CN disorders Flashcards
What is mnemonic for working out if CN are
- Sensory
- Motor - somatic vs visceral
- Both
Some Say Marry Money But My Brother Says Big Brains Matter Motor
Where can CN be damaged
Brainstem where located
Route outside CNS
What is CN1 responsible for
Olfactory
Smell
Where does it pass through
Receptors in cribriform plate
Enter olfactory bulb in anterior cranial fossa
What is 2nd CN palsy for
VISION
Pupil reflex (afferent)
Optic
Where does it pass through and go
Optic canal in skull
Nerves joint at optic chiasm under pituitary
What is CN3 responsible for
Oculomotor
Movement of MR, IO, SR,IR
EPS of eyelid to open
Accommodation + pupil constriction via parasympathetic fibres
Where does it exit
Superior orbital fissure
What is CN4 responsible for
Trochlear
SO
Depresses eye and adducts
Where does it leave
Superior orbital fissure
What is CN6 responsible for
Abducens
LR eye movement
Where does it leave
Internal auditory meatus
What is CN5 / trigeminal nerve responsible for
Facial sensation in all 3 areas V1 - ophthalmic V2- maxillary V3 - mandibular V3 = muscles of mastication
Where do trigeminal nerve roots come out of
V1 = SOF V2 = foramen rotundem V3 = foramen ovale
What is facial nerve CN7 responsible for
Facial movement
Taste anterior 2/3 tongue
Lacrimation via para of sumandibular and sublingual glands
Salivaation from lacrimal gland
Where does it level
Internal auditory meatus
What is CN 8 / vestibular cochlear responsible for
Hearing and balance
Where does it come out from
Internal auditory meatus
What is CN 9/ glossopharyngeal responsible for
Taste posterior 1/3 Saliva from parotid Swallowing Gag reflex Carotid snus input
Where does ti come out of
Jugular foramen
What is CN10 / vagus responsible for
Phonation
Swallowing - gag reflex
Innervating viscera - parasympahtetic
Where does it come out of
Jugular formane
What is CN11 / accessory responsible for and where does it come out from
Trapezius and SCM movement
Jugular foramen
What is CN12 / hypoglossal responsible for and where does it come out from
Tongue movement - somatic
Hypoglossal foramen
What can cause 1st nerve palsy damage
Fracture of cribriform plate
Anterior cranial fossa tumour
Association with Parkinson / Alzeheimers and COIVD
What does this result in
Anosmia
What can cause 2nd nerve palsy and what does it cause
Optic neuritis
Papilloedema/ raised ICP
Tumour if bitemporal hemianopia - problem at optic chiasm
What does 4th nerve palsy cause
Defective downward gaze
Eye up and out
May have head tilt to compensate
Vertical diplopia - double vision when look down
What does 6th nerve palsy cause
Defective abduction
Medial deviation as lose LR which abducts
Horizontal diplopia
What are common causes of 4+6th nerve palsy
DM Hypertension Trauma Raised ICP - as such long course (6th not 4th) Tumour Infection
What does 3rd nerve palsy cause
Ptosis
Eye down and out
Dilated fixed pupil (mydriasis)
No pupil reflex or accommodation if para fibres damaged
What causes dilated pupils
Dim light Anxiety / excitement Mydriatic eye drops Cocaine 3rd nerve palsy Brain death
What causes constricted pupils
Bright light
Miotic eye drop
Opiate
Horner’s
What are microvascular causes of 3rd nerve palsy
DM - pupil is spared Hypertension Vasculitis - SLE / GCA Weber syndrome MS
What are microvascular causes typically 3rd nerve palsy
Painless
Pupil reflex spared
What are compressive causes
Aneurysm - posterior communicating SAH Malignancy Cavernous sinus thrombosis Raised ICP - start of nuclear herniation
What are compressive causes typically
Painful - headache
Pupil affected
Known as hutchinson pupil - feared by neurosurgeon
What does 5th nerve palsy cause
Loss of corneal reflex (afferent)
Loss of sensation
