Head injuries Flashcards
What is an uncul herniation?
A subtype of transtentorial downward brain herniation that involves the uncus, usually related to cerebral mass effect increasing the intracranial pressure.
What is the uncus?
The innermost part of the anterior parahippocampal gyrus, part of the mesial temporal lobe.
What are the signs and symptoms of an uncal herniation?
- Pupils and globe clinical features:
- initially, an ipsilateral dilated pupil that is unresponsive to light, signifying ipsilateral oculomotor nerve compression
- may develop into bilaterally blown pupils due to compression of the mesencephalon and its parasympathetic nuclei
- Ptosis
- Vertical gaze - Altered mental state
- Motor deficits
What is the aetiology of uncal herniation?
Secondary to large mass effect (that can occur from traumatic or non-traumatic haemorrhage, malignancy, etc.) that will lead to increased intracranial pressure and herniation
How would you diagnose uncal herniation?
Uncal herniation can be suggested on CT, however, MRI is the gold standard.
How would you manage an uncal herniation?
Initial management of uncal herniation to alleviate intracranial pressure includes; elevating the head on the bed to at least 30° ensuring that the head is kept midline, hyperventilation, which in turn decreases arterial carbon dioxide and induces vasoconstriction, and hyperosmolar therapy
What are the complications of uncal herniation?
Extensive brainstem ischaemia
What is a Subarachnoid haemorrhage?
Bleeding into subarachnoid space — the area between the arachnoid membrane and the pia mater
What are the signs and symptoms of a subarachnoid haemorrhage?
Mainly: Thunderclap/explosive headache developing over seconds - minutes (pulsates at the back of the head)
Sudden explosive headache may be the only symptom in a third of patients
Potentially vomiting, neck stiffness, confusion and coma
What causes a subarachnoid haemorrhage?
Mostly due to trauma, often near the site of a skull fracture
In spontaneous cases of a subarachnoid haemorrhage, what is the cause?
Cerebral aneurysm
bleeding from a berry aneurysm in the Circle of Willis
How would you diagnose a subarachnoid haemorrhage?
CT without contrast
Every patient in whom SAH is suspected should have a CT scan at the earliest opportunity
Cerebral panangiography continues to be the gold standard for detection, demonstration and localisation of ruptured aneurysms
If the CT scan is negative but the history is suggestive, lumbar puncture should be undertaken
How would you manage a subarachnoid haemorrhage?
Initial management of SAH aims to prevent further bleeding and to reduce the rate of secondary complications, such as cerebral ischaemia or hydrocephalus.
There are two options: neurosurgical clipping and endovascular coiling. Clipping requires a craniotomy followed by the placement of clips around the neck of the aneurysm. Coiling is performed through femoral catheterisation with platinum coils that obliterate the aneurysm by causing a blood clot to form in it (preferred)
What is the prognosis of a subarachnoid haemorrhage?
Re-bleeding is common, with a cumulative incidence by six months of 50%
Not all patients can be saved. The overall death rate is still around 50%, including those who die pre-hospital
What is an Extradural Haematoma?
Extradural haemorrhage (EDH) is a collection of blood in the potential space between the dura and the bone. Usually that bone is the skull but extradural haemorrhage can occur in the spinal column.
What is the order of the meninges?
Dura mater
Arachnoid mater
Pia mater
What is the cause of an Extradural Haematoma?
EDH is most often due to a fractured temporal or parietal bone damaging the middle meningeal artery or vein, with blood collecting between the dura and the skull.
t is typically caused by trauma to the temple just beside the eye
What are the signs and symptoms of an extradural haematoma?
There is usually a history of trauma and head injury that causes loss of consciousness. Classically, this is followed by a lucid interval after which the patient deteriorates.
The patient may experience: headache, nausea and vomiting, seizures, bradycardia (with or without hypertension indicates raised intracranial pressure), alteration in GCS
What investigatinos would you do for an extradural haematoma?
- FBC & U&E
- Plain X-ray of the skull
- X-ray of the cervical spine with views of the odontoid peg. Spinal injury must be excluded.
- CT scanning gives much more information
How would you manage an extradural haematoma?
- If intracranial pressure is raised, it may be treated with osmotic diuretics, such as IV mannitol (or Hypertonic saline)
- Burr holes may be required to evacuate a haematoma.
