Neurology

Question 1

Internuclear Ophthalmoplegia Side

Answer 1

A lesion of the RIGHT MLF will cause failure of ADDUCTION of the RIGHT EYE on LEFT gaze (looking away from the lesion)

Question 2

Features of an INO

Answer 2

Failure of adduction on the side of lesion with contralateral gaze

Question 3

Most common cause of a 3rd nerve palsy?

Answer 3

Aneurysm of the posterior communicating artery

Question 4

Investigation of 3rd nerve palsy?

Answer 4

CT/CTA to assess for aneurysm.

MRI to asses for other causes: ischaemia/infarction, tumour, infectious/inflammatory

Question 5

Anatomy of the 4th cranial nerve?

Answer 5

Dorsal/posterior, medial midbrain.
Exits posteriorly and is the ONLY CN that crosses/decussates.

Question 6

Features of cranial nerve 3 palsy?

Answer 6

1 - Ptosis
2 - Ipsilateral DIVERGENT STRABISMUS at rest
The right eye movements are impaired and the eye is fixed in a DOWN and OUT position.
There is diplopia which is worst on contralateral superior gaze (angulated diplopia)
3 - The pipil is fixed and dilated / mydriasis

Question 7

Features of horners syndrome?

Answer 7

1 - anhydrosis
2 - partial ptosis
3 - anisocoria / meiosis

Question 8

Differential Diagnosis of Cranial nerve 6 palsy?

Answer 8

Raised intracranial pressure
Inflammation: MS, NMO, sarcoidosis, GCA
Infection: Syphilis, Lyme disease
Neoplasm: Pontine tumour
Vascular: infarct, haemorrhage, aneurysm
Cavernous Sinus lesion: thrombosis, infection, tumour, aneurysm.
Subacute meningitis: carcinomatous, lymphomatous, fungal, TB
Trauma
Mono-neuritis multiplex

Question 9

Differential Diagnosis for Cranial nerve III palsy?

Answer 9

Brainstem lesion: tumor, infarct, hemorrhage, demyelination
Cavernous sinus lesions: Tumor, infection, thrombosis, aneurysm.
Tentorial herniation
Posterior communicating artery aneurysm
Superior orbital fissure lesion: trauma, tumor, granuloma
Subacute meningitis: carcinomatosis, lymphomatous, fungal, tuberculosis
Mono-neuritis multiplex

Question 10

Wasting of the small hand muscles:

Answer 10

Spinal Cord:
- Syringomyelia
- Cervical spondylosis with compression of C8
- Tumour
- Trauma

Anterior Horn cell
- Motor neuron disease, poliomyelitis
- Spinal root lesions (pancoast tumour)
- C8 compression

Lower Brachial Plexus Trunk
- Thoracic outlet
- Trauma, radiation, malignant infiltration, inflammation

Peripheral Nerve
- median or ulnar nerve
- peripheral motor neuropathy

Muscle:
- Myotonic dystrophy (forearms > hands)
- Distal myopathy

Trophic disorder:
- Arthropathies
- ischaemia (vasculitis)
- shoulder hand syndrome

Question 11

Differential Diagnosis for both UMN and LMN signs:

Answer 11

• Motor Neuron Disease
• Syringiomyelia
• Cervical myelopathy

Question 12

Differentials for pure motor weakness with LMN signs only

Answer 12

Progressive muscular atrophy variant of MND

Multifocal motor neuropathy

Poliomyelitis

Chronic inflammatory demyelinating polyneuropathy (pure motor variant)

Spinal Muscular atrophy

Question 13

Differential Diagnosis of PROXIMAL Weakness

Answer 13

Myopathy (Hereditary muscular dystrophy, acquired myopathy)

Neuromuscular (MG)

Neurogenic (motor neuron disease, polyradiculopathy)