Neurosurgery Flashcards
When is spinal decompression surgery indicated?
- Tumour
- IVDD
What are the indications for spinal fusion surgery?
- Instability of the spine: atlanto-axial subluxation, Wobbler (dynamic instability), IVDD
- Fracture
- Conditions where ongoing instability may cause ongoing trauma of the spinal cord
Name the surgical options for spinal decompression
- Dorsal laminectomy
- Hemilaminectomy
- Ventral slot
What is a dorsal laminectomy?
Removal of the roof of vertebra
What is a hemilaminectomy?
Removal of the side of vertebra
What is a ventral slot?
Drill up through bone to access ventral part of spinal cord
Explain the basic principles of spinal decompressive surgery regarding maintenance of spinal integrity
- Depends on intervertebral disc and 2 articular facet joints (sit above spinal cord except on C1 and C2)
- Biomechanically can remove one facet joint without expected clinical consequences
- If damage 2, then may encounter problems of stability as only the disc is holding spine together
what are teh treatment options for spinal fractures?
- Fixation if stability is compromised
- Decompression if compression is the cause of pathology (e.g. bone fragment of dislocation compressing spinal cord)
- Conservative therapy if stable
Explain how spinal stability can be assessed based on vertebral compartments
- Vertebra can be divided into 3 compartments
- Dorsal, middle and ventral
- Instability determined as more than one compartment being compromised
What is included in the dorsal compartment of vertebrae?
Lamina and dorsal ligaments
What is included in the middle compartment of the vertebrae?
- Dorsal longitudinal ligament
- Dorsal annulus
- Dorsal portion of vertebral body
What is included in the ventral compartment of the vertebrae?
- Ventral longitudinal ligament
- Ventral annulus
- Ventral portion of the vertebral body
Describe the conservative therapy for spinal fracture
- Strict cage rest 5-6 weeks, minimise mobilisation of spine
- Other management as appropriate: analgesia, bladder management, prevention of bed sores, motivational therapy, physiotherapy as appropriate
Describe the main concern regarding hemilaminectomies in the cervical spine
- Rarely performed in this area
- Vertebral artery runs in canal through vertebrae C1-6
- ## Drilling through this would be fatal
Describe the advantages of a hemilaminectomy
- Allows lateral approach to the spinal cord
- Allows exposure ventral to the spinal cord
Describe the disadvantages of a hemilaminectomy
- Requires lateralisation i.e. need to know what side lesion is on, if midline then can perform on either side, but not both
- Risk of damage to nerve roots/spinal nerves via intervertebral foramina opening
- Risk of damage to ventral venous plexus
Describe the advantages of a dorsal laminectomy
- Useful for bilateral lesions
- Can be performed anywhere along spine except C1-2
- Relatively easy soft tissue approach
- Avoids ventral venous plexus
Describe the disadvantages of a dorsal laminectomy
- Width of laminectomy limited by the articular facet joints (varies along spine)
- Limited exposure lateral and ventral to the spinal cord
- Deep hole in the thoracic region
- Only good for lesion on top of, or down both sides of the spinal cord
Describe the anatomical basis for a ventral approach to the cervical spinal column
- Through vertebral bodies, centred on the intervertebral disc
- Need to avoid previous surgical sites for recurring IVDD
- Easy access if in neck region
- Drill up through vertebral body to get access to vertebral canal
Describe the advantages of a ventral slot surgery
- Allows access to the ventral aspect of the spinal cana
- Easy approach (if know anatomy) down to the bones
Describe the disadvantages of the ventral slot surgery
- Limited access, visibility
- Only feasible in cervical region
- Significant risk of haemorrhage (may drill through ventral venous plexus)
- Post operative morbidity
Discuss the use of ventral slot surgery in a Doberman
- Common require this surgery
- can be significant risk as high risk of drilling through ventral venous plexus
- BUT Doberman also prone to Von Willebrand’s disease
What are the internal spinal fixation options?
- Orthopaedic procedures e.g. plates
- Pins and methylmethacrylate
What are the external spinal fixation options?
Spinal casting only
