Neurological injuries: Head Flashcards
When should depressed consciousness be ascribed to intoxication?
Only after brain injury has been excluded
Aims for high flow O2?
PaO2 >13kPa (98 mmHg)
PaCO2 in the normal range (4.5-5kPa; 34-48 mmHg)
Risks of PaCO2 imbalance in the brain?
If too low then brain vasculature will constrict risking ischaemia
If too high then vasculature will dilate too much and raise intracranial pressure
When should you avoid using a nasopharyngeal airway?
If there are basal skull fractures
Head injury does not cause what?
Hypotension
How do you calculate cerebral perfusion pressure?
Mean arterial pressure - intra-cranial pressure
need to maintain MAP >80 mmHg with IV fluids
Which part of the GCS is most predictive of the outcome of head injury?
Motor
GCS <8?
Intubate as tounge might block airway
What warrants a CT within one hour?
GCS <13 (<15 at 2 hours) Open/depressed skull fracture Any sign of basal skull fracture Post-traumatic seizure Focal neurological deficit >1 episode of vomiting
What warrants a CT within 8 hours?
Amesia/loss of consciousness with any 1 of:
Over 65, bleeding/clotting disorders, dangerous mechanism of injury, >30 mins retrograde amnesia of events
Warfarin treatment alone
Signs of basal skull fracture:
Battle’s sign (behind ear)
Panda eyes (periorbital bleeding)
Haemotympanum
CSF otorrhoea/rhinorrhoea (CSF has high sugar so test with urine dipstick)
Appearance of new vs old blood on CT?
New looks white
Old looks grey like brain tissue
Signs of extradural haemorrhage:
Dilated pupil
Oculomotor nerve palsy
Lucid interval in 1/3 of patients (minutes to hours)
Initially may lose consciousness but will regain
Biconvex
Commonly temporo-parietal - MMA
Good prognosis if early treatment
Features of subdural haemorrhage:
Crescent shape
Venous blood from the rupture of the bridging dural veins
Can be acute or chronic (elderly, alcoholics, anticoagulant)
Mass effect
Non-accidental cause of subdural haemorrhage?
Shaken baby syndrome
Features of subarachnoid haemorrhage:
Traumatic/spontaneous e.g. ruptured aneurysm
Bleed into the ventricles, sulci and gyri
Tearing of small leptomeningeal arteries causing vasospasm and ischaemia
How do you treat leptomeningeal tear and vasospasm?
Nimodipine (CCB) 60mg oral/NG tube helps reduce ischaemia
Causes of spontaneous SAH:
85% is saccular 'berry' aneurysms associated with polycystic kidney disease, Ehlers-Danlos syndrome and coarctation of the aorta AV malformation Pituitary apoplexy Arterial dissection Mycotic (infective) aneurysms Perimesencephalic
Subarachnoid haemorrhage presentation:
Headache, N+V
Meningism: photophobia and neck stiffness
Coma, seizures and sudden death
ST elevation may be seen on ECG
How to confirm subarachnoid haemorrhage?
CT
If CT negative then a lumbar puncture 12 hours after onset to test for xanthochromia - if +ve then urgent neurosurgical referral
Management of SAH:
Vasospasm = nimodipine
Aneurysm = coil/craniotomy + clipping (rarer)
Hydrocephalus treated with an external ventricular drain/long-term ventriclo-peritoneal shunt
Complications of SAH:
Hyponatraemia from SIADH Re-bleeding (30%) Vasospasm (aka cerebral ischaemia) Seizures Hydrocephalus Death
Differential between acute and chronic subdural haemorrhages?
Acute will be from the MMA and will be hyper dense on CT (white)
Chronic will be from fragile dural bridging veins (elderly, alcoholic, baby) and will be hypodense/dark grey on CT
Features of cerebral contusion:
Small bleeds shown as small white spots on CT
Can be subtle
Often frontal/temporal due to impact with the sphenoid ridge/orbital plates
Features of diffuse axonal injury:
Bad prognosis
Acceleration/deceleration causes shearing of neuro axons
Widespread WMI
Hard to see on CT - swollen brain, sometimes pinpoint haemorrhages due to capillary rupture
Need MRI - can be in vegetative state forever
What is concussion?
Stretching of white matter fibres
Symptoms of concussion?
Nausea Amnesia Confusion Loss of consciousness/concentration Dizziness Usually temporary
