Quiz 5 Flashcards
Process that results when a nerve fiber is cut or crushed, where the part of axon separated from neuron’s cell body degenerates distal to the injury:
Wallerian degeneration
usu begins within 24-36 hrs of injury
PNS dz is divided into 2 main categories:
- mononeuropathies - affect single peripheral nerve
* polyneuropathies - more than one peripheral nerve, and often diffusely affect PNS
MC cranial mononeuropathies:
- VII (facial)
- V (trigeminal)
- III (occulomotor)
Acute idiopathic facial nerve neuropathy, aka _________ is the MC cranial nerve neuropathy. The main sx is:
Bell’s Palsy
unliateral facial weakness - abrupt onset preceded / accompanied by pain on the affected side.
Mb Hx of URI in the past 1-3wks
Bell’s palsy is an (upper/lower) motor neuron condition and affects the (upper/lower) face. It is thought to be post-infx or via direct viral infx, with _______ being the suspected etiologic agent.
lower
both
HSV1
85% of pts w/Bell’s palsy recover fully in 1 year. Clinical features assoc w/poor prognosis include:
- old age
- complete palsy (vs weakness)
- hyperacusis (sound sensitivity)
- altered taste
Distinctive facial pain syndrome in which pt experiences intense, paroxysmal pain, ranging from infrequent to dozens of times daily:
Trigeminal neuralgia (tic douloureux)
Trigeminal neuralgia mb caused by:
blood vessel compression of trigeminal n. roots at pons
if caused by tumor - called secondary TN
MC blood vessel responsible for trigeminal neuralgia:
superior cerebellar artery
Since they control most of the eye movements, cranial nerves ___ ___ and ___ are usu tested together.
CN III, IV, and VI
tested by EOMs
CN III palsy is characterized by:
“down ‘n out” sx - lateral, downward deviated gaze
Mononeuropathies of limb nerves are MC related to:
physical nerve compression:
- carpal tunnel syndrome
- ulnar neuropathy
- brachial plexus neuropathy
- peroneal neuropathy
- meralgia paresthetica
MC sx of Carpal Tunnel:
intermittent numbness of thumb/index/middle/1/2 ring finger
(often at night)
may lead to constant numbness, atrophy, weakness
Condition characterized by sensory symptoms in lateral cutaneous nerve distribution of the thigh, with combo of sensory loss, prickling paresthesia, and hypersensitivity over the anterolateral thigh:
Meralgia paresthetica
Meralgia paresthetica is usu attributed to:
compression of the lateral cutaneous n. by inguinal lig as it passes from retroperitoneum to anterior thigh.
(more common in obese)
MC peripheral neuropathy common in DM:
polyneuropathy -
- distal
- symmetrical
- sensorimotor
Classic diabetic neuropathy distribution:
“glove-and-stocking” - combo of sensory loss, numbness, and burning
______ and _____ to nerves mb the most important underlying cause of diabetic polyneuropathy, but another proposed mechanism is chronic _________ leading to accumulation of _______ and the depletion of _______ in the affected nerves, leading to altered conduction in axon.
ischemia and hypoxia
hyperglycemia
sorbitol
inositol
The chief pathologic finding in uremic neuropathy is ____________, which is most abundant in the most distal aspects of the PNS. Risk is related to duration and severity of _____________, and improvements are usu seen in:
axonal degeneration
renal failure
dialysis and renal transplant
MC immune or inflammatory polyneuropathy and MC cause of acute generalized paralysis in the US:
Guillan-Barre syndrome (GBS)
MC first sx of GBS:
prickling parasthesia - from feet, spreading up legs
Condition in which the fundamental pathologic event is stripping of myelin from axons by macrophages, which slows or blocks nerve impulse conduction, causing weakness and sensory loss:
chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)
(Similar/contrary) to GBS, the onset of CIDP is insidious, and autonomic and respiratory involvement is (common/unusual).
Contrary
unusual
usu pattern of CIDP is slow worsening over months, producing chronic moderate disability.
Polyneuropathy characterized by amyloid deposition in nerve:
Occurs in 2 settings:
amyloid neuropathy:
- systemic amyloidosis
- familial amyloidosis
dx by nerve biopsy
T/F: Neuropathy is usu the MC of disability in primary amyloidosis unlike familial amyloid patients where neuropathy is generally less severe.
false / opposite
MC cause of disability in familial amyloid pts.
