disorders of cranial nerves Flashcards
what are some functions of cranial nerves?
“special” senses
ordinary sensation
control of muscle activity
autonomic functions
what are the “special” senses
olfaction (I)
vision (II)
taste (VII IX X)
hearing (VIII)
what nerves control “ordinary” sensation?
mainly trigeminal
the ear from the facial and glossopharyngeal nerves
what nerves control the eye muscles?
oculomotor
trochlear (SO)
abducens (LR)
what nerve controls the muscles of mastication?
trigeminal
what nerve controls the muscles of facial expression?
facial nerve
what nerve controls the muscles of the larynx and pharynx?
mainly vagus
what nerve controls the SCM and trapezius muscles?
accessory
what branch of the nervous system does autonomic function fall under (for cranial nerves)
parasympathetic
what is responsible for pupillary constriction
oculumotor nerve
what is responsible for lacrimation?
facial nerve
what is responsible for innervating the submandibular and sublingual glands?
facial nerve
what is responsible for innervating the parotid gland?
glossopharyngeal nerve
how do we test the function of the olfactory nerve?
smell - unilateral or bilateral loss
how do we test thefunction of the optic nerve?
visual acuity visual fields pupillary reactions fundoscopy colour vision
how do we test the cranial nerves that innervate the muscles of the eye?
any evidence of ptosis
pupil of equal size
pupillary reactions
eye movements - vertical and horizontal
how do we test the function of the trigeminal nerve?
sensation in the opthalmic, maxillary and mandibular divisions
power in muscles of mastication
corneal reflex
jar jerk
how do we test the function of the facial nerve?
muscles of facial expression
corneal reflex
taste
how do we test the function of the vestibulocochlear nerve?
Rinne and Weber’s tests for hearing
vestibular function using dix hallpike maneuver and utenbergers test
how do we test the function of the glossopharyngeal and vagus nerves?
movement of palate
gag reflex
quality of speech
quality of cough
how do we test the function of the accessory nerve?
head turning and shoulder shrugging
how do we test the function of the hypoglossal nerve?
appearance, movement and power of tongue
what cranial nerves are involved in the pupillary light reaction?
afferent - II
efferent - III
what cranial nerves are involved in the corneal reflex?
afferent - V
efferent - VII
what cranial nerves are involved in the jaw jerk reflex?
afferent and efferent - V
what cranial nerves are involved in the gag reflex?
afferent - IX
efferent - X
where are the nuclei of cranial nerves III and IV?
midbrain
where are the nuclei of cranial nerves V,. VI and VII located?
pons
what is the nucleus for cranial nerve VIII located?
pontomedullary junction
where are the nuclei for cranial nerves IX, X, XI and XII located?
medulla
where would the lesion be if the signs were bilateral and affecting cranial nerve III?
midbrain
where would the lesion be if the signs were a combination of cranial nerves III, IV and VI?
superior orbital fissure
where would the lesion be if the signs were a combination of cranial nerves VI and VII?
pons
where would the lesion be if the signs were a combination of cranial nerves V and VIII?
cerebellopontine angle
what would an unusual combination of cranial nerve signs possibly suggest?
chronic or malignant meningitis
what would PURE motor signs relating to cranial nerve possibly suggest?
myasthenia gravis
where can cranial nerves be damaged?
within the brain
crossing the sub arachnoid space
outside of the skull
what is the pathology of optic neuritis?
demyelination within the optic nerve
what are some signs of optic neuritis?
monocular visual loss pain on eye movement reduced visual acuity reduced colour vision optic disc may be swollen
what branch of the nervous system controls constriction of the pupil?
parasympathetic
what does a loss of parasympathetic input to the eye result in?
fixed, dilated pupil
what are some causes of dilated pupils?
dim lighting youth anxiety/excitement mydriatic eye drops amphetamine or cocaine OD third nerve palsy brain death
what are some causes of small (constricted pupils)
old age bright light miotic eye drops opiate overdose horners syndrome
what are some eye movement disorders related to cranial nerves?
isolated third nerve palsy isolated fourth nerve palsy isolated sixth nerve palsy combination of the above nystagmus supranuclear gaze palsy
what are the 2 different kinds of isolated third nerve palsy?
microvascular
compressive
what are some causes of microvascular third nerve palsy?
diabetes
hypertension
what are some characteristics of microvascular third nerve palsy?
painless, pupil spared`
what are some causes of compressive isolated third nerve palsy?
posterior communicating artery aneurysm
raised ICP
what are some characteristics of compressive third nerve palsy?
painful
pupil affected
what are some causes of isolated sixth nerve palsy?
idiopathic
diabetes
meningitis
raised ICP
what can cause nystagmus?
central vestibular/brainstem disease
cerebellar disease
toxins (medication and alcohol)
what is trigeminal neuralgia?
paroxysmal attacks of lancinating pain
what is trigeminal neuralgia caused by?
compression of the fifth cranial nerve in the posterior fossa
how is trigeminal neuralgia treated medically
carbamazepine
what are some features of vestibular neuronitis?
sudden onset
disabling vertigo
vomiting
gradual recovery
what is dysarthria?
disordered articulation, slurring of speech
what is dysphagia?
difficulty swallowing
what is the difference between bulbar and pseudobulbar palsy?
bulbar palsy is LMN
pseudo is UMN
what is the pathology of pseudobulbar palsy?
bilateral UMN lesions
what are some signs of pseudobulbar palsy?
dysarthria dysphonia dysphagia spastic, immobile tongue brisk jaw jerk brisk gag reflex
what is the pathology of bulbar palsy?
bilateral LMN lesions affecting CN IX - XII
what can cause bulbar palsy?
MND polio tumours vascular lesions of the medulla syphilis
what are some signs of bulbar palsy?
wasted, fasciculating tongue
dysarthria
dysphonia
dysphagia
what should you beware of doing to bulbar palsy patients?
feeding them
