Neuroanaesthesia

Question 1

Incidence of neurological damage during scoliosis correction

Answer 1

0.5%

Question 2

SSEP stimulation electrodes placement

Answer 2

Pair of stimulating electrodes placed bilaterally: 1) Posterior Tibial Nerves (Lumbar surgery) 2) Median Nerves (Cervical surgery)

Question 3

Frequency of SSEP stimulation

Answer 3

30mA at 5Hz

Question 4

SSEP recording electrode placement

Answer 4

Proximal to site of surgery: 1) 2 or more scalp electrodes (frontal and cervical) 2) Reference electrode 3) ground electrode

Question 5

Band filter width for SSEP

Answer 5

20-1000 Hz

Question 6

Shape of characteristic response in SSEP

Answer 6

W

Question 7

Changes seen in SSEP with spinal cord compromise

Answer 7

Increased latency Decreased amplitude

Question 8

Critical change in SSEP

Answer 8

50% increase in latency

Question 9

What is an MEP?

Answer 9

Motor Evoked Potential

Question 10

What is a SSEP?

Answer 10

Somatosensory Evoked Potential

Question 11

What does MEP monitor?

Answer 11

Territory of the anterior spinal cord artery (corticospinal tracts)

Question 12

What does SSEP monitor?

Answer 12

Dorsal column integrity

Question 13

Source of stimulation for MEP

Answer 13

Transcranial electrical stimulation Transcranial magnetic stimulation Direct rostral spine stimulation

Question 14

Risk of transcranial electrical stimulation

Answer 14

Injury secondary to mandibular contraction

Question 15

How are MEPs recorded?

Answer 15

S/C / IM needle electrodes in arm and leg muscles

Question 16

Time taken for MEP response

Answer 16

Less than 1 minute

Question 17

Define Serious Traumatic Brain Injury

Answer 17

GCS less than 9 post resuscitation

Question 18

List some primary prevention strategies for STBI

Answer 18

Helmets, airbags, reducing alcohol consumption, speed limits

Question 19

Define secondary brain injury

Answer 19

A hypoxic insult to the brain from oedema, haematoma or low systemic pressure following a primary insult

Question 20

Indications for CT head within 1 hour of TBI

Answer 20

GCS less than 13 at any time GCS 13-14 2 hours post injury Open fracture Skull base fracture More than 1 episode of vomitting Seizure Coagulopathy Event amnesia Focal deficit

Question 21

Oxygen targets in TBI

Answer 21

PaO2 great than 13

Question 22

CO2 targets in TBI

Answer 22

ETCO2 4.5-5

Question 23

MAP target in TBI

Answer 23

great than 80

Question 24

Glucose targets in TBI

Answer 24

6 - 10

Question 25

Describe the features of diabetes insipidus

Answer 25

Raised sodium Polyuria Low urine osmolality

Question 26

CPP target in neuroprotection

Answer 26

greater than 60

Question 27

ICP target in neuroprotection

Answer 27

Less than 20

Question 28

Rescue therapies in TBI

Answer 28

ABC Approach Ensure good venous drainage Increase sedation Hyperventillate to ETCO2 4-4.5 150 mL 5% NaCl Barbiturate Coma (Burst Suppression)

Question 29

What causes the blown pupil in a decompensating head injury?

Answer 29

Falsely localising nerve injury (CNIII)

Question 30

How should you treat seizures in TBI?

Answer 30

Thiopental or Benzodiazepine immediately. Phenytoin loading immediately afterwards

Question 31

The role of steroids in TBI

Answer 31

Generally none

Question 32

Why early fixation in unstable spinal injury?

Answer 32

allows for proper nursing care, PT, cough etc.

Question 33

Classical timing for early complications of SAH

Answer 33

Hydrocephalus - Day 1 Rebleed - Day 1-7 Ischaemia - More than day 7

Question 34

SAH risk factors

Answer 34

Smoking HTN Alcohol Polycystic kidney Family history Female gender Age 40-50

Question 35

SAH incidence

Answer 35

6/100,000 patient years

Question 36

SAH outcomes

Answer 36

10% die before hospital 40% die within 1 month

Question 37

Fisher Scoring System

Answer 37

CT

Question 38

Hunt and Hess Scoring System

Answer 38

Arrival clinical

Question 39

WFNS Scoring System

Answer 39

GCS and motor

Question 40

What are the hallmarks of a cholinergic crisis?

Answer 40

* Flaccid paralysis * Respiratory failure * Salivation * Excess bronchial secretions * Miosis * Sweating (sweat glands are the exception to the rule of SNS innervation)

Question 41

What are the indications for urgent (within 1 hour) CT head?

Answer 41

* GCS \< 13 when first assessed in emergency department * GCS \< 15 when assessed in emergency department 2 hours after the injury * Suspected open or depressed skull fracture * Sign of fracture at skull base haemotympanum, 'panda' eyes, cerebrospinal fluid leakage from ears or nose, * Battle's sign * Post-traumatic seizure * Focal neurological deficit * \> 1 episode of vomiting

Question 42

Cerebral ischaemia monitoring in CEA

Answer 42

* Awake * Transcranial doppler * Stump pressure * EEG * SSEP * NIRS

Question 43

What are the diagnostic criteria for SIADH?

Answer 43

* hypotonic hyponatraemia * serum sodium \< 135 mmol/l * serum osmolality \< 280 mOsm/kg * urine osmolality \> serum osmolality * urine sodium concentration \> 18 mmol/l * normal thyroid, adrenal, and renal function * clinical euvolaemia—absence of peripheral oedema or dehydration.

Question 44

How do you treat SIADH

Answer 44

* Conservatively * Fluid restrict (1000mL/day) * Consider Hypertonic saline (1.8%), but stop at around Na 120 mmol/L * Consider diuretics * Consider demeclocycline/lithium to inhibit renal response to lithium * Consider lixivaptan

Question 45

Cerebral Salt Wasting Syndrome biochemical diagnostic criteria

Answer 45

* low or normal serum sodium; * high or normal serum osmolality; * high or normal urine osmolality; * increased haematocrit, urea, bicarbonate, and albumin as a consequence of hypovolaemia.