Neuro/Ophthal/Psych

Question 1

Where is DNA in a cell?

Answer 1

• mostly cell nucleus

- also small amount dsDNA in mitochondria - encodes protein components of rest chain and some special types of RNA

Question 2

characteristics of mitochondrial inheritance?

Answer 2

• inheritance only via maternal line as sperm contributes no cytoplasm to zygote
• all children of affected males will NOT inherit the disease
• all children of affected females WILL inherit
• generally encode rare neurological diseases
• poor genotype:phenotype correlation - within a tissue/cell there can be different mitochondrial populations = heteroplasty

Question 3

What is the Dx Ix for mitochondrial diseases?

What is shown on histology?

Answer 3

Muscle biopsy

- ‘red, ragged fibres’ due to increased number of mitochondria

Question 4

Examples of mitochondrial diseases?

Answer 4

• Leber’s optic atrophy
• MELAS syndrome: mitochondrial encephalomyopathy lactic acidosis & stroke-like episodes
• MERRF syndrome: myoclonus epilepsy with ragged-red fibres
• Kearns-Sayre syndrome: onset in pts <20yrs old, external ophthalmoplegia, retinitis pigments; posts may be seen
• sensorineural hearing loss SNHL

Question 5

Acute relapse MS Rx?

Answer 5

• high dose steroids (PO or IV methylpred depending on severity) for 5 days to shorten length
• steroids shorten the duration of a relapse & don’t alter the degree of recovery (e.g. to baseline)

Question 6

Upgoing plantars and absent ankle jerks

- DDx?

Answer 6

SCDC
MND
Friedrich's ataxia
Tabes dorasalis = neurosyphilis
dual peripheral with central pathology

Question 7

SCDC (vit B12 deficiency)

- what is affected

Answer 7

• dorsal & lateral columns affected
• joint position & vibration sense lost first then distal paraesthesia
• UMN signs in legs - extensor plantars, brisk knee reflexes, absent ankle jerks
• if untreated, stiffness & weakness persist

Question 8

Anterior interosseous syndrome?

Answer 8

Anterior interosseous n supplies flexor pollicis longus and the lateral half of flexor digitorum profundus

• branch of median nerve
• loss of pronation of forearm & weakness of long flexors of thumb & index

Question 9

Median nerve damage at wrist?

Answer 9

carpal tunnel

• paralysis & wasting of thinner eminence muscles & opponents policies
• sensory loss to palmar aspect of lateral 2.5 fingers

Question 10

Median nerve damage at elbow?

Answer 10

• can’t pronate forearm + weak wrist flexion + ulnar deviation of wrist
• • • paralysis & wasting of thinner eminence muscles & opponents policies
• sensory loss to palmar aspect of lateral 2.5 fingers

Question 11

Stroke rx within 4.5h of Sx?

Answer 11

Thrombolysis

Question 12

Factors that may exacerbate myasthenia graves?

Answer 12

penicillamine
quinidine, procainamide
beta-blockers
lithium
phenytoin
Abx: gentamicin, macrolides, quinolones, tetracyclines