Phantom pain is unfortunately something that many amputees know well and experience more or less regularly. And that's why I want to deal a little bit more with this phenomenon today. In this article you will find a first overview of theories about the development of phantom limb pain on the one hand and various treatment approaches on the other hand. If you want to delve deeper into the matter, you can find some links to further articles below.

Phantom limb pain is unfortunately something that many amputees know well and experience on a more or less regular basis. Phantom pains are painful sensations that are perceived where the amputated limb used to be. In other words, the brain projects pain into a part of the body that is no longer there. In contrast to phantom pain, phantom sensations do not involve pain, but other sensations such as a tingling sensation or the feeling that the limb is still there. Stump pain, on the other hand, manifests itself in the scar area or in the residual limb. Those affected often find it difficult to clearly distinguish this type of pain from phantom limb pain.

The age at which the amputation occurred seems to play a crucial role in how likely phantom limb pain is to occur. Studies have shown that people who experience an amputation in adulthood have the highest risk of experiencing phantom limb pain. Children are much less likely to experience phantom pain. In contrast, phantom limb pain rarely or never occurs with congenital limb differences. 

It is still unclear how exactly phantom limb pain develops. The causes seem to lie mainly in the brain and spinal cord. After an amputation, no more information from the missing limb arrives in the brain. Nevertheless, this area of the body is still represented in the brain. Possible explanations for the development of phantom limb pain include:

• The brain reacts to the missing information from the amputated limb with the oldest warning signal it knows: pain as a sign of "something is wrong here".
• Since parts of the nerve pathways that used to transmit impulses from the amputated limb to the brain are still present, there is irritation in the processing of impulses from these parts of the nerve pathways. In response, the brain sends pain impulses.
• For every part of the human body there is a kind of mapping in the brain. After an amputation, the brain assigns the missing part of the body to a neighbouring region in the brain (reorganisation). For example, touching the cheek may trigger pain in the hand that is no longer there.
• The surgical transection of the nerves in the periphery during the amputation can lead to increased impulse activity in the spinal cord. Spontaneous impulses and pain signals are the result.
• Excessive growth at the nerve endings injured by the amputation (so-called neuroma) at the end of the residual limb can trigger impulse activities that cause pain.
• Due to the pain memory in the brain, people who had pain in the amputated limb for a long time before the amputation may continue to have pain after the amputation because the brain continues to send pain signals. Therefore, adequate pain management prior to amputation is strongly recommended to reduce the risk of developing phantom limb pain.  

Other risk factors that may favour the development of phantom limb pain or trigger a pain attack are stress, depressive states or anxiety.

There are several pillars of treatment for phantom limb pain. Medication is one of them. Procedures that try to reverse the reorganisation in the brain or stimulate the nerves specifically are another. General relaxation procedures are a third option. Usually, different procedures are combined to give people affected by phantom pain the best possible relief. 

• Medication from the group of non-steroidal anti-inflammatory drugs (NSAIDs): These include classic painkillers like ibuprofen or diclofenac.
• Antidepressants: These work against neuropathic pain (pain caused by nerves).
• Anticonvulsants (anti-seizure drugs): They are often combined with antidepressants.
• Opioids: for example, morphine
• Local anaesthetics: for example lidocaine

• Mirror training: A mirror is positioned in such a way that the still existing, healthy limb is reflected in such a way that creates the impression that the amputated body part is still there. If the remaining limb is moved, the impression is created that the amputated part of the body is moving. As a result, reorganisation processes take place in the brain again. Phantom pain can often be alleviated.
• Visualisation exercises: Here, the affected person imagines that he or she would move the missing limb. The effects are comparable to those of mirror therapy.
• Sensory perception training: Here, the residual limb is stimulated, for example, by pressure impulses or with a hedgehog ball. These stimuli should be perceived consciously by the affected person. The combination of conscious stimulation and conscious perception often leads to a reduction in phantom pain.
• Myoelectric prosthesis: With this type of prosthesis, the user has the possibility to control the prosthesis' movements by triggering electrical impulses through muscle contractions in the remaining residual limb. This method is mainly used for arm and hand prostheses. The brain region in which the amputated body part is represented receives signals from the affected limb again. Reorganisation takes place and phantom pain can recede.

