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Fully Implantable Miniature Stimulator for Treatment of Footdrop

IP.com Disclosure Number: IPCOM000032480D
Publication Date: 2004-Nov-05

Publishing Venue

The IP.com Prior Art Database

Abstract

A small implantable stimulator(s) having at least two electrodes is small enough to be implanted adjacent to a nerve and/or muscle in the leg for the stimulation and treatment of footdrop. The small stimulator provides a means of stimulating a nerve structure(s) and/or muscles when desired, and may be implanted via a minimal surgical procedure.

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Fully Implantable Miniature Stimulator for Treatment of Footdrop

Background

                    The present invention generally relates to implantable stimulator systems and methods, and more particularly relates to implantable stimulator systems and methods utilizing one or more implantable microstimulators as a treatment for footdrop. 

Footdrop is a condition resulting from impaired or absent voluntary dorsiflexion of the foot. The normal heel-toe pattern of walking (gait) is disturbed, creating a gait in which initial contact is made with the entire foot or the toes instead of with the heel.  This often results in the person tripping and losing balance.

A microminiature implantable electrical stimulator, referred to herein as a microstimulator, and known as the BION® microstimulator, has been developed to overcome some of the disadvantages of traditional leaded systems.  The standard BION device is a leadless microstimulator, as the implantable pulse generator and the electrodes have been combined into a single microminiature package.  A standard configuration of the BION device is a cylinder that is about 3 mm in diameter and between about 2 and 3 cm in length.  This form factor allows the BION device to be implanted with relative ease and rapidity, e.g., via endoscopic or laparoscopic techniques.  With this configuration, the BION device consists of only two electrodes: a reference, or indifferent, electrode at one end and an active electrode at the other end.  In addition, with this configuration, electrical signals delivered to nerves travel away from the stimulation location along the nerve fibers in both directions.

The present invention provides a means of chronically stimulating the nerves and muscles that contribute to the treatment of footdrop with the BION device.  Electrical stimulation of such targets may provide effective dorsiflexion of the foot, thereby treating footdrop and associated problems of gait.

                    The innervation of the foot and ankle are by the spinal segments of L4, L5, S1, S2, and S3.  These segments make up the sciatic nerve that proceeds out of the low back and descends under the gluteal and hamstring musculature. The sciatic nerve divides at the lower third of the posterior thigh into the posterior tibial nerve and the common peroneal nerve. The common peroneal nerve, about half the size of the posterior tibial nerve, descends obliquely along the outside of the popliteal space to the head of the fibula.  It can be palpated just under the skin behind the head of the fibula.  It then winds around the neck of the fibula where it divides again into the deep peroneal nerve, and the superficial peroneal nerve.  The deep peroneal nerve innervates the tibialis anterior muscle with the innervation stemming from the L4, L5, and S1 levels.  The deep peroneal nerve is primarily motor, where the superficial peroneal nerve supplies both sensation to the anterolateral aspect of the leg a...