Hip / Groin / Leg

Phantom Pain

Definition

Phantom pain comprises all the painful sensations that are experienced in a missing part of the body.

Aetiology

Phantom pain after amputation occurs in 60-80% of patients. Peripheral input can play a role in the perception of phantom pain.

The incidence of phantom pain is not related to age, gender or side or level of the site of amputation. The same is true regarding the reason for amputation: surgical or traumatic. The incidence of phantom pain is lower in children and in persons with a congenital missing part of the body. Phantom pain is more frequently seen in bilateral amputation, amputation of the legs, and when the level of amputation is performed more proximally.

There are indications that serious pain before amputation and postoperative pain are predictors of chronic phantom pain.

Spontaneous and abnormal activity is observed in the neuroma at the nerve endings, and in the spinal ganglia after peripheral mechanical or chemical irritation caused by up-regulation of sodium channels.

The spinal cord may also play a role. When activity in neuroma and spinal ganglia changes in the long term, this can result in adaptations in the central projecting neurons of the dorsal horn. Spontaneous neuronal activity and RNA transcription changes and, as a consequence, increased metabolic activity in the spinal cord and expansion of receptive fields can occur, and can lead to central sensitisation.

 

As well as functional changes, anatomical changes have also been observed in the myelum. Normal stimuli via A-β neurons can lead to other sensations, such as pain. Finally, neuroplastic changes also occur in the thalamus, and in the subcortical and cortical structures. At the same time, there are indications that cortical representation also changes.

 

 

Signs and symptoms

Most patients have intermittent pain, varying from daily to monthly. Pain free intervals of more than a year have even been reported.

The pain can occur in attacks lasting seconds, minutes or hours. Patients most frequently describe the pain as being shooting, stabbing, stinging, pinching or burning. The pain is usually experienced distally to the missing limb.

 

Phantom pain often starts within 14 days of amputation, with half the patients experiencing already pain in the first 24 hours after amputation. Some patients develop phantom pain several years after amputation. But in less than 10% of cases does the phantom pain start a year after amputation. Two years after the onset of phantom pain, there is little difference in prevalence.

Phantom sensations are non-painful sensations such as warmth, tingling, telescoping (especially in the fingers or toes), and a sense of shortening of the limb.

Approximately 50% of amputees also have stump pain, while 50-88% of patients with phantom pain also experience stump pain. Myofascial trigger points are often present in the stump and can trigger phantom sensations and phantom pain.

Diagnostics

Physical Examination

There are few options for physical examination for phantom pain since the pain is located in the missing limb and pain mechanisms mainly take place in the peripheral and central nervous system.

In stump pain, the source of the pain is clearly local. Skin pathology and vascular insufficiency, infections and neuromas play a maintaining role in 20% of phantom pain patients.

The stump must be examined for local trigger points, in particular when the patient is wearing a prosthesis. These trigger points can be the cause of the phantom pain.

Additional Somatic Diagnostics

  • none
  • RAND-36 (quality of life)
  • VAS Pain (maximal, minimal, actual, average/week)
  • PCS (catastrophising)
  • HADS (fear and depression)

Additional Psycho-cognitive Diagnostics

Multidisciplinary Treatment

Whether or not somatic treatment is indicated is based on the pain diagnosis.  Based on the findings of the pain questionnaires, additional diagnostics and/or multidisciplinary treatment comprising various non-somatic treatments may be necessary.

Non-somatic Treatment

Somatic Treatment

Phantom pain treatment is generally refractory and is usually unsuccessful. Although clinicians often report favourably on their results, less than 10% of patients have permanent pain relief.

Somatic Treatment

Pharmacological treatment:

  • Tricyclic antidepressants
  • Anticonvulsives: carbamazepine, oxcarbazepine, gabapentine en pregabaline.

Interventional Pain Treatment