What is the prognosis for an extradural haematoma?
Prognosis in children is excellent.
One study reported that acute EDH in those over the age of 75 had a poor prognosis
The overall mortality rate is about 30%. Those who are alert on admission rarely die but a low GCS worsens the prognosis.
What is a subdural haemorrhage?
A subdural haematoma (SDH) is a collection of clotting blood that forms in the subdural space
How are subdurals haemorrhages divided?
An acute SDH.
A subacute SDH (this phase begins 3-7 days after the initial injury).
A chronic SDH (this phase begins 2-3 weeks after the initial injury).
What is an acutue SDH caused by?
Blunt head trauma is the usual mechanism of injury but spontaneous SDH can arise as a consequence of clotting disorder, arteriovenous malformations/aneurysms or other conditions.
Tearing of bridging veins from the cortex to one of the draining venous sinuses - typically occurring when bridging veins are sheared during rapid acceleration-deceleration of the head.
Bleeding from a damaged cortical artery.
Who’s at risk of developing an acute SDH?
In the infant brain, SDHs are caused by tearing of the bridging veins in the subdural space and may result in significant brain injur. Shaken baby syndrome!
Alcohol misuse leads to a risk of thrombocytopenia, prolonged bleeding times and blunt head trauma and is a risk factor for SDH
What does shaken baby syndrome cause?
Acute subdural haemorrhage
Diffuse axonal injury
What is the most common type of subdural haemorrhage in the elderly?
Chronic
How do people with acute SDH present?
Usually presents shortly after a moderate-to-severe head injury.
Loss of consciousness may occur but not always.
There may be a ‘lucid interval’ of a few hours after the injury where the patient appears relatively well and normal but subsequently deteriorates and loses consciousness as the haematoma forms.
How do people with chronic SDH present?
Usually presents about 2-3 weeks following the provoking trauma.
The initial injury may be relatively trivial (or forgotten), particularly in an older patient on anticoagulants, or in the context of alcohol misuse.
There is often a history of anorexia, nausea and/or vomiting.
Focal limb weakness, speech difficulties, increasing drowsiness/confusion or personality changes
If there is accompanying and progressive headache, this should raise suspicion of the diagnosis.
How would you diagnose subdural haemorrhage?
CT scan of the head is good for detecting acute SDH and is mandatory in children with significant head injury
Subacute SDH may be more difficult to detect, so CT with contrast or MRI is preferred.
Chronic SDH is usually detectable on CT scan
How would you manage subdural haemorrhage?
Hypertonic saline or mannitol may be considered if there is raised intracranial pressure.
Burr holes may be considered if there is rapid deterioration.
Surgery is needed if there are focal signs, deterioration, a large haematoma, raised intracranial pressure or midline shift –> SDH is treated by emergency craniotomy and clot evacuation.
What is raised intracranial pressure?
Raised intracranial pressure (ICP) can arise as a consequence of intracranial mass lesions, disorders of cerebrospinal fluid (CSF) circulation and more diffuse intracranial pathological processes. Its development may be acute or chronic.
What causes raised intracranial pressure?
Localised mass lesions: traumatic haematomas (extradural, subdural, intracerebral).
Neoplasms: glioma, meningioma, metastasis.
Abscess.
Focal oedema secondary to trauma, infarction, tumour.
Disturbance of CSF circulation: obstructive hydrocephalus, communicating hydrocephalus.
Obstruction to major venous sinuses: depressed fractures overlying major venous sinuses, cerebral venous thrombosis.
Diffuse brain oedema or swelling: encephalitis, meningitis, diffuse head injury, subarachnoid haemorrhage, Reye’s syndrome, lead encephalopathy, water intoxication, near drowning.
Idiopathic intracranial hypertension
What are symptoms of raised intracranial pressure?
The combination of headache, papilloedema and vomiting is generally considered indicative of raised intracranial pressure
Headache: more worrying when nocturnal, starting when waking, worse on coughing or moving head and associated with altered mental state
Early changes in mental state include lethargy, irritability, slow decision making and abnormal social behaviour. Untreated, this can deteriorate to stupor, coma and death.
What is papilloedema?
Optic disk swelling
How would you manage raised intracranial pressurer?
- Manage seizures, drain CSF, head of bed elevation, analgesia and sedation, mannitol, hyperventilation
How does hyperventilation lower intracranial pressure?
