Head/Brain Diseases Flashcards
What headache does this describe: a person experiencing pain in the muscles of the region of the head and neck.
Tension headaches
What headache does this describe: a severe pain in the head, un-associated with the musculature of the head, but associated with vascular disturbances.
Migraine headache
What are tension headaches?
Primary headaches due to anxiety, stress, and tension. Characterized by tightness, pressure, or pain in the occipital or forehead area (bilateral)
What are migraine headaches?
Primary headaches with paroxysmal attacks of headaches (throbbing) often preceded by psychological or visual disturbances. It can be accompanied by nausea, vomiting, drowsiness.
What are the two types of migraine headaches?
Classical migraine - associated with a prodromal aura
Common migraine - not associated with a prodromal aura, but can be preceded with vague symptoms
What are the three theories for etiology of migraines?
- vasodilatory theory: extracranial arterial vasodilation during an attack
- inflammation of the dural membranes
- altered normal firing of brain neurons
What are cluster headaches?
Headaches with repeat occurances over weeks or months with a sudden onset of unilateral pain and short duration. The pain occurs several times per day, mostly during REM sleep.
Other symptoms: red eyes, lacrimation, rhinorrhea, stuffiness of nostrils, etc. (autonomic features)
What are sinus headaches?
Headaches that mostly localized to the frontal areas of the head and around the eyes. Bending over exacerbates pain. Often accompanied by nasal congestion and rhinorrhea.
How are tension headaches treated?
counseling, massage, heat application, rest, relaxation
non-narcotic analgesics, anxiolytic drugs
What are preventive treatments for migraines?
propranolol - decreases frequency and severity
methysergide - serotonin antagonist
amitriptyline
calcium channel blockers
What are non-pharmacologic treatments for migraine headaches?
exercise, relaxation, avoiding dietary triggers
What are the abortive treatments for migraines?
- salicylates and acetaminophen (mild cases)
- triptans
- ergotamine
- narcotic analgesics
What is the treatment for cluster headaches?
methysergide - prophylactic serotonin antagonist
can also use propranolol, amitriptyline, calcium channel blockers, and corticosteroids
What is the mechanism of ergotamine?
Alpha-adrenoreceptor antagonist that directly constricts vascular smooth muscle
it asks as a serotonin antagonist
What are symptoms of ergot poisoning?
vomiting, diarrhea, unquenchable thirst, tingling/itching/coldness of skin, rapid and weak pulse, confusion and unconsciousness, abortion in pregnant women
What is the mechanism of methysergide?
Serotonin antagonist that acts as a weak adrenolytic agent, vasoconstrictor, and uterine constrictor
What are the symptoms of methysergide toxicity?
retroperitoneal fibrosis, fibrous tissue adhesions on kidney/lung/heart/aorta/viscera
CNS effects (drowsiness, unsteadiness, weakness, etc)
What is the mechanism of -triptan drugs?
They activate 5-HT receptors in the nerve to reduce the release of 5-HT, leading to vasoconstriction of cranial blood vessels
What are oligodendrocytes?
Myelinating cells of the CNS, have perfectly round and dark nuclei with perinuclear halo
What do astrocytes look like?
oblong nuclei with fine chromatin and cytoplasm that blends in with background parenchyma
What is the appearance of microglia?
in “activated states” –> have thin, elongated, hyperchromatic nuclei
these are the resident macrophages of CNS
What is the appearance of the ependyma?
single layer of cuboidal/columnar ciliated cells that line the ventricular system and form part of the brain-CSF barrier
What are the effects and morphological features of acute neuronal injury?
occurs 12 hours after an acute, sustained neuronal injury and results in neuronal cell death
morphologic features: cell shrinkage, intensely eosinophilic (“red dead”) cytoplasm, pyknotic nucleus, loss of nucleolus
What are the effects and morphologic features of subacute/chronic neuronal injury?
long-standing neuronal injury as part of progressive diseases
morphologic: progressive cell loss of functinoally associated groups, leads to hyperplasia and hypertrophy of astrocytes
What are the morphologic features associated with axonal injury?
rounding up and ballooning of cell body, dispersion of Nissl substance peripherally, and peripheral displacement of nucleus with enlarged nucleolus
What are some examples of neuronal inclusions? Proteinopathies?
Neuronal inclusions - cytoplasmic or intranuclear
Proteinopathies - aggregates of misfolded proteins that accumulate in neurodegenerative disease (ex. lewy bodies in parkinsons)
What changes and morphologies are associated with astrocyte gliosis?
hypertrophy and hyperplasia of astrocytes in response to CNS injury
morphologic: enlarged, eccentric nuclei with abundant, eccentric, eosinophilic cytoplasm
What are alzheimer type 2 astrocytes?
astrocyte changes that occur with long-standing metabolic disorders (not Alzheimer’s disease)
morphologic features: enlarged nucleus, light chromatin, prominent nuclear membrane/nucleolus
What are rosenthal fibers? When do they occur?
morphologic features: thick and elongated, brightly eosinophilic, corkscrew-shaped structures in astrocytic processes
diseases: long-standing gliosis, slow growing tumors, some metabolic disorders of white matter
What is corpora amylacea?
