Neurology

Question 1

What are features of childhood absence epilepsy?

Answer 1

• generalised seizure
• typical age of onset 5-8y (<4 eval. for glucose transporter defect)
• generally last seconds –> may be overlooked
• often precipitated by hyperventilation
• EEG: 3Hz slow spike and wave
• ethosuccimide gives complete seizure control in 80%
• lamotrigine and valproate control seizure in 60%
• carbamazepine may accentuate seizures and cause status

Question 2

What are fetures of Dravet syndrome (severe myoclonic epilepsy of infancy)?

Answer 2

• onset in infancy
• FHx of epilepsy in 25%
• usually de novo but rarely AD (SCN1A)
• first seizures frequently febrile and often prolonged, frequent, focal and clustered (DDx febrile seizures)
• generalised myoclonic seizures appear after 1yoa (allowing diagnosis)
• slowing of development, ataxia and hyperreflexia develop with myoclonic seizures
• EEG: initially normal
• typically requires polypharmacy: sodium valproate + benzodiazepine
• Na channel drugs tend to exacerbate: phenytoin, carbamazepine, lamotrigine

Question 3

What gene is affected in SMA?

Answer 3

Survivor motor neuron (SMN1)

Question 4

What are nerve conduction findings in SMA?

Answer 4

Normal except for mild slowing in terminal stages –> differentiates from peripheral neuropathy

Question 5

What is lissencephaly?

Answer 5

• Neuronal migration disorder, caused by defective neuronal migration during 12th-24th weeks gestation.
• Results in lack of sulci and gyri. Absent cerebral convolutions and rudimentary Sylvian fissure.
• Patients have large venrtricles, microcephaly, microphthalmia.
• Manifests as severe developmental delay, failure to thrive and seizures.

Question 6

What are nerve conduction findings in Charcot Marie Tooth?

Answer 6

• CMT1 is a demyelinating neuropathy.
• Duplication of PMP22, autosomal dominant.
• Expect slow conduction due to demyemination.

Question 7

What are risk factors for SUDEP?

Answer 7

• Most important risk factor is presence and frequency of generalised tonic clonic seizures.
• Other risk factors include: Neurological handicap, high seizure frequency (>1/month), increased episodes of status epilepticus, duration of epilepsy >15y, nocturnal seizures, male, early onset, symptomatic epilepsy, genetic or epilepsy syndrome.

Question 8

Which branch of the facial nerve supplies taste to the anterior 2/3 of the tongue?

Answer 8

• Chorda tympani.

Question 9

What are features of ataxia telangiectasia syndrome?

Answer 9

• Autosomal recessive.
• Involves ATM gene which phosphorylates p53.
• Manifest as ataxia followed by ocular motor apraxia and telangiectasia (sun exposed areas or bulbar conjunctival).
• ATM has a role in T cell development, therefore B cell activation is affected leading to primary immunodeficiency.
• Cancer predisposition, type 1 diabetes.
• AFP elevated.

Question 10

What is PANDAS?

Answer 10

• Paediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcus pyogenes.
• Neuropsychiatric disorder (particularly obsessive-compulsive, tic and Tourettes) with possible relationship to GAS.
• Antibodies to GAS cross react with the basal ganglia.
• 5 clinical characteristics:
• -> OCD and/or tic disorder.
• -> Prepubertal.
• -> Abrupt onset with relapsing remitting course.
• -> Neurologic abnormalities.
• -> Temporal association between symptoms exacerbations and GAS infection.

Question 11

What causes seizures in hypophosphatasia?

Answer 11

• Loss of function mutation in tissue non-specific ALP (TNALP) result in low or absent ALP.
• Duild up in precursors inorganic PO4, pyridoxine 5 phosphate (P5P) and phospoethanolamine.
• P5P is the major circulating form of pyridoxine (B6).
• In order to cross BB in to CSF, P5P must be cleaved by TNALP to form pyridoxine.
• Pyridoxine is water soluble and can cross BBB and be regenerated in to P5P.
• P5P is involved in a reaction that produces inhibitory neurotransmitter GABA.
• Seizures are refractory to all antiepileptics except pyridoxine.