Veins along the course of the sciatic nerve

Article Outline

• Abstract
• Methods
• Results
• Discussion
• Limitations
• Author contributions
• References
• Copyright

Objective

To describe the anatomic variations, symptomatology, and pathophysiology associated with the sciatic nerve (SN), and report the results after treatment of the incompetent veins.

Patients and Methods

Retrospective analysis of prospectively collected data from patients with signs and symptoms of chronic venous disease that had superficial varicosities associated with incompetent veins along the SN. Patients were evaluated with duplex ultrasound scans. In patients with enlarged veins along the SN, the anatomy of the incompetent veins, their size and association with superficial varicosities, and the severity of insufficiency were analyzed. The symptoms associated with their presence and the treatment results were also noted. Patients were re-evaluated following treatment for recurrence of varicosities and symptoms.

Results

We identified 24 limbs in 21 patients with varicosities along the SN and its branches. The duration of signs and symptoms was 4.5 years ranging from 1 to 14. Reflux was detected in 18 veins of the SN, in three persistent sciatic veins and in three veins of the tibial nerve. All limbs with sciatic and tibial nerve veins had varicosities in the lateral and posterior aspect of thigh and calf and were symptomatic. Ten limbs presented with CEAP class 2, 5 with class 3, 2 with class 4, and 1 with class 1. Pain or tingling was reported in 15 limbs, itching in 8, and heaviness in 7. The distribution of pain and tingling was present along the nerves in 19 limbs. One patient had acute thrombosis in a persistent sciatic vein and died from pulmonary embolism. Of the 21 limbs with SN veins, 16 were treated with subfascial vein ligation and phlebectomies. Three patients had sclerotherapy, 1 refused treatment, and 1 had mild symptoms not requiring treatment. Of the 19 treated limbs, in 11 there was relief of their symptoms, 6 had significant improvement, and 2 had no change. Within a year, 4 patients required additional treatment for veins along the same area. Eleven limbs had a follow-up duplex scan 3 to 19 months after their treatment. All limbs showed significant diameter reduction in the nerve veins while mild reflux was present in 3 (4.1 mm vs 2.1 mm, P < .001).

Conclusion

Reflux is the most common pathology of the sciatic and tibial nerve veins which produces significant symptoms along the distribution of the nerves. Treatment of the varicosities offers significant relief while recurrence or residual varicosities are easily managed.

Reflux is the most common pathology in patients with chronic venous disease (CVD).¹ The saphenous veins and their tributaries are involved in the majority of cases including patients with skin damage.² In less than 10% of patients with CVD reflux is found in nonsaphenous veins.³ There are only a few small reports on refluxing veins associated with nerves.³, ⁴, ⁵, ⁶, ⁷, ⁸, ⁹ The most common location is in the distribution of the SN and its branches. Incompetent veins in this area may produce signs and symptoms related to the adjacent nerve in addition to those resulting from CVD. This study was designed to determine the patterns of reflux in veins along the SN, to describe the signs and symptoms, and evaluate the effect of treatment.

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Methods 

Patients that came to the vascular laboratory with signs and symptoms of chronic venous disease (CVD) and had pathology in the veins along the sciatic nerve (SN) and its branches were included in the study. Limbs with varicosities on the posterior and lateral aspect of the thigh and calf underwent detailed evaluation with duplex ultrasonography (DU) to identify their extent and connections. Irrespective of location, other varicose veins that were not communicating with the saphenous veins were interrogated thoroughly. All patients prior to (n = 21) or after the vascular examination (n = 3) were seen by a spine specialist to verify that the patient's symptoms were not secondary to back pathology. Patients that had pain associated with back pathology were excluded. The limbs were classified with the CEAP system.¹⁰

Linear array multifrequency transducers were used from various ultrasound machines (ATL HDI 5000, Philips IU22, Bothell, Wash, and Acuson Sequoia, Mountain View, Calif). Low frequency curvilinear arrays were used in obese patients to identify the veins and the nerve when it was located at >6 cm depth. The superficial, perforating, and deep veins were examined as described previously.¹¹ The exam for reflux was done in the standing position with distal manual compression followed by sudden release. Obstruction was evaluated in the supine position. Criteria for reflux were used as described before.¹¹ The distribution and extent of reflux, the diameter of the refluxing veins, their location and extent, the entry point at the nerve, and the deep fascia were recorded in detail.

