Neuro Flashcards

1
Q

Frontotemporal dementia (Pick’s disease)

A

Atrophy of frontal and temporal lobes. Onset in 50’s and 60’s. Pick bodies: cytoplasmic inclusions of microtubule-associated protein tau. Apathy, socially inappropriate behavior. Autosomal dominant in 20%-40% of cases.

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2
Q

How do nondepolarizing NMJ blockers (e.g. vancuronium) present on train-of-four (TOF) stimulation?

A

TOF is used to assess the degree of NMJ block (a peripheral nerve is stimulated 4 times in quick succession and the response is recorded). Nondepolarizing NMJ blockers (e.g. pancuronium, vancuronium) cause a progressive reduction in the 4 responses (fading pattern).

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3
Q

How do depolarizing NMJ blockers (e.g. succinylcholine) present on train-of-four (TOF) stimulation?

A

TOF is used to assess the degree of NMJ block (a peripheral nerve is stimulated 4 times in quick succession and the response is recorded). Depolarizing blockers initially function by preventing repolarization of the motor endplate and show equal reduction in all 4 twitches (phase I blockade). Persistent exposure to succinylcholine will lead to a phase II blockage in which ACh receptors become desensitized and inactivated leading to a fading pattern on TOF.

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4
Q

What are the signs of uncal herniation?

A

Causes ipsilateral oculomotor nerve palsy with a fixed dilated pupil due to damage to the preganglionic parasympathetic fibers running on the outer portion of the 3rd cranial nerve.

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5
Q

How does a Chiari type I malformation present?

A

Usually presents during adolescence/adulthood with paroxysmal occipital headaches (due to meningeal irritation) and cerebellar dysfunction (e.g. dizziness and ataxia) due to compression of the cerebellar tonsils. It is due to underdevelopment of the posterior fossa, causing the cerebellar tonsils to extend down into the foramen magnum.

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6
Q

How do Chiari type II (Arnold-Chiari) malformations present?

A

More severe type of malformation - usually becomes evident in the neonatal period. Due to the underdevelopment of the posterior fossa, the cerebellum (vermis, tonsils) and medulla herniate through the foramen magnum. This leads to non-communicating hydrocephalus (usually due to aqueductal stenosis). Compression of the medulla may present as dysphagia, stridor and apnea. Patients often have an associated lumbar myelomeningocele, which may result in lower limb paralysis.

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7
Q

Which anti-epileptic is preferred for combination tonic-clonic and absence seizures?

A

Valproate

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8
Q

What is Ménière disease?

A

Caused by increased pressure and volume of endolymph. It causes recurrent vertigo, ear fullness/pain, and unilateral hearing loss and tinnitus.

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9
Q

Why is IV dopamine not able to reach the brain?

A

Because of tight junctions in the BBB composed of transmembrane proteins (e.g. claudins and occludins). L-DOPA (dopamine precursor) is able to cross, however, due to amino acid transporters at the blood-brain barrier.

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10
Q

What is akathisia?

A

Restlessness with inability to sit still

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11
Q

What area of the brain is damaged in Wilson’s disease?

A

Causes cystic degeneration of the putamen

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12
Q

During amniocentesis, which two markers are found to be elevated when a fetus has a neural tube defect?

A

Alpha-fetoprotein and acetylcholinesterase (both can leak out of the spinal canal into the amniotic cavity).

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13
Q

What is the treatment for neuroleptic malignant syndrome (NMS)?

A

Discontinuing the causative agent (e.g. antipsychotic) and give dantrolene (direct-acting msucle relaxant). Dantrolene can reduce muscle rigidity/contraction by antagonizing the ryanodine receptors, thereby inhibiting calcium ion release from the sarcoplasmic reticulum of skeletal muscle. Bromocriptine, a dopamine agonist, has also shown clinical benefit.

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14
Q

What are features of narcolepsy?

A

Charaterized by overwhelming urges to sleep. Commonly associated with cataplexy (sudden loss of muscle tone that occurs in response to intense [usually positive] emotions). Patients have shortened sleep latency and typically enter REM sleep almost immediately. There are often intrusions to REM sleep during sleep-wake transitions, including hypnagogic (upon falling asleep) and hypnopomic (upon awakening) hallucinations and sleep paralysis. Diagnosis can be confirmed by low CSF levels of hypocretin-1 or shortened REM sleep latency on polysomnography.

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15
Q

What is the consequence of damage to the subthalamic nucleus?

A

Contralateral hemiballism (a movement characterized by wild, involuntary, large-amplitude flinging movements involving the proximal limbs on one side of the body). This is due to loss of inhibition of the thalamus (the subthalamic nucleus decreases excitation of the globus pallidus internus, thereby reducing inhibition of the thalamus). Damage most commonly occurs in the setting of lacunar stroke as a consequence of long-standing HTN and diabetes.

