Disorders of the Cranial Nerves Flashcards
Name and function of CN I
Olfactory nerve
Olfaction
Name and function of CN II
Optic nerve
Vision
Name and function of CN III
Oculomotor nerve
Control of eye muscle activity, pupillary constriction
Name and function of CN IV
Trochlear nerve
Control of eye muscle activity
Name and function of CN V
Trigeminal nerve
Ordinary sensation
Control of muscles of mastication
Name and function of CN VI
Abducens nerve
Control of eye muscle activity
Name and function of CN VII
Facial nerve Taste Control of muscles of facial expression Lacrimation Salivation
Name and function of CN VIII
Vestibulocochlear nerve
Hearing and balance
Ordinary sensation from ear
Name and function of CN IX
Glossopharyngeal nerve
Taste
Ordinary sensation from ear
Salivation
Name and function of CN X
Vagus nerve
Taste
Control of muscles of larynx and pharynx
Parasympathetic innervation beyond the diaphragm
Name and function of CN XI
Accessory nerve
Control of sternocleidomastoid and trapezius muscle
Name and function of CN XII
Hypoglossal nerve
Control of tongue muscles
Testing sense of smell would assess the function of what cranial nerve?
Olfactory
How to assess optic nerve function
Visual acuity Visual fields Pupillary reactions Fundoscopy Colour vision
How to assess oculomotor, trochlear and abducens nerves function
Assess for ptosis
Pupils of equal size
Pupillary reaction
Eye movements - vertical and horizontal
How to assess trigeminal nerve function
Assess sensation in ophthalmic, maxillary and mandibular divisions
Power of muscles of mastication
Corneal reflex
Jaw jerk
How to assess facial nerve function
Assess muscles of facial expression (raise eyebrows, bear teeth etc.)
Corneal reflex
Taste
How to assess vestibulocochlear nerve function
Rinne’s and Weber’s tests to assess hearing
Dix-Hallpike manouvre and Unterberger’s test to assess vestibular function
How to assess glossopharyngeal and vagus nerve function
Movement of palate
Gag reflex
Quality of speech
Quality of cough
How to assess accessory nerve function
Head turning and shoulder shrug (sternocleidomastoid and trapezius function)
How to assess hypoglossal nerve function
Appearance, movement and power of tongue
Fibres tested by pupillary light reaction
CN II afferent fibres
CN III efferent fibres
Fibres tested by corneal reflex
CN V afferent fibres
CN VII efferent fibres
Fibres tested by jaw jerk
CN V afferent and efferent fibres
Fibres tested by gag reflex
CN IX afferent
CN X efferent
Causes of dilated pupils
Youth Dim lighting Anxiety/excitement Mydriatic eye drops Amphetamine use Third nerve palsy Brain death
Causes of small pupils
Old age Bright light Miotic eye drops Opiate overdose Horner's syndrome
Examples of eye movement disorders
Isolated third nerve palsy Isolated fourth nerve palsy Isolated sixth nerve palsy Combination of isolated third, fourth and sixth nerve palsies Supranuclear gaze palsy Nystagmus
Microvascular causes of isolated third nerve palsy
Diabetes
Hypertension
(painless, pupil spared)
Compressive causes of isolated third nerve palsy
Posterior communicating artery aneurysm
Raised ICP
(painful, pupil affected)
Causes of isolated sixth nerve palsy
Idiopathic
Diabetes
Meningitis
Raised ICP
Causes of nystagmus
Congenital Serious visual impairment Peripheral vestibular problem Central vestibular/brainstem disease Cerebellar disease Toxins
Clinical features of trigeminal neuralgia
Paroxysmal attacks of lancinating (piercing/stabbing) pain
Cause of trigeminal neuralgia
Vascular loop - compression of fifth nerve in the posterior fossa
Treatment of trigeminal neuralgia
Carbamazepine
Surgery if medication resistant
Presentation of Bell’s palsy
Idiopathic facial nerve palsy
Unilateral facial weakness
May be preceded by pain behind the ear
Eye closure affected
Treatment of Bell’s palsy
steroids
Presentation of vestibular neuronitis
Sudden onset, disabling vertigo, vomiting
What is dysarthria
Disordered articulation and slurring of speech
What is dysphagia
Difficulty swallowing
Cause of bulbar palsy
Bilateral lower motor neurone lesions affecting CN IX-XII e.g. Motor neurone disease Polio Malignancy Vascular lesions of medulla Syphilis
Clinical features of bulbar palsy
Wasted, fasciculated tongue
Dysarthria
Dysphonia
Dysphagia
Causes of pseudobulbar palsy
Bilateral upper motor neurone lesions e.g. vascular lesions in both internal capsules
Clinical features of pseudobulbar palsy
Spastic, immobile tongue Dysarthria Dysphonia Dysphagia Brisk jaw reflex Brisk gag reflex
