Cochlear Implant surgery

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Category: Cochlear Implants and NHS
Last Updated on Wednesday, 18 September 2013 17:07
Written by Nadia Giarbini MD
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The CI surgery is performed under general anesthesia and takes about approximately 2-3 hours. The surgical procedure involves the traditional transmastoid  approach (TM ) with a posterior tympanotomy . There are several approaches for the  skin incision and Figs 1-2 demonstrate two of the most traditional ones.

    

 


The incision begins at the entrance floor of the external acoustic meatus , extending around the circumference back of the external auditory canal and passes above the ear. The incision is extended for seven to nine centimeters. The cochlear implant should be at least 3-4 cm behind the external auditory canal.


       Once the position of the implant is secured , the surgeon proceeds to the milling of a niche ( a) for the housing of the receiver - stimulator. Then performs a mastoidectomy and a posterior tympanotomy ( b ) that allows access to the tympanic cavity where the ossicular chain resides and which overlooks the basal turn of the cochlea (Fig. 3) .



  Then a cochleostomy, a small hole that allows it to penetrate directly into the cochlea,  is created  (Fig. 4-5 ) .

   


The surgeon proceeds with , the housing of the receiver - stimulator in the niche bone , to its mounting , and finally to the insertion of the electrodes in the cochlea,  through the opening of the cochleostomy . This operation must be done very gently so as not to cause damage to the electrodes (Fig. 6-7 ) .

  

 

 




As soon as the electrodes are  introduced, the surgeon  seals the cochleostomy and procees to finally fix the cable -carrying electrodes ( Fig. 8 ) .



The operation finishes  by covering the outer surface of the device with a muscle-cutaneous flap and with  suturing  the superficial layers .



REPORTED COMPLICATIONS

       The risks of the Cochlear Implant intervention are  common to all operations conducted under general anesthesia. However, serious complications are extremely rare , and to avoid those pre -operative tests are performed to assess the risk of hypersensitivity (allergic reactions). More common symptoms are nausea and vomiting typical of the post-operative period , which, however can be resolved quickly. Additional  risks are related to the surgical technique, which is  substantially similar to that of the middle ear surgery .

In particular:

  •     Soreness and numbness in the area around the ear , are due to small section of the sensory nerve endings in the area and resolve spontaneously .
  •     Swelling or bruising in the affected area are trivial complications which does not leave a trace.
  •     Taste alterations can sometimes occur temporarily .
  •     Balance disorders , occur rarely and usually disappear quickly.
  •     Irritation or damage of the facial nerve are rare occurrences , radiological examinations and intra -operative monitoring drastically reduces the chance of a permanent damage.