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16
Q

What is chorea?

A

Involuntary, low-amplitude movements involving the distal limbs.

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17
Q

What does the neuroectoderm give rise to?

A

Central nervous system, preganglionic autonomic neurons, retina, and posterior pituitary.

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18
Q

What medications are effective for treating the spasticity associated with multiple sclerosis?

A

The spasticity associated with MS is due to loss of descending inhibitory control from the upper motor neurons resulting in lower motor neuron overactivity (increased tone and hyperreflexia). Baclofen, a GABA-B receptor agonist is effective monotherapy for treatment of spasticity. Tizanidine, an alpha-2 adrenergic agonist, is also effective and commonly used.

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19
Q

What is Werdnig-Hoffman syndrome?

A

It results from anterior cell horn cell damage. Lower motor neuron lesion signs are present (flaccid weakness, areflexia, muscle atrophy, and fasiculation - “floppy child” syndrome).

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20
Q

What is Eaton-Lambert syndrome?

A

It clinically resembles myasthenia gravis. It is a paraneoplastic syndrome associated with small cell lung carcinoma, and is explained by autoantibodies that react with presynaptic calcium channels and hamper release of ACh.

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21
Q

What effect do fluorinated anesthetics have on the vasculature of the CNS?

A

Decrease vascular resistance in the brain leading to increased cerebral blood flow. It is an undesirable effect as it results in increased intracranial pressure.

Other effects are: myocardial depression that decreases CO (causes hypotension), respiratory depression, decreased GFR, decreased renal plasma flow, and decreased hepatic blood flow.

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22
Q

What are lacunes?

A

Small cavitary infarcts (liquefactive necrosis) located within the basal ganglia, posterior limb of the internal capsule, pons, and cerebellum. They result from occlusion of small penetrating arteries that supply the deep brain structures (e.g. lenticulostriate arteries), most commonly in the setting of chronic uncontrolled HTN or DM. Lipohyalinosis (hyaline thickening of the vascular wall with foamy macrophages) and microatheromas (atherosclerosis within the intimal layer of a penetrating artery near its origin off the parental vessel) are believed to be the primary cause of lacunar infarcts.

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23
Q

What are the manifestations of Wernicke encephalopathy?

A

Ataxia, nystagmus, ophthalmoplegia, and anterograde amnesia. The chronic effects of thiamine deficiency lead to Korsakoff psychosis, which is characterized by anterograde and retrograde amnesia, apathy, lack of insight, and confabulation.

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24
Q

What is the drug entacapone?

A

An COMT inhibitor used to treat Parkinson’s. COMT peripherally methylates levodopa, limiting its half-life. Entacapone can be added to levodopa/carbidopa therapy in patients that experience end-of-dose “wearing off” periods because the drug produces more stable levodopa plasma concentrations.

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25
Q

What is Gerstmann syndrome?

A

A constellation of: agraphia (inability to write), acalculia (inability to carry out mathematical calculations), finger agnosia (inability to identify individual fingers on the hand), and left-right disorientation. It is due to damage to the angular gyrus of the dominant parietal lobe, a brain region supplied by the middle cerebral artery.

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26
Q

How is restless leg syndrome treated?

A

Dopamine agonists (e.g. ropinirole, pramipexole), avoidance of aggravating behaviors (e.g. alcohol, sleep deprivation), and supportive measures (e.g. leg massage, exercise, heating pads).

Iron deficiency is also common in RLS; low iron levels have been found in the substantia nigra of patients with RLS, even in the absence of systemic iron deficiency.

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27
Q

What are the 2 most common manifestations of vitamin E deficiency?

A

Neuromuscular disease and hemolytic anemia. Due to oxidative damage to cell membranes (vitamin E is an anti-oxidant). The cells most susceptible to oxidative damage are neurons with long axons (due to large membrane surface area) and erythrocytes (due to high oxygen exposure).

28
Q

What is first-line medical treatment for trigeminal neuralgia?

A

Carbamazepine (neuroleptic agent that reduces neuronal high-frequency firing by reducing the ability of sodium channels to recover from inactivation). Side effects include bone marrow suppression and SIADH.

29
Q

What is the source of bleeding in intraventricular hemorrhage (IVH), a common complication of prematurity in which hemorrhage occurs into the lateral ventricles?

A

The germinal matrix. It occurs most frequently in infants born before 32 weeks gestation and/or with birth weight < 1500 g, and almost always occurs within the first 5 postnatal days. It can be clinically silent or present with an altered level of consciousness, hypotonia, and decreased spontaneous movements. Symptoms of catastrophic bleeding include a bulging anterior fontanelle, hypotension, decerebrate posturing, tonic-clonic seizures, irregular respirations, and comma.

