Cranial nerve tests Flashcards
How can function of the olfactory nerve be tested?
Test sense of smell by blocking one nostril and holding non-irritating smell to the other.
How can somatosensory division of the trigeminal nerve be tested?
Using cotton wool to test sensation in each part of head corresponding to a division of the trigeminal nerve:
- Opthalmic: Forehead
- Maxillary: Cheek
- Mandibular: Chin
How can the motor component of the trigeminal nerve be tested?
- Closing mouth and feeling bulk of temporalis/masseter
- Opening mouth against resistance (lateral pterygoids)
- Checking for any deviation of the jaw when mouth opened (unilateral lateral pterygoid paralysis)
What does the corneal reflex test?
- Afferent pathway: V1 (Nasociliary nerve)
- Efferent pathway: Facial nerve
What is the corneal reflex?
Blinking reflex elicited by gently touching the cornea with cotton wool.
How can the chorda tympani be tested?
Taste in anterior 2/3 of tongue
How can the motor component of the facial nerve be tested?
- Asking patient to make various facial expressions
- Corneal reflex (efferent pathway)
What facial expressions can be made to test the functions of muscles of facial expression?
- Wrinkling forehead → Frontalis → Temporal branch
- Screw eyes shut tightly → Orbicularis oculi → Temporal/zygomatic branch
- Smiling → Orbicularis oris, risorius… → Buccal branch
- Puffing up cheeks → Orbicularis oris, buccinator → Buccal branch
- Clench teeth + depress angles of mouth → Platysma → Cervical branch
How can Bell’s palsey be tested?
- Forehead cannot be wrinkled
- Eyes cannot be screwed shut
- Patient cannot smile
How can vestibulocochlear nerve be tested?
Hearing:
- Whisper test
- Rinne’s test
- Weber test
Balance:
- Rhomberg’s test
What is Rinne’s test?
- Loudness of sound from tuning fork is compared when held outside external acoustic meatus compared to when held against mastoid process
- Normal hearing/sensorineural hearing loss results in louder air conduction than bone conduction
- Conductive hearing loss results in louder bone conduction than air conduction
What is the Weber test?
- Tuning fork held against forehead.
- If patient hears sound louder in affected ear than unaffected ear, conductive hearing loss.
- If patient hears sound louder in unaffected ear than affected ear, sensorineural hearing loss.
What is Romberg’s test?
- Balance is tested when the eyes are closed
- If balance is lost by patient when eyes closed, test is positive and indicated damage to vestibular nerve
What is the Doll’s eye reflex?
Part of vestibulo-ocular reflex whereby the gaze is fixed when the head is tilted.
What is the “Doll’s eye reflex” used to test?
- Afferent: VIII (Vestibular)
- Efferent: III, IV, VI
What is caloric reflex test?
- Cold/warm water is irrigated into the external auditory meatus and nystagmus (+ nausea if conscious) is created in the eyes.
- The direction of fast phase of nystagmus is determine by temperature of water (COWS): Cold Opposite, Warm Same.
What is the caloric reflex test used to test?
- Afferent: VIII (Vestibular)
- Efferent: III, IV, VI
What is the Gag reflex?
Brisk movement of wooden spatula on posterior 1/3 of tongue/oropharynx causes reflex elevation of soft palate (gagging).
What is the “Gag reflex” used to test?
- Affterent: Glossopharyngeal nerve
- Efferent: Vagus
How can motor component of vagus nerve be tested?
- When patient asked to say “Aah…”, uvula deviates away from the side of weakness.
- Asking patient to cough.
- Checking for hoarseness of voice.
What are the effects of damaging laryngeal nerves?
- Unilateral damage: Minimal phonation effect as there is compensation from other side.
- Bilateral damage:
1. Partial damage: Semon’s law states that posterior cricoarytenoid damaged and vocal cords adduct, preventing breathing.
2. Full damage: Vocal cords in half adducted position.
How can the spinal root of the accessory nerve [XI] be tested?
- Turning head against resistance → Sternocleidomastoid
- Shrugging shoulders → Trazpezius
How can damage to the hypoglossal nerve be tested?
- Wasting of affected side of tongue
- Deviation towards affected side when tongue protruded
What are brainstem reflexes that can be used to test unconscious patients?
- Pupillary reflex
- Corneal reflex
- Vestibulo-ocular reflex:
- Doll’s eye reflex
- Caloric reflex - Gag reflex