Neurology Flashcards
Pupillary light reflex - which CN involved?
Afferent = optic nerve CN II (senses light) – efferent = occumulator CN III (constricts pupils)
Function of CN III
Occulomotor nerve. Controls all eye muscles except LR(6) SO(4). So controls MR, IO, SR and IR. + Pupil constriction + Accomodation + eyelid opening
Important investigaitons in Myasthenia gravis
Check FVC in initial presentation or flare, CT Thorax (check for thymoma), check antibodies
Function of CN X
Vagus, - innervates viscera + phonation and swallowing
Function of CN IX
Glossopharyngael n. - taste to post 1/3 of tongue, salivation, swallowing and mediates input from carotid body and sinus
Lesion in CN XI symptoms
weakness turning head to contralateral side
1st line Tx: Myasthenia gravis
Pyridostigmine (long acting ACh esterase inhibitor), lasts 3-5 hours, reversible, has cholinergic SEs. + Prednisolone for immunosupression ± thymectomy
Loss of gag reflex, what CN lesion involved?
CN X or IX
Causes of CN III palsy
Diabetes, vasculitis (e.g. temporal arteritis, SLE), raised ICP, posterior communicating artery aneurysm (dilated pupil, pain), cavernous sinus thrombosis, weber’s syndrome (psilateral third nerve palsy with contralateral hemiplegia -caused by midbrain strokes), amyloid, MS
“Hypersensitive carotid sinus reflex” is lesion in what CN?
Lesion in glossopharyngeal n. CN IX
What is: CN I
Olfactory nerve - smell sensation
Lacrimation reflex. What CN involved?
Afferent = opthalmic nerve (V1) and efferent/response = facial nerve CN VII
Horizontal diplopia - what CN lesion?
CN VI abducens. Because this usually controls Lateral rectus (remember LR6 SO4 mnemonic)
Jaw jerk reflex - which CN?
Afferent: CN V(3) Efferent: CN V(3) - the mandibular branch of trigeminal
Function of CN II
Optic nerve - sight
LMN or UMN: tongue deviates to ipsilateral side of lesion?
Tongue movement is CN XII (hypoglossal), if the tongue moves to SAME side = UMN lesion. You’d also have atrophy + fasciulations. So if you see fascilations on tongue = LMN .
Bell’s Palsy : Sx
Muscles of face droop on one side (Unilateral!) Abnormal corneal reflex pts. may also have post-auricular pain before the paralysis altered taste dry eyes (facial nerve controls lacrimation) hyperacusis.
Vertical diplopia. what CN lesion?
CN IV trochlear. This usually controls Superior oblique (SO) which controls the down and in movement of eye.
Function of CN V
Trigeminal n. (v1 - ophatlmic, V2- maxillary, and V3-mandibular), - facial sensation for all three. V3 also does motor for mastication
Trigeminal neuralgia: First line Tx
Carbamazepine (an anticonculsant). if don’t respond or atypical features (e.g. <50 y/o) –> prompt referral to neurology (can get surgery- neurovascular decompression)
Cause: Myasthenia gravis
Autoimmune disorder causing abnormal functioning acetylcholine receptors in post-synaptic membrane of NMJ. Antibodies to acetylcholine receptors found in 90% of cases . Type 2 hypersensitivity
Aetiology; Myasthenia gravis
Young women (20-35) or older men (60-75) = bimodal
Lesion in which CN causes nystagmus?
Nystagmus related to balance, seen in lesions of CN VIII (vestibulocochlear)
“Tongue deviates toward left side” is a lesion in which CN?
Hypoglossal nerve lesion. The tongue diviates to the side of the lesion . so this would be of left hypoglossal n.
Difference between UMN vs LMN lesion in CN VII?
CN VII facial n. lesion will cause flaccid paralysis of facia muscles. If it’s an upper motor neurone UMN , the forehead will be unaffected. If it’s LMN - all muscles will be affected
Lesion in CN IV symptoms
Palsy - defective downward gaze and vertical diplopia (double vision)
LMN or UMN: tongue deviates to contralateral side of lesion?
Tongue movement is CN XII (hypoglossal), if the tongue moves to OPPOSITE side = UMN lesion
CN III Palsy symptoms
Ptosis , ‘down and out’ eye (since only LR and SO muscles working from other nerves) , Dilated and fixed pupil
Lesion in CN V symptoms
- Trigeminal neuralgia, loss of corneal reflex, Loss of facial sensation, paralysis of mastication muscles, deviation of jaw to weak side
Function of CN XI
Acccesory n. for head and shoulder movement
Trigeminal neuralgia Sx
Unilateral sensory facial pain of single branch of trigeminal nerve. Brief electric-shock like pains, abrupt in onset and termination. Pain usually evoked by light touch or brushing teeth, talking, even a gust of wind. Pain remits for variable periods. (DDx: rule out TMJ dysfunction and tooth absess)
Function of CN VI
Abducens n. Controls eye muscle - LR (lateral rectus).
