characterized by nausea, vomiting, nystagmus, ipsilateral ataxia, and Horner’s syndrome?
Wallenberg’s syndrome
Which syndrome is associated with stroke involving the basilar artery?
Locked-in syndrome
Where are the two watershed zones in the brain that are the first areas to be affected in hypotensive states?
Between the anterior cerebral/middle cerebral arteries, and between the posterior cerebral/middle cerebral arteries
Which areas, damaged during in hypotensive episodes, result in upper leg and upper arm weakness, and defects in higher-order visual processing?
Watershed zones
What is the most common site of berry aneurysms?
Bifurcation of the anterior communicating artery in the circle of Willis
What are the neurological sequelae of a ruptured aneurysm?
Hemorrhagic stroke/subarachnoid hemorrhage
What type of aneurysm is associated with chronic hypertension?
Charcot-Bouchard microaneurysms; often found in the basal ganglia and thalamus
Adult polycystic kidney disease, Ehlers-Danlos syndrome, and Marfan’s syndrome are associated with which type of aneurysm?
Berry aneurysm
What are four important risk factors for aneurysm formation?
Advanced age, hypertension, smoking, race (blacks have higher risk)
What is the common presentation of epidural hematoma?
Head injury, followed by a lucid interval and then coma and death
What type of intracranial hematoma is commonly the result of rupture of the middle meningeal artery after temporal bone fracture?
Epidural hematoma
What type of intracranial hematoma is usually the result of the rupture of bridging veins?
Subdural hematoma
What type of intracranial hematoma usually occurs in elderly patients with a delayed onset of symptoms and has predisposing factors that include brain atrophy, shaking, and whiplash?
Subdural hematoma
A patient presents with a complaint of the worst headache of her life. She has a bloody spinal tap and dies within minutes of presentation. What type of hemorrhage does this patient have?
Subarachnoid hemorrhage
A rupture of a cerebral arteriovenous malformation typically results in what type of hemorrhage?
Subarachnoid hemorrhage
