Table 3.

Extradural to intradural transfer of nerves to spinal roots

Study	Procedure	Functional recovery (time)	Evidence	Limitations	Possible application
Frazier et al. (1912)27	T12 or L1 nerves → S3 and S4 dv roots Unilateral 1 patient with SCI	Only with mechanical pressure (8 months after L1 transfer)	Partial recovery of bladder emptying	T12 nerve too short to reach sacral roots; Valsalva manoeuvre required for bladder emptying	SCI in lower L and S segments
Carlsson et al. (1980)24	T12 nerves → S2 and S3 dv roots Bilateral, secured with silicone elastomer filter and silver clips Model: Human 2 patients with SCI	Yes (8–12 months; improved further by 30–36 months)	Recovery of penile sensation; With full bladder, one patient able to initiate micturition, the other able to empty with abdominal straining.	Nerve graft needed to link T12 to sacral roots; Possibility of developing detrusor–EUS dyssynergia.	SCI in lower L and upper S segments
Vorstman et al. (1987)42	T10 or T12 nerves → S3 v roots Cadavers	na	na	Nerve graft needed to link T12 to S3 roots	SCI in lower L and upper S segments
Livshits et al. (2004)30	T1 and T12 nerves → S2 and S3 dv roots Unilateral, secured with polymeric film tube and biological glue 11 patients with chronic SCI	Yes (10–12 months)	Recovery of reflex voiding in all patients; Re- established bulbocavernous, cremasteric and anal reflexes in 8 patients	Paresthesias in the groin and scrotum; 3 patients needed Valsalva manoeuvre to empty bladder	SCI in lower L and S segments, spina bifida, and S root injury

Abbreviations: →, transfer to; d, dorsal; dv, dorsal and ventral; EUS, external urethral sphincter; L, lumbar; na, not applicable; S, sacral; SCI, spinal cord injury; T, thoracic; v, ventral.