Disorders of Cranial Nerves Flashcards
The cranial nerve signs from bilateral CN II indicate the lesson is located where
Midbrain
A combination of cranial nerve signs from CN III, IV, VI indicate the lesion is where
Superior orbital fissure
A combination of cranial nerve signs from CN VI + VII indicate the lesion is where
Pons
A combination of cranial nerve signs from CN VI + VIII indicate the lesion is where
Cerebellopontine angle
What does an unusual combination go cranial nerves potentially suggest
Chronic or malignant meningitis
What does pure motor cranial nerve signs potentially suggest
Myasthenia gravis
- chronic autoimmune neuromuscular disease
What is the symptomss of myasthenia gravis
droopy eyelids
double vision
difficulty making facial expressions
problems with chewing anddifficulty swallowing
slurred speech
weak arms, legs or neck
shortness of breathand occasionally serious breathing difficulties
Wha are cranial nerve signs that don’t necessarily imply a cranial nerve lesion
eye movement disorders
facial weakness,
difficulty swallowing after a stroke
double vision in myasthenia
thyroid eye disease
What are the potentially sites where cranial nerves can be damaged
Within the brain
Crossing subarachnoid space
Outside the skull
How can cranial nerves be damaged within the brain
Ischaemia
Tumour
How can cranial nerves be damaged crossing sub arachnoid space
Meningits
What is an example of how cranial never can be damaged outside the skull
base of skull tumours arising in nasopharynx
What is optic neurtis
Demyelination within the optic nerve (CN II)
What is optic neuritis associated with
Multiple sclerosis
What is the signs and symptoms of optic neuritis
monocular visual loss
pain on eye movement
reduced visual acuity
reduced colour vision
optic disc may be swollen
What has control over pupil constriction
Parasympathetic system
What has control over pupil dilation
Sympathetic system
What is the potential causes of small pupils,
Old age Bright light “Miotic” eye drops Opiate overdose Horner’s Syndrome
What is the potential causes of dilated pupils
Youth Dim lighting Anxiety, excitement “Mydriatic” eye drops Amphetamine, cocaine overdose Third nerve palsy Brain death
Loss of parasympathetic and sympathetic input has what affect on the pupil
Parasympathetic - Fixed dilated pupil
Sympathetic - constricted pupil
What is a common cause of parasympathetic input loss to the pupil
Complete third nerve palsy (CN III, oculomotor)
What is the two causes of third nerve palsy
Microvascular - never cant function due to lack of blood supply
Compressive
What are two examples of microvascular third nerve palsy
Hypertension
Diabetes
What are two examples of compressive third nerve palsy
Posterior communicating artery aneurysm
Raised ICP
What is the symptoms of third nerve palsy
Ptosis - closed eye lid
Eye deviated outward and downwards
Diplopia - double vision
Enlarged pupi
Failure of abduction
What is the difference between microvascular third nerve palsy and compressive third nerve palsy
Microvascular is painless and the pupil is spared compared to compressive which is painful and the pupil is affected
What is 5 different eye movement disorders
Isolated third nerve palsy
Isolated fourth nerve palsy
Isolated sixth nerve palsy
(Combination of the above)
Supranuclear gaze palsy
Nystagmus
What is the symptoms of fourth nerve palsy
Vertical double vision
Affects outward rotation (extortion)
What is the symptoms of sixth nerve palsy
Cannot move eye to the outside
side by side double vision
eye debated to the middle of your nose
What is the potential causes of sixth nerve palsy
Idiopathic
diabetes
meningitis
raised intracranial pressure
What is supra nuclear gaze
Inability to look in a particular direction (due to loss of voluntary eye movements) as a result of cerebral impairment
What is the causes of nystagmus (rapid eye movements)
Congenital
Central vestibular / brainstem disease
Cerebellar disease
Toxins (medication and alcohol)
What is the symptoms of nystagmus
Serious visual impairments
Peripheral vestibular problems - vertigo
What is examples of lower motor neurone facial paralsysis (CN VII)
Bells palsy
Lyme
Sarcoid
What occurs in bells palsy
Idiopathic facial nerve palsy due to lower motor neurone lesion
What is the symptoms of bells palsy
Unilateral Facial weakness
drooping mouth and eyes
Cant raise eye brows
often proceeded by pain behind the ear
risk of corneal damage
What is the treatment of bells palsy
Steroids - usual good recovery
what is causes of upper motor neurone facial paralysis
stroke
tumour
What is trigeminal neuralgia (CN V)
Paroxysmal attacks of lacinanting due to triggers
What is the causes of trigeminal neuralgia
Happens middle and old age
caused by vascular loop leading to compression of fifth cranial nerve in posterior fossa
What is treatment of trigeminal neuralgia
Carabamezepine Surgical option (if medication resistance)
What is vestibular neuritis (CNVIII)
Labyrinthitis - is inflammation of the inner ear
What is the symptoms of vestibular neuritis
Disabling vertigo
Vomiting
hearing loss
ringing in the ears
What is bulbar palsy
Bilateral lower motor lesion affecting CN IX- XII
What is the potentially causes of bulbar palsy
Motor neurone disease polio,
tumours,
vascular lesions of the medulla
syphilis
What is the symptoms of bulbar palsy
- wasted, fasciculating tongue
- dysarthria
- dysphonia
- dysphagia
(beware of feeding these patients)
What is pseudo bulbar palsy
Bilateral upper motor lesion
What is the potential causes pseudo bulbar palsy
vascular lesions of both internal capsules
Motor neurone disease
What is the symptoms of pseudobulbar palsy
- dysarthria
- dysphonia
- dysphagia
- spastic, immobile tongue
- brisk jaw jerk
- brisk gag reflex
What is the facial motor nucleus divided into and supply
Upper - supplies facial musculature above zygomatic arch
Lower - supplies facial musculature below zygomatic arch
What is the innervation of the upper part of the facial nucleus
Innervation from contralateral and ipsilateral side of the brain
What is the innervation of the lower part of the facial nucleus
Innervation only from contralateral side
If lesion occurs in lower motor neurones what is the pathology
Ipsilateral paralysis of upper and lower facial musculature
If lesion occurs in the upper motor neurones what is the pathology
Paralysis of contralateral facial musculature
What is symptoms of an upper motor lesion facial paralysis
Drooping of face
Cant smile on affected side
can raise eyebrow
How do you still have control over upper musculature of the face in upper motor lesion facial paralysis
as upper musculatral as bilateral innervation from ipsilateral side as well
What is the symptoms of lower motor lesions facial paralysis
Drooping on affected side of the face
cant raise eye brow on affected side of the face
cant smile on affected side of the face
