Disorders of Cranial Nerves Flashcards
What nerves are responsible for special senses?
- Olfaction –> CN I
- Vision –> CN II
- Taste –> CN VII, XI and X
- Hearing (and balance) - CN VIII
Which nerve provides innervation to muscles of mastication?
Trigeminal (CN V)
Which nerve innervated muscles of facial expression?
Facial nerve (CN VII)
Which nerve provides most of the innervation to the larynx and pharynx?
Mainly vagus (CN X)
Which nerve supplies innervation the the sternocleidomastoid and trapezius muscles?
Accessory nerve (CN XI)
Which nerve innervated the lacrimal gland?
Facial nerve - secretomotor
What nerve innervate submandibular and sublingual glands?
Facial - secretomotor
Which nerve innervates the parotid gland?
Glossopharyngeal - secretomotor
Which nerve provide parasympathetic input?
- Oculomotor
- Facial
- Glossopharyngeal
- Vagus (to organs in thorax and abdomen)
How do you test smell?
Olfactory nerve - is smell unilateral or bilateral loss?
How do you test vision?
Optic nerve: • Visual acuity • Visual field • Pupillary reaction • Fundoscopy • Colour vision
What do you test with eye nerve function?
Oculomotor, trochlear and abducence nerve:
• Ptosis?
• Equal pupil size?
• Pupillary reactions
• Eye movements - vertical and horizontal
How do you test the trigeminal nerve?
- Sensation in the VI, V2 and V3 regions
- Power in the muscles of mastication
- Corneal reflex (afferent is V1)
- Jaw jerk (V3)
How do you test the facial nerve?
- Muscles of facial expression
- Corneal reflex (efferent to orbicularis oculi)
- Taste
How do you test the vestibulocochlear nerve?
- Hearing using Rinne’s and Weber’s tests
* Vestibular function using Dix-Hallpike manoeuvre and Untenberger’s test
How do you test the glossopharyngeal and vagus nerve?
- Movement of the palate
- Gag reflex
- Quality of speech
- Quality of cough
How do you test the accessory nerve?
- Heading tubing and shoulder shrugging - SCM and trapezius function
- Appearance, movement and power of tongue
What nerves are involved in the pupillary light reflex?
- Afferent - optic nerve
* Efferent - oculomotor nerve
What nerves are involved in the corneal reflex?
- Afferent - CN V1
* Efferent - facial nerve
What nerves are involved in the jaw jerk?
Both CN V3
What nerves are involved in the gag reflex?
- Afferent - glossopharyngeal nerve
* Efferent - vagus nerve
Where does the nuclei of the oculomotor and trochlear nerves lie?
Midbrain
Where does the nuclei of the trigeminal, abducence and facial nerves lie?
Pons
Where does the nuclei of the vestibulocochlear nerve lie?
Ponto-medullary junction
Where does the nuclei of the glossopharyngeal, vagus, accessory and hypoglossal nerves lie?
Medulla
Where would the abnormality be if there were signs in bilateral CN III nerve?
Midbrain
Where would the abnormality be if there were signs in the III, IV and VI nerves?
Superior orbital fissure
Where would the abnormality be if there were signs in the VI and VII nerves?
Pons
Where would the abnormality be if there were signs in the V and VIII nerves?