T/F: Neurologic deficits that mb seen as a consequence of paraneoplastic syndromes are a result of metastasis to involved nerve(s).
false - are NOT a result of mets
believed to be immunologic response
Toxic neuropathies tend to begin ________ and progress over _______________.
distally
weeks to months
* from chemicals, drugs, natural compounds
Main feature of toxic neuropathy:
axonal degeneration
* biopsy not helpful *
Danish beer is supplemented with:
thiamine and pyridoxine - unlikely that deficiency is the cause of ethanol neuropathy (cause unclear)
Characteristic of chronic alcoholic neuropathy:
- distal
- usu painful (burning, stabbing)
- dec sensation in feet (mb hands)
- loss of ankle reflexes
- mild distal weakness
T/F: Drug-induced neuropathy is a common problem.
true - esp in a hospital-based practice!
careful drug Hx important in work-up
In some drug related neuropathies, the patient experiences the phenomenon known as “coasting”, which is:
neuropathy continues to worsen for weeks after exposure to the drug has ceased.
Peripheral neuropathy d/t lead exposure is predominantly (sensory/motor), with a predilection for the (upper/lower) limbs.
motor
upper
Polyneuropathy can be a manifestation seen in famine victims or as a result of ________ related to ________. Exact cause is unclear, although it is often though to relate to one of the __ vitamins.
malnutrition
malabsorption
B
Paralytic illness caused by neurotoxins of anaerobic, spore-forming bacterium:
Botulism - Clostridium botulinum
Botulinum neurotoxins work by:
inducing blockage of voluntary motor and autonomic cholinergic neuromuscular junctions -> prevent motor fiber stimulation
Infectious dzs assoc w/ PNS neuropathies:
- leprosy - MC
- HIV/AIDS
- lyme dz
- VZV
Most prevalent tick-borne illness in the US:
Lyme dz - named for Lyme, CT where outbreak was recognized in ‘75.
Vector - Ixodes spp. tick
T/F: B. burgdorferi is a gram-neg bacteria that is rapidly reproducing.
false
does not hold any stain - unclassified
slow reproducing - once in 12-24 hours!
Characteristic rash of Lyme dz:
erythema migrans - target lesion
T/F: Unlike pts with Bell’s palsy, BL facial neuropathy is MC in pts with Lyme disease.
TRUE
MC viral pathogen affecting the PNS:
VZV - usu after childhood exposure, virions lay dormant in dorsal root or cranial ganglia. Reactivation = shingles.
Classic herpes zoster (shingles) manifestation:
- dematomal pain
- vesicular eruption 3-14 days later
- last 7-10 days, area left depigmented, scarred
- mb weakness, sensory loss
Histopathology of herpes zoster:
- multinucleated giant cell
* nuclear accentuation
Herpes zoster ophthalmica is often preceded by a lesion:
on the tip of the nose (Hutchinson’s sign)
Examination of the ____ should be performed on all shingles pts with face/nose involvement, dt likelihood of ________.
eye
corneal ulceration
When shingles is assoc w/facial paralysis it is called:
Ramsay-Hunt syndrome
When Schwann cells (that myelinate axons) proliferate out of control, the resultant bundle of cells is called a:
schwannoma
benign but detrimental when tumor compresses nerve
Benign primary intracranial tumor of the myelin-forming cells of the vestibulocochlear nerve (CN VIII):
vestibular schwannoma - aka acoustic neuroma
Common, benign spindle cell tumor of peripheral nerves:
neurofibroma
MC nerve affected with neurofibroma type I:
CN VIII
unilateral, look for cafe au lait skin spots
Neurofibroma type II is the result of mutation of protein ______ and manifests with bilateral _____________.
merlin
neuromas and hearing loss
hallmark - usu around age 20
Histopathology of perineuromas:
- elongated cells
- parallel bundles
- no atypia
- rare mitotic figures
Malignant tumor that usu arises from major nerves in the neck, forearm, lower leg, or buttocks:
malignant peripheral nerve sheath tumor (MPNST)
50% assoc w/underlying neurofibromatosis / 50% de novo
Histopathology of MPNST:
- increased cellularity
* disordered arrangement
The brain devotes most of its volume and energy to processing received __________ and initiating/coordinating ___________.
sensory inputs
motor outputs
From outside in, the meningial layers are:
dura mater
arachnoid mater
pia mater
The CSF fills the space between which layers?
arachnoid and pia
Birth defects involving what organ are the MC?
brain
although defects leading to infant death it is #3, after heart and lungs
Absence of brain formation:
Anencephaly (neural tube defect)
Diminished forebrain size:
Microcephaly
Absence of gyri:
Agyri
Increased number of smaller than normal, shallow gyri:
Polymicrogyri
Enlarged abnormal gyri:
Macrogyri / pachygyri
Anencephaly has dropped to 1 in 10K incidence d/t:
maternal folic acid supplementation
Some causes of microcephaly:
- fetal alcohol syndrome
- trisomy 18 (Edward’s syndrome)
- congenital Rubella
- congenital HIV
persons w/Down’s have dec volume w/ disproportionate small cerebellum, larger sub-cortical grey matter
MC cause of hydrocephalus:
obstruction of normal CSF flow
* mb 2° to malformations, tumors, hemorrhage, infx
Failure of normal closure of the vertebral column and/or overlying skin over the dorsal aspect of the spinal cord:
Spina bifida
- occulta
- myelocele
- myelomeningocele
Spina bifida occulta:
missing a portion of a posterior vertebral body.
