**3.7 Fixation of the implant and then testing the device function**

Fixation of the implant entails both fixation of the RS, the main body of the implant, and fixation of the electrode array. Fixation of the RS was mentioned before, but whatever is the technique used, the periosteum should be tightened and sewed over the implant during this step [7].

Fixation of the electrode array should be in both its proximal and distal ends; the proximal end is fixed simply by either drilling a deep groove or trough starting from the RS bony well at the site of exit of the electrode to the mastoid cavity [52]. This trough could be drilled deeper. As it reaches the mastoid cavity at the sino-dural angle, the bone at this area is thick, so the trough can be modified in this area into incomplete tunnel with a bony ledge. The electrode could be secured in this tunnel even after electrode insertion (**Figure 6**).

The distal end of electrode array is fixed routinely by both inserting fascial plug around the electrode at the cochleostomy site and also by placing a loop of electrode

#### **Figure 6.**

*The electrode is secured at the sino-dural angle before entering the mastoidectomy cavity, by an incomplete tunnel with a bony ledge.*

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delirium [63].

*Advances in Surgical and Anesthetic Techniques for Cochlear Implantation*

cable against the tegmen mastoideum. Other surgical techniques that can be used,

*A groove in the lower end of the posterior tympanotomy for accommodation and stabilization of the electrode* 

1.Using a titanium clip to attach the electrode array to the incus bar [53].

2.The "split-bridge" technique [54], in which a channel is made through the

3.Making a small inferiorly based bone grove in the posterior tympanotomy into which the electrode array can be squeezed for fixation [55]. The groove is made with 1 mm diamond burr between the facial nerve and the chorda tympani

The use of the Internet for monitoring of CI devices from remote locations is a recent advance in CI programming. In a study by Shapiro et al. [56] remote intraoperative CI device monitoring was compared to in situ monitoring. The results showed that there is a significant reduction of the audiologist's time with remote testing than in situ testing. This represents a significant reduction in time required for testing and consequently the cost. This can be achieved by only Internet connec-

Toner et al. [58] reported a case series of cochlear implantation under local anesthesia; however, using local anesthesia in CI was not widely used till the last 10 years [59–63], especially after the introduction and widespread usage of dexmedetomidine as a sedative drug for cases of CS-LA. Dexmedetomidine can make "cooperative sedation," in which the patient remains arousable and cooperative without causing delirium and unnecessary movements associated with

in addition, for electrode fixation at its distal end are:

incus bar and the lead wedged in it.

nerve (**Figure 7**).

**Figure 7.**

*after insertion.*

tion and a telephone [57].

**3.8 Intraoperative device monitoring**

**4. Advances of the anesthetic techniques**

**4.1 CI under conscious sedation with local anesthesia (CS-LA)**

*DOI: http://dx.doi.org/10.5772/intechopen.88380*

*Advances in Surgical and Anesthetic Techniques for Cochlear Implantation DOI: http://dx.doi.org/10.5772/intechopen.88380*

#### **Figure 7.**

*Advances in Rehabilitation of Hearing Loss*

chlear trauma [45].

is no "best" CI electrode for all CI cases.

sewed over the implant during this step [7].

even after electrode insertion (**Figure 6**).

[47] reported that the better predictor of the outcome for the depth of electrode insertion is the angular depth rather than the intracochlear length of the electrode or even the number of active electrodes that is used in speech processing. It is expected that LW electrodes, especially the long types as FlexSoft™ (MED-EL Corp), can demonstrate greater angular insertion depth, more than 360°, while the PM or MS electrodes are usually designed to encircle the first basal turn making angular insertion depth nearly equal to 360° [48]. Insertion depth at 360°, or less than one cochlear turn, is usually associated with poor speech outcome; however, above 360°, there is no association between the depth of insertion and the speech outcome [49, 50]. Deep insertion is assumed to have the advantage of extending the electrical stimulation into the apical region that is responsible for low-frequency sounds; this provides better place pitch match which may improve the outcomes of CI especially in the music perception [51]. However, deep insertion is usually associated with increasing the risk of intraco-

