Investigations of MS Flashcards
(31 cards)
funcion of x ray
to detect skull fractures after head trauma
positioning for X Ray
AP
PA
Lateral
Function of computerised tomography
detect acute haemorrhage
assess depressed and comminuted skull fractures
can visual bleeding e.g. extradural haematomas, subdural haematomas, actively bleeding parenchymal haemorrhages, brain herniation
describe density in computerised tomography
white = most dense
black = least dense
process of cerebral angiography
catheter inserted in femoral artery and manouvered to carotid or vertebral origin
contrast injected with high pressure pump
benefits of cerebral angiography
- Disorders of the cerebrovascular circulation
- Aneurysm
- Arterio-venous malformation
- Transient ischaemic attack
- Cranial arteritis
- Vascular tumour (haemangioblastoma, angioma)
describe process of MRI
Magnetic field forces H+ protons in body to orient to that field.
radiofrequency is pulsed through patient protons spin out of equilibrium
current switched off and MRI detects energy released when protons re-align w/ magnetic field
MRI - map of proton energy within tissue
benefits of using T1 weighted MRI
Better contrast between gray and white matter
benefits of using T2 weighted MRI
scans better for oedema
what colour is; water, fat, bone, inflammation, muscle, spinal cord, cortex, white matter in T1 weighted MRI
water - dark
fat - bright
bone - dark
inflammation - dark
muscle - grey
spinal cord - grey
cortex - grey
white matter - bright (myelin or fat sheath in axons)
what colour is; water, fat, bone, inflammation, muscle, spinal cord, cortex, white matter in T1 weighted MRI
water - bright
fat - bright
bone - dark
inflammation - bright
muscle - dark grey
spinal cord - light grey
cortex - light grey
white matter - dark grey (myelin or fat sheath in axons)
absolute contraindications for MRI
Ferrous metallic foreign bodies - old gunshot shrapnel, older types of fracture fixation
implanted electrical medical devices - cochlear, pacemaker, insulin pump
pregnancy
claustrophobic
purpose of lumbar puncture
obtain CSF
Positioning for lumbar puncture
side lying knees to chest
needle in L4-L5
Precautions for lumbar puncture
- Raised CSF
- Tentorial herniation-coning
what is an elevated white cell count in CSF indicative of
metastatic tumour
what is an elevated erythrocyte cell count in CSF indicative of
encephalitis
what is an protein in CSF indicative of
polyradiculitis or guillain barre syndrome
what is the presence of oligoclonal bands in CSF indicative of
IgG synthesis - MS
Contraindications of lumbar puncture
- Raised intra-cranial pressure (ICP)
- Coagulation disorder
- Vertebral deformity
process of positron emission tomography
radiation introduced in body using radiotracer
radiation accumulates in organs and measured when it emits small energy - gamma rays which ill be detected
indicate body function e.g blood flow, oxygen uptake
complications of lumbar puncture
Headache (10%)
Radicular pain (10%)
Tonsillar herniation (extremely rare)
function of muscle biopsy
Essential in diagnosis of
inflammatory myopathies
metabolic myopathies
process of electro-encephalography
Recording of cerebral electrical potentials by electrodes on the scalp
* Abnormalities reflect general pathological processes NOT specific diagnoses
