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12.10.24 Teaching notes


Leukoencephalopathy

Stroke imaging
  • http://www.radiologyassistant.nl/en/483910a4b6f14
  • Do an un-enhanced CT first
    • So you don't confuse contrast for blood
  • Early CT signs
    • Loss of grey/white matter differentiation
    • Hyperdense artery
      • Due to thrombus
      • Some thrombi may look different to others
    • Sulcal effacement
    • Mass effect
  • Can use "stroke window" to enhance grey/white contrast
  • Infarct covering >1/3 of the MCA territory are likely to undergo haemorrhagic transformation


T2WI, DWI, ADC
  • ADC = Apparent Diffusion Coefficient
  • In the acute phase T2WI will be normal, but in time the infarcted area will become hyperintense
    • The hyperintensity on T2WI reaches its maximum between 7 and 30 days, then fades
  • DWI is already positive in the acute phase and then becomes more bright with a maximum at 7 days
  • DWI in brain infarction will be positive for approximately for 3 weeks after onset
    • In spinal cord infarction DWI is only positive for one week
  • ADC will be of low signal intensity with a maximum at 24 hours and then will increase in signal intensity and finally becomes bright in the chronic stage


Caudate nucleus




Eye movements
  • Use the patient's words!
    • "Jerky vision", not "Oscilloptia"
  • Distinguish SYMPTOM from EXAMINATION FINDING
    • e.g. Nystagmus => Oscilloptia
  • First check HEAD POSTURE
    • They'll turn their head to reduce the use of the weak muscle
    • But a CN III palsy will cause a complete ptosis so they won't need to :)
  • Check smooth horizontal movement first
    • 1 m away
    • Keep within the binocular field
    • Go slow
    • Pause at the sides
    • Use something coloured
    • NB comes from occipital lobe, so you need an object!
      • Can't do it voluntarily
  • If they have diplopia then the OUTSIDE image is the false one


Cranial nerves

  • Bilateral innervation to the forehead is to protect eye closure
    • => Best test is to screw the eyes up
  • Smiling is a extrapyramidal pathway (emotive)
    • => Doesn't accurately test CN function
  • Trigeminal nerve => Muscles of mastication
    • All have bilateral cortical representation
  • Swallowing has bilateral cortical representation
    • But takes a few days to kick in e.g. after a stroke
  • La-la-la-la-la-la-la-la-la is good to check for a pseudobulbar palsy
    • (Results from an UML lesion to the corticobulbar pathways in the pyramidal tract)
  • SCREW EYES and PURSE LIPS
  • Facial nerve
    • Taste in front of tongue (corda tympani)
    • Laccrimal ducts (greater superficial petrosal nerve)
    • Stapedius muscle
      • => Hyperacusis (raised sensitivity to LOUD noise)
      • cf stethoscope test
  • Bell's phenomenon
    • Blink reflex
    • Eyelids down, but also eyeball up
      • => Can test even with ptosis
  • Inspect the tongue AT REST
    • As you would for other muscles
    • Check movements later
  • Check palatal deviation by looking at the median raphe, not the uvula
  • Deviation
    • Tongue is pushed to the weak side
    • Raphe is pulled to the strong side


Notes
  • Dehydration is the commonest cause of venous stroke
    • Esp. in kids
  • Neck pain + Neurological deficit => Carotid dissection
    • Esp. if young
  • Bulbar palsy refers to impairment of CN IX, X, XI and XII which occurs due to a lower motor neuron lesion
    • Either at nuclear or fascicular level in the medulla oblongata or from lesions of the lower cranial nerves outside the brainstem
  • DHx: Give dose and WHEN STARTED
  • Skin popping => Clostridium botulinum
  • Don't forget handedness and job
  • 70% of diagnosed TIAs weren't TIAs
  • Torticollis
    • Stiff neck associated with muscle spasm
    • Usually SCM + splenius capitus
    • Treat with Botox
  • Ophthalmic branch goes all the way up to the ear-to-ear line

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