Neurosurgery Passmedicine Flashcards
What imaging is most sensitive for diagnosing diffuse axonal injury?
MRI
What are the two types of primary brain injury?
Focal - contusion/haematoma
Diffuse - diffuse axonal injury
What causes diffuse axonal injury?
Mechanical shearing following deceleration, causing disruption and tearing of axons
What are the two types of contusions?
Coup (adjacent to side of impact)
Contre-coup (contralateral to side of impact)
What are the different types of intra-cranial haematomas?
Extradural
Subdural
Intracerebral
What happens in secondary brain injury?
Cerebral oedema, ischaemia, infection, tonsillar or tentorial herniation exacerbates the original injury
The normal cerebral autoregulatory processes are disrupted following trauma so brain more susceptible to hypoxia
What is the cushing’s reflex?
HTN
Bradycardia (often a pre-terminal event, seen prior to coning)
Where do most extradural haemorrhages occur?
Temporal region (where skull fracture –> rupture of middle meningeal artery)
What are the features of an extradural haemorrhage?
Features of raised ICP
Lucid interval
Where is the bleeding in an extradural haematoma?
Between dura and skull
Where does subdural haematoma tend to occur?
Around the frontal and parietal lobes
What are risk factors for subdural haematoma?
Old age
Alcoholism
Anticoagulation
How does subdural haematoma tend to present?
Slower onset of symptoms
May be fluctuating confusion/consciousness
How does subarachnoid haemorrhage tend to present?
Sudden occipital headache
May occur spontaneously in context of rupture cerebral aneurysm or in assoc. with other brain injuries
Which patients with head injuries should be imaged immediately (within 1h)?
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
Which patients should have a CT head 8h after a had injury?
Those with any of the following who have experienced LOC/amnesia:
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
OR any patient on warfarin who has sustained a head injury
When should you do a CT c-spine after an injury?
Patient alert and stable, and clinically suspicion of cervical spine injury + any of:
age 65 years or older
dangerous mechanism of injury (fall from a height of greater than 1 metre or 5 stairs; axial load to the head, for example, diving; high-speed motor vehicle collision; rollover motor accident; ejection from a motor vehicle; accident involving motorised recreational vehicles; bicycle collision)
focal peripheral neurological deficit
paraesthesia in the upper or lower limbs
A patient with GCS of 8 or less needs what before they are imaged?
Urgent neurosurgical review
How should you manage lifethreatening rising ICP after a head injury?
Prepare for theatre/transfer
Use IV mannitol/furosemide
How is diffuse cerebral oedema managed in the context of head injury?
Decompressive surgery
When might exploratory burr holes be used?
Where imaging isn’t available
How should depressed skull fractures be managed?
Formal surgical reduction and debridement
Who might be appropriate for ICP monitoring in the context of head injury?
Those with GCS of 3-8 and normal CT scan
Definitely for those with GCS 3-8 and abnormal CT
Hyponatraemia in head injury is most likely due to what?
SIADH
What minimal cerebral perfusion pressure in adults?
70mmHg
What minimal cerebral perfusion pressure in kids?
40-70mmHg
Unilaterally dilated pupil with sluggish or fixed light response = ?
3rd nerve compression secondary to tentorial herniation
Bilaterally dilated pupil with sluggish or fixed light response = ?
Poor CNS perfusion
or Bilateral 3rd nerve palsy
Unilaterally dilated or equal pupil size with cross reactive (Marcus-Gunn) light response =
Optic nerve injury
Bilaterally constricted pupil =?
Opiates
Pontine lesions
Metabolic encephalopathy
Unilaterally constricted pupil + preserved light response = ?
Sympathetic pathway disruption
Binocular vision post-facial trauma is suggestive of what?
Depressed fracture of the zygoma
Where does the bleed occur in subarachnoid haemorrhage?
In between the arachnoid and pia mater
What is the most common cause of SAH?
Head injury
In the absence of trauma, what is SAH called?
Spontaneous SAH
What can cause spontaneous SAH?
Intracranial aneurysm (most common) AV malformation Pituitary apoplexy Arterial dissection Mycotic (infective) aneurysms Perimesencephalic (idiopathic venous bleed)
What kind of aneurysms rupturing cause SAH?
Berry/sacular
What are berry aneurysms associated with?
Coarctation of the aorta
Adult polycystic kidney disease
Ehlers-Danlos syndrome
How does SAH present?
Thunderclap headache - worst headache of life, occipital, very sudden onset NV Meningism (photophobia, neck stiffness) Coma Seizures Sudden death
What ECG changes may be seen in SAH?
