Adjuvant pharmacological and surgical therapy for testicular torsion: Current state of the art

Summary

Introduction

Although the consequences of testicular torsion (TT) have been recognized for centuries, little progress has been made to improve outcomes beyond those seen with timely scrotal exploration. Even with testicular salvage, ischemia/reperfusion injury cause significant atrophy and functional impairment. Recent efforts have sought to identify adjuvant pharmacological or surgical interventions that may attenuate these consequences. In this review, we assess the evidence supporting clinical use of these nascent interventions.

Methods

We conducted a review of the literature published from 2000 to 2020, using the search terms “torsion”, “testicular”, “reperfusion”, “ischemia”, and “injury”. Clinical and laboratory research focused on adjuvant pharmacological and surgical techniques mitigating torsion-associated injury in animal models and humans were identified. We recorded intervention timing/dose/route, and outcome timing/category through biomarkers of reperfusion injury, histology, and hormonal/reproductive function.

Results

Fifty-four FDA-approved agents, plus 52 herbal/investigational drugs, were reported in animal TT models. In every study, the investigated agents showed beneficial effects on measured endpoints compared to controls. Despite these universally promising animal findings, no pharmacological trials in humans were reported. Surgical techniques studied in animal models included decompression (tunica albuginea incision, TAI), “ischemic conditioning”, and hypothermia. Only three human studies on surgical adjuvant maneuvers have been reported, all involving TAI; these showed potential benefit, but the level of evidence is low.

Conclusion

There is preliminary evidence that adjuvant treatments may mitigate the effects of ischemia/reperfusion injury. However, the pool of investigated pharmacological agents is wide, yet remarkably shallow; most compounds have been reported in a single animal study. To advance this field, a mechanism-based approach should be used to select promising agents that can be tested systematically. This will determine treatment parameters that maximize safety, efficacy, and tolerability. Only then is it possible to move toward human trials. Adjuvant surgical methods such as TAI show promise in humans but require more robust clinical evaluation.

Introduction & background

Testicular torsion (TT) is the most common pediatric urologic emergency in boys, with an incidence of 3.8–8.6 per 100,000 boys, and is bimodally distributed. Although TT is known to increase the risk of long-term fertility sequelae [1], the management of acute TT has largely remained unchanged over the past few decades [2,3]. Prevention is difficult, as there is no accurate way to identify those boys at increased risk. As such, providers continue to rely on well-established symptoms and signs, including pain, nausea/vomiting, hemi-scrotal edema/erythema, abnormal testicular orientation, and absence of the cremasteric reflex [4–6]. The addition of urgent scrotal ultrasonography with color doppler has improved diagnostic confidence, allowing for prompt surgical intervention [7].

The gold standard in management, at present, consists of scrotal exploration with detorsion and testicular fixation (or orchiectomy if the testis is necrotic). The likelihood of irreversible testicular injury after torsion is tightly related to the ischemic time [8,9]. However, the decision between orchiectomy and orchiopexy is surgeon-dependent, and often based on subjective criteria such as perceived degree of necrosis and apparent potential for long term viability if spared. There are maneuvers which may assist with this decision, such as intraoperative doppler ultrasound or incision of the tunica vaginalis to visualize the degree of viable perfusion, but it is unclear whether these maneuvers alter the outcome of surgery [10]. Even with improvements in detection and pathways, a significant proportion of boys still undergo orchiectomy, rather than testicular salvage. This rate has been stable at about 18–40%, and is closely correlated with ischemic time [2,11,12].

There have been attempts to improve outcomes of TT by reducing ischemic time. These efforts have largely been aimed at process improvement strategies. For example, transfer of patients with torsion between medical facilities adds significantly to the time to intervention [13,14]. Delay within the hospital can further increase ischemic times. Many hospital systems have established quality improvement-based pathways to ensure timely assessment and intervention, and minimize delays [12,15]. In 2019, Zee et al. prospectively assessed an institutional accelerated care of torsion (ACT) pathway, which decreased the time from ED to ultrasound, as well as from ED to OR. The presence of a pathway, supported by all members of the team, improved the percentage of patients brought to the OR within 240 min from 72% to 100%. However, this did not change the rate of orchiectomy [11].

Thus, while efforts to decrease the interval to surgery will continue, there is a need to identify adjuvant interventions that may improve outcomes, irrespective of ischemic time. For patients with a frankly necrotic testis at presentation, it seems unlikely that any adjuvant therapy would have an impact. For other patients, however, such therapies may have the potential to reduce testicular injury and improve testicular function after successful detorsion.