Changes seen inaging or areas of long-standing injury, thought to represent degenerative changes in astrocytes
morphologic features: round, basophilic, concentrically lamellated structures prominent in areas of astrocytic end processes, may be calcified
What are the responses of microglia to injury?
- elongated shapes (“rod cells”)
- increased numbers
- microglial nodules (aggregates around areas of necrosis)
- aggregates around dying neurons (neuronophagia, prominant in polio and ALS)
What conditions lead to oligodendrocyte injury?
demyelinating disorders and leukodystrophies
What diseases are associated with oligodendrocyte inclusions?
progressive multifocal laukoencephalopathy, neurodegenerative diseases
What are ependymal granulations?
disruption of ependymal lining with proliferation of subependymal astrocytes and formation of pinched of ependymal canals
occurs as a nonspecific reaction to injury
What is vasogenic edema?
cerebral edema due to increased extracellular fluid which occurs when the normal BBB is disrupted, resulting in increased vascular permeability that can be localized or generalized
What are the macroscopic characteristics of cerebral edema?
flattening of gyri, narrowing of sulci, and compression of the ventricular system
What is cytotoxic edema?
cerebral edema due to increased intracellular fluid secondary to cell injury, leads to inability to maintain normal membrane ionic gradients
common etiologies: hypoxic-ischemic injury, metabolic derangements
What is noncommunicating (obstructive) hydrocephalus?
increased CSF volume in the ventricular system caused by blockage in the ventricles preventing CSF from reaching subarachnoid space
leads to enlargement of the ventricular system proximal to blockage
What is communicating hydrocephalus?
hydrocephalus where CSF in ventricles can communicate freely with the subarachnoid space but leads to enlargement of the entire ventricular system (due to increased production of CSF, scarring of arachnoid granulations, etc)
What are the effects of increased intracranial pressure?
decreased perfusion (which can further raise ICP), displacement of tissue, herniations
What is a subfalcine (cingulate) herniation?
herniation of the cingulate gyrus under the falx, can compress the ipsilateral anterior cerebral artery
What is a transtentorial (uncal) herniation?
Herniation of the uncus/medial temporal lobe through the free margin of the tentorium
can lead to compression of CN III, ipsilateral posterior cerebral artery, and ipsilateral cerebral peduncle
What are duret hemorrhages?
linear midline and paramedian hemorrhages that result from torn perforating vessels of the midbrain and pons
occurs with progression of the transtentorial herniation
What is a cerebellar tonsillar herniation?
life-threatening herniation of the cerebral tonsils through the foramen magnum with compression of vital cardiac/respiratory centers in the medulla
What do perforating arteries supply?
they branch off the circle of Willis and supply the deep gray and white matter structures (basal ganglia, diencephalon, and internal capsule)
What are causes of focal cerebral ischemia?
embolism from a distant source, in situ thrombosis (often due to atherosclerosis), inflammatory processes of vessels, pro-thrombotic conditions
What is global cerebral ischemia?
a condition also called diffuse hypoxic-ischemic encephalopathy, caused by generalized reduction in cerebral blood flow that may cause irreversible damage to CNS tissue
Which neurons are most susceptible to injury in global cerebral ischemia?
- pyramidal neurons in CA1 region of hippocampus
- cerebellar Purkinje cells
- pyramidal neurons in neocortical layers 3 and 5 (watershed areas)
What are the prolonged effects of global cerebral ischemia?
widespread neuronal death, liquefactive necrosis
What are the general characteristics of nonhemorrhagic infarcts?
nearly identical to focal and global ischemia
initially nonhemorrhagic infarcts can undergo hemorrhagic transformation
What are the macroscopic findings of acute nonhemorrhagic infarcts?
no abnormalities within the first 8 hours, after 8 hours can lead to subtle blurring of gray-white junctions
What are the macroscopic findings of subacute nonhemorrhagic infarcts?
prominent softening, blurring of gray-white junction, tissue becomes more gelatinous and friable
occurs between 2-10 days
What are the macroscopic findings of a resolving nonhemorrhagic infarct?
repair process begins with liquefactive necrosis that is gradually removed and leaves to progressive cavitation
occurs after 10+ days to several months
What are the macroscopic findings of a remote nonhemorrhagic infarct?
