Cranial Nerves Flashcards
How would you test CNI in a patient?
Ask them “Have you noticed any changes in your sense of smell?”
Rarely smell cards are used
How would you test CNII in a patient?
Visual fields Ask if any troubles with vision Glasses/contacts? Ichihara chart for colour vision Blind spot testing Visual acuity - Snellen chart Opthalmosocpy Pupillary response
How would you test CNIII, IV and VI in a patient?
Eye movements in H pattern.
Ask patient to report any double vision
Observe resting gaze
How would you test CNV in a patient?
Test sensation in all 3 nerve areas Test power of masseter and temporal muscles Push jaw open against pressure Jaw jerk reflex Corneal reflex
How would you test CNVII in a patient?
Raise eyebrows, close eyes tight (against resistance), puff cheeks out, show teeth and whistle
Ask about changes in taste
How would you test CNVIII in a patient?
Soft whisper hearing Ask if noticed any hearing issues Webers and Rinne's test Vestibular ocular reflex Gait, heel-to-toe walk and Romberg's
How would you test CNIX and X in a patient?
Cough, swallow and say AH
Gag reflex
How would you test CN XI in a patient?
Shoulder shrug and head turning against resistance
How would you test CNXII in a patient?
Open mouth and stick tongue out looking for tongue or uvular devaition
Power of tongue against side of cheek
Observe tongue for wasting or fasciculations
What nerve type(s) does CNI carry?
Sensory
What nerve type(s) does CNII carry?
Sensory
What nerve type(s) does CNIII carry?
Motor (somatic and parasympathetic)
What nerve type(s) does CNIV carry?
Motor
What nerve type(s) does CNV carry?
Sensory
Motor
What nerve type(s) does CNVI carry?
Motor
What nerve type(s) does CNVII carry?
Sensory
Motor (parasympathetic + somatic)
What nerve type(s) does CNVIII carry?
Sensory
What nerve type(s) does CNIX carry?
Sensory
Motor (somatic + parasympathetic)
What nerve type(s) does CNX carry?
Sensory (somatic and visceral)
Motor (parasympathetic + somatic)
What nerve type(s) does CNXI carry?
Motor
What nerve type(s) does CNXII carry?
Motor
What functions does CNI serve?
Sense of smell
What functions does CNII serve?
Vision
What functions does CNIII serve?
SOMATIC
Eye movement: Superior, medial and inferior rectus muscles, inferior oblique muscles. All eye movements apart from outwards, and medial and down.
Eyelid opening: levator palpebrae superioris
PARASYMPATHETIC
Pupillary constriction: sphincter pupillae
Accommodation: ciliary muscle
What functions does CNIV serve?
Eye movement: abduction and internal rotation (superior oblique muscle). Moves eye medially and downwards.
What functions does CNV serve?
SENSORY
Facial sensation: ophthalmic, maxillary and mandibular regions
Somatosensation of anterior 2/3 of tongue
MOTOR
Mastication: masseter, temporalis, medial pterygoid, lateral pterygoid muscles
What functions does CNVI serve?
Eye movements: retracts the eye within the orbit (lateral rectus). Moves eye outwards.
What functions does CNVII serve?
SENSORY
Taste perception of anterior 2/3 of tongue
Pain sensation: skin behind ear
PARASYMPATHETIC
Salivation (submandibular and sublingual glands)
Lacrimation
SOMATIC Opening and closing of jaw (digastric) Eyelid closing (orbicularis oculi) Tongue elevation (stylohyoid muscle) Movement of stapedius bone (stapedius muscle)
What functions does CNVIII serve?
Balance and equilibrium
Hearing
What functions does CNIX serve?
SENSORY
Taste: posterior 1/3 tongue
Somatosensation: middle ear and Eustachian tube (tympanic nerve)
Visceral sensation: carotid sinus (baroreceptors detect BP)
Chemoreception: carotid body (chemoreceptors detect partial pressure of O2 and CO2 and pH)
SOMATIC
Swallowing: pharyngeal muscles and muscles of upper GIT tract
PARASYMPATHETIC
Salivation: parotid gland
What functions does CNX serve?