The germinal matrix is a highly cellular vascularized layer in the subventricular zone from which neurons and glial cells migrate out during brain development. It contains many thin-walled vessels lacking the glial fibers that support other blood vessels throughout the brain. Between 24 and 32 weeks of gestation, the germinal matrix becomes less prominent and its cellularity and vascularity decrease, reducing the risk for IVH.

30
Q

What is the appearance brain biopsies in patients with HIV-associated dementia?

A

Microglial nodules (activated macrophages and microglial cells form groups around small areas of necrosis). Damage is believed to occur from inflammatory cytokine release by macrophages/microglial cells.

31
Q

What is the Golgi tendon organ?

A

Sensory receptors located at the junction of the muscle and tendon that are innervated by a group of Ib sensory axons. GTOs are connected in series with the contracting extrafusal skeletal muscle fibers. When a muscle contracts, the increased tension is transmitted through the tendon, activating the GTO in the process. Ib sensory axons contact inhibitory interneurons in the spinal cord, which in turn synapse with the alpha motor neurons that innervate the same muscle. This means that excessive muscle force (e.g. lifting too much weight) will cause muscle relaxation, thus protecting the muscle fibers.

32
Q

What are intrafusal muscle fibers?

A

Sensory receptors connected in parallel with extrafusal muscle fibers. They are innervated by group Ia and group II sensory axons and are sensitive to changes in muscle length, so that stretching of the muscle will cause reflexive contraction. This stretch reflex is what is tested with deep tendon reflexes. There is a monosynaptic reflex activation of the alpha motor neuron of the same muscle, causing contraction that resists the stretch.

33
Q

What kind of head injury do babies suffer from in “shaken baby syndrome”?

A

Subdural hematoma due to tearing of the bridging veins.

34
Q

Lesions to the left frontal lobe cause what behavioral changes?

A

Apathy and depression

35
Q

Lesions to the right frontal lobe cause what behavioral changes?

A

Disinhibited behavior.

36
Q

What is the principal site of norepinephrine synthesis in the brain?

A

The locus ceruleus (pair of pigmented brainstem nuclei located in the rostral pons near the lateral floor of the fourth ventricle).

37
Q

What is the most common brain complication of Wilson’s disease?

A

Basal ganglia atrophy

38
Q

What is the most common cause of spontaneous lobar hemorrhage in patients >60 years old?

A

Cerebral amyloid agniopathy (consequence of beta-amyloid deposition in the walls of small-to-medium-sized arteries, resulting in wall weakening an predisposition to rupture). Hemorrhage tends to be recurrent and most often involves the occipital and parietal lobes.

39
Q

What is the effect on neurotransmitters in the CNS in the presence of increased serum ammonia?

A

Increased inhibitory neurotransmitters (e.g. GABA) and impaired excitatory neurotransmitter release (e.g. glutamate, catecholamines)

40
Q

What pathway is the lateral geniculate a part of?

A

The visual pathway

41
Q

What pathway is the medial geniculate a part of?

A

The auditory pathway

42
Q

What pathway is the inferior colliculi a part of?

A

The auditory pathway

43
Q

What is hypoxic-ischemic encephalopathy?

A

Due to profound systemic hypotension (e.g. due to cardiac arrest or shock). Patients develop bilateral wedge-shaped strips of necrosis over the cerebral convexity, parallel and adjacent to the longitudinal cerebral fissures. This occurs most often in watershed areas of the brain.

44
Q

What neurotransmitter is there a deficiency of in Huntington disease?

A

GABA (loss of GABA-containing neurons in the caudate and putamen)

45
Q

What structures absorb CSF out of the subarachnoid space?

A

The arachnoid granulations. Theses allow CSF to flow into the venous system.

46
Q

What is the flow of CSF?

A

Lateral ventricles → interventricular foramen of Monro → the third ventricle → cerebral aqueduct → the fourth ventricle → the foramina of Luschka and Magendie → subarachnoid space

47
Q

Damage to what part of the brain results in hemineglect?

A

The parietal association cortex (particularly in the nondominant hemisphere)

48
Q

How can some cerebellar hemangioblastomas cause polycythemia?

A

Some can produce erthropoietin

49
Q

What are the primary serotonergic (serotonin-releasing) neurons in the CNS?

A

The neurons in the raphe nuclei of the brainstem (in midbrain, pons, and medulla).

50
Q

Damage to what portion of the brainstem causes decerebrate (extensor) posturing?