In conclusion, the best design for "ideal" CI electrode is a matter of debate; there

Fixation of the implant entails both fixation of the RS, the main body of the implant, and fixation of the electrode array. Fixation of the RS was mentioned before, but whatever is the technique used, the periosteum should be tightened and

Fixation of the electrode array should be in both its proximal and distal ends; the proximal end is fixed simply by either drilling a deep groove or trough starting from the RS bony well at the site of exit of the electrode to the mastoid cavity [52]. This trough could be drilled deeper. As it reaches the mastoid cavity at the sino-dural angle, the bone at this area is thick, so the trough can be modified in this area into incomplete tunnel with a bony ledge. The electrode could be secured in this tunnel

The distal end of electrode array is fixed routinely by both inserting fascial plug around the electrode at the cochleostomy site and also by placing a loop of electrode

*The electrode is secured at the sino-dural angle before entering the mastoidectomy cavity, by an incomplete* 

**3.7 Fixation of the implant and then testing the device function**

**130**

**Figure 6.**

*tunnel with a bony ledge.*

*A groove in the lower end of the posterior tympanotomy for accommodation and stabilization of the electrode after insertion.*

cable against the tegmen mastoideum. Other surgical techniques that can be used, in addition, for electrode fixation at its distal end are:


#### **3.8 Intraoperative device monitoring**

The use of the Internet for monitoring of CI devices from remote locations is a recent advance in CI programming. In a study by Shapiro et al. [56] remote intraoperative CI device monitoring was compared to in situ monitoring. The results showed that there is a significant reduction of the audiologist's time with remote testing than in situ testing. This represents a significant reduction in time required for testing and consequently the cost. This can be achieved by only Internet connection and a telephone [57].

#### **4. Advances of the anesthetic techniques**

#### **4.1 CI under conscious sedation with local anesthesia (CS-LA)**

Toner et al. [58] reported a case series of cochlear implantation under local anesthesia; however, using local anesthesia in CI was not widely used till the last 10 years [59–63], especially after the introduction and widespread usage of dexmedetomidine as a sedative drug for cases of CS-LA. Dexmedetomidine can make "cooperative sedation," in which the patient remains arousable and cooperative without causing delirium and unnecessary movements associated with delirium [63].

CI under CS-LA achieved comparable results with general anesthesia (GA) regarding perioperative comorbidities and achieved better results than GA regarding patient satisfaction in elderly patient [63].

### **4.2 Indications and advantages of CS-LA in CI**

CS-LA is not only indicated in patients who are unfit for GA, but also it is generally preferred than GA in elderly patients. CI under CS-LA has the following advantages in elderly patients [63]:


#### **4.3 Technique**

According to Shabashev et al. [63], the patient receives dexmedetomidine as the main sedative drug, in addition to fentanyl, midazolam, lidocaine, and propofol, depending on the necessary level of sedation and analgesia. In addition, 8–10 mL of 2% lidocaine with 1:100,000 epinephrine was used as a local infiltration anesthesia. In some instances, when patients experienced additional pain upon exposing the middle ear mucosa, gelfoam pledges soaked in the same local anesthetic solution were applied directly to the middle ear mucosa for 2 minutes before continuing the manipulation. Supplemental oxygen less than 29% was administered via nasal cannula or face mask. Surgical drape was applied around the operative site, but the face was left completely uncovered to facilitate direct communication with the patient during the procedure [63].

#### **5. Hearing preservation during cochlear implantation**

#### **5.1 Surgical technique**

All the previously described refinements and advances in both surgical techniques and electrode design aim at increasing the performance of the electrode within the cochlea and decreasing the traumatic effect of the electrode on the residual neuro-sensitive structures in the cochlea; this can preserve the residual function of these structures aiming at hearing preservation. Through these surgical refinements, nontraumatic "soft" CI surgery can achieve the target of hearing preservation.

