Diagnostics/PE/GA Flashcards
what are examples of abnormal spontaneous activity? (for electromyography)
- fibs and sharps (positives) - differ from indentation of electrode; single fibers - destabilization of sarcolemma membrane
- complex repetitive changes
- polyphasic repetitive waveforms (uniform frequency)
- does change frequency
most often chronic denervation +/- myopathies - Myotonic potentials
- seen with myotonia congenita and radiculopathies
- similar to complex repetitive discharges BUT wax and wane frequency (and increased amplitudes) = dive bomber potentials
what are examples of ‘normal’ spontaneous activity when conducting electromyography
- insertional activity
- irritation from needle advancement - miniature end-plate potentials
- needle close to NMJ = ‘end plate noise’ - End-plate spikes
- single normal myofiber depolarize completely leads to action potential - motor unit action potentials
- light anesthesia or compound action potential with range of electrode
what are the advantages of propofol and etomidate?
propofol - smooth recovery, decreased CBF/ICP preserving cerebral auto regulation, antioxidant properties, decrease vomiting
etomidate - minimal decrease BP, preserves CPP, decreased CMR, CBF, ICP
BUT
may alter epileptiform activity
what is the benefit of cord dorsum potentials?
can reward SC dorsum potentials and somatosensory evoked potential concurrently
what is a key feature of sensory nerve conduction velocity testing?
potential often appears polyphasic
why is ketamine contraindicated?
- increase rate of catechoalmines - increase cardiac output and increased BP
- increase CBF and cerebral metabolic rate in limbic
- decrease CBF/CMR in cortex
- prolonged recovery
what are some advantages of ketamine
- improved ICP in some studies with decreased need for vasopressors
- does not impair cerebral autoregulation
MUSCLE BIOPSIES
1- can use formalin?
2- common places to acquire?
3- order of samples obtained?
4- 2 types of techniques?
1- No formalin; freeze sample for enzyme histochem except 1st sample in formalin for e-microscopy (use biopsy clamp)
2- distal 1/3 of lateral head of triceps, vastus lateralis, cranial tibial (proximal 1/3) and temporalis
3- order : 1st one for e-microscopy
4-
percutaneous biopsy - local block, quick and less cost but not as good sample
OR
open muscle biopsy - anesthesia, more cost, but better orientation of fibers
Ptosis is related to paresis of what muscle
levator palpebral superiaris
Elevation of 3rd eyelid from what deficiency?
loss of pterygoid muscles
what is the flow of CSF?
lateral ventricle -> interventricular foramina -> 3rd ventricle -> mesencephalic aqueduct -> 4th ventricle ->
from 4th ventricle could go to:
1) subarachinoid space via lateral apetures
OR
2) central canal of SC
NERVE BIOPSY:
1- where to sample for generalized NM disease?
2- where to sample for sensory neuropathy?
3- what cranial nerve are described to be biospied?
1 - common fibular (peroneal): has motor, sensory, and autonomic
2- caudal cutaneous antebrachial in TL or caudal cutaneous sural PL
3- facial and trigeminal; recurrent laryngeal (not usually done); hypoglossal medial to digastricus
what are the branch names of the brachial plexus?
- brachiocephalic
- suprascapular
- subscapular
- lateral thoracic
- muscular branch
- axillary
- musculocutaneous
- radial
- long thoracic
- median
- ulnar
- dorsal thoracic
- pectoral
what is the site of spinal nerve root injury for brachial plexus usually? why?
intradural - where roots arise from spinal cord;
because it there is lack of well-defined epineurium and is weakest structure
Downside of cervical collection of CSF?
CSF slower and volume is less
What are normal CSF
- WBC
- TP
CSF normal WBC - 0-5 x 10^6/L
TP:
- cerebellomedullary cistern - <250mg/L
- lumbar cistern <450 mg/L
What nerve and spinal cord segments are tested with:
- Patellar
- Biceps
- Triceps
- Withdrawal TL vs PL
- Patellar: femoral (L4-L6)
- Biceps: musculocutaneous (C6-C8)
- Triceps: radial (C7-T2)
- Withdrawal:
1-TL (dorsal thoracic, axillary, musculocutaneous, median, ulnar, radial C6-T2)
2 - PL (sciatic L6-S1)
Sensitivity and specificity for PCR on diagnosing viral meningoencephalitis?
