Chapter 51 PERINEURAL FAT GRAFTING FOR THE MANAGEMENT OF NEUROMAS AND PAIN SYNDROME

10.1055/b-0038-149587

Chapter 51 PERINEURAL FAT GRAFTING FOR THE MANAGEMENT OF NEUROMAS AND PAIN SYNDROME

Luca Vaienti, Riccardo Gazzola

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.

**Table 51-1 Neuropathic Pain**
	Stimulus	Mechanism	Clinical Description of Pain	Diagnosis
Chronic irritation	Mechanical or chemical stimuli to the axons	Poor myelination of nerve fibers increases sensibility	Spontaneous, hyperesthesia, pain evoked by pressure, and pain evoked by joint flexion†	Clinical examination, Tinel test, selective blocks, ultrasonography MRI can be considered for deep neuromas
Central pain	Not required	Spontaneous activity of the neurons of the radicular ganglion, dorsal horn, and more proximal levels*	Spontaneous†
*Birch R. Nerve repair. In Wolfe SW, Pederson WC, Hothkiss RN, et al, eds. Green’s Operative Hand Surgery, ed 6. Philadelphia: Churchill Livingstone, 2010. †Sood MK, Elliot D. Treatment of painful neuromas of the hand and wrist by relocation into the pronator quadratus muscle. J Hand Surg Br 23:214, 1998.

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).

**Table 51-2 Surgical Options**
Surgery	Indications	Aims	Pros and Cons
Neuroma resection plus direct neurorrhaphy	Available distal nerve stump Adequate soft tissue coverage Primary neuroma The nerve gap can be closed primarily with a direct neurorrhaphy	Remove pain Restore sensitivity	PROS: Effective in restoring sensitivity and removing pain CONS: Limited indications
Neuroma resection plus nerve graft	Available distal nerve stump Adequate soft tissue coverage Primary neuroma The nerve gap is wider and cannot be closed primarily	Remove pain Restore sensitivity	PROS: Effective in restoring sensitivity and removing pain CONS: Limited indications Longer procedure Requires a nerve graft and consequent anesthesia of the donor nerve
Neuroma resection	Distal nerve stump is not available Inadequate tissue coverage and wide scar adherences Secondary neuroma or multiple relapses	Remove pain	PROS: Simple procedure CONS: High rate of relapse Greater chance of success can be achieved by resecting a nerve segment of 10 cm*
Neuroma resection plus “stump-containing” technique (epineural coaptation, diathermocoagulation, epineural ligature, silicone caps,† nerve tube‡)	Distal nerve stump is not available Inadequate tissue coverage and wide scar adherences Secondary neuroma or multiple relapses	Remove pain	PROS: Inhibits axonal growth and fascicular escape More effective than simple neuroma resection Protects against stimuli (when silicone caps or nerve tubes are used) CONS: Frequent relapses
Neuroma resection plus transposition (bones, muscles, veins)	Distal nerve stump is not available Inadequate tissue coverage and wide scar adherences Secondary neuroma or multiple relapses	Remove pain	PROS: Stump is positioned in healthy tissue Protects against traumatisms Venous endothelium increases myelinization of nerve fibers§ CONS: Stability of relocation Fixation of the stump could theoretically damage the nerve during movement, producing a new neuroma Muscle relocation cannot be applied in superficial muscles or muscles with wide excursion¶
*Birch R, Bonney G, Wynn Parry CB. Resection of terminal neuromas. In Birch R, Bonney G, Wynn Parry CB, eds. Surgical Disorders of the Peripheral Nerves. London: Churchill Livingstone, 1998. †Tupper JW, Booth DM. Treatment of painful neuromas of sensory nerves in the hand: a comparison of traditional and newer methods. J Hand Surg Am 1:144, 1976. ‡Dahlin LB, Lundborg G. Use of tubes in peripheral nerve repair. Neurosurg Clin N Am 12:341, 2001. §Koch H, Herbert TJ, Kleinert R, et al. Influence of nerve stump transplantation into a vein on neuroma formation. Ann Plast Surg 50:354, 2003. ¶Laborde KJ, Kalisman M, Tsai TM. Results of surgical treatment of painful neuromas of the hand. J Hand Surg Am 7:190, 1982.