Chapter 51 PERINEURAL FAT GRAFTING FOR THE MANAGEMENT OF NEUROMAS AND PAIN SYNDROME
The management of painful neuromas and pain syndrome is a challenging clinical problem. A neuroma is the natural nerve reaction to damage and can be symptomatic in 3% to 5% of cases. 1 The pain caused by a neuroma is often intense and continuous and, in some cases, can be elicited by a light stimulus on the overlying skin, making even daily manual activities impossible. Uncommonly, pain can arise spontaneously and interfere with sleep. Presentation to the surgeon typically does not occur until the pain is unbearable and after pharmacologic therapies have already been attempted but have been unsuccessful. Moreover, this late presentation to the surgeon usually increases the odds of a centralization of pain, making it difficult for any surgery on the peripheral nervous system to succeed.
A multitude of treatments for neuromas have been described in the literature over the years, but none of these treatments was very effective. All surgical techniques have the common aim of preserving the nerve from microtrauma and scar adherence, avoiding continuous stress and pain. In a neuroma in continuity after the neuroma is excised, the continuity is restored with a nerve graft. Otherwise, the proximal nerve stump is usually transposed into an intact site, usually a muscle or vein.
The introduction of structural fat grafting by Coleman 2 brought a new regenerative substrate to plastic and hand surgery. In fact, the adipose fat graft processed according to his technique can provide effective protection against external stresses, lower perineural adherences, and create an environment that favors nerve regeneration. There are several potential applications of this substrate in pain syndromes without any limitation concerning the site of the pain. In 2010, I (L.V.) first applied autologous fat grafting to the treatment of terminal neuromas of the upper limb. 3 The same technique was then applied in larger series and is now a valid alternative for the treatment of neuropathic pain, extending its indication from terminal painful neuromas to neuromas in continuity and neuropathies.
CAUSES OF PAINFUL NEUROMAS
A neuroma occurs as the result of nerve injury. In particular, it is the regenerative reaction of the damaged axons to the injury. The key phenomenon that better describes this occurrence is the fascicular escape, when the intact perineurium acts as an impenetrable barrier to regenerating axons. When the perineurium is damaged, the axonal regeneration occurs externally to this sheath. Schwann cells, fibroblasts, and neoangiogenesis also support this phenomenon. 4 Although Schwann cells can be found in the neuroma, the axons are usually demyelinated, small, and without any polarized growth.
COMMON NEUROMAS AND SURGICAL OPTIONS
A painful neuroma can be the result of trauma, chronic microtraumas (such as bowler’s thumb, a lesion provoked by microtrauma to the collateral ulnar nerve of the thumb when it is inserted into the bowling ball 5 ), iatrogenic damage, or amputations (10% to 15% of stumps develop chronic neuropathic pain 6 ).
Common sites of neuromas are the superficial branch of the radial nerve, the cutaneous antebrachial nerves, the median nerve (usually an iatrogenic occurrence after carpal tunnel release), and the palmar cutaneous nerves (where a neuroma may develop as a result of a sharp trauma).