SOMATIC SENSORY
Somatosensation: external auditory canal, trachea, larynx
VISCERAL SENSORY
Taste perception: epiglottis and posterior tongue
Visceral sensation: aortic body (baroreceptors detect BP)
Chemoreception : aortic body (chemoreceptors detect partial pressure of O2 and CO2)
PARASYMPATHETIC
Lowering HR
Blood vessel dilatation
Promotes motility of oesophagus, stomach, intestines (up to splenic flexure) and other abdo organs
SOMATIC MOTOR
Swallowing: pharyngeal muscles and muscles of upper GIT tract
Speech: laryngeal muscles
What functions does CNXI serve?
Turn head (sternocleidomastoid) Elevate shoulders (trapezius)
What functions does CNXII serve?
Tongue protrusion: intrinsic and extrinsic muscles of the tongue
How does a CNI palsy present?
Anosmia
How does a CNII palsy present?
Impaired vision
How does a CNIII palsy present?
Paralytic squint (eye looks down and out)
Ptosis
Horizontal diplopia
Non-reactive, dilated pupil
How does a CNIV palsy present?
Inability to depress and addut eyeball simultaneously (eye shoots upwards in attempted adduction)
Diplopia (vertical or oblique) worse on down gaze or if head turned to affected side
How does a CNV palsy present?
Absent corneal reflex
Anaesthesia of forehead/midface/jaw
Muscles of mastication paralysed
Jaw deviates towards side of lesion
How does a CNVI palsy present?
Horizontal diplopia
Esotropia
How does a CNVII palsy present?
Weakness of muscles of facial expression and eye closure
Face sags
Voluntary eye closure may not be possible
LMN - patient can’t wrinkle forehead
UMN - patient can wrinkle forehead and sagging less prominent
How does a CNVIII palsy present?
Sensorineural hearing loss
Vertigo
Horizontal nystagmus
Motion sickness
How does a CNIX palsy present?
Flaccid paralysis of soft palate Uvula deviates to normal side Sensory loss of soft palate, upper pharynx and posterior 1/3 tongue Mild dysphagia Throat and ear pain
How does a CNX palsy present?
Flaccid paralysis of soft palate - nasal speech and deviation of uvula away from palate Epiglottis paralysis (aspiration) Dysphagia Vocal cord paralysis Dysfunction of vagal nerve of stomach
How does a CNXI palsy present?
Weakness turning head to contralateral side
Weakness during elevation of ipsilateral shoulder and lateral winging of scapula
How does a CNXII palsy present?
Atrophy and fasciculation of tongue on side of lesion
Tongue deviates to side of lesion when protruded
What are the main potential causes of a CNI palsy?
Trauma
Neurodegenerative disease
Congenital
SOL
What are the main potential causes of a CNII palsy?
Trauma
Tumours
impaired nutrition
Drugs
What are the main potential causes of a CNIII palsy?
Ischaemic microangiopathy (typically spares pupil involvement) Compression or transection
What are the main potential causes of a CNIV palsy?
Microvascular damage
Trauma
Cavernous sinus thrombosis
What are the main potential causes of a CNV palsy?
Tumour Vascular compression Oral surgery Inflammation of nerve Cavernous sinus thrombosis
What are the main potential causes of a CNVI palsy?
Tumour
Trauma
Pseudotumour cerebri
Cavernous sinus thrombosis
What are the main potential causes of a CNVIII palsy?
Bacterial meningitis
Lyme disease
Tumour
What are the main potential causes of a CNIX palsy?
Often unknown
May be compression by blood vessel
What are the main potential causes of a CNX palsy?
Trauma
Diabetes
Inflammation
What are the main potential causes of a CNXI palsy?
Surgeries at the lateral cervical region
What are the main potential causes of a CNXII palsy?
Tumours
Trauma
What are the potential causes of an UMN lesion in CNVII palsy?
Cerebrovascular disease SOLs MS Syphilis HIV Vasculitides
What are the potential causes of an LMN lesion in CNVII palsy?
Idiopathic (Bell's palsy) - pregnancy and DM Cerebrovascular disease Iatrogenic Infective Trauma Neurological Neoplastic HTN in pregnancy Sarcoidosis Sjogrens syndrome and RA