In order to follow the SN and the associated veins, the transducer was placed in the posterior and lateral thigh. The SN was identified as shown in Fig 1. The tibial nerve (TN) was identified in the neurovascular bundle in the popliteal fossa and the SN in the lower thigh under the biceps femoris muscle. Veins that entered the SN or its branches were called SN veins. A large vein running along the course of the SN but not within it was termed persistent sciatic vein.

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• Fig 1. 

  Imaging of the sciatic nerve by duplex ultrasound. a, Long view of the sciatic nerve at midthigh. It is seen below the muscle at 4 cm from the skin. It is very echogenic and measured 7.8 mm proximally and 5.2 mm distally. b, Transverse view of the sciatic nerve at midthigh. It is seen below the muscle at 4 cm from the skin. It is very echogenic and measured 7.8 × 6.5 mm.

All patients who underwent surgery were treated with subfascial ligation and interruption in the lower thigh and popliteal fossa. This was performed just below the fascia and away from the nerves under duplex scan guidance. Subsequently mini-phlebectomy was performed for the epifascial tributaries. This was important to avoid traction injury of the nerves. Patients who were treated with sclerotherapy had small caliper veins (<3 mm) that had limited extent. Treatment was performed under ultrasound scan guidance using either 1% liquid or 0.5% foam sodium-tetradecol sulfate and volume was limited to <5 mL. Injections were performed in the superficial tributaries away from the nerve. They were followed-up with clinical examination and ultrasound scan. The location and extent of residual or recurrent varicosities and the diameter of the veins associated with the SN were recorded. The veins were measured at their entry into the nerve and just proximal to it. This was done to have a constant location and facilitate the measurement.

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Results 

We identified 24 limbs in 21 patients with varicosities along the SN and its branches. There were 17 females and 4 males with a mean age of 52 years ranging from 32 to 59. The duration of disease (estimated from the time that the patients noticed the veins in their limb) varied from 1 to 14 years. The number of pregnancies in the 17 females were 7 (n = 1), 5 (n = 1), 4 (n = 3), 3 (n = 6), 2 (n = 4), 1 (n = 1), and 0 (n = 1). Most of the limbs (18) had reflux associated with an enlarged vein of the SN. Three with the TN and three had a persistent sciatic vein. The connections between the veins and the SN or TN were single or multiple. The veins extending inside the nerve were dilated, tortuous, or often moved spirally along the nerve. Reflux in the distribution of SN and TN was not associated with saphenous or deep vein reflux (Table I). Reflux was present in 23 of the 24 limbs. One patient had acute thrombosis in the persistent sciatic vein, was found to have thrombus in the vein, and she subsequently died from pulmonary embolism.

Table I. Veins along the sciatic nerve: anatomic distribution and pathophysiology of venous insufficiency

DVT, Deep vein thrombosis; PE, pulmonary embolism.

The reflux in the nerve veins was prolonged for several seconds. During manual compression of the calf there was little augmentation seen. During the release of the compression at high peak (15 of the 18 limbs) was seen followed by prolonged reflux ranging from 2.2 seconds to >5 seconds. In three limbs minimal augmentation was seen during compression with a small peak and continuous prolonged reversed flow during release.

The CEAP classification of the studied limbs is shown in Table II. Most limbs had superficial varicosities connected to the incompetent SN veins. The most prominent location of these superficial varicosities was the posterior and lateral aspect of the upper calf (Table III).

