Disorders of The Cranial Nerves Flashcards
Which cranial nerves contain special senses?
Olfaction - 1
Vision - 2
Taste (7,9 and 10)
Hearing and balance (8)
Which cranial nerves carry ordinary sensation?
Trigeminal
Ear - facial nerve and the glossopharyngeal
What controls the muscles of the larynx and the pharynx?
Mainly the vagus
What cranial nerves have autonomic function? and what is the autonomic function?
3,7,9 and 10
3 - pupillary constriction
7- Lacrimation, salivation (sublingual and submandibular glands)
9 - Salivation (parotid gland) - glossopharyngeal
10 - inout to organs in thorax and abdomen
How do we test olfaction?
- Olfactory –smell – unilateral or bilateral loss
Investigations for 2nd cranial nerve when testing it?
Visual acuity
Visual fields
Pupillary reactions
Fundoscopy
Colour vision
What do you look for when testing the nerves responsible for eye movement?
Ptosis?
Equal sized pupils?
Pupillary reactions?
Eye movements - both vertical and horizontal
Tests for trigeminal?
Sensations in the ophthalmic, maxillary and mandibular divisions
Power in the muscles of mastication
Corneal reflex
Jaw jerk
What do we test for with facial nerve?
Muscles of facial expression
Corneal reflex
Taste
How do we test the vestibulocochlear nerve?
Hearing - rhinnes and webers test
Vestibular function using the dix - hallpike manouvre
and untenbergers test (step test)
How do we test the glossopharyngeal nerve?
Movement of the palate
Gag reflex
Quality of speech
Quality of cough
How do we test the accessory nerve?
Head turning and shoulder shruging
How do we test the hypoglossal nerve?
Appearance, movement and power of the tongue
What are the cranial nerve relfexes and what nerves do they use?
• Pupillary light reaction
afferent – II ; efferent – III
• Corneal reflex
afferent – V ; efferent – VII
• Jaw jerk
afferent and efferent – V
• Gag reflex
afferent – IX ; efferent - X
Which cranial nerve nuclei like in the MIDBRAIN?
3 and 4
(occulomotor and trochlear)
Which cranial nerve nucle lie in the PONS?
5,6,7
Trigeminal, abducent and facial nerve
Which nerve lies in thge pontomedullary junction?
8
Which cranial nerve nuclei lie in the medulla?
9,10,11 and 12
Which nerves are associated with the cerebellopontine angle?
7 and 8
Which nerves are assocaited with the pons?
5 and 7
What may result in bilateral 3rd cranial nerve signs?
Issue with the midbrain
What may cause unusual combinations of cranial nerve problems?
Chronic or malignant meningitis
What may cause pure motor signs with cranial nerve issues?
Myasthenia gravis
What may cause double vision that isn’t a cranial nerve disorder?
Myasthenia gravis or thyroid disease
What are the ways cranial nerves can be damaged?
Ischaemia tumour
Meningitis
What is optic neuritis?
Demyelinating inflammatory condition of the optic nerve
Inflammation also occurs int he muscles of the eye, they are sore to move
What are the signs of optic neuritis?
- monocular visual loss
- pain on eye movement
- reduced visual acuity
- reduced colour vision
- optic disc may be swollen
- often associated with multiple sclerosis
What is a useful test for optic neuritis?
Visual evoked repsonse - shows a delay in nerve conduction as a result of optic neuritis
What is the result of loss of parasympathetic input from the third cranial nerve?
Fixed dilated pupil
What causes a constricted pupil?
Damage anywhere wihtin the sympathetic pathway can lead to a constricted pupil
What are the causes of dilated pupils?
- Youth
- Dim lighting
- Anxiety, excitement
- “Mydriatic” eye drops
- Amphetamine, cocaine overdose
- Third nerve palsy
- Brain death
What are the causes of small pupils?
- Old age
- Bright light
- “Miotic” eye drops
- Opiate overdose
- Horner’s Syndrome
What are eyemovement disorders?
- Isolated third nerve palsy
- Isolated fourth nerve palsy
- Isolated sixth nerve palsy
- Combination of the above
- Supranuclear gaze palsy - inability to look in a particular direction as a result of cerebral impairment (nothiung to do with the cranial nerves)
- Nystagmus
What can cause isolated third nerve palsy?
Microvascular - diabetes, hypertension
Compressive - posterior communicating artery aneurysm, raised ICP
What is the difference in clinical features between microvascular and compressive third nerve palsy?
Microvascular - painless, pupil spared
Compressive - painful, pupil affected
What can cause isolated 6th nerve palsy?
Idiopathic
Diabetes
Meningitis
Raisd intracranial pressure
What causes nystagmus?
- Congenital
- Serious visual impairment (e.g. macular degeneration)
- Peripheral vestibular problem
- Central vestibular / brainstem disease
- Cerebellar disease
- Toxins (medication and alcohol) medication - phenytoin and carbamezapine
What causes trigeminal neuralgia?
Triggered by temperature / touching the face
Caused by a vascular loop causing compression of the fifth nerve in the poeterior fossa
What is the presentation of trigeminal neuralgia?
Paroxysmal attacks of lancinating pain
How is trigeminal neuralgia treated?
Treated medically with carbamazepine
What type of motor neurone type palsy is bells palsy?
Lower motor neurone
What are the features of bells palsy?
Unilateral facial weakness
Often preceeded with pain behind the ear
Eye closure is affected (risk of corneal damage)
How is bells palsy treated?
Steroids
Usually good recovery
Not all patients recover fully
plastics - re-establish facial symmetry
What is the difference between UMN and LMN facial paralysis?
UMN - stroke and tumour
LMN - bells palsy, lyme and sarcoid
UMN - forehead movement is still possible on affected side because innervation is bilateral
LMN - No forehead movement on affected side
What are the features of vestibular neuronitis?
Sudden onset
Disabling vertigo
Vomiting
Gradual recovery
Cause is uncertain (viral?)
What is the treatment for vestibular neuronitis?
Anti-emitics and bed rest
Tends to recover fully
Very often MS can present with something like thid
What is dysarthria and dysphagia?
Dysarthria - disordered articulation, slurring of speech
Dysphagia - difficulty swallowing
•Both occur in bulbar- and pseudobulbar palsy
–Bulbar – lower motor neurone
–Pseudobulbar palsy – upper motor neurone
Myasthenia gravis also presents with slurring although this is usually towards the end of the day
What causes pseudobulbar palsy?
Bilateral UMN lesion - Vascular lesions of both internal capsules (MND)
What are the features of pseudobulbar palsy?
dysarthria
- dysphonia
- dysphagia
- spastic, immobile tongue
- brisk jaw jerk
- brisk gag reflex
What is bulbar palsy?
Bilateral LMN lesion affecting 9 - 12
What causes bulbar palsy?
MND
Polio
Tumours
Vascular lesions of the medula and syphilis
What are the clinical features of bulbar palsy?
- wasted, fasciculating tongue
- dysarthria
- dysphonia
- dysphagia
BEWARE OF FEEDING THESE PATIENTS - may aspirate