In addition to the previously described technical refinements, there are many surgical considerations that should be respected during performing nontraumatic "soft" CI surgery. The most important surgical considerations are:

**133**

*Advances in Surgical and Anesthetic Techniques for Cochlear Implantation*

1.Minimal bone drilling during cochleostomy and avoidance of entrance of bone

2.Careful dealing with the endosteum during cochleostomy by incising it sharply

3.Scala tympani electrode insertion and avoidance of injury of the osseous spiral

4.Preservation of the perilymph in scala tympani by avoiding suction of the

6.In case of using long electrode, avoid excess pressure on electrode during

8. Sealing of the cochleostomy with soft tissue seal to avoid perilymph leakage [36].

Corticosteroid can be administrated during CI surgery aiming at hearing preservation [65]. Perioperative corticosteroids can be used either systemic, intratympanic, or intracochlear. Systemic steroid can be used either intravenously during the surgery or orally after the surgery [64]. Postoperative oral corticosteroid improved hearing preservation rates according to the systematic review conducted by Santa et al. [36]. Intratympanic steroid has been described through either applying a gelfoam soaked with methylprednisolone 125 mg/ml over RW membrane for 30 minutes before cochleostomy [66] or by filling the middle ear by dexamethasone 4 mg/ml

Intracochlear corticosteroid has been described through either using intracochlear injection of triamcinolone acetonide solution in addition to hyaluronic acid [68] or through silicone-based dexamethasone-eluted cochlear implant [69].

Experimental animal study on corticosteroid-eluted cochlear implant devices showed significant hearing preservation rates and histopathologic evidence of lower inflammatory response to the electrode [70–72]. However, until nowadays, many authors still discourage the use of intracochlear or intratympanic corticoste-

In addition to corticosteroid, other drugs can be administrated through drug-eluted CI device. There are many ongoing experimental trials on intracochlear application of

CI surgery was introduced first as the only solution for hearing loss in profound deaf subjects. The US Food and Drug Administration first approved CI for adults with postlingual profound bilateral sensorineural hearing loss in 1985 and children in 1990. Nowadays, with the refinement of the surgical techniques and the advances of electrode design, CI candidacy guidelines have been expanded to include adults

neurotrophins and antiapoptotic drugs through drug-eluted CI device [72].

**5.3 Effect of hearing preservation surgery on CI outcomes**

and children with residual hearing in the implanted ear [73].

*DOI: http://dx.doi.org/10.5772/intechopen.88380*

dusts into cochlear lumen [35].

lamina and basilar membrane [65].

perilymph during cochleostomy [16].

7.Electrode fixation and stabilization [7].

before electrode insertion [67].

roids during CI surgery [16].

5.Smooth and slow electrode insertion [36].

insertion that may cause intracochlear trauma [45].

**5.2 Pharmacotherapy for hearing preservation during CI**

using a sharp needle [64].

*Advances in Rehabilitation of Hearing Loss*

advantages in elderly patients [63]:

time.

CS-LA.

after surgery.

during the procedure [63].

**5.1 Surgical technique**

hearing preservation.

**4.3 Technique**

ing patient satisfaction in elderly patient [63].

**4.2 Indications and advantages of CS-LA in CI**

3.Patient satisfaction was superior with CS-LA.

**5. Hearing preservation during cochlear implantation**

"soft" CI surgery. The most important surgical considerations are:

CI under CS-LA achieved comparable results with general anesthesia (GA) regarding perioperative comorbidities and achieved better results than GA regard-

CS-LA is not only indicated in patients who are unfit for GA, but also it is generally preferred than GA in elderly patients. CI under CS-LA has the following

2.Length of stay was significantly shorter in patients undergoing CI under

1.CS-LA was associated with decreased drug costs, surgery time, and anesthesia

4.Perioperative morbidity was higher, but not significant, with GA than CS-LA.

