Cochlear SPrint Sound Processor Informações Técnicas descarregar pdf (Página 23)

CLINICAL GUIDANCE | SECTION ONE

• Out of Compliance – the condition where the maximum voltage

available from the implant is not sufﬁcient to generate the desired current

level (CL) on a given channel. When this occurs, the implant recipient does

not perceive loudness growth when the CL is increased, i.e. there is

loudness saturation.

• NRT – Neural Response Telemetry - records neural activity within the

cochlea in response to electrical stimulation from the implant. It provides

a quick, non-invasive, objective measure of peripheral neural function.

1.7 VOLTAGE COMPLIANCE

1.7.1 CI500 series, Freedom

™

and N24 series Cochlear

Implant Systems

‘Out of compliance’ refers to the condition where the maximum voltage

available from the implant is not sufﬁcient to generate the desired current

level on a given electrode. When this occurs, the recipient does not perceive

loudness growth when the current level (CL) is increased, i.e. there is loudness

saturation. In addition, when the implant is ‘out of compliance’, ongoing

changes to electrode impedance may affect the amplitude of the biphasic

stimuli generated for a given CL. Such changes may cause the perceived

loudness to ﬂuctuate in response to changes in electrode impedance.

Custom Sound

™

is capable of detecting ‘out of compliance’ electrodes in the

CI500 series, Freedom

™

, and N24 series cochlear implant systems via the use

of compliance telemetry. Electrodes that are ‘out-of-compliance’ are ﬂagged

in red by the software. During psychophysical testing, compliance telemetry

continuously monitors the output current sources of the electrodes and alerts

the clinician if the implant cannot provide sufﬁcient voltage to generate the

requested amount of electrical current to the electrode pair. In cases where the

‘out of compliance’ ﬂag is observed, it may be necessary to:

• widen the pulse width to reduce the C-levels, or

• decrease the per channel stimulation rate

• increase the Power Level (if supported by the battery type used)

Reducing the per channel stimulation rate or widening the pulse width is

possible when using the ACE

™

/ACE(RE) or CIS/CIS(RE) strategies in many

instances. The pulse width(s) that can be selected are dependent on the

total stimulation rate of the MAP (i.e. the stimulation rate per electrode x

the number of maxima). Custom Sound lists the pulse widths and number

of maxima that are valid for a given stimulation rate. For each rate there is a

default pulse width and number of maxima.

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