Mastoid bone

On our team, the ear surgeon performs the initial portions of the surgery isolating the facial nerve within the mastoid. The nerve is decompressed and taken out of its canal so that it can be preserved during the removal of the tumor. The bone around the capsule of the nerve is thinned using high speed air drills with constant water irrigation. Once the nerve is freed, the head and neck surgeon must identify the vessels in the neck leading to the tumor. The cranial nerves are also identified and tagged. The tumor is then removed. The ear surgeon and head and neck surgeon assist each other. In most cases, it is necessary to tie off or pack the jugular vein in the neck and the mastoid portion of the ear to prevent excessive bleeding at tumor removal.


Teaching mastoid surgery with binocular operating microscope and KTP LASER Before antibiotics, mastoid surgery was commonly done in desperate circumstances for acute infection, a mastoid abscess. Our predecessors had nothing better than a hammer and gouge, and no magnification other than some spectacle loupes. It was counted a success if the patient – usually a young child – survived. No delicate work could be done, and most survivors were deafened. It was only after the introduction of the binocular operating microscope in the 1950’s that modern delicate controlled microsurgery of the ear became possible. Even with all the latest high powered microscopes, lasers and modern anaesthetics, mastoid surgery is very difficult. Surgeons have to train for years to get good at it. Like all ear surgeons trained since the 1960’s I did my basic training (in the 1980’s) on temporal bones from cadavers (dead bodies). Although some might find that macabre, I’d prefer the learning curve to be on my dead granny, rather than on my live child. The margin of error in mastoid surgery is measured in fractions of a millimetre. Anatomy varies considerably, and a surgeon needs to practice on lots of bones before embarking on live patients. Simulators and plastic bones just aren’t up to it. Unfortunately, in the UK, a public attitude has become established against the use of post-mortem tissues, which has led to a severe shortage of temporal bones for the next generation of ear surgeons to train on. I teach trainee surgeons ear surgery on live patients every week, sometimes two or three cases. The operations take anywhere between one to six hours. The average is around three hours.

Risks of the surgery are the same as if the cholesteatoma is not removed, but occur less frequently.  Hearing loss and dizziness may occur along with injury to the lining or dura of the brain.  The VII Nerve runs through the center of the middle ear and mastoid cavity and can be injured during surgery.  This may cause a facial paralysis.  However, from the picture on the right, one can see how this nerve can be easily damaged by the cholesteatoma .  Thus, once diagnosed, most cholesteatoma should be surgically removed.  Kos et al. reported on the results for canal wall down mastoidectomies .  He found the average pre-operative hearing loss was 52 dB.  Post-operatively the hearing was unchanged in 41%, improved in 31% and worse in 28%.  Other complications were persistent vertigo and one case of facial paralysis.  View Abstract

A long standing cholesteatoma can erode through the dura and into the brain or into the inner ear.  The horizontal semicircular canal is the inner ear structure most prone to damage.  Below is a link to a CT Scan of a cholesteatoma which produced a fistula of the horizontal semicircular canal.  The patient had a chronic history of hearing loss and ear drainage.  He recently, experienced a severe episode of vertigo from labyrinthitis .  

The ethmoid bone is located in front of the sphenoid bone. It consists of two masses, one on each side of the nasal cavity, which is joined horizontally by thin cribriform plates. These plates form part of the roof of the nasal cavity, and nerves (ethmoidal cells) associated with the sense of smell pass through tiny openings in them. Portions of the ethmoid bone also form sections of the cranial floor, eye sockets, and nasal cavity walls. A perpendicular plate projects downward in the middle from the cribriform plates to form the bulk of the nasal septum. Delicate scroll-shaped plates called superior and middle nasal conchae project inward from the sides of the ethmoid bone toward the perpendicular plate. These bones, which are called the turbinate bones, support mucous membranes that line the nasal cavity.

Mastoid bone

mastoid bone

The ethmoid bone is located in front of the sphenoid bone. It consists of two masses, one on each side of the nasal cavity, which is joined horizontally by thin cribriform plates. These plates form part of the roof of the nasal cavity, and nerves (ethmoidal cells) associated with the sense of smell pass through tiny openings in them. Portions of the ethmoid bone also form sections of the cranial floor, eye sockets, and nasal cavity walls. A perpendicular plate projects downward in the middle from the cribriform plates to form the bulk of the nasal septum. Delicate scroll-shaped plates called superior and middle nasal conchae project inward from the sides of the ethmoid bone toward the perpendicular plate. These bones, which are called the turbinate bones, support mucous membranes that line the nasal cavity.

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