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Titolo et al. Plast Aesthet Res 2023;10:21 https://dx.doi.org/10.20517/2347-9264.2022.113 Page 9 of 13

Index abduction movement might be achieved by an accessory slip of abductor pollicis longus transfer, by
an extensor indicis tendon transfer, or by a palmaris longus to first dorsal interosseous tendon
transfer [54,60-62] .

Both extensor digiti minimi and abductor digiti minimi are considered little finger abductors; usually, the
third palmar interosseous oppose their action, but in UN palsy, this muscle is paralyzed, along with the
abductor digiti minimi, and the extensor digiti minimi is no longer unopposed; when a wider abduction of
the fifth digit occurs, it takes the name of Wartenberg’s sign.

This deformity may be corrected either by a split of the extensor digit minimi transfer or by a junctura
tendinum and medial extensor digitorum communis slip of the ring finger transfer .
[63]

TIMING OF NERVE SURGERY
As demonstrated, a wide range of possible surgical solutions are available for treating hand nerve defects; a
multifactorial approach, considering variables such as gap length, mechanism of injury, and time of
presentation, is pivotal when choosing the best option. In closed injury, whenever clinical signs consistent
with a nerve lesion are detected, active surveillance is usually recommended since the first three degrees of
nerve injuries have a chance to heal well on their own; however, when no signs of recovery are reported by
clinical and electrophysiological findings three months after the trauma, the injured nerve should be
explored to avoid progressive deterioration of both proximal and distal nerve segments and of their target
organ [24,64] .

On the contrary, open wounds with symptoms of nerve lesions require surgical exploration due to the high
chance of complete injury; in case of a sharp cut with none or minimal crush component, good blood
[65]
supply, and clean wound, primary nerve repair is the best option for restoring the function . However,
when immediate repair criteria are not met, a delayed repair is required, such as in cases of blunt trauma or
[64]
gunshot wounds; in such situations, a waiting of up to 2-3 weeks is warranted .
Excessive nerve defect length prohibits an adequate tension-free neurorrhaphy; in these situations,
autologous nerve grafts are the gold-standard option in peripheral nerve repairs . As reported in the
[66]
literature, autologous nerve grafting has better recovery results in long nerve defects (> 3 cm) [26,27] . Despite
these results, however, autologous nerve grafts carry some disadvantages as stated before; considering small
gaps up to 3 cm, the use of nerve guides has the same success rate as nerve autograft repair, achieving
recovery in up to 69% of cases , and when available to the surgeon, they are a valuable resource [32,36,37] .
[64]
Although many advantages have been reported using a muscle-in-vein technique, no concise conclusion is
possible regarding the feasibility of this procedure for the reconstruction of long nerve defects in human
patients ; however, its cost-effectiveness, in particular when compared to manufactured conduits, and the
[67]
preservation of healthy donor nerves, makes this technique a valuable option in bridging nerve gaps up to 3
cm, with comparable outcomes to other available techniques in terms of sensibility recovery and
neuropathic pain resolution [42,68] .

In large nerve defects with greater regeneration times, denervated distal targets may not be successfully
regenerated; unfortunately, there is tremendous variability in expert recommendations for the timing of
repair [64,69] . In a 2021 systematic review focused on clinical evidence-based data on nerve repair and
reconstruction, MacKay et al. provided useful considerations about this subject : pure sensory nerve
[64]
injuries should be treated acutely (within 14 days of injury) when possible to prevent painful neuroma