Round window /Cochleostomy

Device Positioningdevice away from

processor

receiver/stimulator oriented differently in infants

Displacement Force CalculationA

P

L R

mg

the bed the device tied in

Tie-down – Devices with and without a Pedestal

Visualizing the Round Windowkey

to cochleostomy placement is finding landmarks every time

most important landmark is the round window

Visualizing the Round Windowhand position differs

on the left side

care with stapes tendon

Round Windowalways presentoverhangrelationship to oval

window is constant jugular bulbrolls away in

anomalies

round window

stapes tendon

jugular bulb

Common Cavity Right Ear

Round Window

cochleostomydirectionentry into the

scala tympani

Cochleostomy vs. Round Windowbone in round

window

steeper angle at first turn contact

hard to pack/seal right ear bone in hook region

Cochleostomy vs. Round Windowbone in round

window

steeper angle at first turn contact

hard to pack/seal

right ear

coch

leos

tom

yroun

d w

indo

w

Cochleostomy vs. Round Window bone in round window

steeper angle at first turn contact

hard to pack/seal

Preparing the Cochleostomy anterior to the

round window

as inferior as possible

look often

Cochleostomy with curved burs

Curved HS Neurotology Burs Coolant Wrap

Opening the Cochlea pick used in “soft”

technique

hearing preservation

Drilling the Cochleostomyright ear

target is scala tympani

enter cochlea expand in anterior

and inferior direction

slow speed drilling

Drilling the Cochleostomy target is scala

tympani

right ear

Drilling the Cochleostomy slow speed drilling

round off anterior and inferior edges (electrode is 0.8 mm)

flush out bone dust

Ideal Cochlear Entry Point

Photo courtesy CRC for Cochlear Implant and Hearing Aid Innovation, MELBOURNE

Access into Scala Tympani

scala tympani

scala vestibuli

modiolus

SEXN° AGE RANGE TYPE I.C.

148m 156f312 11m. - 16aa

Cochlear

Med- El

AB

MXM

CASISTICA CLINICAmarzo 2003 – dicembre 2011

Abnormal Cochleae

25% of anomalous cochleae have technical challenges at ORgushersanomalous VII n. anatomyproblematic exposure

Perilymph Gushers enlarged vestibular

aqueduct (VAE)

Perilymph Gushers enlarged vestibular

aqueduct (VAE)

common cavity deformity

Perilymph Gushers enlarged vestibular

aqueduct (VAE)

common cavity deformity

incomplete partition (IP-1)

Facial Nerve Anomalies common (14%) and

associated with: CC and HC anomalous stapes nerve can split proximally

facial nerve monitor essential

Problematic Anatomy

anteriorly displaced CN VII

prominent sinus pericrani

hypoplastic cochlea

Re-implantation device failure device infection

(leave array in cochlea if possible)

Re-implantation tips

be prepared to drill around cochleostomy

insert new array immediately old array removed

straight array narrower but more flexible

Choice of electrode array

Options

Pre-curved

Straight

Short

Long

Double or split

Indications

general use, atraumatic AOS insertion

incomplete partition

hearing preservation

apical stimulation

ossified cochleae

Conclusion

keys to success are:appropriate selection of the patientfixation of the receiver stimulatoridentification of landmarks for round

window/cochleostomycare with abnormal cochleaeappropriate selection of the electrode

CI is generally possible in cases with inner ear

malformations

Variable results (neural function) generally

satisfactory results

Surgical issues

Programming difficulties / facial nerve electrical

stimulation

Higher risk of post-op. meningitis

CONCLUSIONS 2

• surgical access

• CSF gusher (difficult to radiologically predict)• type of array • array placement misplacement in the IAC (++IP I, IP III, CC, CH)

Fenestral CSF fistula (++)CSF fistula at cochleostomy site (--)

Facial nerve anomaliesCochlear anomalies

Cochlear nerve aplasia-hypoplasia is not uncommon(unilateral ++)

Cochlear nerve aplasia associated to a normal labirynth is possible

A severely narrowed IAC (2 mm) indicates a severe hypoplasia of the

cochleo-vestibular nerve, but not a sure absence of the cochlear

nerve (if the cochlear duct is present and the labirynth is

malformed, the possibility of a functioning cochlear nerve is higher)

A normal IAC does not garantee the presence of a normal cochleo-

vestibular nerve (unilateral cases, parasagittal reconstructions)

The outcome after CI in pts with aplasia-hypoplasia of the cochlear

n. are generally scarce

Thank You !!!

Azienda Ospedaliera di Rilievo Nazionale

Santobono – Pausilipon NAPOLI