Nervous System Disorders Flashcards
What are of the brain is most affected by Alzheimer’s disease?
Hippocampus and cortex
What area of the brain is affected by Parkinson’s disease?
The dopamine producing substantia nigra
What part of the brain is affected by Vitamin B12 deficiency?
Dorsal columns and corticospinal tracts
What reaction of
neurons to injury involves red neurons that lack nissl?
Acute neuronal injury
What reaction of neurons to injury involves central chromatolysis?
Axonal injury
This reaction indicates crisis
The changes that occur in the distal axon during neuronal injury?
Wallerian degeneration
What cells are associated with infections such as polio, viral encephalitis and rabies?
Negri bodies
What is the wear and tear pigment that accumulates in neurons due to age and chronic hypoxia?
Lipofuscins
What disorder is associated with Lewy bodies?
Parkinson’s disease
What is associated with neurofibrillary tangles and beta amyloid plaques?
Alzheimer’s
Cherry red spot is associated is associated with what metabolic storage disease?
Tay Sachs and Niemann-Picks
What is the function of astrocytes?
Repair and produce glial scars
What is the function of micro glia?
Phagocytes of the CNS that increase in response to injury and infection
What is the function of oligodendrocytes?
Produce myelin for the CNS
They can wrap multiple axons (unlike Schwann cells of the PNS)
What is a common disease that affects the oligodendrocytes?
MS
What is the most common cause of brain edema? What are two other possible causes?
Vascular (vasogenic) edema and swelling
Could also be SOL or cytotoxic (increased cell water due to injury)
How does vascular edema lead to brain edema?
Vascular edema leads to increased vascular permeability that can leak into the brain and cause swelling
What are contributing causes of edema?
- infection
- ischemia
- trauma
- metabolic disturbances
What happens to the CSF and ventricles in hydrocephalus?
Volume of CSF increases
Ventricles dilate
What is it called when ventricles are expanded secondary to atrophy of the brain (CSF pressure is not increased)?
Hydrocephaly ex vacuo
Hydrocephalus ex vacuo is often seen in what conditions?
Brain atrophy due to alcohol abuse or Alzheimer’s disease
What is obstructive hydrocephaly?
Non-communicating, i.e. CSF does not reach subarachnoid space due to INTERNAL blockage
What are some possible causes of obstructive hydrocephaly?
- Tumors, abscess or other SOL
- scarring/obstruction of ventricular system
What is communicating hydrocephaly?
CSF enters the subarachnoid space but the circulation or absorption is blocked EXTERNALLY
What are some causes of communicating hydrocephaly?
- Scars of arachnoid granulation and/or meninges from bacterial meningitis or hemorrhage
- thrombi, neoplasms or other obstruction of cerebral (dural) venous sinuses and associated veins
What are early manifestations of increased intracranial pressure?
Headache
Mental dullness
Nausea
Vomiting
What is papilledema?
Swelling of optic disc due to compression and obstruction of central retinal vein
What causes distortion of the cranial vault and vertebral columns and can injure underlying structures?
penetrating/crushing Trauma
Interstitial bleeding due to blunt trauma?
Contusion (bruise)
Ex: coup/counter coup
Tearing of brain surface with bleeding into surround region?
Laceration
This is a closed head injury that causes edema and swelling
Common closed head injury in the absence of bleeding?
Concussion
What is meningitis?
Infection of the meninges and CSF
When severe, what are systemic sign of meningitis?
Stiff neck Headache Photophobia Rash Fever
What disease is characterized by purulent (septic) exudates in the meninges?
Acute pyogenic (bacterial) meningitis
Which is more severe: viral/lymphocytic or bacterial/pyogenic meningitis?
Pyogenic
What is the most common meningitis in adolescents and young adults?
Neisseria meningitidis (meningococcus)
What are som opportunistic pathogens that can cause acute pyogenic meningitis in immunodeficient people?
E. Coli
H. Influenzae
Strep. Pneumonia
What disease is characterized by elevated lymphocytes and proteins in the CSF and is aseptic?
Acute lymphocytic (viral) meningitis
What are some possible viruses that can cause acute lymphocytic meningitis?
Mumps
Echo virus
Epstein Barr
Herpes simplex II
What disease is characterized by increased mononuclear cells and protein in the CSF as well as subarachnoid space being filled with exudates that become fibrotic?
Chronic meningitis
Which type of meningitis causes insidious and progressive headaches, malaise, vomitting?
Chronic meningitis
What are some possible causes of chronic meningitis?
- TB
- Fungi such as histoplasmosis
- Brucellosis, a slow acting bacteria
What is the most common type of encephalitis?
Viral
The turning of all or part of an organism in a particular direction in response to an external stimulus.