In cases of very severe phantom pain that cannot be sufficiently influenced by other methods, neuromodulation procedures can be used. However, these are usually associated with surgery and the implantation of electrodes.

• Repititive transcranial magnetic stimulation (rTMS): Phantom limb pain can be positively influenced by stimulating or inhibiting certain areas of the brain with the help of external magnetic fields. This procedure does not require surgery.
• Spinal cord stimulation (SCS): In this procedure, an electrode is placed directly over the spinal cord. Via a programmed stimulator inserted under the skin, electrical impulses act on the spinal cord and can reduce phantom limb pain.
• Deep brain stimulation (DBS): Electrodes are placed in specific areas of the brain and then stimulated.
• Motor cortex stimulation (MCS): In this procedure, an electrode is placed on the motor area in the brain during surgery and then stimulated.

• Massages 
• Acupuncture
• Transcutaneous electrical nerve stimulation (TENS): Electrodes placed on the skin stimulate the underlying nerves. Phantom limb pain can be reduced.
• Cannabis preparations: CBD and THC have also been used for chronic pain in recent years. Nebulised as pure flowers, in drop or capsule form, they can also bring relief from phantom pain. Medicinal preparations must be prescribed by a doctor. However, there are also over-the-counter CBD oils for ingestion or for massaging the stump.
• Hypnosis: Various methods of hypnosis therapy can have a favourable influence on chronic pain. In individual cases, the hypnotherapist must be consulted to determine what is appropriate. 
• Biofeedback: In the biofeedback method, electrodes are attached to the skin of the residual limb that measure and report the body temperature. The affected person now tries to lower his or her body temperature. Studies have shown that this often reduces the level of phantom limb pain. 
• General relaxation techniques such as meditation, mindfulness training and many others: All these methods have an influence on the general state of arousal in the body. If this can be lowered, the pain is usually also relieved.

• Thieme connect, Th. Weiss,W. H. R. Miltner – Phantomschmerz: https://www.thieme-connect.de/products/ebooks/lookinside/10.1055/b-0034-86301 (last accessed on 31.07.2022)
• Cleveland Clinic – Phantom Limb Pain: https://my.clevelandclinic.org/health/diseases/12092-phantom-limb-pain (last accessed on 31.07.2022)
• Healtline, Kirsten Nunez – What Causes Phantom Pain, and How Is it Treated: https://www.healthline.com/health/phantom-pain (last accessed on 31.07.2022)
• Mayo Clinic – Phantom pain: https://www.mayoclinic.org/diseases-conditions/phantom-pain/symptoms-causes/syc-20376272 (last accessed on 31.07.2022)
• Gesundheit.gv.at – Phantomschmerz: https://www.gesundheit.gv.at/krankheiten/gehirn-nerven/schmerz/phantomschmerz.html (last accessed on 31.07.2022)
• Österreichische Ärztezeitung – Phantomschmerz: Schmerz-Abgrenzung im Vorfeld: https://aerztezeitung.at/2019/oaz-artikel/medizin/phantomschmerz-schmerzabgrenzung-stumpfschmerz/ (last accessed on 31.07.2022)
• Inselspital Bern – Phantom- und Stumpfschmerzen: https://neurochirurgie.insel.ch/funktionell-schmerz/schmerz/phantom-und-stumpfschmerzen (last accessed on 31.07.2022)
• Deutsche Schmerzgesellschaft e.V. – Spiegeltherapie: https://www.schmerzgesellschaft.de/patienteninformationen/ergaenzende-verfahren/spiegeltherapie (last accessed on 31.07.2022)
• NDR – Cannabis: Wirksames Medikament bei chronischen Schmerzen?: https://www.ndr.de/ratgeber/gesundheit/Cannabis-Wirksames-Medikament-bei-chronischen-Schmerzen,cannabis212.html (last accessed on 31.07.2022) 

Note: The picture is by Camila Quintero Franco. Thanks for allowing me use it here on my blog (Camila Quintero Franco on Unsplash).