CNS Flashcards by R C

DDx of Diplopia / complex ophthalmoplegia? (5)

Brain stem: Stroke, SOL, MS

The base of skull problems: granulomatous disease, meningitis

Peripheral nerve: mononeuritis, cavernous sinus lesions

NMJ: Myasthenia

Soft tissue: Grave’s

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What would you look for in fundoscopy in diabetics? (5)

Cotton wool spot

Hard exudates

Intra-retinal haemorrhages

Microaneurysms

Proliferative: neovascularisation

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Ophthalmoscopy finding of hypertensive retinopathy? (5)

AV nipping

Silver wiring (narrowing of retinal arterioles)

Dot/flame haemorrhages

Cotton wool spots

Hard exudates

Microaneurysms

Papilloedema

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CN III lesion features? (3) What is the key feature distinguishing between compressive vs. mononeuritis?

Eyes in inferolateral at the neutral position (ipsilateral eye)

Ptosis

Dilated, non-reactive pupil (if present, indicates compressive neuropathy). If mononeuritis (e.g. from diabetics, this is spared)

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Causes of CNIII palsy? (4)

Posterior Communicating Artery Aneurysm - until proven otherwise.

Cavernous sinus lesions

Midbrain lesions: MS, SOL, Stroke

Mononeuritis multiplex (pupil spared)

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How would you distinguish between CN II vs. CN III lesion? (2)

Optic nerve lesion: no pupil constriction with direct and indirect

Oculomotor: no pupil constriction with direct but with indirect, constriction present.

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Jaw jerk and Corneal reflex are to test which nerve?

CN V

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Causes of CN VI palsy? (4)

Raised ICP - is a false localising sign

Pontine lesions: MS, Stroke, SOL

Trauma or Tumour compressing on anywhere along it’s path

Mononeuritis multiplex.

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CN VII signs (5)

The weakness of facial muscles

Loss of corneal reflex (CN VII - efferent, CN V - afferent)

Loss of taste sensation anterior 2/3rds

Hyperacusis (stapedius muscle)

Decreased tearing (lacrimal gland)

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Facial nerve causes of LMN pattern weakness? (i.e. involves forehead/upper face) - 4

Most common = Bell’s palsy (idiopathic or viral)

Peripheral nerve lesion - Herpes Zoster, GBS, Sarcoid

Otitis media

Pons (ipsilateral, affecting nucleus): MS, stroke, SOL (e.g. acoustic neuroma)

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Facial nerve causes of UMN?

Lesion affecting contralateral UMN fibres (above nucleus to cerebral motor cortex)

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Clinical signs of CN 9-10 palsy? (6)

Fibres travel together, so their clinical testing is not easily separable.

Loss of taste in posterior 1/3rd (IX)

Uvula deviates (away UMN, towards LMN)

Hoarseness (recurrent LN to vocal cords)

Dysphagia (swallowing muscles - X)

Dysphonia (speech muscles - X)

Decreased Gag reflex

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Causes of CN IX - X palsy? (4)

UMN: 10th nerve tract

MND

Medulla lesions: stroke, SOL, MS

Trauma or Tumour along the CN

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Signs of CN XI weakness (2) and causes? (3)

Weak SCM and Trapezius (Accessory nerve)

Causes:

Medulla lesions: stroke, SOL, MS

Tumour or trauma along it’s path

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Clinical sign of hypoglossal nerve palsy? (CN XII). Where is the lesion?

Protrusion of tongue away (for UMN) or towards (LMN) from side of lesion

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Causes of hypoglossal nerve palsy? (4)

UMN: 12th nerve tract (as part of pseudobulbar palsy)

MND

Medulla: MS, stroke, SOL

Tumour or trauma along it’s path

Where in brainstem CN are located?

Midbrain: CN 3-4

Pons: CN 5-8

Medulla: 9-12 and nuclei 5 (descending)

Cerebellopontine angle CNs are?

CN 5,6,7,8

Cavernous sinus anatomy? and Mnemonic to describe location of CNs within it?

OTOM-CAT.

INO cause?

Lesion in MLF (medial longitudinal fasciculus) - PONTINE lesion.

Causes of complex ophthalmoplegia (diplopia)?

Causes of ptosis? (4)

Muscular: Myotonic dystrophy

NMJ: Myasthenia gravis

PN: CN III palsy, neurosyphilis

Horner’s

What are the causes of Horner’s syndrome? (anhydrosis, ptosis, miosis)

Aka - occulosympathetic paresis

1st order (central): brainstem MS, SOL, stroke, Lateral Medullary Syndrome
2nd order (pre-ganglionic): Pancoast tumour, cervical rib
3rd order (post-ganglionic): carotid artery dissection/tumour

Expressive aphasia - Describe - Where is the lesion?

**Expressive** aphasia: Able to comprehend + read Non-fluent and impaired repetition The lesion in Broca's area = **_left_** (dominant) inferior **frontal**

Receptive aphasia - Describe - Where is the lesion?

Wernicke's aphasia - Fluent but impaired comprehension. - Voluminous, meaningless speech - Lesion in Wernicke's area: = _left,_ superior temporal + inferior parietal Ex: "dorflur" for "shoe" (paraphrase) Ex: "jet" for "airplane" or "knife" for "fork" (paraphrase) Ex: "bap" for "map" (neologism) Ex: "uhhh it's white...it's flat...you write on it…" (when referencing paper; talking around the target - called circumlocution)

Which cerebral artery is occluded/compromised in Expressive vs. Receptive aphasia?

Broca's (expressive) = **anterior MCA** Wernicke's (receptive) = **posterior MCA**

Left Homonymous Hemianopia with macular sparing. Where is the lesion?

Right Occipital Lobe, likely due to **PCA** occlusion. The macula is spared due to **dual blood supply of macula** by **MCA**.

Left Homonymous Hemianopia - where is the lesion? (3)

Lesion would be contralateral 1. R optic tract 2. R optic radiation involving both parietal + temporal lobe (i.e. concomitant superior + inferior quadrantanopia) - rare, means massive infarct. 3. R occipital lobe (usually macula is spared)

Lateral medullary syndrome features?

**4S's** Ipsilateral face pain & temperature sensation (the **s**ensory nucleus of 5th CN) Contralateral pain & temperature affecting arm/legs (**s**pinothalamic) Ipsilateral Horner's (ptosis, miosis, anhydrosis) - **s**ympathetic Ipsilateral Ataxia arms/legs (**s**pinocerebellar)

List 3 sensory pathways in the spinal cord - Their function (which sensation do they carry) - Deccusation point

**Dorsal columns** (medial lemniscus): crude (well-localised) touch, proprioception + vibration **Lateral Spinothalamic** Tract: pain & temperature **Anterior spinothalamic** tract: light-touch (poorly localised) Dorsal column decussate at medulla Spinothalamic: decussate at the level of spinal cord

List 2 motor pathways in the spinal cord: where do they deccusate?

- Corticospinal (motor / UMN) 1. **Lateral corticospinal** (90% - arms/legs / fine movements): decussates just before the spinal cord (**medulla** oblongata – cervicomedullary junction) 2. **Anterior corticospinal** (axial – trunk / neck muscles): decussate at the _level of spinal cord_