Flashcards in PBL - Expanding Mass Lesion Deck (96)
How do you test the olfactory nerve function?
Ask subject to sniff substances through each nostril in turn and name the substance
- e.g. Non irritants such as vanilla, toothpaste and coffee
What can cause olfactory nerve dysfunction?
- commonly trauma
- fracture passing through ethmoid bone
How do you test the optic nerve function?
Test for visual acuity, check visual fields and inspect optic disks
Inspect size and shape of pupils
- compare both sides
- test reactions to light
How do you test the trochlear, occulomotor and abducens nerve function?
Subjects head is held still by an examiner
Subject is asked to follow the examiner's finger with eyes
- horizontal plane - medial and lateral rectus
- vertical plane (outwards) - superior and inferior rectus muscles
- vertical plane (inwards) - superior and inferior oblique
What problems would you also look for when testing the trochlear, occulomotor and abducens nerve function?
Derivation of eye
How do you test the trigeminal nerve function?
Cutaneous sensation in appropriate areas of the face
Ask to clench jaw muscles (clenching teeth)
- palate the masseter and temporalis muscles
Jaw jerk reflex
Ask subject to keep mouth open against resistance
How do you test the facial nerve function?
Puff out cheeks against resistance - buccinator
Keep eyes closed against resistance
How do you test the vestibulocochealr nerve function? - hearing aspect
Rinne's tests - press tuning fork against mastoid and then held next to pinna - sound should be heard longer through the air conduction
Weber's test - press tuning fork against middle of the forehead
What are the different results you can get in a Weber's test - and what do they mean.
Equal sound in both ears - normal hearing
Sound louder in right - left sensorineural problem
Sound louder in left - right sensorineural problem
How do you test the vagus and glossopharyngeal nerve function?
Subject has no huskiness, days phonic, dysphasia and palate moves symmetrically when subject says AHHHHHHHHHHHHH
How do you test the accessory nerve function?
Subject should be able to lift shoulders against resistance
- testing trapezium muscle
How do you test the hypoglossal nerve function?
Subject can hold tongue out of their mouth out of their mouth - equally on both sides
What are the main causes of head injury?
Motor and bicycle crashes
What kind of problems can a head injury cause?
What other problems are heavily associated with a skull fractures?
Underlying sub/epidural heamorrhage
Entrance of bacteria (meningitis) or air (pneumocephalus)
Cranial nerve damage
Which cranial nerve are most likely to be damaged in a skull fracture?
Olfactory, optic, oculomotor, trochlear, trigeminal, facial and auditory
What is the difference between a primary and secondary head injury? - list types of each
Primary - caused by the impact
- diffuse atonal injury
- focal lesions like lacerations, contusions and heamorrhage
Secondary - an injury resulting from a process started by impact
- hypoxia brain injury
What is a cerebral contusion?
Focal brain damage resulting from contact between bony protuberances of the skull base
What are the characteristic distributions for cerebral contusions?
Orbital surface of the frontal lobes
Around the lateral sulcus
Under surfaces of the temporal lobes
What is a traumatic atonal injury?
Widespread axonal injury - as a result of shear and tensile forces acting on the brain when the head is accelerated or decelerated suddenly
What happens to the brain 5 weeks after getting a diffuse axonal injury?
Degeneration of the long tracts and white matter of the cerebral hemisphere
Describe the spectrum of traumatic axon injury.
Graded I-III with the most severe occurring without a lucid interval
Which compartments can a heamatoma arise in?
Which artery tear is most common in causing an epidural heamatoma?
Middle meningeal - crosses the pterion of the skull
Why are epidural haemorrhages more common in young people?
Because the dura mater is less firmly attached to the skull - so is more easily separated from the inner surface, allowing expansion of the heamatoma
Does someone with an epidural heamatoma have a lucid period?
After the initial unconsciousness from the injury, they have a lucid period in which consciousness is regained.
What happens after the lucid interval in an epidural heamatoma?
Rapidly developing unconsciousness and focal symptoms related to the area of brain involved
What are the symptoms of an epidural heamatoma?
- pupil dilation
- eyes point down and out
- hemiparesis (from uncal herniation)
- loss of visual field
What is the pathophysiology of a subdural heamatoma?
A tear in the small bridge veins that connect veins on the surface of the cortex to the venous sinuses
- readily snapped in head injury when brain moves suddenly in relation to the cranium