Neurosurgery/Neuro Critical Care

Question 1

Risk factors for subarachnoid haemorrhage?

Answer 1

Hypertension, alcohol abuse, cocaine abuse, smoking, Polycystic kidney disease, Ehler-Danlos IV, for medial intracerebral aneurysms

Question 2

Where are culprit subarachnoid Aneurysms most commonly found?

Answer 2

At the bi furcation is around the circle of Willis

Question 3

Define secondary neurological injury,

When is it most likely to occur?

Answer 3

The Deletirious changes That occur in the brain as a consequence of the initial injury mediated by inflammatory, neurogenic and vasogenic processes. Occur over hours to days after the initial injury

Question 4

List three scoring systems for subarachnoid haemorrhage

Explain two in detail

Answer 4

Hunt and Hess
WFNS
Fisher grade

WFNS 1= GCs 15
          2= GCS 13-14 no motor deficit
          3= GCS 13-14 motor deficit
          4= GCS 7-12
          5= GCS 3-6

Fisher grade 1= no SAH on CT
2= <1mm blood
3= >1mm blood with clots, no IVH
4= diffuse blood with ICH or IVH

Question 5

List to sensory changes that occur immediately following transaction of the spinal cord at the fourth thoracic vertebra?

Answer 5

 loss of sensation below T4

Variable loss of sensation above T4 due to secondary injury from Haemorrhage/oedema et cetera

Question 6

List two motor changes that occur immediately following transaction of the spinal cord at T4

Answer 6

Flaccid paralysis below T4

Obliteration of reflexes below T4

Question 7

List to autonomic changes that occur immediately following transaction of the spinal cord T4

Answer 7

Neurogenic shock from loss of sympathetic tone, unopposed vagal tone and vasodilation

Loss of autonomic control of bladder voiding and bowel emptying

Question 8

At what Spinal level to the cardiac sympathetic fibres come off?

Answer 8

T2 – T5

Question 9

Explain what is an Asia A – E score?

Answer 9

A - complete spinal injury.
No sensory or motor function preserved in the cycle segments S4 – S5

B - Incomplete spinal injury.
Preservation of sensory but not a motor function below the neurological level and includes the sacred segments S4 – S5

C - Incomplete spinal injury.
Preservation of motor function below the neurological level. More than half key muscles below the neurological level have a muscle grade of < 3

D - Incomplete spinal cord injury.
Preservation of motor function below the neurological level. More than half a key muscles below the neurological level have a muscle grade of >3

E - Normal spinal cord.
Sensory and motor function is normal



Question 10

How is the neurological level of a spinal cord injury determined?

Answer 10

Lowest level of the spinal cord with normal sensation and motor function on both sides of the body

Question 11

Describe the features of interior spinal artery syndrome

Answer 11

Preservation of dorsal columns.

Therefore loss of motor and pain/temperature with preservation of proprioception, Vibration and fine touch

Question 12

Describe the features of brown dash sequárd syndrome

Answer 12

This is a unilateral spinal cord lesion
Loss of IPSILATERAL motor function, IPSILATERAL fine touch and proprioception BUT WITH CONTRALATERAL pain and temperature sensation

Question 13

Features of cauda equina syndrome

Answer 13

Weakness in lower limbs with loss of bladder and bowel function

Question 14

Features of central cord syndrome

Answer 14

Upper motor neuron signs in the legs with mixed upper and lower motor neuron signs in the upper limbs
Often sacral sparing (as these fibres run naturally in the cord)

Question 15

How does the level of a spinal cord injury influence breathing?

Answer 15

Lesions between C3 and C5 will impair diaphragm innovation. Vital capacity will be greatly reduced, cough will be weak or ineffective. Very high proportions require ventilation

Lesions above T8 (But below C5) Lead to a loss of innovation of intercostal muscles and abdominal muscles. This leads to variable reduction in vital capacity with a normal/weak cough

Lesions below T8 lead to loss of lower respiratory intercostals and abdominal muscles. Slight reduction in vertical pasty with a normal/weak cough

Question 16

Why is it so important to control blood pressure on emergence from anaesthesia with an AVM

Answer 16

Vessels around the AVM chronically vasodilated.

When the AVM has been treated the vessels are unable to autoregulate appropriately and normal perfusion pressure breakthrough may occur.

This can result in vasogenic oedema and haemorrhage at normal blood pressures. Hypertension could be catastrophic, coughing et cetera could be catastrophic

Question 17

 Explain the issues using suxamethonium in patients with neuromuscular disorders

Answer 17

Suxamethonium can lead to fatal hyperkalaemia muscle fibre swelling and rhabdomyolysis. This is due to an increase in the number of extra junctional ACh receptors.

Question 18

Which is the only neuromuscular disorder in which you can use suxamethonium?
What would you do to the Dose?

Answer 18

Myasthenia gravis.

You would increase your dose

Question 19

Explain how you would use nondepolarising neuromuscular blockers in patients with neuromuscular disorders

Answer 19

Patients with neuromuscular disorders are particularly sensitive to these drugs.

They should be given in reduced doses, 10 to 20% of usual dose.
Agents such as atracurium are preferred due to their spontaneous Hoffman degradation.

Anticholinesterases cause issues similar to suxamethonium and can lead to hyperkalaemia.

Question 20

What are the main complications that can arise when giving an anaesthetic to a patient with neuromuscular disorders

Answer 20

1. rhabdomyolysis (Either spontaneous secondary to Sustained muscle contraction, or as a result of depolarising neuromuscular blocking drugs)
2. Autonomic dysfunction
3.  Myotonias (Myotonic contractions can be caused bye drugs such as suxamethonium, anticholinesterases, and opioids. They can also be caused by environmental factors such as temperature, acidosis, and shivering.

They are classically not responsive to neuromuscular block, regional or peripheral nerve block.

The treatment, After correction of environmental and physiological conditions are to use drugs which block sodium channels such as local anaesthetics and anti-arrhythmic agents

4. Cardiac and respiratory complications - His patients are sensitive to perioperative catecholamine release which may precipitate arrhythmias or cardiac failure
   - Respiratory failure is the commonest cause of death in patients with neuromuscular disorders due to bulbar weakness, poor pharyngeal and respiratory muscle tone, OSA, and progressive spinal deformity leading to a restrictive lung defect
   Excavation should be achieved as early as possible, but this may be later than it would be for other patients

Question 21

Clinical indications for intubation and ventilation in GBS

Answer 21

1. Vital capacity <20ml/kg
2. Maximum inspiration pressure <30cmH20
3. Maximum expiratory pressure <40cmH20
4. Decrease of >30% in VC, MEP, MIP

Question 22

 what are the management stages of Convulsive status epilepticus

Answer 22

Pre-hospital stage; diazepam 10 to 20 mg PR or midazolam 10mg Buccally

Early stage(5-10min) : lorazepam 0.1mg/kg IV. Can repeat once.
Give usual AEDs if already on treatment.
(Glucose and thiamine if alcoholic)

Established stage (5-30min) : phenytoin 15-18mg/kg IV

Refractory stage (>30min) : general anaesthesia