Yi Sia Surgical HMO The Royal Melbourne Hospital Head Trauma Yi Sia Surgical HMO The Royal Melbourne Hospital

Overview of Anatomy

Meninges Blood Supply to Dura

Brain Circle of Willis

Venous Drainage Ventricular System

Physiology Intracranial pressure Pressure within the cranial cavity Cranial cavity is encased by a skull which is a rigid cavity 80% brain, 10% CSF, 10% blood Normal ICP < 15mmHg or < 20cmH2O

Monro-Kellie Doctrine

Cerebral Blood Flow = 50-55ml/100g of brain tissue per minute Severely elevated ICP can cause decreased CBF and brain ischaemia CBF depends on cerebral perfusion pressure (CPP) CPP = MAP – ICP Autoregulation can compensate for modest reductions in CPP, leading to relatively stable CBF

Classifications of Head Trauma Mechanism Blunt High velocity (MVA) vs low velocity (fall, assault) Penetrating Gunshot wounds, other penetrating injuries Morphology Intracranial lesions Primary brain injuries Immediate result of trauma Secondary brain injuries Develop later as a result of complications Skull fractures Vault Linear vs stellate, depressed/non-depressed, open/closed Basilar With/without CSF leak Severity Minor GCS 13-15 Moderate GCS 9-12 Severe GCS 3-8

Traumatic Brain Injury An acquired brain injury caused by a blow to the head or by the head being forced to move rapidly forward or backward, usually with some loss of consciousness ~150 people admitted to hospital with TBI per 100,000 population per year The leading causes are Falls (42%) MVA (29%) Assault (14%) Other unintentional injuries Males > females Peak incidence is in the age group 15-24 years

Primary Brain Injuries Concussion Diffuse axonal injury (intracerebral shearing) Focal brain injury Cerebral contusion Haemorrhage/haematoma

Secondary Brain Injury Cerebral ischaemia/hypoxia Cerebral swelling/oedema Hydrocephalus (obstructive, communicating) Infection Intracranial bleeding Extradural haemorrhage Subdural haematoma Subarachnoid haemorrhage Intracerebral haemorrhage

Extradural Haemorrhage Between skull and dura Injury to middle meningeal artery or one of its branches Characteristic biconvex shape May present as decreased consciousness or following a lucid internal

Subdural haematoma Between dura and arachnoid Ruptured communicating veins Common in elderly Can be acute, subacute, or chronic

SAH and Contusions SAH Increased attenuation in CSF spaces – filling of the sulci over cerebral hemispheres Intracerebral bleed/haemorrhagic contusion Inferior frontal and anterior temporal lobes are common sites

Skull Fractures Indicates severe impact Simple #s – linear or stellate Depressed #s Compound #s Base of skull #s Anterior cranial fossa – periorbital haematomas (“panda eyes”), subconjunctival haemorrhage, CSF rhinorrhoea Middle cranial fossa, involving petrous temporal bone – CSF otorrhoea, bruising over mastoid area (“Battle’s sign”)

Clinical Assessment Primary survey and resuscitation A – Airway, C-spine protection B – Maintain adequate oxygenation (hypoxia causes vasodilatation and raised ICP) C – Ensure adequate BP (ischaemia results in secondary brain injury) D – GCS, pupils Eye Opening Verbal Response Motor Response Spontaneous 4 Oriented 5 Obeys commands 6 To speech 3 Confused Localises pain To pain 2 Inappropriate words Withdraws None 1 Incomprehensible sounds Decorticate Decerebrate

Secondary Survey Take an AMPLE history Fully assess head and neck for injury including Examination of skull vault Signs of BOS #s (panda eyes, Battle’s sign, CSF rhinorrhoea/otorrhoea) Repeat vital signs Repeat GCS Neurological examination General examination for other injuries

Signs and Symptoms Common signs and symptoms of raised ICP Headache Altered mental state, especially irritability and depressed level of alertness and attention Nausea and vomiting Papilloedema Visual loss Diplopia Cushing’s triad: HTN, bradycardia, irregular respirations

Imaging in Head Trauma Indications for CT scanning (Canadian CT Head Rule) CTB is required for patients with minor head injuries (i.e. witnessed LOC, definite amnesia, or witnessed disorientation in a pt with GCS 13-15 and any one of the following: High risk for neurosurgical intervention Moderate risk for brain injury on CT GCS <15 at 2/24 post injury Suspected open or depressed skull # Any sign of BOS # Vomiting (>2 episodes) Age >65yo Amnesia before impact (>30 min) Dangerous mechanism (e.g. ped vs car, occupant ejected from vehicle, fall from height >3 feet or 5 stairs

Medical Management Intravenous fluids Hyperventilation Mannitol Aim is to maintain normovolaemia Hyperventilation Normocarbia is preferred Mannitol Acute neurological deterioration in a normotensive pt is a strong indication for administering mannitol Anticonvulsants Prophylactic phenytoin reduces the incidence of seizures in the first week of injury

Surgical Management Scalp wounds Depressed scalp #s Intracranial mass lesions (EDH, SDH, intracerebral haematoma) Decompressive craniotomy/craniectomy ICP monitor

Summary Head trauma causes significant morbidity and mortality The primary focus of treatment is to prevent secondary brain injury