A

Damage to the brainstem at or below the level of the red nucleus (e.g. midbrain tegmentum, pons). This is due to loss of descending excitation to the upper limb flexors (via the rubrospinal tract) and extensor predominance (due to unopposed vestibulospinal tract output).

51
Q

Damage to what portion of the CNS causes decorticate (flexor) posturing?

A

Structures above the red nucleus in the midbrain (e.g. cerebral hemispheres, internal capsule).

52
Q

What measure can be used when ventilating a patient to decrease intracranial pressure caused by cerebral edema?

A

Hyperventilation leading to decreased PaCO2. This triggers vasoconstriction of cerebral vessels, thus leading to a reduction in ICP in patients with cerebral edema.

53
Q

What is the typical presentation for idiopathic hypertension (pseudotumor cerebri)?

A

Young obese women with daily headache, symmetric papilledema, and transient visual disturbances. This is related to impaired cerebral venous outflow and elevated intracranial pressure.

54
Q

What causes papilledema?

A

Impaired axoplasmic flow within the optic nerves, causing bilateral optic disc edema. Due to increased ICP which is transmitted through the CSF in the subarachnoid space, which is continuous with the optic nerve sheath.

55
Q

What medication should be given to patients following a subarachnoid hemorrhage to prevent cerebral vasospasm?

A

Calcium channel blocker, particularly Nimodipine

56
Q

What areas of the brain are most susceptible to damage from global cerebral ischemia (too little oxygen content getting to the brain usually due to MI)?

A

The hippocampus is the most vulnerable. The neocortex and the Purkinje cells of the cerebellum are also vulnerable.

57
Q

What is Sturge-Weber syndrome (aka encephalotrigeminal angiomatosis)?

A

Rare congenital neurocutaneous disorder characterized by the presence of cutaneous facial angiomas as well as leptomeningeal angiomas. It is associated with mental retardation, seizures, hemiplegia, and skull radiopacities. Skull radiographs may show characteristic “tram-track” calcifications.
STURGE: Sporadic, port-wine Stain; Tram track calcification (opposing gyri); Unilateral; Retardation; Glaucoma, GNAQ gene; Epilepsy

58
Q

What is a potential neurological complication that may be seen in patients with long-standing rheumatoid arthritis who undergo endotracheal intubation?

A

Cervical spine subluxation (vertebral malalignment). RA frequently involves the cervical spine and causes joint destruction. The atlantoaxial joint is most commonly involved in subluxation due to its relatively high degree of mobility of the atlas (C1) relative to the axis (C2). Subluxation causes compression of the spinal cord which initially will cause flaccid paralysis and decreased reflexes due to spinal shock. The paralysis eventually becomes spastic as spinal shock resolves over the ensuing days to weeks.

59
Q

What vitamin deficiency (besides B12) resembles Friedreich ataxia?

A

Vitamin E deficiency. Degeneration of the spinocerebellar tract (ataxia), degeneration of the dorsal columns (loss of position and vibration sense), and peripheral nerve degeneration (loss of deep tendon reflexes).

60
Q

What are Charcot-Bouchard aneurysms?

A

Associated with hypertension and occur in the basal ganglia, cerebellum, thalamus and pons (deep brain structures)

61
Q

Where is the chemoreceptor trigger zone located?

A

The dorsal surface of the medulla at the caudal end of the fourth ventricle in a region known as the area postrema. The area postrema receives blood from fenestrated vessels (absent BBB), which allows it to sample chemicals circulation in the blood.

62
Q

What is the length constant and how does it relate to multiple sclerosis?

A

It is a measure of how far along an axon an electrical impulse can propagate. It is decreased in MS due to demyelination.

63
Q

What are the symptoms of a pineal gland mass?

A

Obstructive hydrocephalus (aqueductal stenosis) causing papilledema, headache and vomiting; dorsal midbrain (Parinaud) syndrome due to compression of the pretectal region of the midbrain (limited upward gaze with a downward gaze preference, bilateral eyelid retraction, and pupils that react to accommodation but not to light).

The most common pineal mass is a germinoma (arises from embryonic germ cells)

64
Q

What space do cavernous hemangiomas bleed into?

A

Intraparanchymal bleeding because they common occur in the brain parenchyma

65
Q

What is the probable mechanism behind tardive dyskinesia?

A

Upregulation of dopamine receptors in response to long-term dopamine suppression (e.g. first-generation antipsychotics). This causes a compensatory supersensitivity of postsynaptic dopamine receptors.

66
Q

What neurons are unmyelinated (i.e. group C nerve fibers)?

A

Autonomic postganglionic neurons, the afferent neurons that conduct heat sensation, the afferent neurons that transmit slow-onset dull burning or visceral pain, and first order bipolar sensory neurons on olfaction.