Paralysis muscles mastication
Deviation of jaw to weak side
What causes
Trigeminal neuralgia
What nerve is commonly injured and why
Facial nerve as long path
What does it cause
Flaccid paralysis of face as LMN
Loss of corneal reflex (efferent)
Loss of taste to anterior 2/3
What causes facial nerve palsy
Bell’s palsy
What can cause an 8th nerve palsy
Acoustic neuroma (Schwann cell tumour of cochlear nerve) Vestibular neuritis (inflammation of vestibular part of nerve)
What does 8th nerve palsy cause
Hearing loss
Vertigo
Nystagmus
Tinnitus
What are other causes of nystagmus
Macular degeneration Vestibular problem Brain stem Cerebellar Toxins
What are symptoms of vestibular neuritis
Sudden onset vertigo
Vomiting
Blurred vision
Gradual recovery
What are causes
MS
Viral = more common
What does 9th palsy lead too
Hypersenstive carotid sinus reflex
Loss of gag reflex (afferent)
What is also injured commonly with 9th palsy
X - vagus
XI - accessory
XII - hyoglossal
What is this known as
Jugualr foramen syndrome if no XII
Bulbar palsy if all 4
What does 10th palsy lead too
Uvular deviate away from lesion
Loss of gag reflex
Dysphagia
Dysphonia
What does 11th palsy lead too
Weakness turning head to contralateral side + shrugging shoulder
What does 12th palsy lead
Tongue deviates toward affected side as lose muscles on contralateral
Paralysis + atrophy
What causes 12th palsy
Tonsillectomy
What is dysarhtria
Slurring or slowed speech
Disorder articulation
What can cause
Stroke Brain injury Tumour Facial paralysis Tongue or throat muscle weakness
What is dysphonia
Difficulty speaking due to physical problem through vocal cords
What is responsible for corneal reflex
V1 = afferent Facial = efferent
Jaw jerk reflex
V3
Gag
Glossopharyngeal = afferent Vagus = efferent
Carotid sinus
Glossopharyngeal + vagus
Pupil
Optic = afferent Occulomotor = efferent
Lacrimation
V1 = afferent Facial = efferent
What is bulbar palsy
Bilateral LMN lesion of glossopharyngeal, vagus, accessory and hypoglossal nerve
What causes
MND Polio Tumour Syphillis Vascular CN palsy
What does it cause
Wasted tongue
Dysarthria
Dysphonia
Dysphagia
What should you beware of
NOT feeding till assessed by SALT
What is pseudo bulbar
UMN damage
Same symptoms + brisk reflexes - gag and jaw
What causes bilateral LMN facial nerve palsy
Sarcoid
GBS
Lyme’s
Bilateral acoustic neuroma
What causes unilateral LMN facial nerve palsy
Bell's palsy Ramsay Hunt Cholesteatoma Otitis media Acoustic neuroma Brainstem stroke / tumour MS Parotid gland tumour Meningitis TB HIV MS DM
What causes UMN unilateral facial palsy
Stroke
What is Bell’s palsy and what causes / RF
Idiopathic acute unilateral facial nerve palsy
If not idiopathic then not Bell’s
Increased risk in pregnancy and DM
What are the symptoms
Ipsilateral as peripheral nerve Unilateral facial weakness / paralysis of whole side of face Can't close eye Can't raise eyebrow Mouth drop Unable to wrinkle forehead Ipsilateral numbness or pain around eye Taste decreased / altered Pain behind ear Hyperacusis as stapedius paralysis Dry eyes
What might you query
Shingles
Stroke
How do you Dx and Rx
FBC, ESR, glucose, Lyme serology
ALWAYS EXAMINE parotid and ears to exclude cholesteatoma or Ramsay hunt
MRI for SOL / MS
Dx of exclusion so must rule out
Rx
STEROID
Prednisoone 1mg/kg for 10 days
Artificial tears and lubricants
What differentiates from stroke
Forehead has bilateral innervation so as stroke is UMN lesion it is not affected
Important sign
If can’t wrinkle forehead = BELL’s
What tests can you do to rule out other cause
Bloods - ESR + glucose
CT / MRI for SOL
CSF but rare
What causes unilateral UMN palsy
Stroke
Tumour
What causes bilateral UMN palsy (rare)
Psuedobulbar
Monitor neurone
