Table 1.

Characteristics of studies of lower extremity DNS for diabetic peripheral neuropathy

Author (year) Study type; setting; study length; Delphi score (0–9)16	Participants	Intervention	Outcome(s)
Aszmann et al (2000)34,37 (duplicates) Prospective, consecutive, unblinded, contralateral limb control; single-center; follow-up ≥12 months (mean: 23.3); Delphi score: 3	TIDM (n= 14) or T2DM (n=6); painful DPN; +Tinel (ankle or over other nerves decompressed)	DNS tibial (ankle); 6 of 20 had bilateral surgery; (8 subjects had DNS of median and/or ulnar nerves)	Sensation: 2PD
Aszmann et al (2004)50 Retrospective, contralateral limb control; single-center; follow-up ≥ 24 months (mean: 54); Delphi score: 2	TIDM or T2DM (n=50); DPN	DNS peroneal (knee); deep peroneal (foot); four tibial tunnels	Ulcer or amputation
Dellon (1992)41 Prospective, consecutive, unblinded, contralateral limb control (some); singlecenter; follow-up ≥ 6 months (mean: 30); Delphi score: 2	TIDM (n=38) or T2DM (n=22); symptomatic DPN (exclusive burning pain excluded); +Tinel	DNS of peroneal (14); deep peroneal (12); tibial (31)	Sensation: descriptive 2PD NCS (performed on 70% of nerves)
Dellon (2012)25,84 Prospective, consecutive, unblinded; multicenter; follow-up every 6 months up to 3.5 years (all ≥ 12 months); Delphi score: 2	DM (n=628, 465 painful) (described limbs, not cases); symptomatic DPN; +Tinel (ankle)	DNS peroneal (knee); deepperoneal (foot); four tibial tunnels (ankle); 2II of 628 had bilateral DNS	Pain: VAS Ulcer: new or recurrent Sensation: T-P, 2PD
Karagoz (2008)26 Prospective, consecutive, unblinded; singlecenter; follow-up PO day 1 and ≥6 months (mean: 8); Delphi score: I	TIDM (n= 16) or T2DM (n=8); symptomatic DPN (20/24 painful; 12/24 ulcers)	DNS peroneal (knee); deep peroneal (foot); four tibial tunnels (ankle)	Pain: vAS Sensation: 2PD
Knobloch (2012 abstract)27 Prospective, consecutive, unblinded; singlecenter; follow-up ≥6 months (mean: 12); Delphi score: 2/9	DM (n= 12); DPN	DNS peroneal (knee); deep peroneal (foot); four tibial tunnels (ankle)	Pain: vAS Ulcer: new or recurrent Sensation: (Likert) Balance: (Likert)
Lee and Dellon (2004)85 Prospective, cross-sectional, consecutive, unblinded; single-center, follow-up I2 months; Delphi score: 2	DM (n=46); symptomatic DPN, compared + or -Tinel (ankle)	DNS peroneal (knee); deep peroneal (foot); four tibial tunnels (ankle)	Subjective based on interview and sensation: good/excellent or poor/failure
Liao (2104)28 Retrospective; single-center (Xinhua); follow-up every 6 months for 24 months; Delphi score: 4	DM (n=306); painful DPN, focal pain (n=145) or diffuse pain (161); +Tinel Controls (n=92)	DNS peroneal (knee); deep peroneal (foot); four tibial tunnels (ankle)	Pain: vAS, BPI Sensation: 2PD NCS: TMA, PMA, SPA, SSC (Cv) High-resolution US: tibial CSA
Macaré van Maurik (2015)33	TIDM (n=8) or T2DM (n=30);	DNS unilateral peroneal	Pain: vAS
Prospective, consecutive, randomized (surgical side, contralateral limb control), unblinded; single-center; follow-up 3, 6, 12 months; Delphi score: 5	painful DPN; +Tinel (17% of subjects had baseline 2PD)	(knee); deep peroneal (foot); four tibial tunnels (ankle)	Sensation: T-P, 2PD
Macaré van Maurik (2015)42 Same; follow-up 12 months	TIDM (n=10) or T2DM (n=30); painful DPN;+ Tinel	Same	NCS: TMA, PMA, PMAT (amplitude, CV, distal latency)
Macaré van Maurik (2014)31 Same; follow-up mean 28 weeks (23–45 weeks); Delphi score: 4	TIDM (n=10) or T2DM (n=32); painful DPN;+ Tinel; ABI 0.8–1.15; TBI ≥0.7; +PT and DP pulses Controls (n=38)	Same	US: CSA tibial nerve; thickness of flexor retinaculum
Macaré van Maurik (2015)66 Same; follow-up 6 and I2 months; Delphi score: 4	TIDM or T2DM (n=39) painful DPN;+ Tinel	Same	Stability: quantitative sway; eyes open and closed
Nickerson46,86 Retrospective; single-center; follow-up 2.5 1-13) years, extended follow-up additional 3 years,86 Delphi score: 3	DM (n=65 cases, 75 legs); DPN with previous/current ulcer; previous DNS for ulcer or neuropathic pain; palpable pulses	DNS peroneal (knee); deep peroneal (foot); four tibial tunnels (ankle)	Ulcer: new or recurrent