Table II. CEAP classification of the studied limbs

Table III. Location of superficial varicosities associated with chronic insufficiency of the veins along the sciatic nerve

The most common presenting symptom was pain along the SN that was worse with sitting, usually improved with walking and standing, and was reproducible with point pressure in the area of tenderness (Table IV). Most limbs (n = 16) were treated with ligation and stab avulsion phlebectomies of the superficial varicosities associated with the abnormal SN veins. Ultrasound scan guided sclerotherapy was performed in three limbs, 1 patient refused intervention and 1 had mild symptoms not requiring treatment. Of the 19 treated limbs, in 11 there was relief of symptoms, 6 had significant improvement, and 2 had no change. There were four recurrences in the same area that were successfully treated with phlebectomy (n = 1) or injection sclerotherapy (n = 3). Eleven limbs had a follow-up duplex scanning 3 to 19 months after their treatment which showed reduction in the mean diameter of the SN varicosities from 4.1 mm 95% CI 3.7-4.6 prior to treatment, to 2.1 mm 95% CI 1.7-2.6 (P < .001) after treatment. Persistent reflux in the nerve veins was seen in five limbs but it was significantly reduced in duration in four compared to pretreatment exam.

Table IV. Symptoms associated with chronic insufficiency of the veins along the sciatic nerve

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Discussion 

Nonsaphenous vein reflux is uncommon. We have previously reported that only 10% of all limbs with venous insufficiency have no evidence of axial reflux either in the great or in the small saphenous veins.³ In this same study, the prevalence of reflux in veins along the course of the SN was found to be approximately 1%. As previously noted by Ricci et al, in the popliteal fossa the SN and its branches lie close to the axial veins and their tributaries and are occasionally affected by the development of venous insufficiency in this adjacent vein network.⁹ Unfortunately, despite the fact that the main veins in the popliteal fossa are routinely evaluated sonographically in patients with symptoms and signs of venous insufficiency, the veins or tributaries along the course of the nerves are very rarely imaged by the majority of sonographers. It is not, therefore, surprising that this rare entity has been previously described only in isolated case reports or small series.

Ricci has described a simple technique to identify the SN veins sonographically.⁹, ¹² The SN and its branches are very echogenic and this facilitates their visualization. On transverse insonation at the popliteal crease, the TN is identified between the popliteal vein and the small saphenous vein. Moving the probe transversely up and down in the popliteal fossa helps differentiate this structure from muscles and tendons and helps identify the point where the SN divides into the tibial and common peroneal trunks. In a longitudinal view, the nerve lies superficial to the popliteal vein and has a characteristic fibrillar appearance.

The first anatomic description of SN varicosities was published in 1890 by Verneuil.¹³ Almost a century later, Thiery described the association of varicosities along the nerve with sciatic pain arising in the popliteal area and extending along the course of the nerve in the posterior thigh.⁴ The anatomic patterns of venous drainage in the SN and its branches was described in detail in fresh cadavers.¹⁴ Four patterns of extraneural drainage were identified: (1) the direct venae nervora, which is the least common type, draining directly from the nerve to the accompanying vena commitans and representing the main venous drainage of the nerves in that region; (2) the indirect venae nervora that leave the nerve and connect with other larger veins, which usually come off neighboring muscles and subsequently drain to the vena commitans; (3) the periarterial venous plexus, where the nerve veins connect to before the plexus drains into the venae commitans of the artery. This is a common pattern of drainage and of clinical significance since the fine branches of the plexus have no valves; (4) the perivenous venous plexus, where the nerve veins directly drain to a network of valveless small veins surrounding and connecting to larger cutaneous veins (Fig 2). This study clearly demonstrated multilevel connections between the veins within the nerve and the venous network surrounding the nerve. The limited number of valves at these connection sites and the absence of valves in the veins within the nerve may explain the significant dilatation of the latter seen in association with reflux in the veins surrounding the nerve. Normal SN veins and TN veins are not easily identified by DU due to their small size. When these veins become incompetent, they enlarge and are evident by DU as tortuous structures running inside and around the nerve (Fig 3). Enlargement of the SN veins is often associated with the presence of reflux in superficial veins (Fig 4).

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• Fig 2. 

