Disorders of cranial nerves Flashcards
Clinical tests used to assess CN II (think examination) (5)
Visual acuity – Snellen test Visual field test Pupillary reflex Fundoscopy Colour vision test
Clinical test used to assess CN III, IV, VI
Eye movements - follow finger as it makes a H shape
What are we looking for when testing CN III, IV, VI (4)
Evidence of ptosis
Evidence of anisocoria (unequal pupils)
Pupillary reactions
Diplopia
Clinical tests used to assess CN V (4)
Sensation (light and heavy touch) in the ophthalmic, maxillary and mandibular areas
Power of the muscles of mastication (masseter and pterygoids)
Corneal reflex
Jaw jerk reflex
Clinical tests used to assess CN VII (3)
Movements of the muscles of facial expression
- Raise eyebrows/wrinkle forehead
- Squeeze eyes
- Smile with teeth
- Puff cheeks
Corneal reflex
Taste
Clinical tests used to assess CN VIII (5)
Hearing tests
- Whisper test
- Rinne’s test
- Weber’s test
Balance
- Dix-hallpike maoeuvre
- Untenberger’s test
Clinical tests used to assess CN IX & X (4)
Movement of the palate – symmetrical/asymmetrical
Gag reflex
Quality of speech – if poor, indicates weakness at back of palate
Quality of cough
Clinical tests used to assess CN XI (2)
Head turning - SCM
Shoulder shrugging - trapezius
Clinical tests used to assess CN XII (2)
Appearance of tongue - fasciculations, wasting
Movement and power of tongue
What cranial nerve is the afferent and efferent of the pupillary light reflex
Afferent - CN II
Efferent - CN III
What cranial nerve is the afferent and efferent of the corneal reflex
Afferent – CN V
Efferent – CN VII
What cranial nerve is the afferent and efferent of the jaw jerk reflex
Afferent & efferent - CN V
What cranial nerve is the afferent and efferent of the gag reflex
Afferent – IX
Efferent - X
Where is the nuclei of CN III & IV
Midbrain
Where is the nuclei of CN V, VI & VII
Pons
Where is the nuclei of CN VIII
Pontomedullary junction
Where is the nuclei of CN IX, X, XI & XII
Medulla
What is the angle called where CN VI & VIII emerge
Cerebellopontine angle
Pure motor signs sometimes may not actually be a cranial nerve lesion but indicate the pure motor disease:
Myasthenia gravis
Which of the following is an appropriate method of testing coordination of the lower limb:
A Ask the patient to state if his toe is moved up or down, when his eyes are shut
B Assessing the patient’s ability to sit up from lying
C Assessing the plantar response
D Finger-nose test
E Heel-shin test
E
A 51 year old man is noted to have a left trigeminal nerve palsy.
Which of the following is the most likely examination finding:
He has absent taste sensation to the anterior two thirds of the left of the tongue
B He has numbness over the left mandible
C He has numbness over the right maxilla
D He has numbness over the right posterior aspect of the scalp
E He is unable to smile with the left side of his mouth
B
Clinical features of optic neuritis (7)
Monocular visual loss Pain on eye movement (as nerve inflamed) Peri-orbital pain Reduced visual acuity/ blurry Reduced colour vision
Optic disc swollen - papilloedema
Relative afferent pupillary defect
General trigger of trigeminal neuralgia (a type of headache)
Temperature
Clinical features of Bell’s palsy (4)
Unilateral facial weakness
Dry eye - due to inadequate blinking
Post-auricular pain
Synkinesis - involuntary muscular movements accompanying voluntary movements, e.g. voluntary smiling may induce an involuntary contraction of the eye muscles
Bell’s palsy is thought to be due to what
Re-activation of herpes simplex virus
Treatment of Bell’s palsy (2)
High dose steroids
Eye protection - daytime (glasses, artificial tears); Overnight (ophthalmic lubricant, eyelid taped)
In UMN facial paralysis, is the forehead preserved
Yes, forehead unaffected unlike LMN facial paralysis
Clinical features of vestibular neuronitis (inflamed vestibular branch of CN VIII) (3)
Disabling vertigo
Vomiting
Nystagmus
Vestibular neuronitis thought to be due to what
Preceding viral infection
Effect of sympathetic system on pupils
Dilates pupils
Effect of parasympathetic system on pupils
Constricts pupils
Palsy of what CN leads to a fixed dilated eye
CN III
Causes of DILATED pupils (7)
Youth Dim lighting Anxiety, excitement “Mydriatic” eye drops Amphetamine, cocaine overdose CN III palsy Brain death – bilateral dilated
Causes of CONSTRICTED pupils (5)
Old age Bright light “Miotic” eye drops Opiate overdose Horner’s Syndrome – small pupil unilaterally
Causes of isolated CN III palsy
- microvascular causes (2)
- compressive cause (2)
Microvascular causes
- Diabetes
- Hypertension
Compressive cause
- posterior communicating artery aneurysm
- raised ICP
Clinical features of microvascular causes v compressive causes of CN III palsy
Microvascular causes – PAINLESS, PUPIL UNAFFECTED, NO HEADACHE
Compressive causes – PAINFUL, PUPIL AFFECTED
Common cause of isolated CN IV palsy
Diabetes
Causes of isolated CN VI palsy (4)
Idiopathic
Diabetes
Meningitis
Raised ICP
Causes of nystagmus (6)
Congenital Serious visual impairment Peripheral vestibular problem Central vestibular problem/ brainstem disease Cerebellar disease Toxins – medication
What is bulbar palsy (LMN or UMN, affecting what CNs)
LMN PROBLEM (bilateral LMN lesions affecting CN IX-XII – e.g. MND (motor neurone disease), polio, tumours, syphilis)
What is pseudo bulbar palsy (UMN or LMN)
Bilateral UMN lesions - e.g. lesion of internal capsule, MND (motor neurone disease))
Clinical features of bulbar palsy (4)
Wasted fasiculating tongue
Dysarthria
Dysphonia
Dysphagia
Clinical features of pseudobulbar palsy (6)
Dysarthria Dysphonia – loss of speech volume Dysphagia Spastic, immobile tongue Brisk jaw jerk Brisk gag reflex