The clinical consequences of testicular ischemia have been recognized for centuries. The infarcted testis (if not removed) will atrophy [16], but even salvaged testes that do not appear atrophic may suffer declines in endocrine (testosterone) and exocrine (spermatogenesis) function [17]. The cellular mechanism behind these consequences is often described as ischemia-reperfusion injury, which involves numerous pathways functioning in parallel. Briefly, ischemia in the testicle results in accumulation of hypoxic byproducts. Upon detorsion, the prompt reperfusion restores oxygenated blood to the system, but results in high levels of reactive oxygen species (ROS). ROS and other free radicals can a) cause damage to sensitive cells such as endothelium and germinal cells, and b) disrupt cell permeability and cell-to-cell adhesion molecules. Subsequently, apoptosis of these cells via caspase pathways, along with the general inflammatory reaction to reperfusion, further injures the testicle [18]. The resulting damage is often irreversible.

With this background, it is natural to ask whether physical or chemical maneuvers might mitigate the effects of ischemia, and lead to reduce tissue damage. In this narrative review, we aim to examine the evidence for pharmacological and surgical adjuvant treatments for testicular torsion, in animal models and humans, with respect to the impact of such treatments on testicular outcomes.

Material and methods

We queried the NCBI PubMed database with search terms “torsion”, “testicular”, “reperfusion”, “ischemia”, “injury”, between 2000 and 2020. Results describing the effect of torsion on the contralateral testicle, ovarian torsion, non-English manuscripts, or studies of incomplete or intermittent torsion were not reviewed. Perinatal torsion was decided to be out of the scope of this study, due to its controversial management [19,20].

A very large number of chemical agents have been studied in animal models of TT, making meaningful summary challenging. To concentrate on the practical implications of this literature, we elected to focus our review on studies of pharmacologic agents that are FDA-approved for at least one indication, on the grounds that such agents are far more likely to be both available and have a safety profile sufficient to enable actual human use. Herbal or investigational compounds were compiled, but not assessed in detail (52 papers, Supplemental Table 1). All surgical techniques were also included (15 papers). Greater than 110 publications were identified, and after omitting the abovementioned exclusion criteria, and limiting papers to FDA-approved agents only, 48 were selected for detailed review in this paper.

Experimental details such as duration of ischemia, timing of intervention, and timing of endpoint after torsion were recorded. Outcome indicators such as oxidative markers, histology, hormonal and sperm parameters were extracted, for both human and animal model studies. A formal statistical meta-analysis was not possible due to the fact that most adjuvant therapies have only been reported in a single paper; for those few where multiple reports exist, the heterogeneity of both interventions and outcomes precluded aggregation of the data.

Results

Pharmacologic agents

Pharmacological adjuvant therapies with FDA-approved agents were reported in 49 manuscripts between 2002 and 2020, with 54 total agents studied (Table 1). Herbal or investigational medications were studied in 52 papers, with 50 unique agents (Supplemental Table 1). In the FDA-approved drug group, 33/49 (67%) studies were published in the least 5 years, from 2015 to 2020. All studies were conducted in rat animal models of TT; we did not identify any human studies of pharmacological therapy for TT. Most publications evaluated one agent compared to control or vehicle (33/49, 67.3%), whereas only 16 of 49 were comparative studies of multiple agents (32.7%). Six agents were tested in more than one trial. These were ibuprofen, melatonin, N-acetylcysteine, oxytocin, propofol and tadalafil. Based on the reports, these agents first showed promise in a single agent TT study compared to controls, and were now being tested against another agent, or were being studied for TT after showing promise in another ischemic disease model (i.e., ovarian torsion).

Table 1.

FDA-approved Pharmacologic Agents Studying Ischemia-Reperfusion Injury in Rat Testicular Torsion-Detorsion Models. Arrows (↑ or ↓) indicate the direction of effect of the marker after the intervention is applied. [References are listed in Appendix 1].