Lowers ICP by inducing hypocapnoeic vasoconstriction and has been shown to be effective in reducing raised ICP
What is CBF and how is it regulated?
Cerebral blood flow, reacts to:
- CO2 → increase of CO2 triggers vasodilation
- Blood pressure → causes myogenic stretch which causes constriction of BV
What is Cerebral perfusion pressure?
CPP is the force driving blood into the brain, providing oxygen and nutrients
CPP= Mean arterial pressure (MAP) - Intracranial pressure (ICP)
What are the 5 signs of basal skull fracture?
- Panda eyes
- Subhyaloid haem
- Subconjuncitval haemorrhage
- Oto/rhinorrhoea
- Battle’s sign (bruising of the mastoid process)
What bone is most often damaged in a basal skull fracture?
Temporal bone
How would you manage a basal skull fracture?
Non-displaced fractures usually heal without intervention.
Patients with basilar skull fractures are especially likely to get meningitis
How would you diagnose a basal skull fracture?
CT head (NOT MRI)
What are the criteria for performing a CT head scan within 1 hour in adults?
GCS less than 13 on initial assessment in the emergency department.
GCS less than 15 at 2 hours after the injury on assessment in the emergency department.
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.
What is a crescent shape indicative of on a head CT?
Subdural haemorrhage
Bright → acute
Dark → chronic
What are the diifferent types of brain herniation?
- Subfalcine
- Central
- Uncal
- Tonsillar
- Transcalvarial
What are Cerebral contusion?
Scattered areas of bleeding on the surface of the brain, most commonly along the undersurface and poles of the frontal and temporal lobes.
They occur when the brain strikes a ridge on the skull or a fold in the dura mater
What is the difference between a cerebral concussion and a cerebral contusion?
A contusion is a bruise that can occur on your head but isn’t typically serious and tends to resolve within several days.
A concussion is a mild traumatic brain injury characterised by immediate alteration in brain function, including a change in mental status and level of consciousness
What are the different types of fractures?
- Transverse
- Oblique
- Spiral
- Segmental
- Greenstick (little chip)
- Avulsed
When would you refer to neurosurgery after head trauma?
- Persisting coma
- Persisting confusion
- Deteriorating GCS
- Progressive focal neurology
- Seuzire without full recovery
- Depressed skull fracture
- Penetrating injury
- CSF leak
What is diffuse axonal injury?
Diffuse axonal injury (DAI) is a brain injury in which scattered lesions occur over a widespread area in white matter tracts as well as grey matter
Major cause of unconsciousness and persistent vegetative state after severe head trauma
What are the causes of diffuse axonal injury?
DAI is the result of traumatic shearing forces that occur when the head is rapidly accelerated or decelerated, as may occur in car accidents, falls, and assaults
What vessels are involved in an extradural haemorrhage?
Temperoparietal locus (most likely) - Middle meningeal artery
What is the difference in CT appearance between an extradural and subdural haemorrhage?
ED: biconvex lens
SD: crescent-shaped
What is the difference in symptoms between an extradural and subdural haemorrhage?
ED: Lucid interval followed by unconsciousness
SD: Gradually increasing headache and confusion
What is a halo sign?
CSF leak: ring around blood stain indicating spinal fluid
What is a depressed skull fracture?
Depressed skull fractures typically occur when a large force is applied over a small area.
They are classified as open if the skin above them is lacerated.
How would you diagnose depressed skull fractures?
CT should be performed in all suspected depressed skull fractures to determine the extent of underlying brain injury.
Depressed skull fractures require immediate neurosurgical consultation
How would you manage depressed skull fractures?
Treat open fractures with antibiotics and tetanus prophylaxis as indicated.
The decision to observe or operate immediately is made by the neurosurgeon
What is a LeFort fracture?
All LeFort facial fractures involve the maxilla. Clinically, the patient has facial injuries, swelling, and ecchymosis.
LeFort I fractures are those involving an area under the nasal fossa.
LeFort II fractures involve a pyramidal area including the maxilla, nasal bones, and medial orbits.
LeFort III fractures, sometimes described as craniofacial dissociation, involve the maxilla, zygoma, nasal and ethmoid bones, and the bones of the base of the skull.
LeFort IV fractures have been described as a LeFort III fracture that also involves the frontal bone
