Disorders of The Cranial Nerves Flashcards by Callum Anderson

Which cranial nerves contain special senses?

Olfaction - 1

Vision - 2

Taste (7,9 and 10)

Hearing and balance (8)

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Which cranial nerves carry ordinary sensation?

Trigeminal

Ear - facial nerve and the glossopharyngeal

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What controls the muscles of the larynx and the pharynx?

Mainly the vagus

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What cranial nerves have autonomic function? and what is the autonomic function?

3,7,9 and 10

3 - pupillary constriction

7- Lacrimation, salivation (sublingual and submandibular glands)

9 - Salivation (parotid gland) - glossopharyngeal

10 - inout to organs in thorax and abdomen

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How do we test olfaction?

Olfactory –smell – unilateral or bilateral loss

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Investigations for 2nd cranial nerve when testing it?

Visual acuity

Visual fields

Pupillary reactions

Fundoscopy

Colour vision

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What do you look for when testing the nerves responsible for eye movement?

Ptosis?

Equal sized pupils?

Pupillary reactions?

Eye movements - both vertical and horizontal

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Tests for trigeminal?

Sensations in the ophthalmic, maxillary and mandibular divisions

Power in the muscles of mastication

Corneal reflex

Jaw jerk

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What do we test for with facial nerve?

Muscles of facial expression

Corneal reflex

Taste

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How do we test the vestibulocochlear nerve?

Hearing - rhinnes and webers test

Vestibular function using the dix - hallpike manouvre

and untenbergers test (step test)

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How do we test the glossopharyngeal nerve?

Movement of the palate

Gag reflex

Quality of speech

Quality of cough

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How do we test the accessory nerve?

Head turning and shoulder shruging

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How do we test the hypoglossal nerve?

Appearance, movement and power of the tongue

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What are the cranial nerve relfexes and what nerves do they use?

• Pupillary light reaction

afferent – II ; efferent – III

• Corneal reflex

afferent – V ; efferent – VII

• Jaw jerk

afferent and efferent – V

• Gag reflex

afferent – IX ; efferent - X

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Which cranial nerve nuclei like in the MIDBRAIN?

3 and 4

(occulomotor and trochlear)

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Which cranial nerve nucle lie in the PONS?

5,6,7

Trigeminal, abducent and facial nerve

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Which nerve lies in thge pontomedullary junction?

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Which cranial nerve nuclei lie in the medulla?

9,10,11 and 12

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Which nerves are associated with the cerebellopontine angle?

7 and 8

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Which nerves are assocaited with the pons?

5 and 7

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What may result in bilateral 3rd cranial nerve signs?

Issue with the midbrain

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What may cause unusual combinations of cranial nerve problems?

Chronic or malignant meningitis

What may cause pure motor signs with cranial nerve issues?

Myasthenia gravis

What may cause double vision that isn’t a cranial nerve disorder?

Myasthenia gravis or thyroid disease

What are the ways cranial nerves can be damaged?

Ischaemia tumour Meningitis

What is optic neuritis?

Demyelinating inflammatory condition of the optic nerve Inflammation also occurs int he muscles of the eye, they are sore to move

What are the signs of optic neuritis?

* monocular visual loss * pain on eye movement * reduced visual acuity * reduced colour vision * optic disc may be swollen * often associated with multiple sclerosis

What is a useful test for optic neuritis?

Visual evoked repsonse - shows a delay in nerve conduction as a result of optic neuritis

What is the result of loss of parasympathetic input from the third cranial nerve?

Fixed dilated pupil

What causes a constricted pupil?

Damage anywhere wihtin the sympathetic pathway can lead to a constricted pupil

What are the causes of dilated pupils?

* Youth * Dim lighting * Anxiety, excitement * “Mydriatic” eye drops * Amphetamine, cocaine overdose * Third nerve palsy * Brain death

What are the causes of small pupils?

* Old age * Bright light * “Miotic” eye drops * Opiate overdose * Horner’s Syndrome

What are eyemovement disorders?

* Isolated third nerve palsy * Isolated fourth nerve palsy * Isolated sixth nerve palsy * Combination of the above * Supranuclear gaze palsy - inability to look in a particular direction as a result of cerebral impairment (nothiung to do with the cranial nerves) * Nystagmus

What can cause isolated third nerve palsy?

Microvascular - diabetes, hypertension Compressive - posterior communicating artery aneurysm, raised ICP

What is the difference in clinical features between microvascular and compressive third nerve palsy?

Microvascular - painless, pupil spared Compressive - painful, pupil affected

What can cause isolated 6th nerve palsy?

Idiopathic Diabetes Meningitis Raisd intracranial pressure

What causes nystagmus?

* Congenital * Serious visual impairment (e.g. macular degeneration) * Peripheral vestibular problem * Central vestibular / brainstem disease * Cerebellar disease * Toxins (medication and alcohol) medication - phenytoin and carbamezapine

What causes trigeminal neuralgia?

Triggered by temperature / touching the face Caused by a vascular loop causing compression of the fifth nerve in the poeterior fossa

What is the presentation of trigeminal neuralgia?

Paroxysmal attacks of lancinating pain

How is trigeminal neuralgia treated?

Treated medically with carbamazepine

What type of motor neurone type palsy is bells palsy?

Lower motor neurone

What are the features of bells palsy?

Unilateral facial weakness Often preceeded with pain behind the ear Eye closure is affected (risk of corneal damage)

How is bells palsy treated?

Steroids Usually good recovery Not all patients recover fully plastics - re-establish facial symmetry

What is the difference between UMN and LMN facial paralysis?

UMN - stroke and tumour LMN - bells palsy, lyme and sarcoid UMN - forehead movement is still possible on affected side because innervation is bilateral LMN - No forehead movement on affected side

What are the features of vestibular neuronitis?

Sudden onset Disabling vertigo Vomiting Gradual recovery Cause is uncertain (viral?)

What is the treatment for vestibular neuronitis?

Anti-emitics and bed rest Tends to recover fully Very often MS can present with something like thid

What is dysarthria and dysphagia?

Dysarthria - disordered articulation, slurring of speech Dysphagia - difficulty swallowing •Both occur in bulbar- and pseudobulbar palsy –Bulbar – lower motor neurone –Pseudobulbar palsy – upper motor neurone Myasthenia gravis also presents with slurring although this is usually towards the end of the day

What causes pseudobulbar palsy?

Bilateral UMN lesion - Vascular lesions of both internal capsules (MND)

What are the features of pseudobulbar palsy?

dysarthria - dysphonia - dysphagia - spastic, immobile tongue - brisk jaw jerk - brisk gag reflex

What is bulbar palsy?

Bilateral LMN lesion affecting 9 - 12

What causes bulbar palsy?

MND Polio Tumours Vascular lesions of the medula and syphilis

What are the clinical features of bulbar palsy?

- wasted, fasciculating tongue - dysarthria - dysphonia - dysphagia BEWARE OF FEEDING THESE PATIENTS - may aspirate