Cerebellopontine angle
Suggest a cause of an unusual combination of cranial nerve signs
? Chronic or malignant meningitis
Suggest a cause of pure motor signs
? Myasthenia gravis
Give examples of causes of non-cranial nerve lesions that cause cranial nerve signs
- Stroke - eye movement disorders, facial weakness, difficulty swallowing after a stroke
- Double vision in myasthenia or thyroid eye disease
Name seven signs of optic neuritis
- Demyelination within the optic nerve
- Monocular visual loss
- Pain on eye movement
- Reduced visual acuity
- Reduced colour vision
- Optic disc may be swollen
- Often associated with multiple sclerosis
Name seven signs of optic neuritis
- Demyelination within the optic nerve
- Monocular visual loss
- Pain on eye movement
- Reduced visual acuity
- Reduced colour vision
- Optic disc may be swollen
- Often associated with multiple sclerosis
Describe the parasympathetic pupillary response
- Causes constriction of pupil
- Loss of input results in a fixes, dilated pupil
- I.e. complete third nerve palsy
Describe the sympathetic pupillary repsponse
- Causes pupillary dilatation
* Damage anywhere within the sympathetic pathway can lead to a constricted pupil
Name seven cause of dilated pupils
- Youth
- Dim lighting
- Anxiety, excitement
- “Mydriatic” eye drops
- Amphetamine, cocaine overdose
- Third nerve palsy
- Brain death
Name six eye movement disorders
- Isolated third nerve palsy
- Isolated fourth nerve palsy
- Isolated sixth nerve palsy
- Combination of the above
- Supranuclear gaze palsy
- Nystagmus
Name six 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 two different types of reasons which can cause isolated third nerve palsy?
- Microvascular - diabetes, hypertension –> painless, pupil spared
- Compressive - posterior communicating artery aneurysm, raised ICP –> painful, pupil affected
Name four reasons that cause isolated sixth nerve palsy
- Idiopathic
- Diabetes
- Meningitis
- Raised intracranial pressure
Name six causes of nystagmus
- Congenital
- Serious visual impairment
- Peripheral vestibular problem
- Central vestibular / brainstem disease
- Cerebellar disease
- Toxins (medication and alcohol)
What is trigeminal neuralgia?
Mild stimulation of your face — such as from brushing your teeth or putting on makeup — may trigger a jolt of excruciating pain
What are the features of trigeminal neuralgia?
- Paroxysmal attacks of lancinating pain
- Triggers
- Middle age and older
- Caused by vascular loop - compression fifth nerve in posterior fossa
How do you treat trigeminal neuralgia?
- Treated medically with carbamazepine
* Surgical option if medication resistant
What are the features of Bell’s palsy?
- Unilateral facial weakness
- Lower motor neurone type
- Often preceded by pain behind ear
- Eye closure affected
- Risk of corneal damage
What are the features of Bell’s palsy?
- Unilateral facial weakness
- Lower motor neurone type
- Often preceded by pain behind ear
- Eye closure affected
- Risk of corneal damage
How is Bell’s palsy treated?
Treated with steroids
What could cause an LMN facial paralysis?
Bell’s palsy, lymes, sarcoid etc
What could cause an LMN facial paralysis?
Bell’s palsy, lymes, sarcoid etc
What is vestibular neuronitis?
Sudden severe attack of vertigo caused by inflammation of the vestibular nerve
What are the features of vestibular neuronitis?
- Sudden onset
- Disabling vertigo
- Vomiting
- Gradual recovery
- Cause is uncertain ? viral
What is dysarthria?
Disordered articulation, slurring of speech
What is dysphagia?
Difficulty swallowing
What conditions do dysphagia and dysarthria occur in?
Both occur in bulbar- and pseudobulbar palsy:
• Bulbar - lower motor neurone
• Pseudobulbar palsy - upper motor neurone
What is pseudobulbar palsy?
Inability to control facial movements due to bilateral UMN lesions e.g. in vascular lesions of both internal capsules, MND
What are the symptoms and signs of pseudobulbar palsy?
- Dysarthria
- Dysphonia
- Dysphagia
- Spastic, immobile tongue
- Brisk jaw jerk
- Brisk gag reflex
What is bulbar palsy?
Range of different signs and symptoms linked to impairment of function of the cranial nerves IX - XII which occurs due to bilateral LMN lesion in the medulla or from lesions of the lower cranial nerves outside the brainstem
I.e. motor neurone disease, polio, tumours, vascular lesions of the medulla and syphilis
What are the symptoms and signs of bulbar palsy?
- Wasted, fasciculating tongue
- Dysarthria
- Dysphonia
- Dysphagia
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