Disorders of Cranial Nerves Flashcards
What are the Functions of the Cranial Nerves?
- Special” senses
- “Ordinary” sensation
- Control of muscle activity
- Autonomic functions
What are the special sense?
Olfaction (I)
Vision (II)
Taste (VII, IX and X)
Hearing - and balance (VIII)
What is responsible for ordinary sensation?
Mainly the Vth (trigeminal nerve)
The ear from the VIIth (facial) and IXth (glossopharyneal) nerves
What is in control of msucle activity?
Eye muscles – III (oculomotor), IV (trochlear) and VI (abducence) (LR6,SO4, rest 3)
Muscles of mastication – V (trigeminal)
Muscles of facial expression – VII (facial)
Muscles of larynx and pharynx – mainly X (vagus)
Sternomastoid and trapezius muscles - XI (accessory)
What are the autonomic functions
(all parasympathetic) and what is respobisble for them?
Pupillary constriction – III (oculomotor)
Lacrimation – VII (facial)
Salivation – submandibular and sublingual glands – VII (facial)
Salivation – parotid gland - IX (glossopharyngeal)
Vagal (X) input to organs in thorax and abdomen
What is used to test CN I - Olfactory?
smell – unilateral or bilateral loss
What is used to test CN II – Optic?
visual acuity
visual fields
pupillary reactions
fundoscopy
colour vision
What dow e test in CN III, IV and VI – oculomotor, trochlear and abducence?
any evidence of ptosis?
pupil of equal size?
pupillary reactions
eye movements – vertical and horizontal
What do we for for in regards to CN V – Trigeminal?
sensation in the ophthalmic, maxillary and mandibular divisions
power in the muscles of mastication
corneal reflex
•aw jerk
What do we test for in CN VII – Facial?
Muscles of facial expression
Corneal reflex
Taste
What do we test for in CN VIII – Vestibulocochlear nerve?
Hearing using Rinne’s and Weber’s tests
Vestibular function using Dix-Hallpike manoevre and Untenberger’s test
(untenbergers test – close eyes and march on spot and will start to turn to side that is dyfunctioning and need to go to ENT clinic)
What do we test for in CN IX (glossopharyngeal) and CN X (vagal)?
movement of the palate
gag reflex
quality of speech
quality of cough
WHat do we test for in CN XI – Accessory nerve?
Head turning and shoulder shrugging - sternomastoid and trapezius function
How is CN XII – Hypoglossal nerve tested?
Appearance, movement and power of tongue
What cranial nerves are responsible for:
Pupillary light reaction
afferent – II ; efferent – III
What cranial nerves are responsible for:
Corneal reflex
afferent – V ; efferent – VII
What cranial nerves are responsible for:
jaw jerk
afferent and efferent – V
What cranial nerves are responsible for:
gag reflex
afferent – IX ; efferent - X
III and IV (Oculomotor and Trochlear) nuclei lie in the ________
MID-BRAIN
V, VI AND VII (Trigeminal, Abducent and Facial) lie in the ______
PONS
VIII (Vestibulocochlear) lie at the __________ junction
PONTOMEDULLARY
IX, X XI and XII (Glossopharyngeal, Vagus, Accessory and Hypoglossal ) lie in the ________
MEDULLA
What may be some Combinations of Cranial Nerve Signs?
Bilateral III - midbrain
III +IV+VI - superior orbital fissure
VI +VII -pons
V + VIII - cerebellopontine angle
Unusual combinations - ?chronic or malignant meningitis
Pure motor signs - ?myasthenia gravis - affects neuromuscular junction
What different ways can cranial nerves be damaged?
within the brain - e.g. by ischaemia, tumour
crossing the sub-arachnoid space - e.g by meningitis
outside the skull e.g. by base of skull tumours arising in nasopharynx
What is optic neuritis?
demyelination within the optic nerve
an inflammation that damages the optic nerve
What are the signs and symptoms 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
How does parasympathetic effect pupillary response?
constriction of the pupil
loss of parasympathetic input results in a fixed, dilated pupil
e.g. complete third nerve palsy
How would sympathetic effect pupillary response?
pupillary dilatation
damage anywhere within the sympathetic pathway can lead to a constricted pupil
What are 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 - rare disorder characterized by a constricted pupil (miosis), drooping of the upper eyelid (ptosis), absence of sweating of the face (anhidrosis), and sinking of the eyeball into the bony cavity that protects the eye (enophthalmos)
What are some eye movement disorders?
Isolated third nerve palsy
Isolated fourth nerve palsy
Isolated sixth nerve palsy
Combination of the above
Supranuclear gaze palsy
Nystagmus
WHat are the causes of isolated third nerve palsy?
• Microvascular - diabetes, hypertension
Painless, pupil spared
• Compressive - posterior communicating artery aneurysm, raised ICP
Painful, pupil affected
What are the causes of isolated sixth nerve palsy?
Numerous causes including:
- idiopathic
- diabetes
- meningitis
- raised intracranial pressure
What is nystahmus?
Congenital
Serious visual impairment
Peripheral vestibular problem
Central vestibular/brainstem disease
Cerebellar disease
Toxins (medication and alcohol)
What is Trigeminal Neuralgia?
Paroxysmal attacks of lancinating pain
a chronic pain condition that affects the trigeminal nerve, which carries sensation from your face to your brain
What causes Trigeminal Neuralgia?
Triggers
Middle age and older
Caused by vascular loop - Compression fifth nerve in the posterior fossa
What is the treatment of Trigeminal Neuralgia?
Treated medically with carbamazepine
Surgical options if medication resistant
What is bells palsy, cause, symptoms and treatment?
Idiopathic facial nerve palsy
Unilateral facial weakness
Lower motor neurone type
Often preceded by pain behind ear
Eye closure affected
Risk of corneal damage
Treated with steroids
Usually good recovery
What are examples of UMN and LMN disease?
UMN - stroke or tumour
LMN - Bell’s Palsy, Lyme, sarcoid
What is Vestibular Neuronitis?
Sudden onset
Disabling vertigo
Vomiting
Gradual recovery
Cause uncertain ? viral
What is dysarthria ?
disordered articulation, slurring of speech
What is dysphagia?
difficulty swallowing
Both dysarthia and dysphagia occur in bulbar and pseudobulbar palsy, are they UMN or LMN?
Bulbar – lower motor neurone
Pseudobulbar palsy – upper motor neurone
What is Pseudobulbar Palsy and what does it cause?
Bilateral UMN lesions e.g. in vascular lesions of both internal capsules, MND
- dysarthria
- dysphonia - difficulty in speaking due to a physical disorder of the mouth, tongue, throat, or vocal cords. refers to sound production
- dysphagia
- spastic, immobile tongue
- brisk jaw jerk
- brisk gag reflex
WHat is bulbar palsy and what does it cause?
Bilateral LMN lesions affecting IX - XII, eg. MND, polio, tumours, vascular lesions of the medulla and syphilis
- wasted, fasciculating tongue
- dysarthria
- dysphonia
- dysphagia
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