Cochlear SPrint Sound Processor Información técnica descargar pdf (Pagina 21)

CLINICAL GUIDANCE | SECTION ONE

1.5.3 Variable and Pseudomonopolar (PSMP) Stimulation

Variable and pseudomonopolar stimulation modes combine different BP

modes in the same program or MAP. For example, in variable mode some

channels may be programmed in BP1 and others in BP2, BP3, or BPx. Variable

mode can be used to increase the number of active channels in situations

where there are a reduced number of electrodes available due to electrode

anomalies or non-auditory sensations. Variable mode can also be used to

create wider stimulation modes for channels that have too high C-levels in the

nominal mode.

Pseudomonopolar is a speciﬁc application of variable mode. Typically it is

used in cases of partial insertion of the electrode array where the monopolar

reference electrodes are not available, e.g. in the case of the Nucleus 22

System. In these cases, pseudomonopolar is used to maximize the number

of active channels. In pseudomonopolar, when each of the intracochlear

electrodes is designated active, the indifferent electrode is an electrode that

is just outside the cochlea. In pseudomonopolar the current ﬂow is reversed

because the indifferent electrode is basal to the active electrode. For example,

if electrodes 10 – 22 are inside the cochlea, each of these electrodes could be

referenced to electrode 9 that would be at the cochleostomy. Then channel

22 would have the widest BP mode (BP-12) and channel 10 would have the

narrowest mode (BP).

1.5.4 Common Ground (CG) Stimulation

In CG stimulation, current ﬂows between the active electrode and all the other

electrodes on the array, which are connected together electronically to form

a single indifferent or reference (see Figure 4). The extracochlear electrodes

(MP1 and MP2) are not used. CG is an important mode because it can detect

electrode anomalies. As each electrode on the array is activated, the remaining

electrodes form the reference. Impedance telemetry uses CG to detect

potential electrode problems on the intracochlear array.

Just like MP modes, CG allows all 22 electrodes to be used as active compared

to BP where the maximum number of channels is 21. Due to the wider spread

of current in CG, this mode has been considered somewhat analogous to MP or

a wide BP mode. However, T- and C-levels in CG are typically higher than in MP.

Although CG is a programming option with the SPEAK strategy, MP modes are

still the recommended ﬁrst choice. CG should not be used as a programming

mode with implant recipients who have partial insertions of the electrode array.

Because current is ﬂowing to all electrodes on the array, it will ﬂow to any

electrodes outside the cochlea and this may produce non-auditory sensations.

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 77 78

Sin comentarios

Cochlear SPrint Sound Processor Información técnica Pagina 21