Head Injury + Coma Flashcards
What is the difference between: coma, stupor, confused and delirium?
- coma → unresponsive, unrousable state
- stupor → unresponsive, rousable state
- confused → alert, but disorientated
- delirium → like confusion, but also agitated + restless
What are clinical features of a coma?
- unconscious (lasting 6+hrs)
- unrousable
- fails to respond normally to pain, light + sound
- lacks a normal sleep-wake cycle
- does not initiate voluntary movement
- GCS 3-8
How do you calculate the Glasow Coma Scale?
- E4 V5 M6
What are the differentials for coma?
- epilepsy
- trauma → concussion, haematoma
- vascular → stroke
- infective → meningitis, encephalitis, cerebral abscess
- circulatory → MI, septic shock, hypovolaemia
- metabolic → Na, glucose, calcium, uraemia, hepatic failure, DM
- endo → adrenal crisis
- toxins → alcohol, sedatives, TCAs, CO
- psych → catatonia, psychogenic
On what 3 structures in the brain does consciousness depend on?
- pontomesencephalic reticular formation
- thalamus + hypothalamus
- diffuse cortical projections
Predictors of prognosis of coma include causes of coma, depth + duration as well as clinical signs present. After head injury, prognosis is directly proportional to initial GCS.
What causes are associated with a good and bad prognosis?
-
GOOD:
- drug overdose → high proportion of good recovery if adequately treated
- metabolic → 25% good recovery
-
BAD:
- cerebrovascular disease → 75% die, 3% fully recover
- hypoxic-ischaemia → 60% die, 8% recover
What are some complications of coma and how can we prevent them?
- bedsore → good nursing care eg turning pt every 2-3hrs
- infection → pneumonia due to aspiration, lack of gag reflex or from feeding tube - ensure careful feeding + monitoring, can tilt patient up, UTIs 2o to long-term catheters
- atelectasis → chest physio, alteration of ventilator settings
- malnutrition → NG feeding + fluid resuscitation
- contractures → physio
- persistent vegetative state → coma becomes permanent
Initial assessment + management includes ABCDE resuscitation.
What are some examples of treatment for reversible causes of unconsciousness/coma?
- glucose infusion for hypoglycaemia → 50ml of 50% glucose IV
- IV thiamine → alcoholism or unclear diagnosis
- drug overdose antidotes:
- naloxone → for opiates, 0.4-2mg IV
- flumazenil → benzodiazepines, if airway compromise
- if signs of infection:
- meningitis → cefotaxime
- encephalitis → aciclovir
- anticonvulsants if pt is in status epilepticus → lorazepam
What is meant by ‘vegetative state’?
- complete loss of awareness
- with preserved wakefulness + wake-sleep cycles
- thalamocortical function severely disrupted
- commonly due to:
- severe cerebral cortical damage → anoxia-ischaemia or hypoglycaemia
- damage to white matter of cerebrum → diffuse axonal injury from TBI
- thalamic damage → anoxia-ischaemia or structural lesions
What is meant by ‘brain death’?
- irreversible total destruction of all brainstem functions
- including capacity for alertness, cranial nerve functions + apnoea
- must never be diagnosed without an aetiology
Guidelines have been drawn up to diagnose brainstem death. What certain preconditions need to exist before testing can take place?
- patient requires ventilatory support in the absence of drugs
- there is a known cause for coma, capable of resulting in brainstem death
- patients core temperature + any metabolic abnormality or effects of drugs must be normalised
- effects of any sedation must have worn off
Brain death testing should be undertaken by two appropriately experienced doctors on two separate occasions.
Both should be experienced in performing brain stem death testing and have at least 5 years post graduate experience. One of them must be a consultant. Neither can be a member of the transplant team (if organ donation contemplated).
What brainstem reflexes are used in diagnosis of brain death?
- absent pupillary responses to light → pupil fixed + unresponsive
- absent oculocephalic reflexes → eyes move passively in direction of horizontal or vertical head movements, rather than maintaining their position of gaze while head is being moved by examiner
- absent corneal reflexes → no blink w/ corneal stimulation
- firm supraorbital pressure → no grimace in response to facial pain
- absent vestibulo-ocular response → intact reflex consists of transient tonic deviation of eye towards stimulated side when 20-50ml of ice-cold water is instilled into the ear
- absent gag reflex
- no cough in response to pharyngeal or tracheal stimulation + suction
- absence of any resp effort, even after fully oxygenating pt and then allowing PCO2 to rise to 50-60mmHg
Head injury is defined as any trauma to the head, with or without injury to the brain. Traumatic brain injury (TBI) is a non-specific term describing blunt, penetrating, or blast injuries to the brain.
How do you classify brain injury by broad aetiology?
- blunt → occurs when external mechanical force leads to rapid acceleration or deceleration w/ brain impact, typically found in setting of motor vehicle-related injury, falls, crush injuries or physical altercations
- penetrating → occurs when object pierces skull + breaches dura matter, seen commonly in gunshot + stab wounds
- blast → after bombings or warfare, due to combo of conact + inertial forces, overpressure + acoustic waves
The GCS has been used extensively to classify TBI into levels of severity and prognosis. After traumatic brain injury, there is an inverse relationship between the GCS score and the incidence of positive findings on CT; in fact, the rate of intracranial injury (ICI) and need for neurosurgical intervention doubles when the GCS drops from 15 to 14.
What is the classification by clinical severity (GCS)?
- minor/mild TBI → GCS 13-15; mortality 0.1%
- moderate TBI → GCS 9-12; mortality 10%
- severe TBI → GCS <9; mortality 40%
There is a grey area around a GCS of 13 as some argue it should be classed as moderate due to the increased morbidity
TBI can be primarily classified by area involved, as in diffuse or focal, although the two types frequently coexist.
What do these terms mean?
- diffuse → includes diffuse axonal injury, hypoxic brain injury, diffuse cerebral oedema or diffuse vascular injury
- focal → lesions such as contusions, haematomas, infarctions, axonal tears, cranial nerve evulsions + skull fractures
The above refer to causes of primary brain damage, secondary brain damage occurs after impact - it is preventable + treatable.
A thorough physical examination must be performed after the initial ABCDs have been addressed. In addition to vigilance for occult injuries, the physician should perform the physical examination with careful attention to what?
- GCS + pupillary examinations every 15 mins until pt stable
- inspect cranial nerves, periorbital + postauricular ecchymoses, CSF rhinorrhoea or otorrhoea, haemotmpanum
- fundoscopy → retinal haemorrhage + papilloedema
- palpation of scalp → haematoma, crepitance, laceration + bony deformity
- auscultate → carotid bruits
- spinal cord injury → cervical spine tenderness, paraesthesias, incontinence, extremity weakness, pripaism
- obv foreign bodies not to be removed until dura opened in OR
- continuous cardiac + serial BP monitoring - watch out for hypotension
- continuous puls ox + end-tidal CO2 capnography in intubated pts - watch out for hypoxia
- upper and lower limb motor + sensory examination
There are 2 common forms of herniation syndrome that present following trauma.
How does uncal herniation present?
- ipsilateral pupillary dilation (early sign)
- complete ipsilateral 3rd nerve palsy
- loss of consciousness
- contralateral hemiplegia (2o to mass)
- ipsilateral hemiplegia (compression of contralateral cerebral peduncle against edge of tentorium)
- flaccid paralysis