Meningocele:
herniation of the meninges but not cord.
Myelomeningocele:
herniation of the meninges and spinal cord.
100% of pts with myelomeningocele have:
tethered cord - result of scar tissue post surgical repair
AFP can be measured in:
- serum
- urine
- amniotic fluid
Maternal AFP is typically measured at:
14-16 weeks gestation
T/F: AFP is considered to be the fetal form of serum albumin.
true
the function of AFP in adults in unknown
Principle tumors that secrete AFP:
- non-seminomatous germ cell tumors
- neuroblastoma
- hepatoblastoma
- hepatocellular carcinoma
Maternal AFP elevation mb seen in:
- multiple gestation
- placental abruption (separation)
- neural tube defects
- abdominal wall defects
- miscalculation of gestational age
- MTHFR genetic variant mothers
Low maternal AFP mb seen in:
- Down syndrome
* Trisomy 18
T/F: Developmental deficits and brain injury in children with congenital heart disease is a serious problem and mb seen in more than 1/3 of these newborns.
true - In the U.S., ~30K are born/year with congenital heart dz, and ~50% will require open-heart surgery.
unclear if brain injury occurs prior/during/after cardiac surg.
Group of permanent disorders of the development of movement and posture, which cause activity limitation, attributed to non-progressive disturbances in the developing fetal or infant brain:
Cerebral palsy
- during pregnancy - 75%
- during birth - 10%
- after birth - 15%
Intrauterine development of CP has been assoc with :
maternal infx
- Strep. throat
- maternal CNS infx
After birth, CP mb caused by:
- severe jaundice
- encephalitis
- meningitis
- toxins (lead)
- physical injury (SBS)
- brain hypoxia
MC type of CP:
spastic - 70-80% of cases
At a cellular level, damage to the brain in spastic CP affects the nervous systems ability to receive ______________ in the brain area affected.
gamma amino butyric acid
The MC finding on autopsy of newborns / infants with CP is:
periventricular leukomalacia - PVL
necrosis around the ventricles d/t hypoxia and anoxia
Children with PVL have higher levels of:
- nystagmus
- strabismus
- optic nerve hypoplasia
- refractive error
Aseptic meningitis is a term for (non-/bacterial) meningitis, which the other is often called:
non-bacterial
bacterial = purulent meningitis
MC cause of meningitis:
viral infx - usu resolve w/out tx
2nd MC cause of meningitis:
bacterial infx - often results in death or brain damage
MC presenting sx of meningitis:
1st - Headache
2nd - neck stiffness
- rapidly spreading petechial rash mb 1st in MM *
MC bacterial cause of meningitis in neonates:
- E. coli **
- Streptococcus group B
- Listeria monocytogenes
MC bacterial cause of meningitis in infants/children:
- Neisseria meningococci **
- strep pneumoniae
- H. influenza (HiB) (peak@6-9mos)
MC bacterial cause of meningitis in adolescents/adults:
- Neisseria meningococci **
* strep pneumoniae
MC bacterial cause of meningitis in older adults (65+):
- Strep pneumoniae **
- Neisseria meningococci
- Listeria monocytogenes
- mycobacteria
If meningitis pt is immunocompromised, also test for:
- toxoplasmosis
- EBV
- CMV
- JC virus
- fungal infx
Who is at particular risk for infx by encapsulated organisms such a Neisseria meningitis and H. flu?
Pts without a spleen!!
CSF is typically drawn btw what spinal vertebrae?
