Head Trauma

Head Trauma

Types of Injury

·        Effects of head trauma:

o  Direct trauma (eg under skill facture)

o  Cerebral contusion (local or contracoup)

o  Shearing: diffuse axonal injury ® petechial haemorrhage in midbrain, corpus callosum and cerebrum

o  Cerebral swelling

o  Intracranial haemorrhage: epidural, subdural, subarachnoid, intracerebral

o  Concussion: no absolute definition but period of loss of consciousness and anteriograde or retrograde amnesia

·        Types of skull fracture:

o  Simple: linear of vault

o  Depressed

o  Compound: open to skin or sinuses

o  Skull base ® rhinorrhoea or otorrhoea

·        Principal injuries from acceleration/deceleration injury:

o  Contusion: coup and coutracoup

o  Subdural haematoma from ruptured bridging veins

o  Diffuse axonal injury (shearing injury). Ranges from concussion (very mild, temporary, physiological disturbance) to severe

Assessment

·        ABC

·        Gross assessment:

o  Localise injury by looking for lumps, depressed fractures, etc 

o  CSF from nose or ears Þ basal skull fracture

o  Neuro assessment: 

§  Use level of consciousness: GCS – best response to verbal, motor and eye response.

§  Also pupillary size and exam, limbs

·        In diffuse injury the main enemy is ischaemia, which leads to oedema. In localised injury, oedema is the main enemy – acts like a mass lesion

·        Presume cervical spine injury until cleared: 

o  Need 3 xray views: anterior, lateral and peg (open mouth to view facet joints of C1 and C2, and odontoid peg)

o  Clearance requires clear X-rays AND normal exam.  If x-rays clear but tender C spine then CT

·        Assess other systems

·        Investigations:

o  SXR for minor HI (OK now but were knocked out): mainly for medico legal cover!

o  Cervical spine Xray, even if minor, for occult dens or cervical fracture

o  CT brain if GCS < 15, neuro signs in limbs, cranial nerve palsy or CSF leak

·        Criteria for admission, etc:

o  Discharge if GCS 15, low velocity, no seizures or fractures, adequate supervision at home and readmission checklist given to patient

o  Admit if: loss of consciousness/marked post traumatic amnesia or under 5 or over 50

o  CT indicated if GCS < 15 at 4 hours or < 9 at any time, seizures or focal neurological signs

o  Neurosurgical referral if compound head injury or GCS < 15

Raised Intracranial Hypertension (ICP)

·        Other causes of ­intracranial pressure: 

· Bleeding

o   Neoplasm

·        Brain oedema results from:

o   Inflammatory lesions

o   Infarction

o   Head injury

o   Neoplasms

·        Types of brain oedema: 

o   Vasogenic cerebral oedema: ­permeability of cerebral vessels

o   Cytotoxic cerebral oedema: rare. Toxic effect ® intracellular oedema

o   If severe acts as a space occupying lesions

·        ­ICP leads to displacement of CSF and compression of veins, then:

o   Herniation of the:

§  Cingulate gyrus under the falx

§  Parahippocampal gyrus past the free edge of the tentorium cerebelli

§  Cerebellar tonsils into the foramen magnum (fatal)

§  And pushing of the midbrain against the tentorium on the opposite side

·        Treatment of intracranial hypertension: 

o   Aim: Keep ICP low. Principle danger is ­ICP ® ischaemia, transtentorial herniation (uncus of temporal lobe on ipsilateral side) and coning 

o   ABC:

§  Maintain airway.  If breathing OK then lateral position.  100% O₂

§  Intubate if GCS < 9 

o   Aim to keep CPP (Coronary Perfusion Pressure) > 70. CPP = MAP less the greater of ICP or JVP. Coronary blood flow = CPP / CVR (cerebral vascular resistance)

o   In general, keep BP normal: 

§  If hypotension then ¯perfusion pressure (bad)

§  Use colloids to maintain BP at 120 – 160 systolic (don‟t over-hydrate, especially infants)

§  Diuretic: frusemide 40 mg iv

o   Tilt head up ® ­venous return ® ¯venous pressure ® ­perfusion pressure 

o   ¯O₂ requirements by sedation (Propofol or barbiturates eg thiopentone) and cooling 

o   Hyperventilate ® reduce CO₂ to 30 – 35 mmHg ® ¯cerebral blood flow ® ¯cerebral blood volume ® ¯brain volume ® ¯ICP (but only for short term otherwise ischaemia) 

o   Cushing's Reflex (bradycardia, ­­hypertension) kicks in when O₂ falls below 20 mls/100g/min 

o   Mannitol 0.5 – 1g/kg over 20 mins iv if life threatening – draws fluid from brain, but also a diuretic, so watch for hypotension

o   Drain fluid from ventricle if severe

o   Evacuation of intra-cerebral bleeds

o   Seizures: Clonazepam 0.25 mg/min up to 1 mg plus loading dose of phenytoin

o   Nutrition, urine and bowel management

o   Steroids not effective after head injury