Fat Grafting for Nerve Entrapment Within Burn Scars
C. Scott Hultman
Yuen-Jong Liu
DEFINITION
Mortality from burn injury has markedly decreased in the second half of the 20th century as wound sepsis, wound coverage, kidney failure, and shock have been largely remedied.
Patients who have undergone tangential excision of burn injuries, escharotomies, and autografting often develop symptomatic scars.
Superficial sensory nerves may become entrapped in burn scars and cause debilitating paresthesias, such as burning pain, tingling, or hyperesthesia.
Although nerve decompression and neurolysis are the primary treatments for entrapment, fat grafting is a low-risk adjunct procedure that can mitigate neuropathic symptoms by capitalizing on anti-inflammatory effects and physical cushioning by autologous fat.1,2,3,4,5,6,7
The principles of fat grafting for burn scars may also be applied to scars from other etiologies, such as chemical exposure, frostbite, abrasion, electrical injury, or a combination of injurious energy transfer to the skin and superficial soft tissues.
ANATOMY
Nerve entrapment may occur at any location of the body where there are sequelae of burn injury.
Superficial sensory nerves are affected, frequently in the extremities, such as the superficial radial nerve, the medial antebrachial cutaneous nerve, the saphenous nerve, the sural nerve, and lateral dorsal cutaneous nerve.
PATHOGENESIS
Hypertrophic scarring and contractures develop in burn scars or in split-thickness skin grafts over excised burn scars.
The fibrotic tissues constrict around superficial sensory nerves and cause a combination of pain, hyperesthesia, and paresthesia.
Sensory receptors in the damaged skin may also received aberrant innervation from sensory nerves, as the integument heals.
NATURAL HISTORY
The neuropathic symptoms are a source of frustration for the patient, often preventing return to school and work.
They require narcotic and non-narcotic analgesics and may become tolerant.
Adjunct analgesics include gabapentin and pregabalin, which have adverse effects of varying severity.
PATIENT HISTORY AND PHYSICAL FINDINGS
Complete patient history should be elicited, focusing on the type of energy delivered: scald, electrical, flame, contact, chemical, cold, friction, or abrasion.
Previous treatments and their effects should be noted, including skin grafting, laser treatments, topical scar treatments, and medications.
Complete physical exam should be performed, focusing on the burned area, noting whether it is a native burn scar or burn scar after skin grafting.
Total body surface area of the burn injury should be observed, as this often dictates algorithms for treatment, that include medical therapy (compression, silicone), laser photothermolysis and ablation, nerve decompression, and fat grafting.
Functional deficits should be noted, such as loss of range of motion or loss of sensation.
Gentle percussion around the symptomatic area can elicit Tinel sign corresponding to the location of nerve tethering or entrapment.
The Tinel sign can be followed to assess the effectiveness of treatment.
DIFFERENTIAL DIAGNOSIS
Nerve compression amenable to decompression and possible transposition
Discrete neuroma formation that may benefit from exploration, resection, and implantation of nerve below fascia or into muscle or even bone
Persistent hyperemia of hypertrophic burn scar, which may respond to laser resurfacing
IMAGING
Imaging is not required, although ultrasound may be helpful in guiding diagnostic nerve blocks, to confirm diagnosis of entrapped nerve vs neuroma, and to provide temporary relief.
SURGICAL MANAGEMENT
Fat grafting is a modality that can offer significant relief of neuropathic symptoms, after patients have been considered for or treated with laser resurfacing, nerve decompression, or neuroma resection.
Fat grafting involves surgically controlled incisional release of the integument from the underlying subcutaneous tissues and fascia.
The grafted fat contains adipocytes and possibly stem cells, which are thought to have anti-inflammatory effects on the entrapped nerves and scar tissue.
The grafted volume provides mechanical padding that decreases nerve sensitivity by effectively burying afferent end fibers, deeper and away from direct contact.
Other reasonable surgical options include scar subcision and open neurolysis.
LipiVage is the preferred system for small volume grafting, and Puregraft is preferred for large volume, structural fat grafting.
Preoperative Planning
Overall, fat grafting is indicated for patients with any of the following criteria:
Require significant pharmacologic therapy for neuropathic pain
Have previously undergone laser therapies for hypertrophic burn scars
Have multiple areas of dysesthesias not necessarily corresponding to the anatomic distribution a sensory nerve
Have already undergone major peripheral nerve decompression, neurolysis, and neuroma resection
The senior author prefers to use fat grafting as “rescue” therapy for patients with chronic, neuropathic burn scar pain, who have undergone other modalities with documented success in the literature, such as laser resurfacing and peripheral nerve decompression.Related posts:
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