Ex: what determines which neurons or parts of the brain are affected (selected) by encephalitis
Tropism - selectivity is poorly understood
Examples of disease that cause encephalitis
- arbor virus
- childhood infections such as measles, rubella, chicken pox
- HSV I and II
- poliomyelitis
- rabies
What is the most common epidemic form of viral encephalitis?
Arbor virus
An unconventional agent that causes encephalopathy and is characterized by microscopic vacuolization of brain tissue known as spongiform degeneration.
Prions
Subacute spongiform encephalopathy from infection with prions that causes extensive atrophy of areas of gray matter
Creutzfeldt Jacob disease
What prion disease can be acquired by consuming infected animals?
Mad cow disease aka bovine spongiform encephalopathy
Focal bacterial infection that can be caused by hematogenous dissemination and local extension
Abscess
What are some causes of abscesses in the CNS?
- sinus infection
- dural venous sinus infection
- penetrating injury
- surgery
Focal nodular infection consisting of macrophages, giant cells, etc. that leads to local, expansive and destructive lesions
Granulomas
What is the most common cause of granulomas in the CNS?
TB when it extends to the meninges
Fungi and syphilis are other causes
Collapse of vertebral bodies as seen in Pott’s disease (TB of the spine) leads to what finding?
Gibbous deformity
What are other common names for stroke?
Apoplexy
CVA - cerebrovascular accident
Focal loss of neurological function of vascular origin that lasts more than 24 hours and/or leads to death
Stroke
Sudden focal and reversible neurological (sensory and motor) disturbances due to disruption of blood supply (often emboli) that last less than 24 hours
TIA transient ischemic attacks
What is the most common cause of stroke?
ischemic infarcts (focal loss of neurological function due to vascular origin) accounts for 75-90% of strokes
Ischemic infarcts are mostly caused by what?
Atherosclerotic disease
Other than atherosclerotic disease, what are the other causes of ischemic infarcts?
- inflammatory arthritis
- arterial spasm
- dissecting aneurysm
What are atherosclerotic lesions associated with ischemic infarcts?
Thrombi
Fragments of atherosclerotic plaques that are carried into smaller vessels
Emboli
Ischemia of the entire brain (usually caused by hypotension events such a heart failure or shock) generally causes what?
Ischemic encephalopathy
Where are ischemic encephalopathy infarcts found?
Can involve entire brain or may be limited to more susceptible parts or in the “watershed” regions of the brain and spinal cord
What are the two types of spontaneous (non traumatic) hemorrhages?
- Intracerebral
- Subarachnoid
What is the peak incidence of intracerebral hemorrhage?
60 years
Where are common locations of intracerebral spontaneous hemorrhage?
- basal ganglia
- internal capsule
- brain stem
What accounts for over 50% of brain hemorrhage cases?
Hypertension
Other than intracerebral hemorrhage, what are CNS effects of hypertension?
- arteriolar sclerosis with occlusion of small penetrating arteries and arterioles causing lacunar infarcts
- rupture of small penetrating arteries giving rise to slit hemorrhages
- acute hypertensive encephalopathy
- multi-infarct dementia
What is the most common cause of subarachnoid hemorrhage?
Rupture of congenital berry aneurysms
Where are berry aneurysms located?
Circle of Willis
What is typically caused by rupture or lacerations of the middle meningeal artery?
Epidural hematoma
What is the “lucid interval”?
The absence of neurological manifestations during the first few hours after epidural hematomas?
What is typically associated with rupture of small communicating veins between cortex and dural venous sinuses that accumulates in a potential space between the dura and arachnoid?
Subdural hematoma
What are the clinical symptoms present with Parkinsonism?
- festinating gait
- pill-rolling tremor
- mask-like facies
Spontaneous onset of Parkinsonism in the absence of exposure to toxic agents that commonly begins in middle age and progresses slowly
Idiopathic Parkinson’s disease (paralysis agitates)
What type of Parkinsonism is more common in younger subjects and is the result of exposure to dopamine antagonists, vascular disease or repeated head trauma?
Parkinsonism secondary to encephalitis
Characterized by depletion of substantia nigra with formation of neurofibrillary tangles
Condition associated with degeneration of cortical neurons and substantia nigra resulting in dementia and Parkinsonism.
Diffuse Lewy body disease
Loss of cortical function leading to profound dementia, progressive memory loss and motor dysfunction is characteristic of what disease?
Alzheimer’s
What are the characteristic microscopic features of Alzheimer’s disease?
- increased neuritic plaques (neurofibrillary tangles and amyloid plaques) in the cerebral cortex as well as granulovacuolar degeneration
What is a common cause of death in Alzheimer’s?
Aspiration pneumonia due to decreased motor function
What is ex vacuo?