Author	Year	Intervention	Route	Timing of intervention	Duration of ischemia (hours)	Timing of endpoint (after detorsion)	Oxidative Markers												Histology				Apoptosis and Necrosis	Hormonal profile	Fertility potential
							MDA (↓ = lowerMDA = less damage)	SOD (↑ = higher SOD = less damage)	tGSH/GPx/GST (↑ = higher level = less damage)	NO (↓ = lower NO = less damage)	TNF-α (↓ = lower TNF = less damage)	Caspase-3 (↓ = lower level = less damage)	IL-2/IL-6/IL-10 (↓ = lower IL = less damage)	Catalase (↓ =lower level = less damage)	TOS (↓ = lower level = less damage)	TAOS (↑ = higher level = less damage)	XO (↓ = lower XO = less damage)	MPO (↓ = lower MPO = less damage)	Johnsen Score (↑ = higher score = less damage)	Cosentino Score (↓ = lower score = less damage)	STD (↑ = higher score = less damage)	GET (↑ = higher score = less damage)	TUNEL (↓ = lower score = less damage)	Hormones (↑ = higher level = better profile)	Sperm parameters (↑ = higher level = better profile)
Comparative Studies - agent in red had a greater effect
Azizollahi, S	2011	Vitamin C versus dopamine, or both	Unclear	Unclear	4	Unclear	↓												↑		↑
Quintaes, IPP	2020	EGF versus decopressive fasciotomy with flap, or both	Subcutaneous	Immediately after detorsion	4	21 days													↑
Keseroglu, BB	2019	Ibuprofen versus metamizole versus paracetamol	Oral	60 mins after torsion	4	8 days	↓			↓								↓		↓
Semercioz, A	2017	Melatonin* or zinc, or both	Intra-peritoneal	3 weeks post-op	1	1 hour	↓		↑										↑					↑
Sekmenli, T	2017	Colchicine versus melatonin	peritoneal or oral	15 mins prior to detorsion	6	Unclear					↓		↓		↓	↑			↑				↓
Yurtcu, M	2009	Melatonin versus methylprednisolone	peritoneal (melatonin)	detorsion, 1 dose versus 7 doses	6	3 months													↑
Isikdemir, F	2014	Zileuton versus montelukast	Intra-peritoneal	30 mins prior to detorsion	1	3 hours	↓												↑
Salmasi, AH	2005	Morphine versus naltrexone, or both	Intravenous	Immediately prior to detorsion	1	4 hours	↓	↑	↑					↓					↑
Yuvanc, E	2018	Nebivolol versus Pheniramine maleate	Intra-peritoneal	60 mins prior to detorsion	2	4 hours									↓	↑			↑
Kostakis, ID	2017	Sildenafil versus erythropoeitin (low versus high dose)	Intra-peritoneal	60 mins after torsion	1.5	24 hours						↓							↑	↓
Dejban, P	2019	Sumatriptan versus GR-127935 (selective antagonist of 5HT1B/1D-R)	Intra-peritoneal	Unclear	1	7 days		↑			↓								↑	↓
Ameli, M	2018	Tadalafil versus verapamil, or both	Unclear	30 mins prior to detorsion	Unclear	24 hours	↓	↑	↑										↑		↑	↑		↑
Yildirim, C	2018	Tadalafil versus darbopoetin, or both	Intra-peritoneal	30 mins after torsion	2	30 mins						↓							↑	↓
Karagoz, MA	2018	Papaverine versus alprostadil	spermatic cord	Immediately after detorsion	4	14 days													↑	↓
Mertoglu, C	2010	Methylprednisolone versus heparin	Intra-peritoneal	30 mins prior to detorsion	2	2 hours	↓	↑	↑	↓				↓					↑
Ozmerdiven, G	2017	Tadalafil versus L-arginine, or both	Intra-peritoneal	30 mins prior to detorsion	3	4 hours			↑										↑
Single-Agent Studies
Un, H	2015	Aliskiren	Oral	30 mins prior to torsion	2	2 hours	↓	↑	↑	↓			↓								↑
