Disorders of Cranial Nerves Flashcards
What are each of the cranial nerves called?
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What is CN I called?
Olfactory nerve
What is CN II called?
Optic nerve
What is CN III called?
Oculomotor nerve
What is CN IV called?
Trochlear nerve
What is CN V called?
Trigeminal nerve
What is CN VI called?
Abducens nerve
What is CN VII called?
Facial nerve
What is CN VIII called?
Vestibulocochlear nerve
What is CN IX called?
Glossopharyngeal nerve
What is CN X called?
Vagus nerve
What is CN XI called?
Accessory nerve
What is CN XII called?
Hypoglossal nerve
What are different functions of cranial nerves?
- ‘Special’ senses
- ‘Ordinary’ sensation
- Control of muscle activity
- Autonomic functions
What cranial nerves transmit the ‘special senses’?
- Olfaction (I)
- Vision (II)
- Taste (VII, IX and X)
- Hearing and balance (VIII)
What cranial nerve is responsible for olfaction?
CN I
What cranial nerve is responsible for vision?
CN II
What cranial nerve is responsible for taste?
CN VII, IX and X
What cranial nerve is responsible for hearing and balance?
CN VIII
What cranial nerve controls the eye muscles?
CN III, IV and VI
What cranial nerve controls the muscles of mastication?
CN V
What cranial nerves control the muscles of facial expression?
VII
What cranial nerves control the muscles of the pharynx?
Mainly X
What cranial nerves controls the muscles of the pharynx?
Mainly CN X
What cranial nerve controls the sternomastoid?
CN XI
What cranial nerve controls the trapezius muscles?
CN XI
What cranial nerve controls pupil constriction?
CN III
What cranial nerve controls lacrimation?
CN VII
What cranial nerve controls salvation?
- Submandibular and sublingual glands VII
- Parotid gland IX
What does physical examination of CN I test?
- Smell, unilateral or bilateral loss
What does physical examination of CN II test?
- Visual acuity, visual fields, pupillary reactions, fundoscopy, colour vision
What does physical examination of CN III, IV and VI test?
- Evidence of ptosis (drooping of the upper eyelid), pupil of equal size, pupillary reactions, eye movements (horizontal and vertical)
What is ptosis?
Drooping of upper eyelid
What does physical examination of CN V test?
- Sensation in ophthalmic, maxillary and mandibular divisions, power in the muscles of mastication, corneal reflex, jaw jerk
What does physical examination of CN VI test
- Muscles of facial expression, corneal reflex, taste
What does physical exmination of CN VIII test?
- Hearing using Rinne’s and Weber’s tests, vestibular function using Dix-Hallpike manoeuvre and Untenberger’s test
What does physical examination of CN IX test?
- Movement of the palate, gag reflex, quality of speech, quality of cough
What does physical examination of CN XI test?
- Head turning and shoulder shrugging
What does physical examination of CN XII test?
- Appearance, movement and power of tongue
What are exampes of cranial nerve reflexes?
- 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
What cranial nerves are responsible for the pupillary light reaction reflex?
- Afferent II
- Efferent III
What cranial nerves are responsible for the corneal reflex?
- Afferent V
- Efferent VII
What cranial nerves are responsible for the jaw jerk reflex?
- Afferent and efferent V
What cranial nerves are responsible for the gag reflex?
- Afferent IX
- Efferent X
The nuclei of what cranial nerves are locacted in the mid-brain?
CN III and IV
The nuclei of what cranial nerves are locacted in the pons?
CN V, VI and VII
The nuclei of what cranial nerves are locacted in the pontomedullary junction?
CN VIII
The nuclei of what cranial nerves are locacted in the medulla?
A combination of cranial nerve signs can indicate where the problem is in the brain, what does bilateral III indicate?
Midbrain
A combination of cranial nerve signs can indicate where the problem is in the brain, what does III and IV and VI indicate?
Superior orbital fissure
A combination of cranial nerve signs can indicate where the problem is in the brain, what does VI and VII indicate?
Pons
A combination of cranial nerve signs can indicate where the problem is in the brain, what does V and VIII indicate?
Cerebellopontine angle
A combination of cranial nerve signs can indicate where the problem is in the brain, what does unusual combinations indicate?
Chronic or malignant meningitis
What do cranial nerve signs usually indicate?
Cranial nerve lesion
Not all cranial nerve signs imply a cranial nerve lesion, what are examples?
- Eye movement disorders, facial weakness, difficulty swallowing after stroke
- Double vision in myasthenia or thyroid eye disease
Where are the different locations that cranial nerves can be damaged?
- Within the brain
- Such as by ischaemia or tumour
- Crossing the subarachnoid space
- Such as by meningitis
- Outside the skull
- Such as by base of skull tumours arising in nasopharynx
What can cranial nerves be damaged by within the brain?
Ischaemia or tumour
What can cranial nerves be damaged by when crossing the subarachnoid space?
