MedEd CNS Flashcards
What cranial nerve palsy results in an eye that is down and out?
III
How many nerves cross over at the optic chiasm?
50%
Where will the lesion be to cause monocular blindness?
At the optic nerve right beind the eye where there is a loss in vision
Where will the lesion be to cause bitemporal hemianopia?
Optic chiasm
Where will the lesion be to cause right homonymous hemianopia?
Left optic tract
Where will the lesion be to cause right superior homonymous quadrantanopia?
The lower fibres in the left temporal lobe
Where will the lesion be to cause right inferior homonymous quadrantanopia?
Left upper fibres in the anterior parietal lobe
Why is there macular sparing in occipital lobe lesions?
Lesions in the occipital lobe because the occipital lobes doesnt have the same blood supply
What acronym is used to remember cranial nerve supply to the eye muscles?
LR6 SO4
lateral rectus=CN 6
Superior oblique= CN 4
All other muscles= CN 3
What is the traid for 3rd nerve plasy?
Ptosis
Mydriasis
Down and out gaze
What is myadriasis?
Dilation of the pupil
How will 4th nerve palsy present?
Prevents eye moving in and down
Eye is up and out
How will 6th nerve palsy present?
Eye can’t move outwards
Eye is abducted
What is the most common cause of bitemporal hemianopia?
Pituitary adenoma (compressing the optic chiasm)
What is trigeminal neuralgia?
Severe episodic facial pain the in distribution of one or more branches of CN 5
What are the 3 branches of CN5 on the face?
Forehead
Cheek
Mouth
What are causes of trigeminal neuralgia?
Compression of CN5 nerve root
Most commonly caused by a vascular loop
Otherwise caused by a tumor, chronic meningeal inflammation or MS
What are RF for trigeminal neuralgia?
Increasing age
Female
How will trigeminal neuralgia present?
Sudden intense stabbing pain that lasts for seconds and is recurrent
How is trigeminal neurgalia triggered?
Talking Cold wind Eating Washing Shaving
What investigations are done for trigeminal neuralgia?
None, diagnosis is clinical
What is Bell’s palsy?
Acute unitlateral lower motor neurone nerve palsy
What is Ramsay Hunt syndrome?
A complication of varicella zoster infection where there is a lower motor neuron nerve palsy
What causes bells palsy?
idiopathic
What are RF for bells plasy
15-45 years of age
May be increased in pregnancy
Common in DM
How does bells palsy present?
Inability to raise the brows
Drooping eyelid and cant close eye
Drooping mouth, can’t smile or pucker lips
No muscle tone in cheek
Dry eye (keratoconjunctivitis sicca)
Hypersensivity to sound on the ipsilateral side (hyperacusis)
How do you differentiate bells palsy and stroke?
Bells palsy does not spare the forehead
Stroke does
What is bells phemomena?
Eye ball rolls up when the patient tries to close it
How is bells palsy investigated?
CT scan to rule out stroke
Bloods- WCC to rule out infection
Clinical diagnosis after ruling out other things
Hw does ramsay hunt syndrome present?
Unilateral facial paralysis and painful blisters in insilateral ear canal, anterior 2/3 of tongue and hard palate
What is horner’s syndrome?
Triad of miosis, partial ptosis and anhydrosis
What is neurofibromatosis
Autosomonal dominant genetic disorder affecting cells of neural crest origin that leads to development of multiple neurocutaneous tumors
What are RF for horners syndrome
What is miosis?
Constriction of pupil
What causes horners syndrome?
Anything that disrupts the face’s sympathetic nerve supply eg
Brainstem tumor or stroke
Pancoast tumor
Carotid artery dissection
Disruption of what causes horner’s syndrome?
Sympathetic nerve supply to the face
What is anhydrosis?
Sweating
What inevstgations are done for horner’s syndrome? Why is each done
CXR- rule out pancoast tumor
CT head- rule out stroke
MRI angiography- rule out carotid dissection
How is horners syndrome managed?
Treat the cause
How is neurofibromatosis inherited?
Autosomal dominant
What genes are mutated in each type of neurofibromatosis and
NF1- chromosome 17 (mutation in neurofinromin)= type 1
NF2- chromsome 22 (mutation in merlin)= type 2
Which type of neurofibromatosis is more common?
Type 1
What are RF for neurofibromatosis?
Fhx
Severe crush trauma
What is affected in neurofibromatosis 1 vs 2?