Sens - >95%
Speci - >99%
what are the 4 reasons you can’t rule out infectious meningoencephalitis with PCR of CSF?
- individual PCR insensitive?
- nucleic acids in CSF are at indetectable levels
- nucleic acids in CNS parenchyma, not in CSF
- disorder ‘triggered’ by pathogen that is not there
what inhalant is most recommended for neuro anesthesia?
sevoflurane
Describe formation of tympanic plexus
CN IX (glossopharyngeal) and caroticotympanic nerve
CN IX (PS) and (S) craniocervical ganglion carotid plexus
- preganglionic fibers to Parotid/Zygomatic glands
- postganglionic to Parotid gland sensory to middle ear cavity
- postganglionic S to go to dilator pupillae and nictating membrane
Which antibiotics have good BBB penetration?
GOOD:
3rd gen ceph
fluroquinolones
metronidazole
sulfonamides
chloramphenicol
trimethoprim
Which antibiotics have poor penetration of BBB?
BAD:
1st and 2nd gen cepha
aminoglycosides
clindamycin
vancomycin
what sections skin innervated by:
- fibular and tibial?
- saphenous?
fibular and tibial - dorsal and plantar paw
saphenous - medial pelvic limb
how does a patient walk with sciatic nerve paralysis?
plantigrade - tibial n dysfunction - during stance
paw misplaced on dorsal surface (fibular n dysfunction)
limb supported because femoral nerve intact to extend stifle joint in weight bearing
how do you calculate nerve conduction velocity?
m/s
= distance between (+) electrodes (mm)/proximal latency - distal latency (ms)
for muscle biopsy specimen processing:
name three ways to secure sample to enable cut on transverse plane?
- blocks (0.5 cm) on cork squares
- tissue embedding media - gum tragacanth
- tissue - T&K O.C.T. compound
What is the underlying result of FLAIR and STIR
FLAIR:
- fluid attenuated invasion recovery fluid suppressed
- T2 FLAIR - helps distinguish pure fluid with little protein from solid but high water-content lesions like edema
STIR:
-short tall inversion recovery
- fluid or solid tissues with high water hyperintense against dark fat (can work like T2W)
what is an M wave and what is its latency?
for motor nerve conduction velocity testing
- orthodromic (impulse travels in normal direction) propagation of action potentials along nerve, ach release @ NMJ junction and myofiber depolarization
- latency - marking point which baseline deflects in upward direction
Signs seen with myopathic syndrome versus neuropathic syndrome
myopathic:
- general weakness
- exercise intolerance
- stiff gait
- body tremors
- local/general atrophy - ‘percussion dimple contracutre’
- muscle pain, megaesophagus
neuropathic:
- motor - paresis/paralysis of structures, neurogenic atrophy; decreased to absent tone, muscle fasciculations
- sensory - hypalgesia, or hyperesthesia; CP deficits, abnormal sensation of face and trunk, limbs without atrophy; self mutilation, decreased to absent reflexes
what drug can be used to treat hypotension and to maintain CPP > 70?
phenylephrine IV CRI
what is the ‘clasp knife relfex’
what causes it
very difficult to flex up until certain point then suddenly resistance gone and can completely flex
UMN tract lesion
what is benefit of spectral fat saturation
ID fatty masses - can help distinguish contrast enhancement from natural hyperintense fat to ID lesions
what are functions of CN 1-4?
1 - olfactory: smell
2 - optic: vision
3 - oculomotor:
- motor to extraocular muscle
- parasympathetic to pupil (constrict)
4 - trochlear: motor to dorsal oblique
what are functions of CN5-8?
5 - trigeminal:
- motor to muscle of mastication (mandibular)
- sensory to face (ophthalmic, maxillary, mandibular branches)
6 - abducens: motor to lateral rectus and retractor bulbi
7 - facial:
- motor to muscles of facial expression
- parasym to lacrimal glands
- sensory to rostral tongue
8 - vestibulocochlear - hearing; balance
what is repetitive nerve stimulation ?
what is it useful for?