Nickerson (2014)49 Retrospective; multicenter; subset prospective cohort; follow-up 1 and 3 years; Delphi score: 3	Subset of above with painful DPN (n=42), ≥1 ulcer healed; +Tinel, ≥1 pulse, or ABI >0.8	Same	Ulcer: recurrent ipsilateral vs new ulcer contralateral control leg
Rader (2005)29 Prospective, consecutive, sensory technician blinded; single-center; follow-up 3 and 6 months; Delphi score: 3	TIDM (n=7) or T2DM (n=32) DM; (39 cases, 49 legs); painful DPN or ulceration strongly + Tinel	DNS peroneal (knee); deep peroneal (foot); four tibial tunnels (ankle) ± neurolysis; 10 of 39 bilateral surgery	Pain: VAS Sensation: T-P, 2PD
Rozen et al (2017 abstract only)32 Prospective, consecutive, randomized (2:1 surgery [DNS vs sham] vs control), blinded subjects and evaluators; multicenter; follow-up 1, 3, 4.5 years; Delphi score: 7	DM (n=40 surgical [one or both legs] and n=27 nonsurgical controls); painful DPN	DNS peroneal (knee); deep peroneal (foot); four tibial tunnels (ankle), with neurolysis	Pain: Likert QOL
Tekin et al (2015)44 Retrospective, unblinded; single-center; follow-up 3 months; Delphi score: 3	DM (n=27); DPN; +Tinel	DNS posterior and anterior tarsal tunnel	Doppler US: posterior tibial artery
Trignano et al (2016)45 Prospective, consecutive; unblinded; singlecenter (Italy); follow-up 18 months; Delphi score: 2	DM (n=20); DPN and concurrent bilateral tarsal tunnel syndrome; no vascular disease; +Tinel	DNS tibial nerve (ankle) (four legs had additional DNSs)	Microcirculation: transcutaneous oximetry dorsum foot
Wieman and Patel (1995)38 Prospective, consecutive; unblinded; single-center; follow-up: >2 months (mean 13 months); Delphi score: 2	DM (n=28); painful DPN; +Tinel 32 of 33 ankles; no ischemia (tibial and dorsalis pedis pulses)	DNS tibial nerve (ankle); internal neurolysis not performed	Pain: vAS Sensation: T-P; 2PD NCS: “standard studies”
Wood and Wood (2003)39 Prospective, consecutive, unblinded; single-center; follow-up >1 month (1–6, mean 3); Delphi score: 2	DM (n=33); symptomatic DPN (pain [n=30] and/or numbness); nine had NCS confirmed DPN; +Tinel; ankle/brachial index >7	DNS of peroneal (knee); deep peroneal (foot); four tibial tunnels (ankle)	Pain: vAS Sensation: 2PD Subjective: excellent, good, fair, or failure
Yang et al (2016)30 Prospective, consecutive, unblinded; single-center; follow-up I, 2 years; Delphi score: 2	TIDM (n=4) or T2DM (n=7) DM; painful DPN for ≥2 years; +Tinel; 2PD (great toe) >8 mm; no limb ischemia	DNS peroneal (knee); deep peroneal (foot); four tibial tunnels (ankle)	Pain: vAS Sensation: 2PD QOL
Zhang (2013)40,87 (overlapping data) Prospective, consecutive, sensory technician blinded; single-center; follow-up I8 months (ulcer follow-up: 2–5 years); Delphi score: 4	DM type 2 (n=560); DM controls without DPN (n=40); +Tinel; 2PD (great toe) >9 mm	DNS peroneal (knee); deep peroneal (foot); four tibial tunnels (ankle) with neurolysis	Ulcer: new or recurrent Sensation: 2PD, CPT, thermal NCS: TMA, PMA, SPA, SSC (Cv) US: CSA tibial and peroneal nerves TCS: symptoms and signs

Abbreviations: 2PD, two-point discrimination; A, amplitude; ABI, ankle–brachial index; BPI, brief pain inventory; CPT, cold perception threshold; CSA, cross-sectional area; CV, conduction velocity; DM, diabetes mellitus; DNS, decompression nerve surgery; DPN, distal symmetric diabetic peripheral neuropathy; NCS, nerve conduction study; PMA, peroneal motor, recording extensor digitorum brevis; PMAT, peroneal motor, recording anterior tibialis; PO, postoperative; QOL, quality of life; SSC, sural sensory, recording ankle; SPA, superficial peroneal, recording ankle; TBI, toe–brachial index; TCS, Toronto clinical scoring; TMA, tibial motor, recording abductor hallucis; T-P, touch-pressure; T1, type 1; T2, type 2; US, ultrasonography; VAS, visual analog scale.