Dogan, C	2016	Amlodipine	Intra peritoneal	30 mins prior to torsion	2	2 hours	↓	↑	↑		↓								↑
Hirik, E	2018	Anakinra	Intra-peritoneal	Unclear	4	4 hours	↓		↑				↓					↓
Gozukara, KH	2020	Colchicine	“Infusion”	30 minutes prior to detorsion	3	Unclear	↓	↑	↑			↓							↑		↑	↑	↓
Yazdani, I	2019	Cyclosporine	Intra-venous	30 and 90 mins after torsion	1	hours Histology at 24	↓	↑	↑			↓		↓						↓	↑		↓		↑
Dejban.P	2019	Dapsone	Intra-peritoneal	Unclear	1	7 days		↑			↓								↑
Hand,V	2010	Dexmedetomidine	Intra-peritoneal	30 mins after torsion	1	4 hours	↓			↓						↑							↓
Uguralp, S	2004	EGF on gelatin film	Testicular wrap	Immediately after detorsion	4	7 and 21 days	↓		↑										↑		↑
Rashed, FK	2013	Erythropoietin	Intra-venous	Immediately after torsion	2	7 days													↑	↓
Bozkurt, M	2020	Hydrogen sulfide	Intra-peritoneal	30 mins prior to detorsion	2	4 hours	↓	↑	↑	↓	↓								↑				↓
Dokmeci, D	2007	Ibuprofen	Oral	40 mins prior to detorsion	5	5 hours versus 7 days	↓			↓									↑		↑
Kazemi-Darabadi, S	2019	L-carnitine + betamethasone	Intra-peritoneal	Immediately after torsion	6	12 hours													↑		↑	↑			↑
Kurt, O	2016	Mannitol	“Infusion”	Immediately after torsion	3	2 hours	↓	↑	↑					↓			↓		↑		↑		↓
Yurtcu, M	2008	Melatonin*	Intra-peritoneal	15 mins prior to detorsion	6	7 days	↓												↑					↑
Ghasemnejad-Berenji, M	2018	Metformin	Unclear	Unclear	1	hours Sperm	↓	↑	↑			↓									↑		↓		↑
Yousefi-Manesh, H	2019	Modafinil	Intra-peritoneal	7 days post-op	1	7 days	↓				↓		↓						↑			↑
Acer-Demir, T	2019	N-acetylcysteine	Intra-tunica vaginalis	30 minutes prior to detorsion	3	30 days													↑	↓	↑	↑
Kazaz, 10	2019	N-acetylcysteine	Intra-peritoneal	30 minutes prior to detorsion	4	2 hours													↑				↓
Mestrovic, J	2014	Nifedipine	Intra-peritoneal	30 mins prior to detorsion	3	3 hours	↓	↑	↑														↓
Lee, JW	2019	Nitrous versus nitrous + C-PTIO (NO Scavenger)	Intra-venous	Unclear	5	24 hours	↓	↑				↓							↑		↑			↑
Ghasemnezhad, R	2015	Oxytocin	Intra-peritoneal	Immediately after detorsion	2	3 hours													↑			↑	↓	↑
Firat, F	2018	Oxytocin	Intra-peritoneal	30 mins prior to detorsion	3	3 hours	↓	↑	↑	↓									↑
Savas, C	2002	Pentoxifylline	Intra-peritoneal	15 mins prior to torsion	0.5	30 mins	↓													↓
Mahmoud, NM	2019	Pioglitazone	Intra-peritoneal	30 minutes prior to detorsion	4	4 hours	↓	↑	↑		↓	↓	↓		↓	↑				↓
Wei, SM	2017	Probucol	Intra-peritoneal	Immediately after detorsion	2	hours Histology at 3	↓											↓	↑
Urt Filho, A	2012	Propofol	Intra-peritoneal	45 mins after torsion	1	90 days															↑
Unsal, A	2004	Propofol	Intra-peritoneal	30 mins prior to detorsion	2	Unclear	↓		↑					↓			↓				↑
Zheng, N	2018	Rosiglitazone	Unclear	Unclear	2	24 hours	↓				↓		↓					↓		↓
Kara, O	2016	Selenium	Unclear	Unclear	3	Unclear	↓	↑	↑							↑			↑				↑
Jafari, A	2020	Topiramate	Unclear	30 mins prior to detorsion	1	5 hours	↓	↑	↑					↓					↑
Erol, B	2009	Vardenafil	Intra-peritoneal	30 mins after torsion	1	4 hours	↓			↓					↓				↑				↓
Tunckiran, A	2005	VEGF	Intra-testicular	Pre-torsion	2	2 months						↓							↑		↑	↑