5.GA in elderly patient carries the risk of unexpected cognitive consequences

According to Shabashev et al. [63], the patient receives dexmedetomidine as the main sedative drug, in addition to fentanyl, midazolam, lidocaine, and propofol, depending on the necessary level of sedation and analgesia. In addition, 8–10 mL of 2% lidocaine with 1:100,000 epinephrine was used as a local infiltration anesthesia. In some instances, when patients experienced additional pain upon exposing the middle ear mucosa, gelfoam pledges soaked in the same local anesthetic solution were applied directly to the middle ear mucosa for 2 minutes before continuing the manipulation. Supplemental oxygen less than 29% was administered via nasal cannula or face mask. Surgical drape was applied around the operative site, but the face was left completely uncovered to facilitate direct communication with the patient

All the previously described refinements and advances in both surgical techniques and electrode design aim at increasing the performance of the electrode within the cochlea and decreasing the traumatic effect of the electrode on the residual neuro-sensitive structures in the cochlea; this can preserve the residual function of these structures aiming at hearing preservation. Through these surgical refinements, nontraumatic "soft" CI surgery can achieve the target of

In addition to the previously described technical refinements, there are many surgical considerations that should be respected during performing nontraumatic

**132**


#### **5.2 Pharmacotherapy for hearing preservation during CI**

Corticosteroid can be administrated during CI surgery aiming at hearing preservation [65]. Perioperative corticosteroids can be used either systemic, intratympanic, or intracochlear. Systemic steroid can be used either intravenously during the surgery or orally after the surgery [64]. Postoperative oral corticosteroid improved hearing preservation rates according to the systematic review conducted by Santa et al. [36].

Intratympanic steroid has been described through either applying a gelfoam soaked with methylprednisolone 125 mg/ml over RW membrane for 30 minutes before cochleostomy [66] or by filling the middle ear by dexamethasone 4 mg/ml before electrode insertion [67].

Intracochlear corticosteroid has been described through either using intracochlear injection of triamcinolone acetonide solution in addition to hyaluronic acid [68] or through silicone-based dexamethasone-eluted cochlear implant [69].

Experimental animal study on corticosteroid-eluted cochlear implant devices showed significant hearing preservation rates and histopathologic evidence of lower inflammatory response to the electrode [70–72]. However, until nowadays, many authors still discourage the use of intracochlear or intratympanic corticosteroids during CI surgery [16].

In addition to corticosteroid, other drugs can be administrated through drug-eluted CI device. There are many ongoing experimental trials on intracochlear application of neurotrophins and antiapoptotic drugs through drug-eluted CI device [72].

#### **5.3 Effect of hearing preservation surgery on CI outcomes**

CI surgery was introduced first as the only solution for hearing loss in profound deaf subjects. The US Food and Drug Administration first approved CI for adults with postlingual profound bilateral sensorineural hearing loss in 1985 and children in 1990. Nowadays, with the refinement of the surgical techniques and the advances of electrode design, CI candidacy guidelines have been expanded to include adults and children with residual hearing in the implanted ear [73].

This expansion in CI candidacy criteria was based on the strong evidence of two hypotheses: the first is the ability of CI surgery to preserve the residual hearing, and the second is the beneficial effect and the better speech outcomes of CI surgery in ears with residual hearing.

Systematic review studies were conducted on the effect of CI surgical techniques on hearing preservations [36, 65, 74]; all of these studies gathered that nontraumatic "soft" CI surgery can preserve hearing. Gantz et al. conducted a multicenter study on the outcome of CI surgery on 87 ears with residual hearing. At initial activation, 90% of the subjects maintained a functional low-frequency pure-tone average; this percentage was reduced to 80% after 12 months [75].

Regarding the benefit of CI in ears with residual hearing, a systematic review study was conducted on the outcome of CI in children with residual hearing; this study demonstrated that the better the preoperative residual hearing, the better the postoperative speech perception outcomes [76].
