Cranial Nerves Lesions + Bell's palsy Flashcards
CN 2 - OPTIC
- Function
- Vision pathway
- Light reflex
- Accomodation
Function is vision
What is an Argyll-Robertson pupil?
Most common cause
- No light reflex
- Normal accomodation [to close object]
Cause; diabetes mellitus, neurosyphilis
What is Holmes-Adie pupil?
Wheres the lesion
Common presentation
- Sluggish light reflex (large pupils)
Lesion: postganglionic fibers of ciliary gangion of parasympathetic innervation
Young women with limb areflexia
What is Horner’s syndrome?
- Draw the relevent pathway
- Common cause
- Cardinal signs
Damage to sympathetic orbit supply
Pathway
- Hypothalamus ⇒ Brainstem ⇒ T1 exit
- ⇒ Stellate ganglion ⇒ Sup. cerical ganglion
- ⇒ Plexus around int. carotid ⇒ ciliary ganglion
- With CN5 to pupil
Cause
- Pancoast (lung apex) tumour
- Cerebral vasc. disease
Cardinal signs PEAM;
- Ptosis (drooping up. eyelid)
- Enapthalmos (eye shunk in socken)
- Anhydrosis (no sweat ipsilaterally)
- Miosis (constricted pupil)
What is pancoasts tumour
Tumour in lung apex ⇒ compresses ganglion causing Horner’s syndrome
Draw the vision pathway with its lesions & results
What nerves control eye movement
- Names & full functions of each nerve
- Draw H diagram detailing muscles
- Oculomotor 3
- Motor - S, I & M Rectus, I oblique & upper eyelid
- Parasympathetic - Spinchter pupillae
- Trochlear 4
- Motor - S oblique
- Abducens 6
- Motor - Lateral rectus
What is diplopia?
Double vision
What is 3rd nerve palsy?
How does it present?
Common cause
Oculomotor not working correctly
- S, I & M rectus, I oblique not working
- Unopposed L rectus & S oblique cause eye to go DOWN & OUT
- Motor part of light reflex (from Edinger Westphal nucleus to ciliary ganglion)
- LARGE pupil UNREACTIVE to light
- Upper eyelid [levator palpebrae superioris]
- Droopy eyelid
What is 4th nerve palsy
How does it present
Trochlear not working correct (rare in isolation)
- Diplopia when looking down & away from affected side
- ie When you use the Superior Oblique on the affected side you get diplopia!
Weakness in depression of the adducted eye
What is 6th nerve palsy
Common cause
Abducens not working correctly (L Rectus)
- Vascular lesions or raised intracranial pressure
Outline the causes and presentation of pseudobulbar palsy
Bilateral damage to pyramidal tract system
- Dysphagia
- Dysarthria
- Emotionalism
- Small tongue stuck to floor of mouth
What is the fucntion of the 5th nerve?
- Name
- Branches
- Corneal reflex
Trigeminal, 5th nerve
- Sensory - face, scalp, cornea (sensory part of corneal reflex)
- Motor - mastication (temporalis, masseter and pterygoids), tensor tympani
Branches
- Opthalmic (sensory)
- Maxillary (sensory)
- Mandibular (sensory & motor)
Corneal reflex
- Cornea touches ⇒ Masociliary branch of opthalmic branch of trigeminal
- ⇒ Passes through semilunar ganglion
- ⇒ Spinal nucleus of trigeminal nerve
- ⇒ Facial motor nucleus (both sides!)
- ⇒ Temporal branch of facial nerve
- ⇒ Orbicularis occuli
What is acoustic neuroma?
Pressure of 5th nerve in cerebello-pontine junction
⇒ Problems with corneal reflex
What is trigeminal neuralgia?
Problem with trigeminal 5th nerve.
Lancinating pain (stabbing)
Unkown aetiology
Affects 60-70 year olds.
What is the function of the 7th cranial nerve?
- Name
- Branches
Facial 7th
- Sensory
- Ant 2/3 tongue [Chorda Tympani branch]
- Motor
- Face [to zanzibar..]
- Stapedius muscle [Stapedius branch]
- Parasympathetic
- Salivary/ lacrimal [Greatr petrosal nerve branch] glands
Branches (To Zanzibar By Motor Car)
- Temporal
- Zygomatic
- Buccal
- Marginal mandibular
- Cervical
Draw the nuclei to the 7th nerve
Draw a diagram detailing the upper and lower motor facial nerve lesions
Draw the passage of the 7th nerve and the branches it gives off
Outline the pathophysiology of Bell’s palsy
Describe;
- Cause
- Location of lesion & associated structures
Inflammation (unknown cause) in the facial canal as it exits via the stylomastoid foramen causes facial palsy.
Facial canal contains;
- Stapedial nerve [sound]
- Chorda tympani nerve [taste]
- Facial nerve exiting via Stylomastoid canal [facial expression]
Outline the symptoms & signs of Bell’s palsy
Symptoms
- Unilateral facial weakness [facial]
- Ipsilateral numbness/ pain around ear
- Ageusia [chorda tympani]
- Hyperacusis [stapedius palsy]
LMN lesion so its unilateral.
Greater superficial petrosal muscle is spared (and hence lacrimation)
What are important differentials & relevent investigations of Bell’s palsy?
7th Nerve Palsy;
- Ramsey Hunt syndrome [Varicella zoster in Geniculate nucleus, check VZV AB]
- Lyme disease [check Borrelia (bacteria) AB]
Outline the management of Bell’s palsy
Non.
- Acute: Prednisolone
- Remind to close eyes, tape at night, lagophthalmos: lid loading with gold
What is an acoustic neuroma?
How might it affect the 7th nerve and why
Draw a diagram perhaps?
aka Vestibular schwannoma
Benign brain tumour growing on the 8th cranial nerve
May affect 7th nerve as 7 & 8 enter the I.A.M together.
All functions may be lost
