bone - anchored hearing aids ( bahas ) are an essential component of an ent surgeons ' armamentarium for treating patients with impaired hearing . their indications include patients with conductive , sensorineural , and mixed ipsilateral losses and for contralateral stimulation in single - sided deafness . in selected groups , the satisfaction ratings are very high ( 98% ) , with the number of nonusers low . the standard technique involves harvesting a split skin graft , centred on the point of optimal insertion 55  mm behind and 30  mm above the external auditory canal ( eac ) . soft tissue reduction is then performed prior to inserting a titanium fixture ( and abutment ) and replacing the skin graft . there are multiple reasons for the soft tissue reduction : ( a ) to reduce signal loss and decay from mechanical energy being absorbed by the surrounding myofascial tissues from the titanium implant ; ( b ) to achieve thin immobile around the abutment preventing the creation of granulation tissue at the skin baha junction as can happen with mobile skin ; ( c ) to create hairless skin to enable easy use and cleaning of the baha ; ( d ) to reduce skin height ensuring that the baha is easy to fit and the aid does not touch the skin reducing the energy imparted to the abutment . the tissue from the soft tissue reduction is routinely discarded . bahas can be used with great benefit in patients with conductive deafness , but it is in the rehabilitation of patients with active chronic ear disease where they out perform most other amplification devices as some patients develop otorrhoea when wearing a conventional hearing aid . this is due to a variety of factors , including reduced ventilation , increased humidity , and impairment of skin migration pathways . the otorrhoea is likely to be exacerbated in patients with mastoid cavities , not simply due to the above reasons , but also factors such as presence of a meatal stenosis , high facial ridge , deep sump , recurrent cholesteatoma , or exposed mucosa . in many such cases , surgery is the only option to provide a dry ear . the components of revision mastoid cavity surgery include the eradication of disease and granulation tissue , performing an appropriate meatoplasty , lowering the facial ridge , obliterating the cavity , and covering all exposed bone with fascia . obliteration of the cavity leads to a smaller , shallower , less - troublesome cavity . many techniques have been used for obliteration , including muscle flaps , bone dust , hydroxyapatite crystals , and cartilage . successful mastoid obliteration with temporalis muscle or abdominal fat has been documented in conjunction with cochlear implantation previously . the postauricular periosteal pericranial flap for mastoid obliteration has been shown to have up to a 90% success rate when looking at primary outcome measures such as the creation of a small dry low - maintenance cavity and secondary outcomes of haematoma , infection , flap necrosis , and meatal stenosis .   we present a method of combined baha and mastoid obliteration utilising the soft tissue from the baha soft tissue reduction to obliterate the cavity . this technique was used for good effect in six cases , for patients with a unilateral discharging mastoid cavity not amenable to medical treatment along with a conductive hearing loss . between may 2005 and may 2006 , six patients underwent combined baha and mastoid obliteration . they all had primarily conductive deafness , some with an additional element of sensorineural deafness . each patient had a persistently discharging mastoid cavity despite water avoidance and treatment with combined topical antibiotic and steroid drops and aural toilet for a minimum of 3 years prior to surgery . 2% lidocaine with 1  :  80,000 adrenaline local infiltration was administered at the site of the proposed incisions and in the ear canal . the postauricular incision , approximately 5  cms from the posterior aspect of the eac incision , is designed to facilitate both procedures ( figure 1 ) . two posterior limbs are created , between which the split skin graft is elevated . soft tissue reduction at the baha site is performed as a flap and left attached anteriorly as an anterosuperiorly based musculopericranial flap ( figure 2 ) . all dermal and epidermal elements have to be removed , and then the flap is trimmed to an appropriate width which will fit inside the mastoid cavity . the mastoid cavity is revised , preserving as much of its healthy keratinous squamous epithelium as possible , which is then used to reline the revised obliterated cavity . the musculopericranial flap is narrower at its tip , compared to its base , and these dimensions are 10  mm and 25  mm respectively . anchor sutures are applied from the base of the flap to sternomastoid in order to maintain its position inside the cavity until the ear has been closed and packed . homologous bone pate and tisseel are used to smooth over any gaps and irregularities , particularly spaces around the side of the flap and the obliterated cavity . the preserved mastoid keratinous epithelium is trimmed of any redundant or abnormal parts and placed over the flap , and a steroid- and antibiotic - soaked ribbon gauze pack is then inserted gently . ( baha implantation ) is performed first , and the  dirty procedure  ( revision mastoidectomy ) second . osseointegration was achieved in all cases , and none have reported further ear discharge twelve months postoperatively . all patients are using their baha daily and report a vast improvement and good sound localisation . a wide variety of methods have been described in the literature to obliterate mastoid cavities , and comparative analysis is difficult due to the lack in conformity of data collected . pedicled musculopericranial flaps have been successfully used to perform mastoid obliterations [ 4 , 6 ] . these have a dual benefit of eliminating dead space and promoting epithelialisation because of the vascular nature of the tissues . the multitude of axial and random flaps consisting of periosteum , temporoparietal fascia , temporalis fascia , and muscle would suggest that there is no ideal flap for mastoid obliteration . an anterosuperiorly based flap can be easily fashioned during surgery for a baha implant . despite numerous previous operations performing both operations simultaneously is convenient for the patient and allows the surgeon to utilise the soft tissue reduction in the obliteration . yoshida et al .   have reported good outcomes in patients with chronic otitis media with blind pit closure and baha . they have documented their technique in two separate stages as opposed to our single - stage approach . closure of the external auditory canal eliminates exposure to potential pathogens and allows the patient to resume water exposure . however , there is a risk of implantation cholesteatoma , and patients need to be followed up annually with ct of mri to exclude recurrence as direct microscopic evaluation is not possible . in theory , mastoid obliteration does carry a risk of the obliterating muscle flap covering residual cholesteatoma in the cavity . a good surgical technique will ensure that all squamous remnants are drilled out to reduce this possibility . clinical observation can still be performed under the microscope looking for swelling under the muscle flap . the alternative to mastoid obliteration is cavity revision , including removal of recurrent disease , lowering the facial ridge , and performing a meatoplasty to aid suction clearance . the patient would still require outpatient aural toilet on a regular basis and would have to adopt water precautions to prevent active infection of the cavity . we therefore conclude that the single - stage procedure of baha insertion with mastoid obliteration using the soft tissue reduction has clear advantages over the other techniques discussed and should be considered in future practice .
a single - stage fitting of a bone - anchored hearing aid ( baha ) implant and abutment with mastoid obliteration both obviates the need for two separate procedures and utilises the baha soft tissue reduction in the mastoid obliteration . 
 such a procedure has good outcomes in terms of osseointegration and achieving a dry ear . 
 we present a 6-patient case series report highlighting the technique of combined baha insertion and mastoid obliteration in six patients . 
 all patients at twelve - month followup have a good degree of sound localisation and hearing thresholds with their baha and are free from the social stigma associated with a foul smelling discharging ear .