Abbreviations are as follows: malonedialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), total glutathione (tGSH), glutathione S-transferase (GST), nitric oxide (NO), tumor necrosis factor-α (TNF-α), TOS (total oxidant status), TAOS (total anti-oxidant status), myeloperoxidase (MPO), transforming growth factor-beta (TGF-beta), xanthine oxidase (XO), STD (seminiferous tubule diameter), GET (germinal epithelium thickness), and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL).

^*on formulary at hospitals but not strictly FDA-approved

Ischemic times in each study were variable (median 2 h of ischemia, range 0.5–9 h, IQR 1–4), and outcomes were assessed at an even wider range (1 h–3 months after intervention). Outcomes measures were heterogeneous, and we categorized them into five broad areas: oxidative markers (27 unique markers), histology, markers of apoptosis/necrosis, hormonal measures, and sperm parameters. The oxidative markers are not specific to testicular pathology; rather, they are general indicators of ischemia or reperfusion injury. Most papers (43/49, 88%)) reported multiple outcome categories, while 6/49 (12%) reported only one outcome category.

The most commonly-reported oxidative markers were tissue malondialdehyde (MDA, reported in 65%), glutathione markers (GPx/tGSH/GST, 41%), superoxide dismutase (SOD, 37%), caspase-3 (18%), and nitric oxide (NO, 16%). As a whole, the results were remarkably congruent across all rat studies: torsion results in expression of markers consistent with oxidative stress, and detorsion plus the agent reverses the effect. Most studies showed greater reversal with the agent than with detorsion alone. Of the 40 studies that reported oxidative marker results, 100% showed significant improvement (i.e. decrease in oxidative stress) with the pharmacologic agent.

Histologically, the Johnsen score was utilized most commonly (37/49, 76%). Other markers included the Cosentino score, mean seminiferous tubule diameter (STD) and thickness (Supplementary Table 2). Of the 44 studies that reported any histological results, 43 (98%) showed a significant improvement with the pharmacologic agent. Thirteen publications used apoptotic markers/TUNEL assay (13/49, 26.5%). Of these 13 studies, 100% showed a significant improvement with the pharmacologic agent. Only 8/49 (16%) looked at hormonal profile (testosterone, LH, FSH, and/or inhibin B) or sperm parameters (morphology, motility, etc.). All of these (100%) showed a significant beneficial effect of the pharmacologic agent.

Surgical maneuvers

Fifteen studies were identified (12 rat models, and 3 human) that evaluated surgical adjuvant measures to testicular detorsion (Table 2). Techniques included decompression (typically via tunica albuginea incision (TAI) with or without tunica vaginalis flap), ischemic conditioning, and hypothermia. Ischemic conditioning, is based on the concept that tissue damage from an ischemic event can be mitigated by inducing either prior ischemic stress (“ischemic pre-conditioning”) or by manipulation of tissue blood flow during the early phase of reperfusion (“ischemic post-conditioning”). In remote ischemic conditioning, a distant organ is made ischemic, in order to divert the molecular cascade away from the ischemic testicle. Hypothermia treatment involves ice packing around the testis after detorsion.

Table 2:

Surgical Strategies on Ischemia-Reperfusion Injury in Rat Testicular Torsion-Detorsion. Arrows (↑ or ↓) indicate the direction of effect of the marker after the intervention is applied. [References are listed in Appendix 1]

Author	Year	Intervention	Route	Timing of intervention	Duration of ischemia (hours)	Timing of endpoint (after detorsion)	Oxidative Markers							Histology			Apoptosis and Necrosis	Hormonal profile	Fertility potential	Other
							MDA (↓ = lower MDA = less damage)	tGSH/GPx/GST (↑ = higher level = less damage)	MPO (↓ = lower MPO = less damage)	SOD (↑ = higher SOD = less damage)	NO (↓ = lower NO = less damage)	XO (↓ = lower XO = less damage)	Catalase (↓ = lower level = less damage)	Johnsen Score (↑ = higher score = less damage)	Cosentino Score (↓ = lower score = less damage)	STD (↑ = higher score = less damage)	TUNEL (↓ = lower score = less damage)	Hormones (↑ = higher level = better profile)	Sperm parameters (↑ = higher level = better profile)	Laser Doppler Tissue Flowmetry (↑ = less damage)
Akcora, B	2008	Gradual Detorsion Detorsion of 360° for 20 mins, then full detorsion thereafter for 100 minutes	-	-	2	2 hours	↓	↑		↑					↓	↑
Shimizu, S	2009	Ischemic pre- and post-conditioning	-	-	Cyclic	120 mins	↓		↓	↑			↓				↓
Ozkisacik, S	2012	Ischemic postconditioning	-	Intermittent reperfusion upon detorsion	4	60 days									↓
Oktar, T	2013	Tunica albuginea incision with tunica vaginalis flap	-	-	2	Unclear								↑		↑
Jozsa, T	2016	Tunica albuginea incision and tunica vaginalis flap vs detorsion only	-	-	2	2 and 8 days								↑						↑
Moghimian, M	2016	Tunica albuginea incision with tunica vaginalis flap	-	-	1, 5, or 9 hours	Biochem at 24 hours Histology at 30 days	↓	↑		↑				↑				↑
Moghimian, M	2017	Tunica vaginalis flap versus vitamin C, or both	Intra-peritoneal	30 mins prior to detorsion	5 or 9 hours	Biochem at 24 hours Histology at 30 days	↓	↑		↑				↑		↑		↑
Gultekin, A	2018	Tunica albuginea incisions only	-	Immediately after detorsion	4	Unclear								↑			↓
Mansour, M	2019	Remote Ischemic conditioning via tail clamping	Tail clamping	5 mins after torsion for 35 mins	0.45	5 mins								↑
Ceylan, H	2005	Ischemic pre-conditioning	-	Cycles of 10 mins ischemia, 10 min reperfusion prior to torsion	1.5	Unclear	↓		↓	↑	↓	↓		↑
Sahinkanat, T	2007	Ischemic pre-conditioning	-	Cycles of ischemia and reperfusion PRIOR to torsion	3	Unclear	↓				↓			↑
Erdem, AO	2019	Hypothermia versus intermittent reperfusion, or both	-	-	4	1 hour	↓	↑	↓	↑			↓	↑

