CHRONIC MASTOIDITIS 339 cavity liable to infection and requiring supervision. Additionally good functional results are difficult to achieve later by tympanoplasty. (6) Closed techniques—combined approach mastoidectomy avoids the formation of a cavity and provides better conditions for functional restoration but exposure of all disease is technically difficult and may on occasion be impossible. The recurrence rate of cholesteatoma is higher and less easily detected. RADICAL MASTOIDECTOMY The object of this operation is to remove chronic infection, especially chole- steatoma, from the mastoid cavity and middle ear, and, by creating a window in the posterior meatal wall, to allow of toilet of the cavity until healing takes place. The steps of the operation are shown in Fig. 174, and the incisions in the posterior meatal wall to create a flap of soft tissue to turn outwards and effect a window are illustrated in Fig. 175. Once the mastoid cavity has been entered all cholesteatoma is meticulously removed because any that is overlooked will result in regrowth and a recur- rence of symptoms. This entails dissection forwards through the mastoid antrum into the attic. Removal of the outer attic wall and the lateral wall (bridge) of the aditus exposes the attic and ossicles'. Cholesteatoma and granulations are removed from this area, and necrosis of the ossicles may necessitate the removal of the incus and the amputation of the head of the malleus. When the ossicles and tympanic membrane can safely be retained the operation is one of modified radical mastoid, but when the malleus, incus and drumhead are sacrificed the operation is called a radical mastoidectomy. The plastic flap to create a window in the posterior meatal wall is fashioned in both these operations. The cavity is packed via the external meatus, and the incision is completely closed. The sutures and pack are removed 1 week later, and thereafter the cavity is dressed regularly until squamous epithelium grows into it from the meatal skin, and healing is complete. This takes an average of 2 months although the patient may be discharged from hospital in 2 or 3 weeks, and will attend as an outpatient. Healing occurs more quickly in an adult with an acellular cavity than in a child with a cellular mastoid cavity. The aim of the operation is to make the ear safe in that cholesteatoma is not shut off from inspection via the meatus. Should it recur it may be removed at a suction clearance using an operating microscope, usually under anaes- thesia although it may be done in the outpatient department in a suitable patient. The resulting hearing level depends upon whether the ossicles have been removed or not. Removal of the incus will cause a loss of at least 50 dB. ny patients are left with a moist ear, which disappoints them as it requires cleaning. Some of this catarrh is of Eustachian origin, but some is • a low-grade infection in the cavity, and it may continue throughout atal Operation. Many surgeons favour an incision through the I meatus rather than a postaural one. The operation is then conducted L the same manner. This approach is particularly useful in those patients ho have a limited cholesteatoma in an acellular mastoid, but is less satis- factory in an extensive infection.