Neurosurgery

Question 1

Name a time you would do decompression surgery (2)

Answer 1

–Tumour

–IVDD

Question 2

Name a time you would do fusion surgery (2)

Answer 2

–Fracture

–Instability

• AASlx
• Wobbler
• ?IVDD

Question 3

What are these different surgery types?

Answer 3

1. Dorsal laminectomy
2. Hemilaminectomy
3. Ventral slot

Question 4

What are the 2 things spinal integrity depends upon?

Answer 4

–Intervertebral disc

–2 articular facet joints

Question 5

How many facet joints can we remove without clinical consequences?

Answer 5

One

Question 6

What is a dorsal laminectomy useful for?

Answer 6

Bilateral lesions

Question 7

What is the width of laminectomy limited by?

Answer 7

Articular facet joints

Question 8

Discuss dorsal laminectomy and how it may be done

Answer 8

• Can be performed anywhere along the spine except C1-2
• Relatively easy soft tissue approach
• Avoids ventral venous plexus
• Limited exposure lateral and ventral to the spinal cord
• Deep hole in the thoracic region

Question 9

Where is a hemilaminectomy done and where is it complicated?

Answer 9

• The most common surgical approach in the TL region
• Complicated in cervical region by vertebral artery

Question 10

Discuss what a hemilaminectomy allows, requires and the risks.

Answer 10

• Allows lateral approach to the spinal cord
• Allows exposure ventral to the spinal cord
• Requires lateralisation
• Risk of damage to nerve roots/spinal nerves
• Risk of damage to ventral venous plexus

Question 11

What is the ventral slot?

Answer 11

•Surgical approach through the vertebral bodies centred on the intervertebral disc

Question 12

Dicuss what a ventral slot allows, and the limitations.

Answer 12

• Allows access to the ventral aspect of the spinal canal
• Easy approach (if know anatomy)
• Limited access/visibility
• Only feasible in cervical region
• Significant risk of haemorhage
• Post operative morbidity

Question 13

What happens if the spinal cord is:

A) Unstable?

B) Compressed?

Answer 13

A) Requires stabilisation/conservative

B) Needs decompressing

Question 14

What are the spinal cord compartments and how are these used to assess stability?

Answer 14

• Lamina
• Dorsal ligaments
• Dorsal longitudinal ligament
• Dorsal annulus
• Dorsal portion of vertebral
• Ventral longitudinal ligament
• Ventral annulus
• Ventral portion of vertebral body

If more than one compartment compromised then would predict unstable

Question 15

What is internal fixation?

Answer 15

–Orthopaedic proceedures such as plates (may not be feasible anatomically)

–Pins and methymethacrylate

Question 16

What can we do as consrvative therapy?

Answer 16

• Strict cage rest
• Other management as appropriate
• Using the dogs apaxil and hypaxial muscles to act as a splint
• Minimise spine mobilisation
• Stabilise for a minimum of 6 weeks
• Analgesia
• Bladder control – do we need to catheterize?
• Prevent bed sores – regular turning
• Motivational therapy
• Physiotherapy as appropriate

Question 17

What must we consider about the anaesthesia of spinal cord surgery?

Answer 17

•Injury to SC develops after the weight has been dropped over 48 hours? So what happens in first 48 hours is crucial

–Inflammatory and vascular pathways increase SC compromise

–Vascular processes in first 48 hours, the worst thing you can do for the SC is to MRI. This can make them worse. Take the patient out of ICU and then because they are disconnected the pressure drops and all support is lost

–Lower pressure – lower perfusion of SC and brain

Question 18

Do we use steroids or spinal/cranial trauma?

Answer 18

Acute – THERE IS NO PLACE for steroids . No evidence it worse but there is evidence for side effects

Chronic – yes there might be a place for it

Question 19

What are the 2 hardest parts of intracranial surgery?

Answer 19

• Anaesthesia
• Post op

Question 20

What is status epilepticus?

