Neuropathic pain occurs at the burn wound itself (especially IIb and III grade burns) as well as at donor sites for skin grafting.

Cyclooxygenasis-inhibitors are not effective in this case and the effective dose of opioids is increased.

Special case: phantom-limb pain

Sensations of pain in a limb that has been amputated are called phantom-limb pain. Afferent fibers are cut at their axons and during regeneration an upregulation of sodium canals with an alteration of the sensoric afferences occurs. The uncontrolled sprouting of the ends of C- and demyelinised A -fibres can generate neurons. On the peripheric level this results in spontaneous, ectopic impulses and an increased sensitivity to thermal and mechanic stimuli. Apart from that morphologic and biochemical alteration at the spinal cord and the cortical level (central plasticity) also play a role in the incidence of phantomlimb pain [4].

50% of the relevant patients suffer from chronic pain after amputation of extremities (phantom-limb pain and stump pain) [8]. Phantom-limb pain occurs significantly more often after amputation due to an electrical burn injury than after amputation due to a flame burn injury [9]. A consequent multimodal treatment can minimize the incidence of chronic pain after burn injuries.

Sympathetically Maintained Pain (SMP)

Sympathetically Maintained Pain occurs due to interaction or pathological linkage between sympathetical postganglionic neurons and primary afferent neurons after trauma with or without nerve injury.

Clinical indications are allodynia, hyperalgesia, autonomous disorders (sweating, perfusion and trophicity) and distal swelling of extremities.

A promising treatment is blocking the sympathetic nervous system. Depending on localization and risk factors, continuous sympathetic blockades with local anesthetics (e. g. ganglion stellatum) or neurolysis with alcohol or radio frequency thermolesions (e. g. thoracal trunk) are carried out. Neurolysis requires imaging diagnostics, sometimes accompanied by computertomographic checks.

Complex regional pain syndrome (CRPS)

Complex regional pain syndrome is a disorder which occurs after injuries of the extremities. There are 2 forms of CRPS: type 1 (no injuries of the peripheral nerves) and type 2 (injured nerves). CRPS can occur anytime after sever flame burns or electrical burns [10–13].

Pain rating and documentation

Patients with burn injuries suffer from various forms of pain to various times (chronic pain, breakthrough pain, pain caused by the treatment and postinterventional pain). These forms of pain require dynamic and flexible management. A regular and standardized documentation of the pain is the key to a successful pain management.

Sensation of pain is subjective and individual. Thus, sometimes the degree of the burn may be the same but the pain the patients suffer from may be different in each case.

Currently there are numerous ways to rate pain (one-dimensional scales, multi-dimensional scales and behavior-oriented scales). A one-dimensional scale is sufficient for the documentation of acute pain:

Numerical analog scale (0–100; 0 = no pain, 100 worst possible pain)

Visual analog scale (10 cm vertical scale, no subdivisions; bottom = no pain, top = worst possible pain)

Verbal rating scale (no pain, mild pain, severe

pain, very severe pain, extremely severe pain) During rehabilitation pain can also be documented by multi-dimensional questionnaires, as for example the McGill Pain Questionnaire [14].

For children (approximately aged 4 to 10) it is recommended to use images to describe their pain as for example the faces pain rating scale.

Patients who cannot articulate their pain verbally need to be observed carefully and their pain can be rated due to behavior-oriented treatments:

In the intensive care unit, pain of patients who are analgo-sedated and are receiving artificial respiration, can be rated by means of the Behavioral Pain Scale (BPS), (see also Intensive care patient/Analgesia monitoring and Fig. 2) [15].