Lumbar 3 and 4
Which strain is latex agglutination most sensitive for:
** H. influenza (HiB) ** also test for - strep pneumoniae - N meningitidis - E coli - GBS
Meningococcal meningitis (MM) is another name for:
Neisseria meningitidis meningitis
Histopathology of meningococcal meningitis:
- gram neg diplococci in a neutrophil
* prominent dilated blood vessels
Complications of MM:
- permanent brain damage
- possible mental retardation
- hydrocephalus
- deafness
- muscle paralysis
- myocarditis
- Waterhouse-Friderichsen syndrome
- death
Gross inspection of MM:
yellow-tan clouding of meninges d/t exudate (acute)
CSF analysis in bacterial meningitis shows:
- possible high WBCs w/PMN predominance
- low glucose
- usu gram + / culture +
Describe the rash of MM:
- mb first sx
- rapid spreading
- small irreg red/purple spots
- trunk/LE/mucous membranes/conjunctiva/palms/soles
HiB meningitis may follow a ____ and spreads:
URI
from resp tract to blood to meninges
Risk factors for HiB meningitis:
- recent URI/OME/sinusitis/pharyngitis
- family members w/HiB infx
- daycare
- Native American / Eskimo race
Pt who recover from HiB meningitis may have long term:
- hearing loss
- seizures
- mental retardation
- hydrocephalus
- learning disorders
- behavioral problems
- speech / language development abn
What is aseptic meningitis?
Pt with ssx of meningitis with negative CSF culture
- viral
- fungal
- TB
- meds
- epidural abscess
What two enteroviruses account for 1/2 of the cases of aseptic meningitis?
Coxsackie B and echovirus
others:
- VZV
- polio
- mumps
- rabies
- HIV
- HSV 1 and 2
- EBV
- CMV
HSV type ___ can cause meningitis in children, especially _______, and adults.
types 1 and 2
infants
______________ is a yeast that may cause meningitis, particularly in _____________ people.
Cryptococcus neoformans immunocompromised * AIDS * lymphoma * diabetes
MC life threatening fungal pathogen that infects AIDS pts:
cryptococcus neoformans
- soil fungi
- MC in Africa
- primarily affects lungs
- usu no neck stiffness
- mb papilledema (1/3)
Dx of Cryptococcal meningitis involves:
- yeast on CSF stain with INDIA INK
- CSF culture
- CSF + for cryptococcus antigen
Histopathology of cryptococcus neoformans:
** encapsulated cells (India ink) **
Most cases of viral encephalitis arise as a complication of:
common systemic viral infections (2-12 days post infx)
Name seasonal viral meningitis/encephalitis correlations:
- arboviruses - spring/summer
- enteroviruses - late summer
- mumps / varicella - spring
- HSV - not seasonal
MC cause of viral meningitis in children:
Previous MC cause:
Enteroviruses (present)
Mumps (past)
MC cause of viral meningitis in adults:
2nd MC:
** Enteroviruses **
HSV type 2
T/F: Enterovirus refers to the sx of infx.
false - refers to mode of transmission, mostly asx
MC cause of sporadic encephalitis in developed countries:
HSV
type 2 - almost all adult cases
type 1 - more commonly in infants, infx via vaginal birth
Encephalitis d/t HSV infx characteristically involves the _________ lobes.
temporal
Gold standard for dx of carcinomatous meningitis:
detection of tumor cells in CSF
MC non-hematologic cancers that mets to CNS:
- lung
- breast
- melanoma
mb also head/neck/GI/GU
MC histologic type of carcinomatous meningitis:
adenocarcinoma
MC cerebral sx in carcinomatous meningitis:
MC cranial nerve sx:
headache
diplopia
T/F: Fever is often present with carcinomatous meningitis.
false - rarely unless there is a supervening infx
Describe the protective and harmful characteristics of brain abscess.
Protective - area of infx becomes enclosed in a membrane.
Harmful - mass effect, puts pressure on surrounding tissue.
Histopathology of Aspergillus brain abscess:
slender hyphae which branch at 45° angles
Brain abscesses are MC in what decades?
Higher in what populations?
first 4
AIDS and other immunocompromised
T/F: In 80-90% of brain abscesses, only one organism is identified.
false - usu more than one
mb bacterial, fungal, or parasitic
MC organism found in brain abscesses:
gram stain MC in infants:
streptococcal
gram -
MC neuro-parasitic infx in humans is a CNS infx by larvae of the pork tapeworm, Taenia solium:
Neurocysticercosis
Neurocysticercosis has a worldwide distribution, but MC in:
- Central and Latin America
- Mexica
- Asia
- Africa
- Spain
- Portugal
- Eastern Europe
The only definitive host of T. solium is:
humans (pig is intermediate)
Describe the mechanism of neurocysticercosis infx.
pig ingests eggs, which grow in GI, burrow into circulation, and encyst in tissues/brain. humans ingest tapeworms and are infected.
* humans can be intermediate host also, if ingest eggs, which can then burrow into brain => neurocysticercosis
CT of neurocysticercosis:
multiple, small nodular, and annular areas of abn enhancement in brain parenchyma.
Diet not working?
swallow a tapeworm!
the end!!
