Neurosurgery Flashcards
Name a time you would do decompression surgery (2)
–Tumour
–IVDD
Name a time you would do fusion surgery (2)
–Fracture
–Instability
- AASlx
- Wobbler
- ?IVDD
What are these different surgery types?
- Dorsal laminectomy
- Hemilaminectomy
- Ventral slot
What are the 2 things spinal integrity depends upon?
–Intervertebral disc
–2 articular facet joints
How many facet joints can we remove without clinical consequences?
One
What is a dorsal laminectomy useful for?
Bilateral lesions
What is the width of laminectomy limited by?
Articular facet joints
Discuss dorsal laminectomy and how it may be done
- 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
Where is a hemilaminectomy done and where is it complicated?
- The most common surgical approach in the TL region
- Complicated in cervical region by vertebral artery
Discuss what a hemilaminectomy allows, requires and the risks.
- 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
What is the ventral slot?
•Surgical approach through the vertebral bodies centred on the intervertebral disc
Dicuss what a ventral slot allows, and the limitations.
- 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
What happens if the spinal cord is:
A) Unstable?
B) Compressed?
A) Requires stabilisation/conservative
B) Needs decompressing
What are the spinal cord compartments and how are these used to assess stability?
- 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
What is internal fixation?
–Orthopaedic proceedures such as plates (may not be feasible anatomically)
–Pins and methymethacrylate
What can we do as consrvative therapy?
- 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
What must we consider about the anaesthesia of spinal cord surgery?
•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
Do we use steroids or spinal/cranial trauma?
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
What are the 2 hardest parts of intracranial surgery?
- Anaesthesia
- Post op
What is status epilepticus?
- Ongoing for at least 5 minutes
- Or multiple uncontrolled seizures – comes out of seizure and goes back down into one before fully recovered
What are the 2 treatment goals of status epilepticus?
–Terminate seizure activity
–Identify and treat cause for seizures
What are the possible therapeutic treatments for status epilepticus?
- Diazepam
- Phenobarbital (barb)
- Propofol
- Midazolam (BZD)
- Pentobarbitone (Barbiturate)
What i the first line treatment for ongoing seizure activity? How is thi given?
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!)
What is the second line treatment for ongoing seizure activity? How is it given?
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
What is an issue with using phenobarbital as an anticonvulsant? What could we do?
•Relatively long time to effect so may need to supplement
–Could use diazepam to gain you time in the 20 mins
–Or use propofol
Discuss the use of propfol as an anitconvulsant.
How it acts?
Issues?
- 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
What do we use midazolam the same as?
Diazepam
Discuss pentobrabitone:
How effective?
Use?
Issues?
- Very effective
- Up to 8 hour effect
- However not been available for ~10 years as a sterile preparation
- Euthatal cannot be recommended
What is the protocol or status epilecticus?
Diazepam x3 ->
Phenobarbital –>
Propofol
What are the 3 things contributing to intracranial pressure?
- Blood
- CSF
- Tissue
What is the issue with an increased intracranial pressure?
Become ischamic
What is going on with this cerebellar herniation
- Transtentorial
- Foraminal
Dicuss the causes o these pupil changes and the prognosis
- Unilateral III nucleus or nerve damage
- Guarded
- Midbrain compression
- Guarded
- Bilateral III nucleus or nerve damage
Lost PLR
Measure of trauma severity
- Grave
How do we deal with cranial trauma?
- 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
What are the three areas of the Glasgow Coma Scale? What do we measure?
Motor activity
Brain stem reflex
Consciousness
On a sclae of 1-6 (6 is good)
What can we do to treat cerebellar herniation?
•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
What do we suspect?
–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.
