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.