Meningitis
What can cranial nerves be damaged by outside the skull?
- Such as by base of skull tumours arising in nasopharynx
What is optic neuritis?
Inflammation of the optic nerve, demyelination within the optic nerve
What is the clinical presentation of optic neuritis?
- Monocular visual loss
- Pain on eye movement
- Reduced visual acuity
- Reduced colour vision
- Optic disc may be swollen
- Often associated with MS
What effect does parasympathetic innervation have on the pupil?
Constriction of pupil
What does loss of parasympathetic innervation to the pupil result in?
- Loss of parasympathetic input results in a fixed, dilated pupil
- Such as CN III palsy
What effect does sympathetic innervation have on the pupil?
Pipillary dilation
What can loss of sympathetic innervation on the pupil cause?
- Damage can lead to constricted pupil
What are some causes of dilated pupils?
- Young
- Dim lighting
- Anxiety, excitement
- “Mydriatic” eye crops
- Amphetamine, cocaine overdose
- CN III palsy
- Brain death
What are some causes of constricted pupils?
- Old age
- Bright light
- “Miotic” eye drops
- Opiate overdose
- Horner’s syndrome
What are some examples of eye movement disorders?
- Isolated CN III palsy
- Isolated CN IV palsy
- Isolated VI palsy
- Combination of the above
- Supranuclear gaze palsy]Nystagmus
What can isolated CN III nerve palsy be caused by?
- Microvascular
- Diabetes, hypertension
- Painless, pupil spared
- Compressive
- Posterior communicating artery aneurysm
- Raised ICP
- Painful, pupil affected
What can isolated CN VI nerve palsy be caused by?
- Idiopathic
- Diabetes
- Meningitis
- Raised ICP
What are some causes of nystagmus?
- Congenital
- Serious visual impairment
- Peripheral vestibular problem
- Central vestibular/brainstem disease
- Cerebellar disease
- Toxins (medication and alcohol)
What is nystagmus?
Vision condition in which the eyes make repetitive, uncontrolled movements
What is trigeminal neuralgia?
This is a chronic pain condition affecting CN V, where even mild stimulation of your face may trigger a jolt of excruciating pain
What is the clinical presentation of trigeminal neuralgia?
Paroxysmal attacks of lancinating pain
Middle age and older
Has triggers
What is trigeminal neuralgia caused by?
Caused by vascular loop:
- Compression of CN V in posterior fossa
What is the treatment of trigeminal neuralgia?
Treated medically with carbamazepine, surgical options if medication resistant
What is Bells’s palsy?
Is idiopathic facial nerve palsy
What is the clinical presentation of Bell’s palsy?
Unilateral facial weakness
Lower motor neuron type
Often preceded by pain behind ear
Eye closure affected
Risk of corneal damage
What is the treatment of Bell’s palsy?
Treated with steroids, usually good recovery
Is Bell’s palsy a UMN or LMN disease?
LMN
What is the difference between UMN and LMN paralysis?
Main difference is that in UMN there is hemiplegia (paralysis of one side of the body) of the contralateral mid and lower face, whereas LMN there is complete hemiplegia of the ipsilateral face
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What is hemiplegia?
Paralysis of one side of the body
What is vestibular neuronitis?
Inflammation of the vestibular nerve (branch of CN VIII)
What is the clinical presentation of vestibular neuronitis?
Characterised by sudden severe attack of vertigo
Vomiting
Gradual recovery
What is vestibular neuronitis characterised by?
Sudden severe attack of vertigo
What is dysarthria?
Disordered articulation, slurring of speech
What is dysphagia?
Difficulty swallowing
In what disease does dysarthria and dysphagia occur?
Both occur in bulbar and pseudobulbar palsy:
- Bulbar is lower motor neuron
- Pseudobulbar is upper motor neuron
Is bulbar palsy UMN or LMN?
LMN
Is peudobulbar palsy UMN or LMN?
UMN
What is pseudobulbar palsy?
Caused by bilateral UMN lesions such as in vascular lesions of both internal capsules or MND
What is the clinical presentation of pseudobulbar palsy?
- Dysarthria
- Dysphonia (involuntary spasms in the muscles of the larynx causing the voice to break having a strained sound)
- Dysphagia
- Spastic, immobile tongue
- Brisk jaw jerk
- Brisk gag reflex
What is dysphonia?
Involuntary splasms in the muscles of the larynx causing the voice to break having a strained sound
What is bulbar palsy?
Caused by LMN lesions affecting CN IX to XII, such as:
- MND
- Polio
- Tumours
- Vascular lesions of the medulla
- Syphilis
What are causes of Bulbar palsy?
Caused by LMN lesions affecting CN IX to XII, such as:
- MND
- Polio
- Tumours
- Vascular lesions of the medulla
- Syphilis
What is the clinical presentation of Bulbar palsy?
- Wasted, fasciculation tongue
- Dysarthria
- Dysphonia
- Dysphagia