Abbreviations are as follows: malonedialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), myeloperoxidase (MPO), total glutathione (tGSH), NO (nitric oxide), and XO (xanthine oxidase).

In the rat studies, outcomes evaluated mirrored those in studies of pharmacologic agents. The most common oxidative markers were MDA (7/12, 58%), SOD (6/12, 50%), and GPx/tGSH (4/12, 33%), while the Johnsen score was used in two-thirds (8/12) of rat studies. Again, virtually all animal studies reporting oxidative markers (8/9, 89%) and histology (9/10, 90%) reported significant outcome improvement in the intervention arms. No animal study of surgical adjuvants evaluated sperm parameters.

The first human study was published in 2008 and was a case series of 3 boys with TT who underwent needle compartment pressure measurement, and demonstrated decreases in intra-testicular pressure after TAI and tunica vaginalis flap [21]. No postoperative outcomes were reported. In 2012, Figueroa et al. reported on their experience with 59 TT cases, of whom 11 underwent TAI with tunica vaginalis flap after the testis failed to show improvement in appearance after detorsion [22]. While they found that their overall orchiectomy rate decreased after they began performing TAI, and the rate of salvage (defined as testicular volume of 50% or greater compared to normal contralateral testis) appeared acceptable in the TAI group, objective outcome comparisons were not possible due to the retrospective design and patient selection bias. Chu et al. also reported a retrospective series of 182 patients with TT, of whom 36 underwent TAI with tunica vaginalis flap [23]. They found that, after matching 1:1 with the orchiectomy group on age and ischemic time, the rate of atrophy (defined as palpable decrease in size relative to contralateral testicle) among the TAI group was 67% (for ischemic time ≤24 h) and 83% (for ischemic time >24 h). Once again, the short-term (median follow-up 2.7 months) retrospective nature of the design preclude any conclusive determination of efficacy for TAI, although the findings do suggest that at least some testes presumed to be irreversibly damaged may be worth preserving, and that decompression via TAI may contribute to improved outcomes in some fraction of these. None of the human studies reported oxidative markers, histology or apoptosis measures, hormone levels, or fertility metrics.

Discussion

Pharmacologic agents

Numerous pharmacologic agents have been tested in rodent models to either attenuate the initial ischemic insult or curtail the reperfusion injury after detorsion. In general, the categories of pharmacologic agents include known antioxidant, anti-inflammatory, or ROS-scavenging drugs. While limiting the list to FDA-approved agents excludes potentially promising compounds, it focuses on drugs with a known therapeutic and safety profile, that are readily available in the hospital, or that a patient may already receive during a torsion event (i.e., morphine, ibuprofen, propofol).

In all the studies, the rat torsion model proved to be not only consistent between studies, but also a reliable method of achieving ischemia through torsion. This was done through 720 degrees of cord twist, if not more, which is sufficient to induce ischemic changes [24]. In a few papers, an atraumatic vascular clamp was used instead of torsion. These in vivo models simulate the complete physiologic response to torsion, and could also facilitate drug testing for safety, efficacy, and toxicity. Unfortunately, no study reported on the toxicity or safety profile of the agents used.

