INvestigations Flashcards
What are nerve conduction studies used for?
To assess peripheral nerves ofr damage
Purpose of an MRI in motor neurone disease
Rule out cervical cord compression and myelopathy
What do nerve conduction studies meaduer?
Speed of firing of a nerve
What is an EMG
Elctromyography - electrode measures electrical activity in a muscle to assess motor neuron health
Bedisde tests for neuro
Blood + urine
CK, U+Es, TFTs, ammonia
PERF/peak flow if any weakness esp global - 40-50 = normal
Lying/stnading BP is falling
Glucose
What can raised CK suggest
Myositis
Beyong neuro tests
ECG
CXR
CT head
What look for in CXR in neuro
- horners (apical tumour), paraneoplastic synrome or cord compression, sarcoidosis, TB
When do ECG in neuro
LOC/collapse,systemic muscle disease, antipscyhs etc
When do LP in neuro
If drowsy or any focal neuropathy
Confirm safe to do if sus meningitis/encephalitis - danger of cerebral oedema if bleeding
What dos T1 MRI show
White matter = white etc
Shows structure, abnormalities are dark
What does T2 MRI sow
Photo negative
ABnormaloiteis = bright white eg infarct
Can be lost in CSF as also bright
What does flair MRI head show
CSF is made dark so can identify inflam disease specifically even in areas of CSF otherwise blocked in T2
Features of MS on MRI
Punk rock/dawsons fingers of corpus callosum
LP in GBS
Protein high
LP in bacterial infection
Increased opening pressure >30
Turbid
Increased protein
Decreased glucose <0.4 CSF:serum ratio
+ gram stain
WCC - predominantly neutrophils
Viral infectionLP
Normal pressure, appearance, glucose
Normal to decreased protein
>0.6 glucose:CS ratio
WCC - lymphocytes predominant
SAH LP
Increased opening pressure
Bloody, xanthrochrmic or clear CSF
Increased protein
May have increase WCC
Why are EEGs more helpful in chidlren
More likely ot have abnormal EEG between events
Demyelinating vs axonal neuropathy effect on APs
Dem - slows Aps, reversible
Axonal - reduces APs smaller - more permanenet - metabolic
AI cna cause both
What see on EMG with inflammation
Small brief discharges with fibrillation
What seen in MND/motor nerve loss on EMG
Increaed apmplitude - bigger APS
Nerve projections are dying back so remaining nerves firing mroe
