Sensory Retraining for Phantom Limb Pain

86-87% of people who have had an amputation still feel pain in the limb that has been amputated - Phantom limb pain (PLP). Sensory retraining is a form of treatment for PLP where a special form of electrical stimulation is delivered to the residual limb.

The theory is that this stimulation changes activity in the brain that helps to reduce the person's pain. Two new types of sensory retraining device for the treatment of phantom limb pain have been developed. One type requires the user to interact with the device while the other is a non-interactive device. Both devices are new so it is unknown as to how well they may work, or which is best, therefore both will be tested in this study.

This study will be undertaken remotely, using video call, telephone and email for communication. The study will compare the effect of both devices for efficacy. One hundred people with PLP will be recruited from the NHS and the general public and randomised to receive either the interactive or non-interactive device or their placebo equivalents. A health care professional will train the research participants how to use their device. Participants will then use their device at home for 3 weeks. To ensure that they are using their devices as required, the researchers will keep in contact throughout the three week treatment period, using a schedule of video calls, weekly phone calls and daily texts. Pain and function will be measured before treatment, after treatment and at a 3 month follow-up. Twelve participants will also be invited to a one-to-one interview to give their experience of the acceptability and usability of their device.


Eligibility Criteria:
* Living in the UK
* All Genders
* Aged ≥18 years of age
* People who self-declare at that they are not pregnant and could never become pregnant
* Anyone who does not make both of those self-declarations:

if it is at all possible (self-declaration at eligibility checking) they may be pregnant before the Trial but not know they are - will be required to undertake a highly sensitive urine pregnancy test (as close in time as possible to the first video call) and return (and share at the first videocall) a negative result and/or if it is at all possible (self-declaration at eligibility checking) that they may become pregnant, during the 21 days they will be using a device - will be required to use a form of contraception considered to be highly or acceptably effective by the Clinical Trials Facilitation and Coordination Group (CTFG, 2020) (listed below\*)

* fully healed residual limb (or stump) \*\*
* single or multi limb amputation with the intervention applied to the participants limb of choice
* experienced PLP rated as ≥4 on a 0-10 scale on at least 2 days in the week prior to enrolment
* agree to inform us of the use of any new (to them) prescribed drug for their pain during the study
* any prescribed pharmacological treatment for the treatment of PLP stable for one month prior to commencing the study, and agree not to undertake any non-pharmacological treatments for their PLP during the study (e.g., mirror therapy)
* agree to inform us of any other health care received related to the amputated limb during the study (e.g., physiotherapy or occupational therapy) whether specific to PLP or not
* any previous non-pharmacological PLP treatment must have terminated at least 1 month prior to commencing the study
* Participants will need access to a mobile smart phone and a device (laptop, iPad etc.) at home to receive text messages and take part in secure video conference calls and completion of online forms

  \*Highly effective contraceptive methods being:
* Combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation either oral, intravaginal, or transdermal
* Progestogen only hormonal contraception associated with inhibition of ovulation, either oral, injectable, or implantable
* Intrauterine device IUD
* Intrauterine hormone-releasing system IUS
* Sexual abstinence

Acceptably effective contraceptive methods being:

* Progestogen-only oral hormonal contraception, where inhibition of ovulation is not the primary mode of action
* Male or female condom with or without spermicide
* Cap, diaphragm or sponge with spermicide
* A combination of male condom with either cap, diaphragm or sponge with spermicide (double barrier methods) (CTFG, 2020)

  * Fully healed criteria: no bleeding, no oozing, no broken skin, no obvious sign of infection, such as swelling or redness, around the scar.

4.1.2 Exclusion criteria

* lacking Mental Capacity to give Informed Consent
* people who self-declare that they are pregnant
* people who self-declare that they will be trying to become pregnant, during the 21 days they will be using a device
* impaired sensation as measured by hot/ cold test and sharp/ blunt test
* known allergy to acrylates\*\*\*
* unable to read and speak English - the questionnaires being used have not been translated and validated in multiple languages and no facility is available to conduct nor translate/ back-translate semi-structured interview data
* epileptic
* active deep vein thrombosis, thrombophlebitis, or varicose veins
* fitted with a pacemaker or defibrillator (internal or external), implanted neurostimulator, programmable hydrocephalus shunt, cochlear implants, ECG monitors or infusion pumps.
* has a metal implant in the area to be stimulated
* any residual limb complications such as cellulitis, wounds, infections etc.
* Active regions of known or suspected malignancy
* Any actively bleeding tissue or to persons with untreated haemorrhagic disorders
* Participating in any research trial of any intervention hypothesised to affect PLP
* Any current or recent history of substance misuse, alcohol, or drug dependency
* Any person, otherwise eligible, who commences any non-pharmacological treatment for PLP during the study period

  * Acrylates can be found in solvent adhesives such as super glue, artificial nail products, nail and eyelash adhesives, hair extensions, denture products and medical adhesives used for dressings, plasters. And body worn sensors (such as blood glucose monitors).