However, while the rodent model is a consistent feature of the published literature, the heterogeneity among studies is also noteworthy. First, the wide range of ischemic times produces different degrees of impact on the testicle. The short duration of torsion in some papers (e.g. 30 min) may be associated with such minimal injury that adjuvant medications are irrelevant. Clinically, these short ischemic times would rarely undergo orchiectomy. Second, tissue analysis was performed at widely variable times, making comparisons difficult. Since the ultimate goal is to see if adjuvant medications would attenuate reperfusion injury and improve testicular functional outcome, long term assessment of the testicle would be preferred. However, very few studies assessed time points beyond 7 days, with the majority being <24 h after the injury.

Unfortunately, two-thirds of these studies investigated single agents. The remainder compared multiple agents against each other, and only six agents were studied by different researchers. For the few agents for which multiple studies have been published, the outcome markers were different, making comparisons difficult. To the extent that there was consistency in outcomes reported, a group of oxidative markers were consistently reported (MDA, SOD, and GPx), and the Johnsen score was a frequently-used histologic scale. Oxidative markers and histology, however, are merely indirect indicators of testicular function. Interestingly, few studies assessed hormonal or sperm parameters, as these are the most clinically relevant outcomes, although even sperm parameters are not completely reliable indicators of fertility potential [25]. Pakyz et al., in 1990, was the only group that studied true reproductive potential by counting progeny in rats treated with cyclosporine and prednisone after torsion [26].

In all studies, the effect of the pharmacologic agent on the outcome was consistent – torsion induces changes consistent with ischemia/reperfusion injury, and detorsion plus the agent reduces the effect, usually significantly more than with detorsion alone. The ischemic changes never reverse back to pre-torsion levels, reflecting the huge impact of ischemia itself, and different agents reversed the effect to variable degrees. Within the changes in oxidative markers, the most that can be gleaned from this is that these markers verify the involvement of multiple complex cellular signaling pathways underlying ischemia-reperfusion injury. The markers that most consistently showed significant differences between treatment groups were MDA, SOD, caspase-3, glutathione markers and lipid peroxidation markers. Others markers, such as total anti-oxidant status or xanthine oxidase, did not reveal consistent differences between treatment groups.

What is remarkable about the animal literature on adjuvant treatments for TT is the minimal degree to which any one agent or treatment has been pursued in-depth. The vast majority of agents are the subject of a single report, and for most there does not appear to have been any further follow-up or mechanistic investigation, nor have there been subsequent attempts to elaborate dose-response relationships, therapeutic windows, or tolerability and safety profiles. We are unaware of any human trials of these agents. The result is that despite a substantial literature, virtually no progress has been made in moving these interventions from the laboratory to the emergency ward or operating room. Clearly, the biology suggests that there may be ways to intervene in the ischemia-reperfusion injury cascade to reduce its impact on tissue viability and function; unfortunately, it remains difficult to even know where to begin in designing a human trial.

Based on our review, there are a handful of agents which have both shown promise in experimental models, and are known to have generally benign risk profiles in human beings, making them plausible candidates for putative human trials; a preliminary list of these might include colchicine, zileuton, vitamin C, ibuprofen, and a combination of tadalafil with darbopoeitin or L-arginine.

Surgical interventions

The concept of increased intra-testicular pressures as a mechanism of injury in TT, akin to compartment syndrome, was first acted upon in humans by Kutikov et al. [21]. The technique involved TAI with tunica vaginalis flap to salvage the testicle as an alternative to orchiectomy. Only two other subsequent human studies have reported on this technique. Outcomes focused on intra-testicular pressures, and short-term atrophy and viability.

TAI is perhaps the only adjuvant therapy for TT that has even a modicum of both human evidence and supporting animal model data. The insight that TT is in many ways analogous to a compartment syndrome is potentially transformative. It is quite clear that intra-testicular pressure increases after torsion, and decreases after detorsion, although not down to pre-torsion or control levels. The degree of pressure change also correlates to testicular weight, histologic markers (i.e., Johnsen score, mean seminiferous tubule diameter) and sperm counts as well [27]. Only two studies reported on intra-testicular pressures (Kutikov et al. in humans and Oktar et al. in a rat model) [21,28]. Functional studies on the impact of TAI on hormone or sperm parameters have not been reported; in the five rat studies evaluating this method, the focus was once again on oxidative and histologic markers. In human studies, data on atrophy or salvage rates have varied due to different outcome definitions and insufficient follow up. Future work in this field (animal or human) would benefit immensely from a consensus on the optimal short and long-term outcomes that should be reported. The current use of ad-hoc metrics that vary tremendously among studies, as well as the lack of long-term results, limit the opportunities for progress. Nonetheless, the human data provided by Chu et al. is a valuable first step to standardize the decision algorithm for when TAI with tunica vaginalis flap may be appropriate adjuvant maneuver [23].