Type 1= whole body
Type 2= ears
What happens in neurofibromatosis type 1?
Skin lesions
Pain related to skin lesions
May also have: Learning difficulties Headaches Disturbed visions Severe constipation
What happens in neurofibromatosis type 2?
Hearing loss
Tinnitus
Balance problems
Vertigo
Can have:
Headache
facial pain
facial numbness
MAY BE BILATERAL!!
What skin leasions are seen in neurofibromatosis type 1? How many are needed for diagnosis
Cafe au lait macules- need to have over 5 in the body (pre puberty >5mm and post puberty >15mm)
Neurofibromas- cutaneous, subcut and diffuse plexiform
Armpit freckling
What investigations are done for neurofibromatosis?
Type 1= full body examination Opthalmological assessment Type 2= hearing test CT/MRI if you are looking for tumors Can also go genetic testing but not common
How many cafe au lait macules are needed to diagnose neurofibromatosis? What size do they need to be?
over 5 over the body
pre puberty= >5mm
post puberty= >15mm
How do you remember what is affected in neurofibromatosis type 1 v 2?
Type 1= 1 thing is affected= you have 1 body= affects the body
Type 2= 2 things are affected= you have 2 ears= affects the ears
What eye will be affected and on which side if a lesion is pre chiasmal?
One eye on the ipsilateral side
What eye will be affected and on which side if a lesion is chiasmal?
Both eyes, temporal visual field
What eye will be affected and on which side if a lesion is post chiasmal?
The contralateral eye, homonymous visual field
As an optic nerve lesion gets further back, what generally happens?
The area affected gets smaller
As an optic nerve lesion is further farward, what generally happens?
The area affected is larger
What are some causes of a prechiasmal lesion?
Optic neuritis Amaurosis fugax Optic atrophy Retrobulbar optic neuropathy Trauma
What are some causes of a chiasmal lesion?
Pituitary adenoma
Suprasellar aneurysm
What are some causes of a post chiasmal lesion?
Stroke
Tumor
Trauma
Where in the optic tract is a stroke most likely to cause a lesion?
Post chiasmal
What are a lot of cases of Bell’s palsy preceded by?
Respiratory tract infection
What is ramsey hunt syndrome?
Reactivation of chickenpox
What organism causes ramsey hunt syndrome?
Varicella zoster
How is Bell’s palsy managed?
High dose corticosteroids- 60 mg within 72 hrs (prednisolone or hydrocortisone)
Eye protection- eye cover and artificial tears
What investigations are done for Bell’s palsy?
Borellia serology
Electroneurography if symptoms are severe
Needle electro myography if electroneurography
What pathway is disrupted in horner’s syndrome?
Sympathetic
What is anhydrosis?
Lack of sweating
Why do you get one sided sweating in horner’s syndrome?
Anhydrosis occurs on the side of the face where sympathetic supply is lost so the other side appears sweaty
How many seizures have to occur for a diagnosis of epilepsy?
2 unprovoked seizures
What type of seizures most commonly get aura?
Focal temporal seizures
What happens post ictally in epilepsy?
Confusion
Myalgia
Somnolence
How will limb jerking differ in focal vs generalised seizures?
Focal= only some limbs may jerk Generalised= all 4 limbs will usually jerk
What is the cause of epileptic seizures?
They have no cause- are idiopathic
What hormone is raised in a true seizure?
Prolactin
What are the first and second line drugs for focal and generalised seizures?
Focal first line= carbimazepine second line= lamotrigine Generalised first= sodium valproate second= carbimazepine
What is drug escalation is status epilepticus?
first line= iv lorazepam or buccal diazepam
second line= IV phenytoin
third line= IV phenobarbitol
fourth line= rapid sequence induction
What are causes of cord compression?
Slipped IV disc
maliganancy
Infection
Trauma
What are symptoms of cord compression?
Back pain
Bilateral UMN weakness
Parasthesia
Sphincter disturbance
What are symptoms of spinal shock syndrome?
Flaccid paralysis
Absent reflexes
What are the 2 main causes of cord compression?
Slipped disc
Tumor
In cauda equina vs cord compression which will have upper and lower motor neurone lesion signs?
Cauda equina= LMN signs
Cord compression= UMN signs
How is cord compression managed?
Emergency management of high dose steroids, surgical decompression
In cauda equina vs cord compression which will have more sphincter disturbance?
Cauda equina
