Referral

Patients are only seen following referral by their GP or Medical Consultant. Referrals are reviewed to check the patient’s suitability for treatment and it is not uncommon for it to be necessary to seek further information from the referring doctor to clarify the patient’s condition or diagnosis. A common inappropriate referral is where patients have a dropped foot due to a peripheral nerve lesion such as sciatic nerve damage following knee or hip surgery. This leads to a lower motor neurone lesion and it is not possible to excite the muscle using the electrical stimulation techniques we have available.

Assessment

Patients are first seen at an assessment clinic. Subjects are suitable for treatment if they have a dropped foot due to an upper motor neurone lesion and are able to walk at least a few metres with appropriate aids or assistance. The patient is given a physical examination including estimates of active and passive joint range, spasticity (Ashworth) and muscle strength about the hip, knee and ankle. A description of their gait is recorded and a provisional treatment plan made. The following are contraindications; fixed contractures of the ankle, poorly controlled epilepsy (there is some anecdotal evidence of symptoms being exacerbated by electrical stimulation) and poor skin condition in the area of the electrodes. The effect of the stimulation is not known in pregnancy and pacemaker users are assessed by a cardiologist to ensure the ODFS does not interfere with the pacemaker. Patients must be sufficiently cognitively aware to understand the operation and purpose of the device and have sufficient motivation to use it. Where a patient is not capable of donning and doffing the device independently, it can still be used if they have assistance at home from a carer. The stimulator is tried and if gait can be improved, the patient is recommended for treatment.

It is not uncommon for the response to common peroneal stimulation to be a little weak or for increased calf tone to prevent a good range of movement. In such cases it can be useful to use an exercise stimulator for a period of a month or 6 weeks before starting to use the ODFS. We use the Microstim 2 stimulator because it has a very slow and gentle ramp. This makes the stimulation more comfortable and the gradual change in dorsiflexion produced is slow enough to avoid the production of a stretch reflex in the calf muscles. Electrodes are placed in the same positions as for the ODFS. Treatment times begin with just 10 minuets a day increasing over the 6 week period to about 2 periods of thirty minutes. A reduction in calf tone in response to stimulation is commonly seen but it is also not uncommon to see a carry over effect leading to reduced calf tone while walking, even before the ODFS is used.

Where patients are very sensitive to the sensation the same procedure is followed. The stimulation level can be started at a low amplitude and increased a little each day until a good movement is produced. Using larger electrodes can also reduce the sensation a little as the density of current is reduced. We often find that many patients find the Platinum Blue Pals hypo-allergesic 50 x 50 mm electrodes more comfortable than other electrodes and increasingly we are using these electrodes with most patients unless they have small legs and therefore require smaller electrodes. Another advantage of larger electrodes is that finding the correct positions can be a bit easier. However, if electrodes are too large, it can be difficult to avoid stimulation of other muscle groups. As with the ODFS we use a 40Hz stimulus with an intermittent pattern (mode 6 on the old Microstim 2, mode 0 on the new Microstim 2V2). These exercises are set up at the first assessment clinic.

Setting up the ODFS

The ODFS is fitted over two clinic sessions on consecutive days. On the first day the user is taught how to apply the device while on the second day their ability to do so is assessed and further training given if necessary. Patient education is key to successful use of the ODFS and it is worth spending a lot of time to make sure they understand the device and what is trying to be achieved. If appropriate, carers are also instructed in its use. We usually mark the electrode positions with an indelible felt tip pen, colour coded for the red and black lead. (The ink fades after about three days) The patient is given an instruction manual and taken through the main points of the manual, in particular the section on skin and electrode care and precautions. The electrode positions are marked on a diagram of the leg and sometimes digital photographs are also taken and given to the patient to help them find electrode positions. We ask the patient (and / or carer) to read the manual and come back to the second appointment with any questions that they may have.

At the second appointment we measure walking speed and physiological cost index (PCI) over 10m both with and without the ODFS. Generally 3 walks with and 3 walks without the ODFS are recorded and the order of walks randomised to compensate for fatigue. If a patient is unable to complete 3 walks, fewer walks are done. This is used as a record of the patient’s progress and is reported back to the referring Doctor. Patients receive a copy of all correspondence about their treatment. The ODFS settings and accessories are recorded in the patient notes and this information used for sending out spares if required. Finally the patient is given spare electrodes and a spare foot switch.

Follow up

Follow up is made at 6 weeks, 18 weeks, 45 weeks and 72 weeks from first use and then yearly for as long as the device is used. If users experience problems they are encouraged to contact the clinic so advice can be given, equipment repaired or extra clinic sessions arranged if necessary. Many problems can be solved with telephone advice and we make it clear that we prefer people to phone as soon as they have a problem rather wait to the next appointment. We try to solve technical problems by sending out spare equipment by next post. Our technical staff are also trained in the clinical application of the ODFS and this aids them in understanding patient queries. However, we encourage patients from other clinics to contact the clinic where they received their ODFS, as it is that clinic's responsibility to provide continuing follow up care.

At follow up clinics the patients use of the stimulator is checked. Sometimes the stimulator settings need adjusting, particularly if their gait has changed; for example, it may be necessary to reduce the rising edge ramp if their gait is significantly faster. Skin condition is always checked and advice on skin and electrode care re-emphasised if needed. Any changes in gait are noted, in particular, changes in spasticity, which might indicate a problem. The walking speed and PCI tests are repeated and changes fed back to the patient to give them an indication of their progress. The patient is given enough electrodes to last them to their next appointment.

Conclusion

We have been using this clinical model for eight years and it has proved to be successful. This is reflected in the compliance rate for the ODFS, which is 92% at 18 weeks and 86% after 1 year. This is high for any orthotic aid. We believe the key has been to provide a high level of patient and carer education at the start of treatment, re-enforced with continuing follow up. This is supported by rapid response to problems and good technical back up.

Paul Taylor