Use of Hand Prosthesis With Surface Electrical Stimulation for Treatment of Phantom Limb Pain
Use of Hand Prosthesis With Surface Electrical Stimulation for Treatment of Phantom Limb Pain
Phantom limb pain (PLP) is a frequent consequence of amputation, and it is notoriously
 difficult to treat. Amputation usually follows traumatic injuries or surgery following
 vascular diseases, diabetes, osteomyelitis or tumours in cases where the loss of the limb is
 required for the survival of the patient. The loss of a limb or other body parts is usually
 followed by the sensation that the lost body part is still present and can be felt. These
 phenomena are called, respectively, phantom awareness and phantom sensation. In 50-80% of
 amputees neuropathic pain develops in the lost limb also referred to as phantom limb pain
 (PLP). PLP can be related to a certain position or movement of the phantom limb, and might be
 elicited or worsened by a range of physical factors (e.g. changes in the weather or pressure
 on the residual limb) and psychological factors (e.g. emotional stress). It is well known
 that most treatments available for PLP today, such as pharmacological, surgical, anaesthetic,
 psychological and other, are ineffective.

 Today it is believed that phantom limb pain may be related to changes in the cortex of the
 brain. There is evidence that these changes may be modulated - or even reversed - by
 providing sensory input to the stump or amputation zone. For example, cortical reorganization
 and alleviation of phantom limb pain has been observed in amputees following intense use of a
 hand prosthesis. However, there is no consistent knowledge on which type of peripheral
 sensory feedback may be effective in affecting the cortical plasticity or on how to best
 apply the sensory feedback.

 The aim of the proposed research is to create natural, meaningful sensations through
 providing non-invasive sensory feedback (i.e. surface electrical stimulation) and the
 effectiveness to alleviate phantom limb pain and restore the cortical neuroplastic changes.
Purpose of the experiment Up to 50-80 % of persons with amputations experience pain in the
 part of the body that is missing. This phenomenon is called phantom limb pain. It is not
 clear today why phantom limb pain occurs, and since the pain can be difficult to treat, it
 can affect the quality of life. Other scientific studies have shown, that the use of
 electrical stimulation applied through surface electrodes, can assist to decrease or
 alleviate the phantom limb pain. The aim of this study is to investigate if surface
 electrical stimulation for a period of 3 months can decrease or alleviate the phantom limb
 pain.

 Methods Before the study begins, it will be necessary to test if the participant can tolerate
 the electrical stimulation and that the participant fulfill all criteria for participating in
 the study. During the study, different electrical stimulation sequences will be applied. The
 participant will be asked to fill out a series of questionnaires before, during and after the
 electrical stimulation, to describe how the electrical stimulation is experienced, and if the
 stimulation had an effect on the phantom limb pain and phantom sensations. The participant
 will also be asked about their general mood to investigate if this has an effect on the pain.
 The brain signals of the participants will be measured twice with either surface electrodes
 or with a scanning technique, while the participant is thinking about moving the amputated
 arm/hand, while moving the healthy arm, or while receiving electrical stimulation.

 Plan for the experiment The experiment will take place over a period of 3 months and consists
 of a series of measurement and intervention sessions planned in 2 phases (intensive and
 semi-intensive therapy). All sessions will take place at the University Hospital of Lausanne
 (CHUV), Switzerland.

 Visit 0. Interview and meeting with the subject (before the experiment begins, 1 session, 1-2
 hours). Before the experiment begins, the participant is invited to a meeting and interview
 with project responsible to inform the participant about the experiment.

 Visit 1. Preliminary investigations (before the experiment starts, 1 session, maximum 3 hours
 pr session). Before the experiment starts, but after the participant has signed the informed
 consent, the investigators will test if the participant can tolerate the electrical
 stimulation.The evoked sensory feedback sensations over the hand, will be characterized by
 non-invasive, transcutaneous electrical stimulation of the peripheral nerves in different
 locations on the upper limb, both when stimulating single channel per at time, or several
 channels simultaneously. This session will allow to identify the electrical stimulation
 optimal parameters (amplitude, frequency and pulse-width) to induce sensations on the hand
 and how to modulate these sensations, close to natural pattern. A protocol to be integrated
 in a close-loop (bidirectional control) system of artificial hand will be developed. If all
 criteria for participation are fulfilled, the participation of the subject will be decided.

