Superior Semicircular Canal Dehiscence

Submitted by ZaniniOtavio on Fri, 12/01/2017 - 00:50

Dear Colleagues,

I would like to discuss the case of a male patient, 45 years old,  with history of intermitent tinnitus in the right side for the last two years. The patient complains of tinnitus worsening during physiscal activities (reported as pulsatile in such situations), associated with oscillopsia, even in fast walk. Also complains of short episodes of vertigo in physical efforts and when he gets up.

He does not remind any head trauma occurred recently. He has no complain about his hearing abilities, but in audiometry there is a right side mild sensorineural hearing loss just at 6 and 8khz. No airbone gap. A VEMPc was requested, but we still don't have the results.

We investigated with a CT scan (attached) that shows a Superior Semicircular Canal Dehiscence at a different location, posteriorly, next to the common crus.

I would like to ask the colleagues the following questions:

- Do you have experiences with patients like this one?

- Would you operate this patient? What is the risk for the hearing/vestibular funcion?

- Which is the best access for treating this uncommon location of dehiscence? Transmastoid? Are there difficulties expected?

- Which technique should be used? Canal plugging? Canal ressurfacing (at the posterior fossa??)?? With which material/grafts?

Best regards,

Otavio Zanini

Curitiba-Brazil

 

Pingling Kwok

Thu, 12/07/2017 - 19:38

Dear Otavio,

thank you for sharing your interesting case with us. The location of the dehiscence is indeed a bit unusual and difficult to reach over a trans temporal approach.

As the mastoid is so well pneumatized, the better approach might be trans mastoid, then open the bony superior canal from opposite side of dehiscence, trying to keep endolymph-space intact and put plugging material into both ends.

We recommend plugging, as resurfacing leads to recurrence more often than plugging.

Do not use bone wax, as you cannot control up to where it is pushed and bone wax produces adverse tissue reactions. Use bone pate, bone chips or teflon pistons from stapes prostheses. We have used teflon (0.6mm diameter) plus goretex sutures to secure teflon pistons in place (one piston in each end of dehiscence) , in one case so far with no inner ear hearing loss, the vertigo stopped completely and teflon cannot not get eroded away. As we took the middle fossa approach we then covered the plugged dehiscence with bone pate and fibrin glue and fascia plus placed 2 layers of cartilage on top of that. In our case even the endolymph-tube was open and we put the teflon right into the endolymph-space. 

Best Regards,

Pingling

 

 

Very interesting perspective, Dr. Pingling.

Thank you very much. I agree with you in many points.

I wonder if it will be possible to make a good plugging of both ends of the dehiscence, because it seems to be very close to the common crus. Maybe with the Transmastoid approach the posterior canal can be a little bit in front of the working space. But I don't see a better way to deal with this situation.

Best regards,

Otavio Zanini