Lesion in CN VII symptoms
Flaccid paralysis of upper and lower face (if UMN lesion - spares forehead e.g. stroke), loss of corneal reflex, loss of taste and hyperacusis
Causes of bilateral facial n palsy?
sarcoidosis, Guillain-barre, lyme disease, bilateral acoustic neuroma,
Tx of myasthenic crisis
this is where there is mucsle weakness in myasthenia gravis. Tx: IV immunoglobulins ± Plasmaphoresis
Dx: Myasthenia gravis
1st line - single fibre EMG (will show increased jitter) or EMG repetitive stimulation (will show decrementation in muscle APs)
Function of CN XII
Hypoglossal n. - tongue movement
Lesion in which CN causes vertigo?
CN VIII vestibulocochlear
Function of CN VII
Facial n. Mnemonic: “face, ear, taste, tear”. Controls facial movements (but mastication is CN V) + taste to anterior 2/3 of tongue + lacrimation + salivation + Motor control of the stapedius in the ear – needed to dampen down sounds
Tx of Bell’s palsy
oral prednisolone within 72 hours of onset + consider eye care (artificial tears and eye lubricants)
Exacerbation factors of myasthenia gravis
Drugs that make MG worse: penicillamine, qunidide, beta blockers, lithium, phenytoin, Abx (gent, macrolides, quinolones ,tetracyclines).
What CN control sensory and motor function to tongue?
Sensory: Facial nerve CN VII is taste of ant. 2/3 , glossopharyngeal is taste to post. 1/3, and hypoglossal is motor control of tongue muscles).
What is bell’s palsy?
Facial nerve (CN VII) LMN lesion - all muscles of face are affected. Bell’s palsy is acute, unilateral, idiopathic facial nerve paralysis. Associated with herpes simplex virus (causes inflammation of nerve). Peak incidence = 20-40 y/o (associated highly with pregnancy!).
Gag reflex control
Sensory through CN IX (Glossopharyngeal) and motor to CN X (Vagus)
Causes of unilateral facial n palsy (UMN and LMN)?
UMN = stroke, LMN = bell’s palsy (is idiopathic), ramsay-hunt syndrome, acoustic neuroma, parotid tumours, HIV, MS, diabetes
Lesions in CN IX symptoms
Hypersensitive carotid sinus reflex, loss of gag reflex
The Corneal reflex (aka blink reflex)
Light touch to cornea - Sensation (afferent) received by CN V1 (trigeminal) -> signal to motor fibres of CN VII (Facial nerve) which responds by contracting the orbicularis oculi muscle.
Damage to what nerve causes hoarse voice?
Recurrent laryngeal nerve. Which is a branch of the vagus nerve.
Lesion in which CN causes hyperacusis?
CN VII (facial nerve) – it controls stapedus muscle in ear which dampens sound.
Function of CN VIII
Vestibulocochlear nerve. For hearing and balance.
Pt. develops a head tilt, and when they look straight, the affected eye appears to deviate upwards and rotate outwards. What CN affected?
CN IV trochlear n lesion. Causes vertical diploplia (typically noticed when reading or going down stairs), tilting of objects (torsional diplopia), head tild and affected eye deviates upwards and rotates outwards
Mnemonic for sensory or motor CN.
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Major complications of myasthenia gravis
Respiratory failure, aspiration pneumonia, increased VTE risk
Causes of trigeminal neuralgia
Most are idiopathic. Other cauess: compression of trigeminal roots by tumours or vascular problems
Lesion in CN VI symptoms
Palsy results in defective abduction of eye -> horizontal diplopia
Sx : Myasthenia gravis
Ptosis weakness of eye muscles blurred or double vision. Mainly - Fatiguable weakness - muscles get weaker as they are used. Weakness improves with rest. Can also have ocular and bular involvement = swallowing difficulties, speech disturbance.
Lesion in which CN? “Uvual deviates away from site of lesion”
CN X (vagus)
Function of CN IV
Trochlear nearve. Controls the SO muscle of eye
What CN controls mastication?
CN V (V3 division), remember V3 is sensory + motor.
What controls accommodation reflex?
Change in distance of an object, is sensed by CN II optic nerve. The response is CN III occulomotor. which adjusts the size of the lense to accommodate
Red flag sx of trigeminal neuralgia
Sensory changes Deafness or other ear problems History of skin or oral lesions that could spread perineurally Pain only in the ophthalmic division of the trigeminal nerve (eye socket, forehead, and nose), or bilaterally Optic neuritis A family history of multiple sclerosis Age of onset before 40 years
What condition has ‘Café au lait’ spots?
mostly associated with neurofibromatosis , but also tuberous sclerosis
“Lethargy, optic neuritis, paraesthesia, spastic weakness” is typica history for?
Multiple sclerosis