Ventricular dilation mainly in frontal, temporal and parietal regions of atrophied dementia brains
Upper motor neuron lesion results in what kind of paralysis?
Spastic
Lower motor neuron lesion results in what kind of paralysis?
Flaccid
Most common motor neuron disorder that affects both upper and lower motor neurons but generally does not affect sensory elements?
Amyotrophic lateral sclerosis (ALS)
In ALS, where is the loss of motor neurons most striking?
Anterior horn cells of spinal cord, cranial motor neurons and upper motor neurons known as Betz cells
What is the most common cause of selective demyelination in the CNS?
MS
What is the most common neurological disorder associated with young adults, especially women?
MS
65% of patients with MS exhibit was marker?
HLA antigens of the D class
Although the etiology of MS is not fully understood, what are 4 mechanisms that appear to contribute?
- host susceptibility: 1st order relatives of those with MS have 15x greater risk
- exposure to certain infectious agents
- higher temperature latitudes
- autoimmunity to components of the myelin sheath
The demyelinating plaques seen in MS are commonly found in what locations?
- optic nerve and chiasm
- periventricular white matter
- brain stem
- cerebral peduncles
- dorsal columns of spinal cord
What are the three clinical variants of MS?
- acute progressive
- chronic progressive
- relapsing-remitting
Listed in order of shortest to longest survival
Syphillis affects tha CNS during which stage?
Tertiary (15-350 years following primary infection) = neurosyphillis
What are the three CNS manifestations of tertiary syphillis?
- paresis
- tabes dorsalis
- meningeo-vascular lesions known as gummas
What is paresis as seen in neurosyphillis and what are the clinical effects?
Progressive neuronal loss with cerebral atrophy resulting in dementia, behavior change, tremors, memory loss and Argyll-Robertson pupil
What is tabes dorsalis as seen in neurosyphillis and what are the clinical effects?
Fibrosis and gliosis of posterior columns of spinal cord resulting in painful paresthesias, ataxia/loss of deep tendon reflex, Charcot joint bladder dysfunction
Primary tumors of the CNS are commonly derivatives of what cell type?
Glial cells
What is the difference between extra-axial and intra-axial tumors of the CNS?
Extra-axial tumors arise outside of the CNS
Intra-axial tumors arise from within the CNS
CNS tumors that arise from outside the CNS and cause compression on the brain and spinal cord such as pituitary tumors?
Extra-axial tumors
Intra-axial tumors of the CNS most often arise where in adults?
Supratentorial location in the cerebral hemisphere (70%)
Intra-axial tumors of the CNS most often arise where in children?
Intratentorial location in the cerebral hemispheres (70%)
There are three major classes of intra-axial CNS tumors. What are they?
- gliomas
- medulloblastomas
- neuroblastomas (although most are extra-axial, they can be intra-axial)
Medulloblastomas and neuroblastomas are more common in what age group?
Kids
What glioma is the most common intra-axial tumor?
Astrocytoma
What is associated with neurosyphillis meningeo-vascular lesions?
Chronic meningitis with scarring and obliterating arthritis
A small vascular tumor of the adrenal medulla that causes irregular secretion of epi/norepi leading to attacks of HBP, palpitations and HA.
Pheochromocytoma and type of neuroblastic tumor of the CNS
What vitamin deficiency are vegans at risk for, that causes myelin degeneration and loss of axons in the PNS?
Vitamin B12 (thiamine) deficiency
What is the distribution of neuronal damage in polyneuropathy?
Affects multiple neurons in wide patterns. Initially symmetrical and peripheral (glove and stocking distribution)
What is the most common cause of polyneuropathy?
Diabetes
What is the distribution of neuronal damage in mononeuropathy?
Affects single or isolated group of neurons
What causes mononeuropathy?
Localized mechanical factors or other isolated pathology such as compression or entrapment
In diabetic neuropathy, sensory fibers are most greatly affected, however autonomic fibers can also be affected in 20-40% of chronic diabetes. This contributes to what?
Bladder, bowel and cardiovascular disturbances, visceral pain and sweating anomalies
What are some common toxins that can cause neuropathy?
- diphtheria (exotoxins)
- lead
- mercury
- uremia
- arsenic
Bell Palsy is caused by inflammatory swelling and compression of which nerve?
CN 7, facial nerve
Most common acute paralytic disease with inflammatory mechanism in young adults
Guillain-Barré syndrome
Acute onset and rapid progression of weakness from distal to proximal muscle groups due to neuropathy, usually following acute influenza/pharyngitis in young adults?
Guillain-Barré syndrome
Spontaneous episodes of lightning pain affecting one or more divisions of CN 5 that may be precipitated by light stimulation of skin of face or mouth
Tic douloureux
