CN Pathologies Flashcards
Answer - A, which represents the optic nerve
If you have a monocular problem its going to be in the eye itself or in the optic nerve, bascially in front of the optic chiasm
If its coming on gradually then more likely to be an inflammatory problem - autoimmune - (less likely to be sudden onset like stroke)
Most likley to have optic neuritis
Describe Optic neuritis
which cranial nerve affected + therefore 4 symptoms, most common cause, treatment
compare Retrobulbar neuritis vs Papillitis
CN2 optic nerve affected
Symptoms: painful eye movements, monocular vision loss, impaired visual acuity, impaired colour vision
Most common cause=demyelination
Treatment is with 5 days high dose corticosteroids
Retrobulbar neuritis: optic nerve affected behind the eyeball
whereas in Papillitis, - optic nerve head is affected!
A 53 year old woman presents w sudden onset, severe headache.
During intercourse with her partner, she describes feeling as though she had been hit round the back of the head. She also has double vision.
On examination, the patient has right sided ptosis. The right eye is facing ‘down and out’ in neutral gaze. The right pupil is larger than the left pupil. She appears lethargic, and complains of nausea and neck stiffness.
How can you explain these findings? Where is the lesion likely to be? + explain the reasons why
The lesion is most likley CN III (oculomotor nerve). This is bc hay:
-Inability to lift the eyelid–> ptosis
-Unopposed action of the lateral rectus (supplied by the abducens) + superior oblique (supplied by trochlear) = resulting in the eye going down and out
Parasymp. fibres run with the oculomotor nerve - lesion causes unopposed symp innervation–> dilatation
SUDDEN onset headache, Lethargic, nausea, neck stiffness = due to a sub arachnoid haemorrhage
3 things CN3 supply?
CN3 (oculomotor nerve). This supplies:
- Levator palpebrae superioris to lift eyelid
- Superior, medial, inferior rectus + inferior oblique
- Constrictor pupillae (parasymp. )
How can the location of a lesion impact symptoms?
compare aneurysmal compression of CN3 nerve vs diabetic opthalmoplegia?
Red eye - whole orbit
Some ptosis
Pupil dilated
Eyeball slightly pushing out of the face - proptosis
Lady has cavernous sinus syndrome
A 52-year-old man complains of a unilateral headache. He describes it as a sharp stabbing pain in his cheek and jaw, lasting for a few seconds at a time. He has noticed that both shaving and eating seem to trigger bouts of pain.
What is the likley diagnosis?
Trigeminal neuralgia: short, sharp pain, often triggered by touch
Cause: pressure on the trigeminal nerve close to where it enters the brainstem - e.g You can have an artery press on the trigeminal nerve - causing irritation.
How can you tell if facial weakness is caused by an upper or lower motor neurone lesion?
For strokes - only the lower part of face affected. This is bc: lower half of the face is only supplied by one side of the brain
BUT the upper part of the face has bilateral innervation- you’re still going to have the upper part of the face supplied by the other side of the brain
Draw a table to describe the differntial diagnosis of LMN facial weakness:
Pons vs Cerebellopontine angle vs Geniculate ganglion vs Facial canal vs Temporal bone vs Parotid
Describe Bell’s palsy
3 clinical features
management
4 complications
prognosis
Bells sign - eye isn’t closing properly. Can lead to corneal ulceration. To prevent this - tape eyes shut at night.
Describe Ramsay-Hunt Syndrome
Findings show right sided sensorineural hearing loss
Dry eyes - facial nerve problem (lacrimation)
Afferent (trigeminal) & efferent (facial) nerves of the corneal reflex
Nystagmus - cerebellum or vestibulocochlear nerve
She had dysmetria on finger-nose testing= cerebellum is involved too. So…
Problem in cerebellum, CN7, CN8
Location where all three things are affected together? = cerebellopontine angle. Most commonly caused by acoustic neuroma; aka tumour growing on CN8 (vestibulocochlear)
This: Compresses facial nerve + presses on the cerebellum
Fasciculations - LMN problem
Dysarthria - slurred speech
Brisk jaw jerk - UMN problem
Dorsal interossei - muscles between the tendons on the back of the hand
Brisk tendon reflexes - UMN problem
Brisk reflexes with extensor plantars on the foot - UMN problem
Mix of LMN and UMN=Motor neuron disease
Compare Bulbar vs pseudobulbar palsy
Speech, tongue, jaw jerk, other features?
Bulbar palsy - pt may have problem w the medulla or the nerves that come off the medulla (9-12)
Problems with speaking, either dysarthria or dysphonia, swallowing problems
Could be problem at the neuromuscular junction
What are the main types of motor neuron disease?
ALS vs PBP, PLS vs PMA
Amyotrophic lateral sclerosis (ALS): Mixed UMN & LMN signs
Progressive bulbar palsy (PBP): UMN & LMN bulbar dysfunction. - If dysfunction spreads to other areas, then referred to as bulbar-onset ALS
Primary lateral sclerosis (PLS): Predominantly UMN signs + Longer survival than ALS
Progressive muscular atrophy (PMA): Predominantly LMN signs + Longer survival than ALS
