Disorders of Cranial Nerves Flashcards
How is the first cranial nerve tested?
Smell- unilateral or bilateral loss
How is the second cranial nerve tested?
Optic- visual acuity, visual fields, pupillary reactions, fundoscopy and colour vision
How are the third, fourth and sixth cranial nerves tested?
Evidence of ptosis?
Pupils of equal size?
Pupillary reactions
Eye movements
How is the fifth cranial nerve tested?
Sensation in the ophthalmic, maxillary and mandibular divisions
Power in the muscles of mastication
Corneal reflex
Jaw jerk reflex
How is the seventh cranial nerve tested?
Muscles of facial expression
Corneal reflex
Taste
How is the eighth cranial nerve tested?
Hearing using Rinne’s and Weber’s tests
Vestibular function using Dix-Hallpike manoevre and Untenberger’s test
How are the ninth and tenth cranial nerves tested?
Movement of the palate
Gag reflex
Quality of speech
Quality of cough
How is the eleventh cranial nerve tested?
Head turning
Shoulder shrugging
How is the twelfth cranial nerve tested?
Appearance, movement and power of the tongue
What is the afferent and efferent supply of the pupillary light reflex?
Afferent- second cranial nerve
Efferent- third cranial nerve
What is the afferent and efferent supply of the corneal reflex?
Afferent- fifth cranial nerve
Efferent- seventh cranial nerve
What is the afferent and efferent supply of the jaw jerk reflex?
Afferent- fifth cranial nerve
Efferent- fifth cranial nerve
What is the afferent and efferent supply of the gag reflex?
Afferent- ninth cranial nerve
Efferent- tenth cranial nerve
Where are the nuclei of the third and fourth cranial nerves found?
In the midbrain
Where are the nuclei of the fifth, sixth and seventh cranial nerves found?
In the pons
Where is the nuclei of the eighth cranial nerve found?
Lies at the pontomedullary junction
Where are the nuclei of the ninth, tenth, eleventh and twelfth cranial nerves found?
Lie in the medulla
Where can cranial nerves be damaged?
Within the brain
Crossing the sub-arachnoid space
Outside the skull
What are the symptoms of optic neuritis?
Monocular visual loss Pain on eye movement Reduced visual acuity Reduced colour vision Optic disc may be swollen
What are the 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 constricted pupils?
Old age Bright light "Miotic" eye drops Opiate overdose Horner's syndrome
What is the difference between microvascular and compressive isolated third nerve palsies?
Microvascular- caused by diabetes or hypertension. Painless and pupil spared
Compressive- caused by posterior communicating artery aneurysm or raised ICP. Painful and affects pupil
What are the causes of isolated sixth nerve palsy?
Idiopathic
Diabetes
Meningitis
Raised intracranial pressure
What are the causes of nystagmus?
Congenital Serious visual impairment Peirpheral vestibular problem Central vestibular/brainstem disease Cerebellar disease Toxins
What are the characteristics of trigeminal neuralgia?
Paroxysmal attacks of lancinating pain
Triggers
Middle age and older
Caused by vascular loop
How is trigeminal neuralgia treated?
Medically with carbamazepine
Surgical options if medication resistat
What are the characterstics of Bell’s palsy and how is it treated?
Unilateral facial weakness Lower motor neurone type Often preceded by pain behind ear Eye closure affected Risk of corneal damage Treated with steroids
What are the symptoms of vestibular neuronitis?
Sudden onset
Disabling vertigo
Vomiting
Gradual recovery
What are the signs and symptoms of pseudobulbar palsy and what lesions cause it?
Caused by bilateral UMN lesions Dysarthria Dysphonia Dysphagia Spastic, immobile tongue Brisk jaw jerk Brisk gag reflex
What are the signs and symptoms of bulbar palsy and what lesions cause it?
Caused by bilateral LMN lesions affecting CNIX-XII Wasted, fasciculating tongue Dysarthria Dysphonia Dysphagia
