Neurosurgery
Transbasal Approaches to the Skull Base and Extensions
Built from Feldman — Neurosurgical Operative Atlas: Neuro-Oncology
What’s inside
12 sections · 55 slides
Overview
- First, what is a transbasal approach?
- The price of admission: loss of smell
- The transbasal approach at a glance
What it reaches, and where it stops
The bony territory the approach can and cannot expose
- The corridor and its boundaries
- Why it pairs so well with the endoscope
Choosing the right patient
Who benefits, and the rule that biopsy always comes first
- The typical candidate
- Biopsy first: exclude the tumors that should not be cut
Preparing for surgery
Protecting against the specific risks of opening a clean skull into a contaminated nose
- Infection control: opening into a dirty space
- Managing spinal fluid and the airway
- Consent, clots, and the cornea
Matching the approach to the tumor
How the graded variations are chosen from tumor extent
- A ladder of exposure
- When to extend the exposure
- Lateral orbital wall osteotomy and eyeball retraction
- Reaching the sphenoid sinus and clivus
Saving the sense of smell
The cribriform plate osteotomy: lifting the smell plate out in one piece
- The idea behind sparing olfaction
- Making the cuts and preserving the mucosal cuff
- Freeing the cribriform plate with its mucosal cuff
- Repair and closing the plate back down
The standard transbasal approach
The base operation on which every extension is built
- Positioning and the head holder
- The scalp flap and the precious pericranium
- Bifrontal craniotomy and taming the frontal sinus
- Exposing the fossa and reconstructing
- Bifrontal exposure and division of the olfactory fila
The extended transbasal approach
Adding a supraorbital-bar osteotomy to drop the angle and spare the brain
- What the extension adds
- Cutting the supraorbital bar
- Osteotomy cuts of the extended transbasal approach
- Putting the brow back together
The subcranial transbasal approach
Taking the nasal bone as well, to open the nasal cavity and reach the clivus
- What the subcranial version adds
- Detaching the nasal complex and medial canthus
- Subcranial osteotomy and medial canthopexy wiring
- Reattaching and the medial canthopexy
The radical transbasal approach
The most extensive version, adding the lateral orbital wall
- The widest exposure of all
- Osteotomy cuts of the radical transbasal approach
- The four transbasal variations compared
Partnering with the endoscope
Why open and endonasal approaches are used together
- Two complementary corridors
- Transbasal versus endonasal exposure on coronal MRI
- When the open route is still needed
After the operation
Watching for the specific hazards of a skull opened into the sinuses
- Early recovery and monitoring
- Pneumocephalus and CSF drainage pitfalls
- Why does the standard transbasal approach cost the patient their sense of smell, and how can it be avoided?
- Take-home messages
- Sources cited in this chapter
- Neurosurgical Operative Atlas: Neuro-Oncology