 Week 1 to week 12. Experiments with the superficial stimulation and hand prosthesis control
 (sEH) will then be performed three days per week for up to 3 hours per day according to the
 daily experiment aims and the compliance of the subject. The duration of the experiments will
 be 3 months. sEH will be divided in two different phases:

 1. intensive (from 1st to 6th week) ; during this period the experiments will be carried
 out three days per week;

 2. semi-intensive (from 7th to 12th week); during this period the experiments will be
 carried out one to two consecutive days per week;

 The stimulation protocol will be composed of different programs (Exp):

 The program 1 (Exp1) of the experiment will be performed in order to characterize the best
 positions and parameters for the stimulation. The subjects will provide his/her feedback by
 means of a dedicated psychophysical platform specially designed for this purpose.

 The program 2 (Exp2) will be performed with the aim of trying different combination of
 channels and to identify the best pattern to deliver the most natural and useful sensation.

 After each stimulus is delivered with the different combination of electrodes, the
 participant will provide his/her feedback on the type, strength and location of the sensation
 (if any) through the psychophysical testing platform.

 sEH programs (Exp 3) The investigators will test the possibility to drive the stimulation
 produced by electrical stimulator with the transformed signals from sensors in (or over) the
 robotic hand, which is voluntary controlled by the user.

 If everything works, the investigators will then proceed with the therapeutic use of the
 robotic hand prosthesis. More specifically, they will ask the participant to perform several
 tasks (depending on capacity, availability and motivation):

 i) execution of different force levels ii) Identification of objects physical properties iii)
 Embodiment tests (ownership) iv) Functional improvement tests (activities of daily living):

 Risks, side effects and disadvantages Surface stimulation may cause muscle-contractions.
 Attachment of the surface electrodes may cause the skin to become red or irritated for some
 hours following the experiment. The type of electrical stimulation used in this experiment is
 not associated with any known risks or side effects. When the sensory threshold is determined
 (i.e., the lowest strength of the electrical stimulation that the participant can feel), it
 may feel unpleasant or painful for a short period of time, but the unpleasantness or pain
 will disappear as soon as the electrical stimulation stops. The electrical stimulation
 applied during the intervention period will be adjusted such that is it not painful.

 Measurement of the brain signals using the functional magnetic resonance imaging technique
 (fMRI) is safe, and there are no known risks or side effects of this procedure. The
 participant may, however, find that being placed inside the scanner is unpleasant.
 Measurement of the brain signals with surface electrodes is also considered safe, and there
 are no known risks or side effects of this procedure. There may be risks associated with the
 experiment that are unknown to the investigators. Therefore, the participant are asked to
 inform the investigators if the participant experiences any health problems during the
 experiment. If any side effects are discovered by the investigators, the participant will be
 informed immediately.

 Benefits of the experiment There will be no benefits for the subject by participation in the
 study. However, the participant may find that his/her phantom limb pain is alleviated during
 the experiment as a result of the electrical stimulation. However, it is not possible for the
 investigators to predict if the electrical stimulation will affect the phantom limb pain,
 when the effect will start, how large the effect will be, or how long the effect will last.
 It is not possible to offer the participants a permanent or lasting solution after
 termination of the study.

 Exclusion from and suspension of the experiment If the participant, according to the
 assessment of the investigator, react unexpectedly on the procedures or in any other way are
 not suitable for continuing in the experiment, the participation in the experiment can be
 terminated at any time. In general, the experiment will be terminated if it turns out that
 the subjects in general cannot tolerate the procedures of the project or find the experiment
 too exhausting.
Inclusion Criteria:

 -  Amputation or peripheral nerve damage of an upper limb.

 -  Injury should be in the chronic, stable phase, such that any traumatic injuries or
 surgical wounds have healed and the person apart from eventual phantom pain (PLP) is
 healthy and able to carry out experiment.

 -  Other treatments for PLP tried with poor results.

 -  Patient accepts the study protocol as explained by the physician.

 -  The subject experienced intractable PLP (i.e. pain in the denervated or missing
 extremity) of more than 6 on numerical rating scale (NRS) or visual analog scale (VAS)
 (0-10 scale). The frequency of PLP episodes presents more than once a week.

 -  Amputee subjects without PLP are eligible for part of the study that targets the
 sensory feedback induction within advanced bidirectional prosthesis control.

 Exclusion Criteria:

 -  Cognitive impairment

 -  Current or prior psychological impairments: Major personality disturbance (i.e.
 borderline, antisocial), Major depression, Bipolar I.

 -  Pregnancy

 -  History of or active substance abuse disorder

 -  Acquired brain injury with residual impairment

 -  Intellectual Disability (IQ < 70)

 -  Prior neurological or musculoskeletal disease

 -  Current or prior dermatological conditions

 -  Excessive sensitivity to electrical stimulation with surface electrodes. People afraid
 of electrical stimulation or pain.

 -  People with other diseases which may affect the function of the nervous system.
 (Diabetes, HIV, Renal Failure)

 -  Patients implanted with pacemakers