Answer 20

• Ongoing for at least 5 minutes
• Or multiple uncontrolled seizures – comes out of seizure and goes back down into one before fully recovered

Question 21

What are the 2 treatment goals of status epilepticus?

Answer 21

–Terminate seizure activity

–Identify and treat cause for seizures

Question 22

What are the possible therapeutic treatments for status epilepticus?

Answer 22

• Diazepam
• Phenobarbital (barb)
• Propofol
• Midazolam (BZD)
• Pentobarbitone (Barbiturate)

Question 23

What i the first line treatment for ongoing seizure activity? How is thi given?

Answer 23

Diazepam

•Can be given by multiple routes (depending upon formulation):

–IV – Best way! But hard if they are seizuring

–PO – unreliable

–PR …. When you cant give it IV

• Best IV if can gain intravenous access
• Dose 0.5-1 mg/kg (whole vial normal size dog!)

Question 24

What is the second line treatment for ongoing seizure activity? How is it given?

Answer 24

Phenobarbital

• Very effective anticonvulsant
• Slow absorption PO so will need to use IV preparation
• IV dose 2-3 mg/kg (as PO dose) but can increase to 10 mg/kg

Question 25

What is an issue with using phenobarbital as an anticonvulsant? What could we do?

Answer 25

•Relatively long time to effect so may need to supplement –Could use diazepam to gain you time in the 20 mins –Or use propofol

Question 26

Discuss the use of propfol as an anitconvulsant. How it acts? Issues?

Answer 26

* Neurosteroid – anaesthetic and some anticonvulsant activity * Used IV titrated to effect * Aiming for seizure control not anaesthesia * May need anaesthesia support eg endotracheal intubation and ventilation * Transient effect, but useful whilst IV phenobarbital become effective * Dose for anti convulsant is less than for GA * Use to effect * If you use GA then you will suppress gag reflex and need to ET them –Try to support without GA and intubating Works for about 20 mins as an anti convulsant (the time needed for PB to work

Question 27

What do we use midazolam the same as?

Answer 27

Diazepam

Question 28

Discuss pentobrabitone: How effective? Use? Issues?

Answer 28

* Very effective * Up to 8 hour effect * However not been available for ~10 years as a sterile preparation * Euthatal cannot be recommended

Question 29

What is the protocol or status epilecticus?

Answer 29

Diazepam x3 -\> Phenobarbital --\> Propofol

Question 30

What are the 3 things contributing to intracranial pressure?

Answer 30

* Blood * CSF * Tissue

Question 31

What is the issue with an increased intracranial pressure?

Answer 31

Become ischamic

Question 32

What is going on with this cerebellar herniation

Answer 32

1. Transtentorial 2. Foraminal

Question 33

Dicuss the causes o these pupil changes and the prognosis

Answer 33

1. Unilateral III nucleus or nerve damage 2. Guarded 3. Midbrain compression 4. Guarded 5. Bilateral III nucleus or nerve damage Lost PLR Measure of trauma severity 6. Grave

Question 34

How do we deal with cranial trauma?

Answer 34

* Important to maintain cerebral perfusion * increase oxygenation (don’t overdo) * maintain sufficient cerebral bloodflow by maintaining arterial blood pressure * ?ICP measurement * ??cerebral microdialysis * ?general anaesthesia * ?craniotomy to relieve pressure

Question 35

What are the three areas of the Glasgow Coma Scale? What do we measure?

Answer 35

Motor activity Brain stem reflex Consciousness On a sclae of 1-6 (6 is good)

Question 36

What can we do to treat cerebellar herniation?

Answer 36

•mannitol 1 gm/kg –Need to give high fluid rate to make up for reduce BP * ?steroids – not much point * ?frusemide – Another diuretic. Would you give another one or not? * CPR

Question 37

What do we suspect?

Answer 37

–Ischaemic episodes caused by aortic thromo emobilsim –Spinal fracture? Need to think about how we transport –Tail pull - the cat doesn’t quitte get run over; flaccid tail and some sort of paresis in back legs.