RNS - repeat supramax (+) of motor or mixed nerve while recording M waves from muscles innervated
test- helps diagnose junctionopathies (MG, botulism)
(RNS)
difference between decremental, facilitation, pseudofacilitation?
decremental - AUC and amplitude decrease
facilitation - AUC and amplitude increase
pseuodacilitation - AUC same and amplitude increase
what is purpose of single fiber electromyography?
to investigate physiologic status of end plate in NM junction transmission disorders (sensitive to diagnosing MG)
evaluates jitter - latency from stimulus to response varies with consecutive stimulation of single muscle fiber
nerve biopsy: tips of securring?
- dissect fat and fascia away
- can pin to balsa wood or tongue depressor
- suture to CTA
- suspend with weight
what stain is used for light microscopy? on nerves for biopsy?
toluidine blue
what are the 2 forms of assessing nerve root function? how are each explicitly used?
F- wave:
- long latency action potential (antidromic AP)
- lower amplitude, latency inversely related to M wave
- represents motor event - assess ventral nerve root and proximal part of motor/mixed nerves
H-reflex:
- electrically stretch reflex (tap tendon)
- afferent arm group 1a sensory fiber; efferent and motor neuron ventral gray column
- use low stimulus
- diagnose polyneuropathies, proximal nerve injury
what are minimum database tests for neuromuscular disease?
- CK - >10,000 U/L (muscular dystrophy, myopathies)
- electrolytes (especially to r/o hyper/hypokalemia
- lactate and pyruvate (measure rest and 10 min post exercise)
- urine myoglobin (to differentiate from Hg -> NH4SO4 test)
- thyroid screening
- acetylcholine receptor antibody
- others: 1) masticatory myositis serum ab against 2m. 2) infectious agents/tick diseases
Name the neurological grades 0 -> 5
0: tetraplegia or paraplegia w no deep pain
1: tetraplegia or paraplegia w no superficial pain
2: tetraplegia or paraplegia w nociception
3: nonambulatory tetraparesis/paraparesis
4: ambulatory tetraparesis with GP ataxia
5: spinal hyperesthesia only or no dysfunction
explain the cusing’s reflex
intracranial pressure increased leading to CPP decrease
CPP decrease leads to decreased CBF which increased catecholamine increase
the catecholamine increase leads to increase in MAP and stimulation of carotid bodies
stimulation of carotid bodies leads to decrease in HR
increase in ICP leads to decrease in HR but increase in systemic MAP
what are 2 syndromes of protozoal meningoencephalomyelitis?
what serology tests are needed to diagnose?
treatment?
prognosis?
meningoencphalitis - multifocal neuro signs; cerebellar
myositis - polyradiculoneuritis (<6 mo age)
T. gondii: IgM >1:64 means active infection
T. gondii IgG >1:64 support active
Neospora IgG >1:64 suspect
clindamycin/TMS; pyrimethamine
Guarded in young dogs and cats
What are the benefits of dexmedetomidine for neuro anesthesia?
- blunt sharp increase in HR to protect ICP
- cooperative sedation
- decrease ischemic cortical volume by 40% and helps with hemodynamics
- short extubation times
- less bleeding
- lower nausea and vomiting
what are options to help prevent spike in HR/BP with intubation
IV lidocaine or fentanyl to decrease sympathetic input
what are the benefits of opioids with neuro anesthesia?
doesnt alter cerebral vascular response to changes in PaO2 and PaCO2 and MAP
which near/skin areas innervated by:
median and ulnar
ulnar alone
radial
ulna and musculocutaneous
median and ulnar: palmar surface of paw
ulnar alone: lateral digit 5
radial: dorsal paws; craniolateral antebrachium
ulna and musculocutaneous: caudal and medial antebrachium and brachium
which matters make up leptomeninges? pachymeninges?
L - pia and arachnoid
P - dura and arachnoid
where is subarachnoid space? contains?
subarachinoid space - between pia and arachnoid - CSF
what is subdural space? contains?
subdural - between dura and arachnoid - blood vessels
