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