Biology Reference
In-Depth Information
the connection with the brain or the spinal cord or that no longer is receiv-
ing appropriate signals for its normal function. FES of target organs aims to
support or replace the lost central control of CNS-injured patients and
helps them to improve quality of life and independency. With the help of
closed-loop control, FES systems can process different outputs to adapt
the stimulation to a better performance (
Micera &Navarro, 2009
). Different
FES systems have been successfully developed and implanted in patients to
enhance various aspects of everyday activities.
Sacral root stimulation.
Implantable sacral nerve stimulation is a minimally
invasive and durable procedure for patients with urinary and fecal inconti-
nence or neurogenic overactivity who are refractory to conservative ther-
apy. It involves stimulation of the sacral nerves with electrodes, cuff, or
topic type, implanted around sacral spinal roots and connected to a pulse
generator. Additional neuromodulation via stimulation of the afferent
nerves helps to inhibit inappropriate neural reflex behavior. This technique
has been shown to improve incontinence, retention, and reduce urinary
infections (
Brindley, 1994; Creasey & Craggs, 2012; Mayer & Howard,
2008
). The sacral anterior root stimulation has also been reported to reduce
constipation, improve bowel function, and satisfaction in spinal cord-
injured patients (
Vall`s, Rodr´guez, Borau, & Mearin, 2009
). Regarding
sexual dysfunction, stimulation of parasympathetic efferents is able to pro-
duce penile erection and seminal emission, whereas reflex erection and ejac-
ulation can also be produced by stimulation of afferent nerves (
Creasey &
Craggs, 2012
).
Ventilatory pacing
. Diaphragm pacing by electrical stimulation of the
phrenic nerve can provide significant benefits to selected patients with respi-
ratory paralysis, such as those with high cervical tetraplegia. The phrenic
nerve, stimulated by epineural or cuff electrodes, produces diaphragm-paced
contractions for ventilatory assistance (
Creasey et al., 1996
). Multichannel
electrodes have the advantage of stimulating different portions of the nerve
each time with the intention of reducing muscle fatigue (
Jarosz, Littlepage,
Creasey, & McKenna, 2012
).
Correction of foot drop
. Lower limb neuroprostheses in the form of peroneal
nerve stimulators are effective in improving the gait of stroke patients with
foot-drop. Electrical stimulation of the peroneal nerve during the advance
phase of the affected leg produces contraction of foot dorsiflexor muscles
lifting the foot from the ground, thereby improving the walking ability
(
Lyons et al., 2002
). Feedback to improve control of the stimulation has
been achieved by using mechanoreceptive signals from the sole recorded