  Patterns of extraneural drainage from sciatic nerve veins. a, Direct venae nervora; direct drainage is seen form the nerve to the vena comitantes. b, Indirect venae nervora; veins from the nerve unite with surrounding veins (mostly muscular) and drain into the vena comitantes. c, Periarterial venous plexus; veins from the nerve drain into the periarterial venous plexus, which in turn empties into the vena comitantes. d, Perivenous venous plexus; veins from the nerve drain into a perivenous venous plexus, which surrounds, runs parallel and empties directly into subcutaneous veins. (Modified from Del Pinãl F and Taylor GI¹⁴).

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• Fig 3. 

  Varicose veins within and outside the sciatic nerve. a, These veins run spirally along the course of the nerve and their diameter ranged from 1.4 to 3.7 mm. b, Prolonged reflux is seen in a vein outside the sciatic nerve.

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• Fig 4. 

  Tributaries in the popliteal fossa emerging from sciatic nerve veins. a, Schematic drawing demonstrating varicosities along the sciatic nerve and connections with refluxing veins in the popliteal fossa. b, Superficial varicosities in a young female who presented with aching and tingling sensation in the right lower limb.

With the advent of DU and its widespread use in the diagnosis of venous pathology in the past two decades, few small series and case reports describing varicosities along these nerve structures and the associated symptoms and signs have been published. Our study is not only the largest series with CVD involving the veins around the SN and its branches, but also offers follow-up data related to the effect of treatment. Most of the patients were females (17/21) and 15 of them had at least two pregnancies. We have reported similar findings in patients with reflux in nonsaphenous veins.³ In the previous study, there were 72 patients of whom 67 were females. Most of them had more than two pregnancies. This may be attributed to hormonal variation from the onset of menses until menopause and during pregnancy.¹⁵, ¹⁶, ¹⁷, ¹⁸, ¹⁹, ²⁰ The prevalence of reflux in SN and TN among all the limbs studied was 1% (9/835) and of the limbs with nonsaphenous vein reflux 10.7% (9/84).

Over the past 10 years we have discovered 21 limbs with incompetent veins in the course of the SN and its branches. Most of these veins are encased inside the epineurium and enlarge as reflux develops and worsens with time (Fig 5). DU indicates that the veins may either run within the main trunk of the nerve, surrounded by the nerve fibers, or may have a spiral course around the main trunk of the nerve, inside the epineurium. The length of involvement of the nerve and the associated superficial refluxing veins are nicely demonstrated with varicography (Fig 6) and computed tomography (CT) venography (Fig 7). At the level of the popliteal fossa, these veins emerge from the epineurium and drain in a network of superficial veins which are most commonly visualized in the postero-lateral aspect of the upper calf or lower thigh and occasionally in the anterior or medial aspect (Fig 4). Invariably, there are superficial varicosities of various extents which are clinically apparent in the popliteal fossa area. The development of reflux in the SN veins is usually associated with symptoms of local nerve irritation, presenting more commonly as pain in the posterior thigh that is reproducible with digital pressure in the area of the incompetent vein. A tingling sensation in the ipsilateral leg and foot is another common complaint and is usually worse with prolonged sitting. Symptoms of heaviness and itching were probably not related to nerve irritation but from the varicosities. These symptoms are common in patients with venous insufficiency.

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• Fig 5. 

  Varicose veins within the sciatic nerve. a, Schematic drawing of varicose veins within the perineurium and the sciatic nerve. b, Sciatic nerve at midthigh with varicose veins within the nerve (arrow) in a patient who presented with pain and swelling. A larger refluxing vein is also seen in adhesion with the nerve.

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• Fig 6. 

  Selective varicography demonstrating varicose veins within and outside the sciatic nerve giving rise to varicose veins in the posterior calf. Courtesy of Mr. John T. Hobbs MD, FRCS.

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• Fig 7. 

  Cross-sectional view and 3-D reconstructions of venography CT (VENO-CT) demonstrating varicose veins within and outside the sciatic nerve. 1, sciatic nerve; 2, sciatic nerve veins; 3, muscular veins connecting with the femoral veins; 4, femoral veins; 5, posterior thigh muscles. Courtesy of Jean-Francoise Uhl, MD.

