Phantom limb refers to the persistence of the sensation that a limb is still present even after amputation. About 90% of patients undergoing amputation experience phantom limb after its removal.
Phantom Limb Causes
The phenomenon of the phantom limb can occur due to:
- The amputation of a limb is followed by changes in the brain's cortex. It continues to receive signals from nerves used to supply the amputated limb.
- The damage to nerve ending during amputation also causes persistent pain and phantom limbs.
- The formation of scar tissue causes physical memory of the sensations in the limb, causing phantom limb.
Signs or Symptoms of Phantom Limb
The most common sensation associated with a phantom limb is pain. But few patients experience different forms of sensations like:
- The feeling of cold and warmth
- Shooting, stabbing pain
- The sensation of burning
- Crushing and throbbing pain
- The feel of pins and needles
- Vibrations in the amputated limb
- A feeling of electric shock
Possible Treatment of Phantom Limb
In most cases, phantom limbs recover with time. But if the symptoms like pain are prolonged, the treatment modalities will be required. Multiple treatment options are available to treat symptoms associated with a phantom limb, as mentioned below:
These medications can relieve the pain associated with a phantom limb. Antiseizure, antipsychotics, muscle relaxants and painkillers drugs can also help.
Therapies like acupuncture and mirror therapy also help to relieve symptoms associated with a phantom limb.
Some cases may require invasive therapies like spinal cord stimulation and deep brain stimulation. Transcutaneous electric nerve stimulation and transcranial magnetic stimulation are also beneficial.
If other treatments do not help, surgical brain stimulation is used for stimulation of the motor cortex.
Risk Factors of Phantom Limb
Some risk factors that increase the chances of developing phantom limb include:
Pain before amputation
If the limb that has to be amputated has pain, the brain will retain the feeling of pain in the limb even after its removal.
Residual pain in remaining limb
If during amputation the nerves get damaged, the pain in the remaining limb increases the chances of the phantom limb with pain sensation
If the amputation site develops a blood clot, the risk of phantom limb increases.
Typical Test of Phantom Limb
There is no specific test to diagnose the phantom limb and its pain. The physical examination and medical history related to amputation are used to analyse the condition. In addition, if the phantom limb is associated with pain sensation, the doctor will rule out other causes of pain, including infection and pain in the residual limb. Ultrasounds and blood tests are advised to rule out these causes.
Primary Prevention of Phantom Limb
- As the phantom limb carries on the sensations present in the limb before amputation, using an effective pain management technique can prevent pain in the phantom limb. Some studies have shown that regional anaesthesia before amputation can be a preventive measure.
- Epidural anaesthesia can be combined with calcitonin and ketamine to prevent postoperative pain in the phantom limb.
- Proper care of the stump and rehabilitation prevents the phantom limb. After treatment, multimodal pain helps prevent a phantom limb's reoccurrence.
- The use of gabapentinoids from the first day after surgery can be used as a preventive measure for phantom limbs.
- NSAIDs and paracetamol as analgesics are also preventive measures.
- Using a team approach with close integration of surgeon, physician, anesthesiologist, physiotherapist, and rehabilitation staff also helps post-amputation prevention of phantom limb and phantom pain.
Epidemiology of Phantom Limb
- Phantom limb occurs in 80-90% of patients undergoing limb amputation.
- The phantom limb is more common in adults than in children. The occurrence rate increases with the patient's age undergoing amputation.
- The prevalence of phantom limbs does not differ specifically with gender, but the intensity of sensations associated with a phantom limb is more in females than males.
- There is no association between ethnicity and phantom limb prevalence.
Expected Prognosis of Phantom Limb
The chronic pain associated with the phantom limb can affect the day-to-day activities of amputees. But the combination of treatment with non-invasive and invasive treatment modalities can help recover from the phantom limb and pain associated with it.
Natural Progression of Phantom Limb
Usually, the phantom limb decreases with time and even disappears after a few months. As the healing of a wound after amputation takes 3-6 months, at the same time, the nervous system signals adjust to changes in the sensory input from the amputated limb leading to the disappearance of the phantom limb.
Pathophysiology of Phantom Limb
There are multiple theories to explain the pathophysiology of phantom pain. During amputation, the peripheral nerves of the limb get damaged and disrupt the input and output signals associated with an amputated limb. These changes lead to persistent sensation in the amputated part of the limb. Due to the restructuring of cortex receptors after amputation, the neighbouring sensory receptors in the cortex that supplies the remaining limb appear as sensations in the amputated limb.
Possible Complications of Phantom Limb
The phantom limb is commonly associated with chronic pain sensation. This regular pain results in disturbed sleep related to patients waking up multiple times. The sleep disturbance further leads to worsening pain.
An additional complication commonly associated with phantom pain includes depression. Due to impaired activities in the presence of chronic pain, patients experience anxiety and depression.
Early detection and an appropriate treatment plan prevent pain progression and save an individual from associated complications.
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