ST elevation may be seen
How do you confirm a SAH has occurred?
CT - +ve if acute blood (hyperdense) seen in basal cisterns, sulci + in severe cases in the ventricular system
If -ve carry out LP at least 12 hours after onset of symptoms to allow development of xanthochromia
What is xanthochromia?
Production from breakdown of red blood cells
What other CSF findings may you see with SAH?
Raised/normal opening pressure
How can you distinguish between traumatic tap and true SAH from LP?
Xanthochromia
What should you do as soon as a diagnosis of SAH is made?
Refer to neurosurgery
What investigations should be done after a diagnosis of SAH is made?
CT intracranial angiogram to identify AVM/aneurysm)
+/- digital subtraction angiogram (catheter angiogram)
Why should intracranial aneurysms be treated within the first 24h of a rupture?
They are at risk of a rebleed
How are most intracranial aneurysms managed?
Coil insertion by interventional radiologist
Few req. craniotomy and clipping by neurosurgery
How should a patient with a ruptured intracranial aneurysm be managed until they are coiled?
Bed rest, well controlled BP to avoid re-bleed
Vasospasm prevented using 21d course of nimodipine
How should vasopasm following ruptured aneurysm be treated?
Hypervolaemia, induced HTN and haemodilution
How is hydrocephalus treated in SAH?
Temporarily - external ventricular drain (CSF diverted into bag at bedside)
If long term may need ventriculo-peritoneal shunt
What are complications of SAH?
Re-bleed (30%) Vasospasm (usually 7-14d after onset) Hyponatraemia (due to SIADH) Seizures Hydrocephalus Death
What are important predictive factors in SAH?
Conscious level on admission
Age
Amount of blood on CT
What is xanthochromia?
Yellowish appearance of CSF due to breakdown of RBCs and bilirubin release
What kind of bleed may cause neonatal deterioriation in premature babies?
Intraventricular haemorrhage
Mass effect on the brain in extradural haematoma can lead to what?
Uncal herniation –> fixed, dilated pupil due to CNIII compression
What do extradural haematomas appear like on CT?
Hyperdense (bright) biconvex collection around surface of brain
What is the definitive management of an extradural haematoma?
Craniotomy and evacuation of the haematoma
What do you see on CT in acute subdural haematoma?
Hyperdense crescentic collection surrounding the brain that is not limited by suture lines
How is acute subdural haematoma definitively managed?
Decompressive craniectomy
How do those with chronic subdural haematoma tend to present?
Several weeks after a mild head injury with progressive confusion, LOC, weakness or higher cortical function
How is symptomatic chronic subdural haematoma managed?
Burr hole drainage
What is a intracerebral haematoma?
Collection of blood within the substance of the brain
What are risk factors for intracerebral haematoma?
HTN Vascular lesions (e.g. AVM, aneurysm) Cerebral amyloid angiopathy Brain tumour Infarct (esp. in those undergoing thrombolysis)
How do those with intracerebral infarct present?
Like they are having an ischaemic stroke
What will CT show in intracerebral haematoma?
Hyperdensity within substance of brain
How is intracerebral haematoma managed?
Usually under stroke physicians
Large clots may warrant surgical evacuation
What is an intraventricular haemorrhage?
Bleed into ventricular system
What tends to cause IVH in kids?
Prematurity of periventricular vascular structures
What can cause IVH in adults?
May extend from SAH, vascular lesions (e.g. aneurysms/AVM) or tumours
What does IVH look like on CT?
Hyperdensity within the dark CSF spaces within the ventricles
What are patients with IVH at risk of?
Obstructive hydrocephalus
In neonates when do most IVH occur?
In first 72h after birth (may be because of birth trauma + cellular hypoxia)
What should be the first thing you do when a patient becomes unresponsive?
Assess and secure airway
What are the three things that make up Cushings triad?
Widening of pulse pressure
Respiratory changes
Bradycardia
How might rises in ICP be accommodated?
Shifts of CSF
Does the brain autoregulate its blood supply?
Yes, so if the ICP rises the systemic circulation will display changes to try and need the perfusion needs of the brain
Usually –> HTN
What occurs if ICP keeps rising?
Brain compressed
Cranial nerve palsies
Compression of essential centres in brainstem
Cardiac centre compression –> bradycardia
Uncal herniation –> dilated pupil due to compression of what nerve?
CNIII
What is uncal herniation?