Other surgical techniques have been described as well. Gradual detorsion (a form of ischemic post-conditioning), where partial detorsion is performed initially, followed by full detorsion later, is one approach to allow less congestion and better venous outflow of ROS [29]. Ischemic pre-conditioning has little application in acute TT, as it is relies on knowledge of when the torsion will occur so that ischemia can be introduced prior to the event. This concept is more applicable to controlled ischemic situations, such as in cardiac or vascular surgery. Another approach is remote ischemic conditioning [30]. While useful as a research technique, the clinical applicability of this approach is likely negligible, as applying a tourniquet or blood pressure cuff to a child’s limb to intentionally produce ischemia would be difficult to justify, even to preserve a torsed testis.

Selecting appropriate outcomes

One difficulty in studying ischemia-reperfusion injury is the selection of appropriate outcomes. Molecular markers or histologic grading after torsion may provide practical and immediate data, but these are indirect measures and do not necessarily reflect long-term functional outcomes. For example, malondialdehyde, an oxidative stress marker reported in the majority of rat studies, has been previously studied in humans after torsion. Kehinde et al. trended MDA levels pre- and post-operatively in 34 pediatric patients, where testicular salvage was possible in 24 of these cases [31]. Compared to controls, MDA was indeed higher after TT, but at 24 h, 1 and 3 months post-operatively, there was no difference between those who received an orchiectomy versus a salvage orchiopexy. In this study, no adjuvant surgical or pharmacological agents were administered, and MDA levels innately decreased with time. Using this as a human clinical marker after intervention would only provide individual-level trends, instead of a prediction on functional response, especially since normal MDA levels are not established. Additionally, at our institution, MDA assays are not available for patient care.

Furthermore, measures such as histology cannot practically be obtained in humans after a torsion event, and so animal results presented using this metric are difficult to correlate with human outcomes. Systemic measurements are similarly challenged by the confounding effect of the normal contralateral testis. Clearly, long-term hormonal and sperm parameters would be the most directly relevant and important results, yet, <10% of animal model studies reported these outcomes.

However, hormone and sperm profiles are not perfect either. Jacobsen et al. reviewed the overall impact of torsion on long term testicular function across numerous case series [17]. Early studies from the 1980s revealed that even when detorsion occurred within 4 h of ischemia, nearly 50% of those patients had abnormal exocrine function (sperm count, motility, volume), and elevated FSH [32–35]. Other studies had no difference in sperm quality between controls and orchiopexy patients, while others reported even better sperm motility in orchiectomy patients compared to orchiopexy, though both were normal [34,36]. These varying results indicate that sperm parameters by themselves can be difficult to interpret. In longer term studies, Gielchinsky et al. reported fertility rates in torsion patients to exceed 90%, regardless of whether they received orchiectomy or orchiopexy [37]. From an endocrine standpoint, the testosterone and LH levels in torsion patients are similar to matched controls [17,34]. However, some endocrinologists argue that for orchiectomy patients, who are mono-orchid, gonadotropins are an unreliable way of assessing the function [38,39]. Given that our understanding of the consequences of torsion is still incomplete, selecting outcomes for the study of novel techniques and drugs remains challenging.

There are several limitations to this review. A single database was used (NCBI PubMed), and only FDA-approved agents were deeply evaluated, limiting the contribution of herbal or investigational drugs in this realm. Ideally, data from multiple experiments would be aggregated to produce a composite assessment of the most effective agent or technique. However, the lack of duplicate studies for comparison, and the wide range of different outcome markers used, makes this unfeasible. We also recognize that there may be publication bias in this field. There may be other medical or surgical adjuvant interventions which have not been reported, or there may be unpublished studies of one or more interventions included in this review which failed to show a beneficial effect. Formal analysis for publication bias is not feasible in this context, given the state of the current literature, but the possibility should certainly be kept in mind.

Conclusions

The next frontier of testicular salvage may be in adjuvant surgical or pharmacological therapies, and while literature is abundant, reflecting the high degree of interest, it is largely unfocused. Numerous pharmacologic agents show promise in rodent studies, but none have been studied in humans. Surgical methods with decompression via TAI have encouraging results, including in humans, but require much more robust evaluation in the clinical setting. To advance this field, a mechanism-based approach should be used to select promising agents that can be tested in a comparative pre-clinical or human trial.

Abbreviations

TT

testicular torsion

TAI

tunica albuginea incision

ROS

reactive oxygen species