Elimination of the varicose veins above the fascia and away from the nerve with phlebectomies and sclerotherapy had good results at an early follow-up. The few recurrences were easily treated locally. All but 2 patients were satisfied with the results of treatment. The diameter of the SN veins decreased significantly after treatment. We do not know the mechanism for this but we believe that the removal of the reservoir (distal varicosities) reduced or eliminated the reflux in the SN veins and as a result their diameter decreased. The deep connections are usually small veins and may not dilate like the superficial veins in the subcutaneous space. Over time the superficial veins may dilate further. As we have not examined the patients prior to reflux development, it is not known if the superficial veins are responsible for the development of reflux in the nerve veins or if the latter was the cause of the superficial varicosities.

Reflux in the veins of the TN is described for the first time in the current study. The superficial varicosities join the veins of the TN which is less frequent than those from the SN. Veins from the TN were smaller than those from the sciatic. They emerged at the popliteal fossa, lower than those from the SN. The symptoms and the superficial topography were similar for both nerves as well as the relief of the symptoms after treatment. No refluxing veins were found in association with the common peroneal nerve. It has been demonstrated in cadaveric studies that the common peroneal nerve has a limited blood supply and this would explain the susceptibility of this nerve to injury.²¹

The persistent sciatic vein is well described in multiple reports. It is most often associated with Klippel-Trenaunay syndrome.²² Two of the patients had reflux, 1 presenting with swelling and the other with skin changes. The latter had a previous ipsilateral DVT as it was shown from the intraluminal webs. Both patients were treated conservatively. The third patient presented with DVT in the persistent sciatic vein but she died of massive pulmonary embolism (PE) 15 hours after diagnosis while being on heparin for 12 hours. PE and fatality have been reported in the study by Cherry et al.²² Five of their patients had PE, 1 of whom died from it. Another patient died after a splenectomy which was performed for bleeding. Both these patients were young, 22 and 26-years-old, respectively.

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Limitations 

The small sample size in this study is understandable given that this is a rare pathology. Because of this we were not able to perform subgroup analysis in the CEAP classes or to compare the findings in patients with TN and SN varicosities. The short follow-up does not permit evaluation of recurrence rate and symptom relief at long-term.

As we have not tested the accuracy of the vein diameter measurement by DU at the nerves, the variability and precision of this method in our hands is not known. However, the difference between the two measurements was large enough to let any doubt in about the effect of treatment. The time taken to identify this series was 10 years. It is likely that the prevalence of these veins is underestimated as in the last 5 years we detected most of the cases.

