What are FES devices and how can they be used to treat upper motor neuron conditions?
Functional Electrical Stimulation (FES) was first documented as a treatment option for dorsiflexion weakness post CVA, in 1961 by Liberson et al. Since then there have been numerous studies into the use of FES in upper motor neuron conditions and the NHS integrated FES into its services in the late 1980s.
The National Institute for Health and Care Excellence (NICE) released the following guideline; Electrical stimulation for drop foot of central neurological origin, [IPG278] in January 2009. The guideline states that FES can be routinely offered as a treatment option for people with foot drop, caused by damage to the brain or spinal cord, if the health professional considers it is appropriate.
An FES device commonly supplied by the NHS utilises single self-adhesive electrode pads, which are positioned over the required nerve and muscles belly. The electrodes connect to the control box/ pulse generator via long wires, which run inside the patient’s trouser leg and attach onto the box situated on their belt. In some instances, the heel switch may also be attached via wires, resulting in cables running the full length of the leg. There are now more readily available wireless heel switches, which require a sizable box to be clipped to the collar of the shoe in order to transmit information to the control box.
Bioness has developed the L300 Go and L100 Go, lower leg FES devices with wireless technology.
The L300 Go (left) and the L100 Go (right).
The simple design makes it easy for users to don/doff, with the potential for single-handed application. The self-contained electric pulse generator (EPG) uses accelerometers and gyroscopes to provide 3D motion detection in all 3 kinematic planes and enables users to walk without the need for a heel switch, opening up freedom of choice for footwear and allowing the user to walk barefoot. The 3D motion detection and learning algorithm provides consistent stimulation, deployed in 0.01seconds and adapts to the users gait dynamics.
There is a range of electrodes available for use with the L300 Go and L100 Go. The variety of options are designed to provide easy day-to-day use. In the simplest format, the electrodes should be ran under a tap to dampen, patted dry and then clipped into the cuff using the colour co-ordinated poppers. The cuff can then be applied to the leg, using the orange marker to position below the patella and turned on to walk, providing easily reproducible stimulation. The simple system prevents the need for ‘fishing’ for the correct stimulation spot and saves the user time and frustrations as part of their morning routine.
The image below highlights the type of electrodes, followed by a brief description of their benefits:
Quick fit electrodes: Provide dorsiflexion control, inversion and eversion can be altered in small amounts by adjusting the cuffs position, or altering the waveform, phase duration and/ or pulse rate. If further control of the inversion/eversion position is required then the clinician may look to use the alternative electrodes.
Steering electrodes: Allow individualised control of inversion and eversion as well as the standard dorsiflexion. By adjusting the stimulation through the medial and lateral electrode, foot alignment can be optimised for the user. No more excessive eversion!
In cases where there is unique anatomy/ or skin sensitivity, the use of round cloth or hydrogel electrodes can overcome this, allowing the clinician to position the electrodes anywhere within the region of the cuff. Using electrode bases, these electrodes remain in position on the cuff between each days use so that the user does not have to reassess the position on a daily basis.
The range of electrodes ensures that the patient’s needs can be met most efficiently and if these needs change over time, then the electrode type can be changed in accordance to this.
The L300 Go is also available with an upgrade thigh cuff or the thigh can be used as a standalone option. The thigh can be used to stimulate either the quadriceps or hamstrings. The thigh cuff also uses clip in electrodes and allows for easy replication of position. The stimulation is most commonly applied to the hamstrings to resist hyperextension. In this position, stimulation can be set to occur in both stance and/or swing phase, helping to resist hyperextension but also offering support to transition the knee from terminal stance into swing phase in patients who walk with a stiff knee gait pattern.
Both the L300 Go and L100 Go, can be programmed for both gait and training mode. Training mode can be run in 30 minute cycles, with the stimulation intensity (mA) independent of that set for gait mode, allowing the user to build up tolerance, facilitate muscle re-education and maintain range of motion. In addition when using the thigh unit, a cycling mode is available which can be programmed to enable the user to work with stimulation on a static bike.
Once set up by the certified clinician, the FES devices can be controlled either directly from the cuff or via the users phone, using the MyBioness App. The app allows users to turn the stimulation on and off, switch between modes and to increase and decrease stimulation within a small range of the clinicians determined settings, optimising the ability to adjust the intensity depending on their requirements throughout the day.
The L300 Go and L100 Go have many of the same great features including; 3D motion, bluetooth programming, use of the MyBioness App and single channel stimulation. The L300 Go provides additional features including multi-channel stimulation, the ability to upgrade and include the thigh cuff, optional foot sensor and control unit (worn around the neck). For progressive conditions, the L300 Go can provide flexibility and additional support if and when required.
If you would like to know more about any of these Bioness products or would like to see case studies of the product in action please feel free to get in touch via www.ottobock.co.uk.
