Neurosurgery Flashcards
How do you test for brain death?
Fixed pupils which do not respond to sharp changes in the intensity of incident light
No corneal reflex
Absent oculo-vestibular reflexes - no eye movements following the slow injection of at least 50ml of ice-cold water into each ear in turn (the caloric test)
No response to supraorbital pressure
No cough reflex to bronchial stimulation or gagging response to pharyngeal stimulation
No observed respiratory effort in response to disconnection of the ventilator for long enough (typically 5 minutes) to ensure elevation of the arterial partial pressure of carbon dioxide to at least 6.0 kPa
Must be done by two separate doctors, on two occasions.
What are the types of brain herniation?
- Subfalcine
- Displacement of the cingulate gyrus under the falx cerebri - Central
- Downwards displacement of the brain - Transtentorial / uncal herniation
- Displacement of the uncus of the temporal lobe under the tentorium cerebelli. Clinical consequences include an ipsilateral fixed, dilated pupil (due to parasympathetic compression of the third cranial nerve) and contralateral paralysis (due to compression of the cerebral peduncle) - Tonsillar
- Displacement of the cerebellar tonsils through the foramen magnum. This is called ‘coning’. In raised ICP this causes compression of the cardiorespiratory centre. In Chiari 1 malformation, tonsillar herniation is seen without raised ICP - Transcalvarial
- Occurs when brain is displaced through a defect in the skull (e.g. a fracture or craniotomy site)
Intracranial haematomas types, and features?
Extra-dural haematoma
- Bleeding between dura mater and skull
- Temporal region trauma
- Lucid interval
- Raised ICP
- Acceleration-decelleration injury
Subdural haematoma
- Acute/Chronic
- Bridging veins between the subarachnoid and dura (subdural space).
- Slower onset
- Old age and alcoholics
Subarachnoid haemorrhage
- Acute onset (occipital pain)
- Thunderclap headache
- Neck stiffness
- Photophobia
What is the cushings effect?
Hypertension and bradycardia
Pre terminal event in response to raised ICP
Management in severe raising ICP?
Immediate surgery, whilst being prepared IV mannitol and furosemide
Management of diffuse cerebral oedema?
Decompressive craniotomy
Pupils unilaterally dilated and sluggish or fixed to light cause?
3rd nerve compression secondary to tentorial herniation
Pupils bilaterally dilated and sluggish or fixed to light cause?
- Poor CNS perfusion
2. Bilateral 3rd nerve palsy
Pupils unilaterally dilated or equal with cross reactivity to light?
Optic nerve injury
Pupils bilaterally constricted cause?
Opiates
Pontine lesions
Metabolic encephalopathy
Unilaterally constricted pupils preserved reaction to light cause?
Sympathetic pathway disruption (horners - pancoast)
Nice recommendations for immediate CT head following head injury?
- GCS < 13 on initial assessment.
- GCS < 15 at 2 hours post-injury.
- Suspected open or depressed skull fracture.
- Any sign of basal skull fracture (haemotympanum, ‘panda’ eyes, cerebrospinal fluid leakage from the ear or nose, Battle’s sign).
- Post-traumatic seizure.
- focal neurological deficit.
- More than 1 episode of vomiting.
Nice recommendations for CT head 8 hours since head injury?
- On warfarin
Adults with any of the following risk factors who have experienced some loss of consciousness or amnesia since the injury:
- Age 65 years or older
- Any history of bleeding or clotting disorders
- Dangerous mechanism of injury (a pedestrian or cyclist struck by a motor vehicle, an occupant ejected from a motor vehicle or a fall from a height of greater than 1 metre or 5 stairs).
- More than 30 minutes’ retrograde amnesia of events immediately before the head injury
Types of traumatic brain injury (broad)?
Primary brain injury may be focal (contusion/haematoma)
Diffuse
- diffuse axonal injury from shearing of axons in deceleration injury
What is hydrocephalus?
Hydrocephalus is defined as a condition in which there is an excessive volume of cerebrospinal (CSF) fluid within the ventricular system of the brain and is caused by an imbalance between CSF production and absorption, or obstruction in the CSF pathway.
