Cranial Nerve Disorders

Question 1

what are the 4 functions of cranial nerves?

Answer 1

special sensory, general sensory, motor activity and autonomic functions

Question 2

what are the special senses and their nerves?`

Answer 2

olfaction (I), vision (II), taste (VII, IX), hearing and balance (VIII)

Question 3

what are the general sensation of the cranial nerves?

Answer 3

mainly the Vth which supplies sensation of the face in 3 branches

Question 4

what is the parasympathetic innervation of the cranial nerves?

Answer 4

pupillary constriction= III, lacrimation= VII, salivation= VII (submandibular and sublingual glands) and IX (parotid glands), vagal input to organs in the thorax and abdomen

Question 5

what is the motor activity of the cranial nerves?

Answer 5

eye muscles- III, IV and VI (LR6, SO4, rest 3), muscles of mastication- V, muscles of facial expression- VII, muscles of larynx and pharynx= mainly X, sternocleidomastoid and trapezius muscles= XI

Question 6

what are the cranial nerve reflexes?

Answer 6

pupillary light reaction, corneal reflex, jaw jerk, gag reflex

Question 7

what nerves are involved in the pupillary light reaction?

Answer 7

afferent= II and efferent= III

Question 8

what are the nerves involved in the corneal reflex?

Answer 8

afferent= V and efferent= VII

Question 9

what are the nerves involved in the jaw jerk?

Answer 9

afferent and efferent= V

Question 10

what are the nerves involved in the gag reflex?

Answer 10

afferent= IX and efferent= X

Question 11

what are the locations of the cranial nerve nuclei?

Answer 11

III and IV nuclei lie in the midbrain, V, VI and VII lie in the pons, VIII lies at the pontomedullary junction, IX, X, XI and XII lie in the medulla

Question 12

what causes a fixed dilated pupil?

Answer 12

loss of parasympathetic input eg complete 3rd nerve palsy

Question 13

what causes a constricted pupil?

Answer 13

damage anywhere within the sympathetic pathway

Question 14

what is dysarthria?

Answer 14

disorder articulation or slurring of speech

Question 15

what is dysphagia?

Answer 15

difficulty swallowing

Question 16

what is pseudobulbar palsy?

Answer 16

bilateral UMN lesions eg in vascular lesions of both internal capsules, MND- dysarthria, dysphagia, spastic, immobile tongue, brisk jaw jerk and gag reflex

Question 17

what is bulbar palsy?

Answer 17

bilateral LMN lesions affecting IX- XII eg MND, polio, tumours, vascular lesions of the medulla and syphilis - wasted, fasciculating tongue, dysarthria, dysphagia

Question 18

what is vestibular neuronitis?

Answer 18

sudden onset, disabling vertigo, vomiting, gradual recovery, causes is uncertain but thought to be viral

Question 19

what is Bell’s palsy?

Answer 19

idiopathic facial nerve palsy, unilateral facial weakness, LMN, often preceded by pain behind the ear, eye closure affected, treated with steroids

Question 20

what is trigeminal neuralgia?

Answer 20

paroxysmal attacks of lancinating pain, triggers= chewing, speaking or cold air, treated with carbamazepine

Question 21

how do we determine between an UMN vs LMN facial nerve palsy?

Answer 21

UMN lesion the forehead will be spared and the patient will be able to move their forehead on the affected side but in a LMN lesion the forehead will not be spared and the patient cannot move their forehead on the affected side

Question 22

what does a IIIn palsy look like?

Answer 22

ptosis (drooping eyelid), dilated, non-reactive pupil, divergent strabismus (squint)= down and out position of affected eye

Question 23

what are the triad of symptoms caused by Horner’s syndrome?

Answer 23

ptosis, miosis and anhidrosis (loss of sweating)

Question 24

what causes Horner’s syndrome?

Answer 24

damage to the sympathetic nervous system supplying the face

Question 25

what nerve would be affected if the eye does not close?

Answer 25

the facial nerve as the obicularis oculi closes the eyelid

Question 26

what does a VIn palsy look like?

Answer 26

affected eye points towards the nose= away from the direction of the paralysed muscle