Micro ear surgery is done with a surgical microscope. Surgery for the human sensory organs like the ear requires precision to achieve desirable results.

The unaided eye is not adequate to visualize and work in the narrow confines of the ear where dimensions are measured in millimeters. Holmgren was the first among the many surgeons who pioneered the development of the microsurgery for the ear using surgical microscopes. He used magnification spectacle loupes with the surgical microscope to perform fenestration operations in the 1930’s for the disease of otosclerosis. The American Surgeon Shanbaugh in 1940 converted a dissection surgical microscope by adding a light source for illumination in the surgical microscope thus opening a new vista in reconstructive ear surgery.

Along with the surgical microscope, other developments in medicine and medical technology contributed to these developments. Tiny scissors and forceps, micro electric drills for drilling away bone for exposure and removal of ear disease were also developed in conjunction for use with the surgical microscope. Special video cameras integrated inside a surgical or operating microscope helped to teach and develop the micro surgical technique. A small introduction to the ear is needed before going any further the ear when using a surgical microscope.

Designed to convey the sense of sound and balance, the ear is divided into the outer, middle and inner parts. These parts can be viewed using a surgical microscope. The ear drum and the bone bridge formed by 3 ossicle bones along with other small muscles and bony walls make the middle ear. This space varies in its depth from 2mm to 6mm. The middle ear serves the function of impedence matching to transfer air borne sound to the inner ear neural elements which are surrounded by fluid. The middle ear is also linked to the nose through the eustachian tube which serves to equalize the air pressure in the middle ear to the varying atmospheric pressure. The inner ear contains neural cochlea for perceiving sound and the labrinthine system for detecting the position of our head in relation to space and for forces of acceleration and deceleration. The nerve for controlling the muscles in our face and part of the taste sensation from the tongue also courses through the middle and inner ears.

For a successful outcome of treatment in this demanding area, accurate diagnostic techniques using surgical microscope, are a must. Audiometry is the time tested tool used to estimate the hearing. Tympanometry gives a clue about what is happening behind an intact ear drum. It is especially useful in children who after getting a head cold suffer from minor degree of hearing loss. This problem encountered in many of the pediatric age group at one time or other is caused by accumulation of thick mucus called glue inside the ear. Insertion of a small ventilating tube through the drum by microsurgery using surgical microscopes is currently used when the condition does not resolve with medical treatment.

Tympanoscopy uses small endoscopes or a surgical microscope, which can look sideways, helps to estimate the damage to the ossicular chain inside an ear drum perforation. Brain stem Evoked Response Audiometry (BERA) provides accurate diagnosis of hearing loss even in new borns. Septic conditions of the middle ear are basically divided into safe and unsafe based on the clinical findings. The safe ear accompanied by discharge, and deafness does not result in life threatening infections for the majority of patients. Left untreated over a long time it can result in permanent nerve deafness when medical help is of no avail.

The dangerous type of sepsis arises in the ear due to misplaced skin inside bone, a condition called cholesteatoma. Due to pressure and enzymatic dissolution the surrounding bone of the middle ear is destroyed in a slowly progressive manner and the infection spreads to the brain and other intracranial structures. Prior to the developments mentioned above 50% of the brain abscess were caused by unsafe ear diseases and many of the victims were permanently disabled and lives were lost. Currently several techniques with the use of surgical micoscopes are available to the ENT specialist to recognize and treat these conditions. Apart from removing the disease, hearing in most cases can be simultaneously restored using patients own or banked ossicle bone, cartilage or ceramic prosthesis. The middle ear is an area in the body where many foreign objects are tolerated without antigenic reaction and rejection and this fact has helped us to use several man made prosthesis. It is note worthy to mention that even the patient’s own tooth have been used after refashioning it to aid in sound conduction inside the ear.

Sialastic is used to create a new middle ear space in a grossly diseased patient before the sound reconstruction is done at a second operation using surgical microscopes. To recreate the torn or missing ear drum, a thin membrane called temporalis facia is used. This is the covering of the temporal muscle lying above and in front of the ear. Preserved dura mater (covering of the brain) also is being used for this purpose. For using this tissue it is to be dried which takes some time. To cut short this time some of us use hair driers on this facia. Such adaptation of every day tools in medicine like surgical microscopes is dictated by the need. Non cancerous growths occuring in the cerebello pontine angle of the brian, and internal auditory canal is effectively dealt with by a trans-otic micro surgical approach under surgical microscopes. When trouble starts in this area, unsteadiness, ringing noises with deafness of one ear are the initial symptoms. Audiometry is an inexpensive non invasive test and is accurate in determining the cause of these symptoms. When a growth is suspected CT Scan or MRI confirms the disease and up to 3cm size growths can thus be effectively dealt with by neuro-otological techniques. Patients who have lost the functioning of the innear ear nerves suffer from sensory hearing loss and the treatment recommended for them is the hearing aid. When a conventional hearing aid is found to be not adequate to perceive sound an indwelling aid termed cochlear implant can be used under surgical microscope. In India, the government has been making and supplying surgical microscopes which have greatly helped the diffusion of this technique throughout the country. Though the surgical microscope cannot boast of the full range, most of the basic equipment for carrying out these surgeries uses surgical microscopes. Such a precise technique using a surgical microscope is also not without pitfalls. Even the most skilled surgeons cannot produce a successful result in chronic middle ear sepsis with the use of surgical microscope. The factor responsible for this is the tiny eustachian tube which makes the ear pop when going up or down a hill. Techniques for assessing and treating the eustachian tubal problems are still being evolved. Looking back at the progress that has been made in the past 50 years since the surgical microscope was invented. The tubal problem will be overcome soon with the aid of the surgical microscopes.