The repair process is complete and left with CSF-filled cystic cavity
occurs after several months
What are the microscopic findings of an acute nonhemorrhagic infarct?
no changes within 12 hours, “red dead” neurons appear at 12 hours and can persist for days, influx of neutrophils
What are the microscopic findings of a subacute nonhemorrhagic infarct?
macrophages (seen at 48 hours), reactive astrocytes and capillary proliferations appear at the periphery
What are the microscopic findings of a resolving nonhemorrhagic infarct?
repair process begins as liquefactive necrosis proceeds with removal of necrotic tissue by macrophages
What are the microscopic findings of a remote nonhemorrhagic infarct?
complete repair process, some macrophages remain
left with cystic cavity and rim of reactive astrocytes
What are lacunar infarcts?
small perivascular, ischemic, cavitary infarcts that are seen in hypertension
most often involve the putamen, globus pallidus, thalamus, internal capsule, deep white matter, caudate nucleus, and pons
What is vascular dimentia?
neurologic decline as a result of multiple, bilater gray and white matter infarcts that can mimic other neurodegenerative diseases
often due to multifocal vascular disease of different types
What are ganglionic hemorrhages?
deep gray and white matter hemorrhages, most often in the putamen/thalamus/pons/cerebellum, caused by hypertension
What are the macroscopic findings of ganglionic hemorrhages?
acute - central core of clotted blood with compression of surrounding parenchyma
subacute - resorption of hematoma, friable and gelatinous surrounding tissue
resolving - liquefactive necrosis and progressive cavitation and gliosis
remote - cavitary lesion with brown rim
What are the microscopic findings of ganglionic hemorrhages?
acute - central acute hemorrhage and “red dead” neurons
subacute - influx of hemosiderin and lipid-laden macrophages
resolving - removal of necrotic tissue by macrophages with progressive cavitation
remote - cavitary lesions lined by gliosis and hemosiderin-laden macrophages
What are lobar hemorrhages? Microscopic features?
intraparenchymal hemorrhages involving cerebral hemispheres, most often caused by cerebral amyloid angiopathy
microscopic features: rigid leptomeningeal and intracortical vessels, vessel walls with dense/glassy pink material, positive stain for beta-amyloid
What are secondary hemorrhagic infarcts?
hemorrhagic transformation of an initially non-hemorrhagic ischemic infarct
leads to petechial hemorrhages
What is the most common non-traumatic cause of subarachnoid hemorrhage?
saccular (berry) aneurysm
Where do saccular aneurysms most commonly form?
arterial branch points in the anterior circulation
What are the macroscopic and microscopic findings of saccular aneurysms?
macroscopic: wide or narrow-necked thin walled outpouching, usually at an arterial branch point
microscopic: saccular wall that lacks internal elastic lamina and smooth muscle media (instead made of thickened intima and adventitia)
What are the macroscopic and microscopic findings of vascular malformations?
macroscopic: mass of irregular, tortuous, “worm-like” vessels in the subarachnoid and/or intraparenchymal
microscopic: large caliber vessels involving the subarachnoid space and/or brain parenchyma
Cell injury in the central nervous system is characterized by all the following EXCEPT:
a) red dead neurons
b) gliosis
c) microglial nodules
d) ciliated columnar cells lining the ventricles
d) ciliated columnar cells lining the ventricles
The following areas are most sensitive to hypoxic-ischemic injury EXCEPT:
a) caudate nucleus
b) CA1 region of hippocampus
c) cerebellar Purkinje cells
d) watershed cortical areas
a) caudate nucleus
All of the following are true about cerebral infarcts EXCEPT:
a) remote infarcts are usually cystic
b) remote infarcts can be dated based solely on histopathology
c) macrophages are a prominent feature of subacute infarcts
d) lacunar infarcts originate from arteriosclerosis of deep perforating arterial vessels
b) remote infarcts can be dated based solely on histopathology
What is this?
Red dead neurons
What is this?
axonal reaction with central chromatolysis
C) 12 hours
B) hypertension
D) 2 years
All pathways using glutamate are ________; all pathways using GABA are ________.
excitatory; inhibitory
What is the mainr eceiving area of the basal ganglia?
Striatum
The cerebral cortex sends _________ __________ projections to the striatum in a somatotopic fashion.
excitatory glutamatergic
In the basal ganglia, somatosensory and motor areas project to the __________ and association cortex to the _________.
putamen; caudate
What is the primary role of the substantia nigra?
Regulating dopamine production to modulate the direct and indirect pathways
What is the path of the indirect pathway of the basal ganglia?
