Flashcards in Investigations Deck (14)
What does the history for headache involve?
- SOCRATES - how it started, when it comes on etc
- Previous episodes
- PMH - previous headaches or other illnesses
- Drug history - oral contraceptive pill, codeine
- FH e.g. migraine
- SH - smoker, caffeine, job, impact on life
What are red flags for headaches?
- Blurred/swollen optic discs - papilloedema, sign of raised intracranial pressure
- Peripheral field loss, enlarged blind spots - raised intracranial pressure
- Sixth nerve palsy - false localising sign, giant cell arteritis
- Extensor plantar
- Ataxia - lesion in posterior fossa
- Oral hairy leukoplakia - Epstein-Barr virus
- Purpuric rash - meningococcal septicaemia
- Livedo reticularis - at risk of venous clots, antiphospholipid Ab syndrome, vasculitis
What investigations can you do for a headache?
- CT - hydrocephalus
- MRI - large loculated mass (tumour)
- CSF manometer - measures pressure in brain
- Yellowish spinal fluid - xanthachromic fluid, seen when there is blood break down products in fluid - SAH
- Neutrophils in CSF - bacterial infection e.g. meningitis
What is the most important sample for suspected meningitis?
What investigations for meningitis should be done in a child under 1?
Full septic screen should include lumbar puncture as well as standard urine and blood cultures.
What are the contraindications for lumbar puncture?
Any sign of raised ICP (papilloedema or focal neurological signs), coagulation defects and signs of infection at the site where needle is inserted.
What does the colour of the CSF mean?
Normal - clear, colourless
Bacterial - turbid
Tuberculosis - turbid, vicous straw
Viral - clear
What are other investigations for meningitis?
- Blood cultures
- Serology for viruses causing meningo-encephalitis
- Throat swab for Neisseria meningitides and streptococcus pneumoniae
- Urine pneumococcal antigen
- Kernig’s test - flex leg and neck, pain down back
What tests can you do for encephalitis?
- CT or MRI - may show oedem of the temporal lobes
- Electroneceohalogram (EEG) - show characteristic slow waves
What would CSF show for bacterial meningitis?
Increased WBC, increased neutrophils, increased protein, decreased glucose. Gram stain bacteria.
What would CSF show for viral meningitis/encephalitis?
Decreased protein, normal glucose, increased WBC (normal monocytes). Gram stain negative, viral PCR might be positive.
How do you measure ICP?
- EVD with strain-gauge pressure transducer
- Fibre optic intra-parenchymal transducer
- Air-pouch balloon
- Combined with temperature and microdialysis
How do you calculate cerebral perfusion pressure?
CPP = ABP - ICP