Head trauma Flashcards by K D

CSF production, circulation and reabsorption

Produced by choroid plexus in lateral, 3rd and 4th ventricles

Reabsorbed by arachnoid granulation in superior sagittal sinus

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3 layers of meninges

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Which blood vessels are responsible for extradural bleed

Meningeal arteries, especially middle meningeal artery

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Which blood vessel responsible for subdural bleed

Bridging veins

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Which blood vessels are responsible for intra-cerebral bleed (subarachnoid haemorrhage)

Major blood vessels at the base of the brain

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Brainstem parts

Midbrain

Pons

Medulla

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Function of midbrain and upper pons

Reticular activating system (state of alertness)

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Function of medulla

Cardiorespiratory centre

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Tentorium cerebelli

Separates intracranial cavity into supratentorial and infratentorial

Midbrain passes through tentorial hiatus

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Which nerve could be compressed against the tentorium

Oculomotor leading to a blown pupil (carries PSN, if impaired, eye only gets sympathetic)

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Which part of brainstem herniates through tentorium due to raised ICP

midbrain

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Which part of brain herniates through tentorium due to raised ICP

the medial part of temporal lobe known as uncus

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Sx of uncus herniation

Ipsilateral pupillary dilatation (PSN fibers of CN3)

Contralateral hemiparesis (corticospinal tract of the midbrain)

Reduced GCS (reticular system)

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Normal ICP

10mmHg

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What sustained ICP is associated with poor outcome

>22mmHg

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Monro-kellie doctorine

Total volume of intracranial content is constant

Total volume = Venous volume + arterial volume + brain + CSF

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Cerebral perfusion pressure (CPP) formula

CPP = MAP - ICP

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At what MAP is cerebral blood flow autoregulated (constant)

MAP of 50-150 mmHg

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GCS depending of severity of traumatic brain injury (TBI)

Mild 13-15

Moderate 9-12

Severe 3-8

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When calculating GCS and there’s discrepancy between left and right side, which score do you use

The best motor response (the higher score)

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Types of skull vault (roof) fracture

Linear vs stellate

Depressed vs non-depressed

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Clinical signs of basilar skull fracture

Periorbital ecchymosis (raccoon eyes)

Retroauricular ecchymosis (Battle’s sign)

Rhinorrhoea (CSF from nose)

Otorrhoea (CSF from ear)

CN7,8 dysfunction

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Classic epidural haematoma presentation

Lucid period before deterioration

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Which region of the brain often affected by epidural bleed

Temporoparietal

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Further investigation after CT showing contusion

Repeat CT within 24 hours to look for change in the pattern of injury (20% of patients will end up having enough mass effect requiring evacuation)

Definition of mild traumatic brain injury

GCS 13-15 witnessed loss of consciousness, definite amnesia or witnessed disorientation

High risk indications for CT head for pt with mild traumatic brain injury

Any one of high risk or moderate risk: GCS\<15 for 2 hrs post-injury Suspected open or depressed skull Signs of basilar skull fracture Vomiting more than 1 episodes Age \>65 Anticoagulation

Moderate risk indications for CT head for pt with mild traumatic brain injury

LOC for 5 mins Amnesia before impact \>30mins Dangerous mechanism (pedestrian struck, ejected out of the car, fall from more than 3 feet or 5 stairs)

Initial management of moderate traumatic brain injury

Neurosurgery evaluation or transfer required

Initial management of severe traumatic brain injury

Urgent neurosurgery consultation or transfer required

Admission criteria for mild traumatic brain injury

1. CT: - not available - skull fracture - CSF leak 2. Focal neurology 3. GCS does not return to 15 after 2 hrs

Secondary management of severe traumatic brain injury with raised ICP

Mannitol Brief hyperventilation (reduces CO2, vasoconstriction) Hyperosmotic saline Surgery Barbiturates

PCO2 aim for hyperventilation

No less than 25 mmHg - 30 mmHg (3.3 to 4.7kPa)

PCO2 aim for severe traumatic brain injury

\<35mmHg

Blood pressure aim in brain injury

SBP\<100 between 50 to 69 SBP \<110 between 15 to 49 and older than 70

ICP goal for TBI

5-15mmHg

Reversal agent for morphine

Nalaxone

Reversal agent for benzos

flumazenil

How much shift of midline structures indicate the need for surgery

A shift of 5mm or more

Reversal for antiplatelet agents eg aspirin

Platelets | (may need repeat or desmopressin)

Reversal for warfarin

Vit K and Prothrombin complex

Reversal for heparin

protamine

Reversal for LMWH

protamine

Reversal for direct thrombin inhibitors (eg dabigatran)

Idarucizumab (praxbind)

Reversal for rivaroxaban

none

Use of mannitol

Osmotic diuretic For the acute neurological deterioration of pt under observation (A bolus of 1g/kg, over 5mins before transferring to CT)

Contraindication to mannitol use

Hypotension (SBP \<90) Mannitol does not lower ICP in hypovolaemia and is an osmotic diuretic, leading to a further drop in BP, and cerebral ischaemia

Monitoring with Mannitol

ICP monitor, keep \<320mOsm

Use of hypertonic saline for raised ICP

IN concentrations of 3% to 23.4% Preferable agent in hypotension as doesn't act as a diuretic, however, equally ineffective in hypotension

Use of barbiturates in raised ICP

Only used after other measures both surgical and medical have failed Long half-life, so needs monitoring for longer (before declaring brain death) Don't use in hypovolaemia or hypotension

Use of anticonvulsants in TBI

Can inhibit brain recovery, so only use when essential No evidence for late epilepsy prevention

Factors increasing the risk of late epilepsy post-TBI

Seizures occurring within the first week Intracranial haematoma Depressed skull fractures

Which anticonvulsants used for post TBI seizures

Phenytoin +/- diazepam/lorazepam If not, general anaesthesia

Dosing of phenytoin for post TBI seizure

Loading on 1g given at 50mg/min Maintaining on 100mg/8hrs

Management of scalp depression

Generally need operative elevation eg when - open contaminated - degree of depression \> thickness of adjacent skull In less severe depression, just closure of scalp over suffices

Indication for use of prophylactic abx in TBI

Penetrating brain injury Open skull fracture CSF leak

Management of objects that penetrate the intracranial compartment or infratemporal fossa that remain partially exteriorised

Must be left in place until the possible vascular injury has been evaluated and definitive neurosurgical management established

Surgical management of intracranial mass lesions

If in remote areas/no access to imaging or neurosurgery: Burr hole craniotomy Otherwise, bone flap craniotomy

Definition of brain death

no possibility of recovery of brain function

Criteria for brain death

GCS=3 Nonreactive pupils Absent brainstem reflexes (eg oculocephalic, corneal and gag reflex) No spontaneous ventilatory effort on formal apnoea testing Absence of confounding factors such as alcohol, drug intoxication or hypothermia

Investigations that could help establishing brain death

Electroencephalography CBF studies Cerebral angiography

Oculocephalic reflex

AKA doll's eye reflex If brainstem affected eyes move with the head