D2 efferents (striatum) project to external globus pallidus (inhibitory) –> projects to subthalamic nucleus (eGP inhibits STN, so STN is uninhibited since eGP activity is inhibited) –> projects to GPi and SNr (STN excites them) –> projects to venterolateral and ventral anterior nuclei of the thalamus then the cerebral cortex (inhibits them)
disinhibition of STN ultimately leads to inhibition of the motor cortex and dampening of motion
What is the path of the direct pathway of the basal ganglia?
D1 efferents project directly onto the GPi/SNr (inhibits them) –> projects to the VL nucleus of the thalamus (uninhibits it, leading to motion)
What is the effect of a lesion of the substantia nigra pars compacta?
disruption of the pathway –> results in loss of dopamine, loss of inhibitory effects on striatum –> increased inhibition of the GPe, disinhibition of the STN, and therefore GPi
excitation of the GPi is also enhanced by lack of inhibition via the direct pathway
ultimate effect: slow movement, lack of movement, parkinsonism
What changes in the basal ganglia pathway lead to dyskinesias and hyperkinetic movements?
STN and GPi become excessively inhibited and do not suppress unwanted movements
What are the general criteria for parkinsonism?
brady kinesia + one other feature (rigidity and/or tremor)
How is parkinson’s disease definitively diagnosed?
pathological confirmation of the presence of degeneration of SNc and other brain stem pigmented nuclei, and the presence of Lewy bodies
What are Lewy bodies?
histopathological hallmarks of parkinson’s disease
intracytoplasmic inclusion bodies found in SNc, locus ceruleus, dorsal nucleus of vagus, pigmented nuclei, and cerebral cortex
How is parkinson’s disease diagnosed clinically?
Clinical evaluation of symptoms with some imaging (MRI, PET and SPECT tracers, etc)
What are some other diseases that should be considered in the parkinson’s disease differential?
progressive supranuclear palsy
multiple system atrophy
dementia with lewy bodies
What is the treatment for parkinsonism?
Levodopa - a precursor to dopamine that is capable of crossing the blood brain barrier
Also treated with dopamine agonists, COMT-inhibitors, MAO-B inhibitors, amantadine, and deep brain stimulation
How is levodopa converted to dopamine?
it is converted by aminoacid decarboxylase
What is the role of MAO-B inhibitors in treatment of parkinson’s disease?
MAO-B inhibitors block reuptake of dopamine and enhance dopamine’s effect in the synapse
What are the long term effects of levodopa treatment?
can lead to motor complications and dyskinesias
What are the most common clinical features of parkinsonism?
bradykinesia (required)
tremor, rigidity, postural instability, premotor symptoms (hyposomia, constipation, etc) and nonmotor symptoms (anxiety, cognitive impairment, etc)
How is the diagnosis of Parkinson’s disease made?
Clinically - based on history, exam, and sometimes imaging to rule out other conditions that can mimic PD
What are the diagnostic criteria for multisystem atrophy?
autonomic failure, levodopa resistant parkinsonism, and cerebellar dysfunction
What is the “hot cross bun” sign?
cruciform hyperintensity in an atrophied pons in multisystem atrophy due to selective loss of myelinated transverse pontocerebellar fibers
What are the characteristic features of progressive supranuclear palsy?
downward gaze abnormalities, postural instability, unexplained falls, bradykinesia and rigidity (symmetrical), non-motor symptoms, pseudobulbar palsy
definite diagnosis: Tau neurofibrillay tangles/straight filaments on histopathology
What are the core clinical features of cortico-basal syndrome?
cortical dysfunction (dementia, asymmetric apraxia, alien limb phenomena, cortical sensory loss, visual neglect)
extrapyramidal dysfunction (asymmetric parkinsonism, action tremor, focal limb dystonia, myoclonus)
What is the “triad” associated with dementia with lewy bodies?
visual hallucinations, fluctuating cognition, parkinsonism
Which PD patients are ideal deep brain stimulation candidates?
tremor is a significant symptom
unpredictable off periods
responds well to levodopa
good surgical risk
What is a tremor?
involuntary, rhythmic, oscillatory, sinusoidal movement about a joint produced by contractions of reciprocally innervated antagonist muscles
Describe benign essential tremor.
- action-kinetic, postural, during voluntary movement, rarely at rest
- worse with anxiety, fatigue, temperture extremes, older age
What is chorea?
excessive spontaneous movements from a flow of muscle contractions that are “dance-like”: irregularly timed, randomly distributed, abrupt, and semi-directed
What is the treatment of chorea?
neuroleptics (dopamine receptor blockers)
dopamine depeleting agents
What is dystonia?
sustained, but not fixed muscle contraction that can cause twisting or repetitive movements and abnormal postures
What are tics?
sudden, brief, intermittent movements or utterances that are briefly suppressible and usually associated with an urge for the action
What is myoclonus?
brief, “lightening”-like muscle jerks