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Author contributions 

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References 

1. Labropoulos N. Hemodynamic changes according to the CEAP classification. Phlebolymphology. 2003;40:130–136
   • View In Article
2. Tassiopoulos AK, Golts E, Oh DS, Labropoulos N. Current concepts in chronic venous ulceration. Eur J Vasc Endovasc Surg. 2000;20:227–232
   • View In Article
   • Abstract
   • Full-Text PDF (98 KB)
   • CrossRef
3. Labropoulos N, Tiongson J, Pryor L, Tassiopoulos AK, Kang SS, Mansour MA, et al. Nonsaphenous superficial vein reflux. J Vasc Surg. 2001;34:872–877
   • View In Article
   • Abstract
   • Full Text
   • Full-Text PDF (176 KB)
   • CrossRef
4. Thiery L. La veine du nerf sciatique impact clinique et the′rapeutique. Phle′bologie. 1988;41:687–689
   • View In Article
5. Trigaux JP, Vanbeers BE, Delchambre FE, de Fays FM, Schoevaerdts JC. Sciatic venous drainage demonstrated by varicography in patients with a patent deep venous system. Cardiovasc Intervent Radiol. 1989;12:103–106
   • View In Article
   • MEDLINE
   • CrossRef
6. van der Stricht J. Varices du nerf Sciatique. Phle′bologie. 1999;52:349–350
   • View In Article
7. Lemasle P, Uhl M, Lefebvre-Vilardebo JF, Gillot C, Baud JM, Vin F. Veine du nerf Sciatique et maladie variqueuse (Aspects echo-Anatomiques et he′modynamiques). Phle′bologie. 2001;54:219–228
   • View In Article
8. Lemasle P. De la clinique aux ultrasons: varicose du nerf sciatique. Phle′bologie. 2003;56:67–68
   • View In Article
9. Ricci S, Georgiev M, Jawien A, Zamboni P. Sciatic nerve varices. Eur J Vasc Endovasc Surg. 2005;29:83–87
   • View In Article
   • Abstract
   • Full Text
   • Full-Text PDF (330 KB)
   • CrossRef
10. Eklof B, Rutherford RB, Bergan JJ, Carpentier PH, Gloviczki P, Kistner RL, et al. American Venous Forum International Ad Hoc Committee for Revision of the CEAP Classification Revision of the CEAP classification for chronic venous disorders: consensus statement. J Vasc Surg. 2004;40:1248–1252
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (79 KB)
    • CrossRef
11. Labropoulos N, Tiongson J, Pryor L, Tassiopoulos AK, Kang SS, Mansour MA, et al. Definition of venous reflux in lower-extremity veins. J Vasc Surg. 2003;38:793–798
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (111 KB)
    • CrossRef
12. Ricci S. Ultrasound scan observation of the sciatic nerve and its branches at the popliteal fossa: always visible, never seen. Eur J Vasc Endovasc Surg. 2005;30:659–663
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (465 KB)
13. Verneuil A. In: ‘Traite′ de chirurgie' de Duplay et Reclus, Paris, Tome II 221; 1890. Cited by J. Vander Stricht. (Reference 4).
    • View In Article
14. Del Pinãl F, Taylor GI. The venous drainage of nerves; anatomical study, and clinical implications. Br J Plast Surg. 1990;43:511–520
    • View In Article
    • Abstract
    • Full-Text PDF (1002 KB)
    • CrossRef
15. Dindelli M, Parazzini F, Basellini A, Rabaiotti E, Corsi G, Ferrari A. Risk factors for varicose disease before and during pregnancy. Angiology. 1993;5:361–367
    • View In Article
16. Mashiah A, Berman V, Thole HH, Rose SS, Pasik S, Shwarz H, et al. Estrogen and progesterone receptors in normal and varicose saphenous veins. Cardiovasc Surg. 1999;3:327–331
    • View In Article
17. Sparey C, Sissons G, Haddad N, Rosser S, de Cossart L. Serial colour flow duplex scanning of the veins of the lower limb throughout pregnancy. Br J Obstet Gynaecol. 1999;106:557–562
    • View In Article
    • MEDLINE
18. Sparey C, Haddad N, Sissons G, Rosser S, de Cossart L. The effect of pregnancy on the lower-limb venous system of women with varicose veins. Eur J Vasc Endovasc Surg. 1999;18:294–299
    • View In Article
    • Abstract
    • Full-Text PDF (189 KB)
    • CrossRef
19. Rabhi Y, Charras-Arthapignet C, Gris JC, Ayoub J, Brun JF, Lopez FM, et al. Lower limb vein enlargement and spontaneous blood flow echogenicity are normal sonographic findings during pregnancy. J Clin Ultrasound. 2000;28:407–413
    • View In Article
    • MEDLINE
    • CrossRef
20. Boivin P, Cornu-Thenard A, Charpak Y. Pregnancy-induced changes in lower extremity superficial veins: an ultrasound scan study. J Vasc Surg. 2000;32:570–574
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (29 KB)
    • CrossRef
21. Kadiyala RK, Ramirez A, Taylor AE, Saltzman CL, Cassell MD. The blood supply of the common peroneal nerve in the popliteal fossa. J Bone Joint Surg Br. 2005;87:337–342
    • View In Article
    • MEDLINE
    • CrossRef
22. Cherry KJ, Gloviczki P, Stanson AW. Persistent sciatic vein: diagnosis and treatment of a rare condition. J Vasc Surg. 1996;23:490–497
    • View In Article
    • Abstract
    • Full-Text PDF (3326 KB)
    • CrossRef