When the uncus of the temporal lobe herniates under the free edge of the tentorium cerebelli and compresses CNIII –> ipsilateral fixed, dilated pupil and contralateral paralysis (due to compression of cerebral peduncle)
What is brainstem compression called?
Coning
How is coning managed?
Osmotherapy with hypertonic saline/mannitol or surgical decompression
What is subfalcine herniation?
Displacement of cingulate gyrus under the falx cerebri
What is central herniation?
Downwards displacement of the brain
What is tonsillar herniation?
Displacement of the cerebellar tonsils through the foramen magnum, aka. coning
What does tonsillar herniation lead to?
Compression of the cardiorespiratory centre
In which condition is tonsillar herniation seen without raised ICP?
Chiari 1 malformation
What is a transcalvarial herniation?
Brain displaced through a defect in the skull, e.g. fracture, craniotomy site
Define hydrocephalus
Excessive volume of CSF within ventricular system of the brain
What causes hydrocephalus?
Imbalance between CSF production and absorption
What are the clinical features of hydrocephalus?
Due to raised ICP - Headache (worse in morning, when lying down + during Valsalva) NV Papilloedema Coma
In infants –> increased head circumference as sutures not fused yet (ant. fontanelle will bulge + become more tense) + failure of upward gaze
Why do children with hydrocephalus get failure of upward gaze?
Due to compression of the superior colliculus in the midbrain
What are the two types of hydrocephalus?
Obstructive - non-communicating
Non-obstructive - communicating
What causes obstructive hydrocephalus?
Structural pathology blocking flow of CSF
What do you see on imaging in obstructive hydrocephalus?
Dilatation of ventricular system superior to site of blockage
What are causes of obstructive hydrocephalus?
Tumours
Acute haemorrhage (eg. IVH, SAH)
Developmental abnormalities, e.g. aqueduct stenosis
What are causes of non-obstructive hydrocephalus?
Increased production of CSF –> choroid plexus tumour (v. rare)
Decreased resorption of CSF - e.g. meningitis or post-haemorrhagic
What is normal pressure hydrocephalus?
Non-obstructive hydrocephalus where there is ventriculomegaly with normal ICP
What are the classical symptoms of normal pressure hydrocephalus?
Dementia
Incontinence
Disturbed gait
What investigation is first line for suspected hydrocephalus?
CT head
What other investigation may be used for hydrocephalus?
MRI to check for underlying lesions
What investigation is therapeutic and diagnostic in hydrocephalus?
LP - can sample CSF and measure opening pressure and drain CSF
In what type of hydrocephalus would you avoid using LP and why?
Obstructive hydrocephalus since the difference of the cranial and spinal pressures induced by drainage –> brain herniation
What is an external ventricular drain?
A drain inserted into the right lateral ventricle that drains into a bag at the bedside
What is a ventriculoperitoneal shunt?
Long term CSF diversion that drains CSF from the ventricles to the peritoneum
What drain is used in acute severe hydrocephalus?
EVD
What is the management of obstructive hydrocephalus?
Surgically treating the obstructing pathology
How does hydrocephalus present in children?
Increasing head size Bulging fontanelles Impaired upward gaze Dilated scalp veins Bradycardias Seizure Coma
How do you differentiate between cerebral salt wasting syndrome and SIADH?
Both can occur following SAH BUT
CSWS - sodium loss accompanied by water loss as kidneys are functioning normally so there is a relative fluid depletion
SIADH - kidneys hold on to too much water –> concentrated urine
What are the criteria for testing for brainstem death?
Deep coma of known aetiology
Reversible causes excluded
No sedation
Normal electrolytes
Who should test for brain death?
2 appropriately experienced doctors on two separate occasions
Both experienced in performing brainstem death + with at least 5 y post-grad experience
One must be a consultant
Neither can be a member of the transplant team
What are the 6 tests to confirm brain death?
Pupillary reflex Corneal reflex Oculo-vestibular reflex Cough reflex (give bronchial stimulation or to gag response) Absent response to supraorbital pressure No spontaneous respiratory effort
What is the oculo-vestibular reflex?
Eye movements following slow injection of at least 50ml ice cold water into each ear in turn
Patients with intracranial bleeds who become unresponsive should have a CT urgently to rule out what?
Hydrocephalus
What are the two components of diffuse axonal injury?
- Multiple haemorrhages
2. Diffuse axonal damage in the white matter
What are the classical symptoms of basilar skull fracture?
Periorbital bruising (racoon eyes)
Post-auricular bruising (Battle’s sign)
CSF leaking from nose or ear
Haemotympanium
