The impact of direction of great saphenous vein total stripping on saphenous nerve injury

Abstract

Objectives

To examine and compare the effects of downwards versus upwards total stripping of great saphenous vein (GSV) on saphenous nerve (SN) injury using clinical and electrophysiological studies.

Methods

Fifty patients with varicosities were equally and randomly assigned to undergo total, upwards stripping (group A) or downwards stripping (group B) of GSV during saphenectomy. SN function was measured with electroneurogram (ENG) before operation, two weeks and 12 weeks after, in order to record the incidence and type of SN injury. Clinical signs of SN injury were also recorded at the same time points. The results were statistically analysed.

Results

There were no statistical significant differences on the occurrence of SN injury between groups A and B at two and 12 weeks, respectively, as confirmed with ENG studies and clinical evaluation. There were no differences between the two techniques with regard to the type of SN injury. SN injury was significantly ameliorated from 34% to 6% during the first three months.

Conclusion

SN injury was equally observed after downwards or upwards total stripping of the GSV, as confirmed by ENG and clinical evaluation, with no differences in injury type. SN injury tends to be relieved through time in most patients.

Keywords

great saphenous vein saphenous nerve stripping direction varicose surgery complications electrophysiological nerve studies

Introduction

Saphenous nerve (SN) injury represents a complication of great saphenous vein (GSV) stripping, with an incidence which ranges between 3% to above 50%.^1–3 It is mainly associated with procedures of total GSV striping from ankle to thigh and attributed to the nerve trauma from the passage of the stripper head near or over the SN and its branches. In order to reduce its incidence invaginated and short stripping have been introduced as less traumatic techniques; however, the role of the first is debated through randomized studies,^4,5 while the second, although reducing SN damage, may be associated with persistent below knee GSV reflux after surgery and recurrence of clinical symptoms.⁶ Total GSV stripping may be a choice for treating patients with GSV reflux extending to its below knee portions, ignoring the higher incidence of SN injury because the latter is supposed to have minimal clinical significance.⁷ Despite the debated clinical impact of SN injury,^3,8 several attempts have been made in order to recognize and reduce the factors associated with its occurrence. The direction of stripping has been suggested as one of those;⁹ however, data from several studies raise questions about its direct association with SN damage.^10,11

In the present study, we compared upwards to downwards total GSV stripping with regard to the occurrence, type and clinical course of postoperative SN injury. In addition to clinical evaluation, electroneurogram (ENG) measurements were also used to reliable define the type and occurrence of SN sensory impairment.

Materials and methods

Fifty candidates for surgery for superficial chronic venous disease with clinical CEAP (clinical, aetiological, anatomical and pathological elements)¹² score from 2 to 4 were randomly assigned to underwent either upwards GSV striping (n = 25, group A) or downwards striping (n = 25, group B) during saphenectomy. All patients had colour duplex ultrasound-documented significant reflux, extending to the tibial portions of the GSV and its branches. The two groups were matched according to age, sex, body mass index and clinical CEAP score (Table 1). All patients were adequately informed about the study and gave written informed consent before the operation. The study protocol was approved by the ethics committee of the University Hospital of Ioannina in accordance to the Helsinki Declaration.

Table 1

Preoperative characteristics of the patients according to age, sex, BMI and CEAP score

	Upwards stripping	Downwards stripping
Sex (male/female)	12/13	12/13
Age (mean ± SD)	44.6 ± 11.45*	46.4 ± 11.48*
BMI (mean ± SD)	23.36 ± 3.32*	23.92 ± 2.87*
CEAP score (2/3/4/5/6)	8/8/9/0/0	9/8/8/0/0

BMI, body mass index; CEAP, clinical, aetiological, anatomical and pathological elements

*P = 0.6 and 0.495 for age and BMI, respectively, when the two types of stripping compared (Mann-Whitney U test)

The day before surgery all patients underwent a baseline ENG measurement to exclude cases positive for SN injury prior to surgery, as well as patients with undetectable nerve responses. All procedures were performed under general anaesthesia by the same surgical and anaesthesia team. Surgery was consisted of a standard high ligation and disconnection of the GSV to the saphenofemoral junction accompanied by total, one-stage GSV conventional (not invaginated) stripping and local phlebectomies. We used medium stripper heads in all cases (TELIC, S.A. Barcelona, Spain). Distal capture of the GSV was done through a 10 mm incision above the medial malleolous. The subcutaneous fat and perivenous tissue were dissected carefully and the vein was ligated and cut only after we were sure that it was clear from any surrounding tissues. Local phlebectomies near the ankle were avoided to all patients. Leg compression bandage was applied after the end of the procedure in cases of downwards striping. In cases of upwards striping leg bandage was applied from the foot to the middle thigh simultaneously to striper removal. Patients were allowed to stand up and walk by the same day and dismissed home the day after.

Follow-up was performed at two and 12 weeks and SN injury was assessed with both clinical evaluation and ENG. Clinical evaluation consisted of patient's description of any pain, hypoesthesia, numbness or tingling at the lower calf as well as sensory evaluation after touching the area with a small gauge (Table 2), and was performed by an independent surgeon. If the patient mentioned any deficit, and/or if the examiner recorded any sensory loss at the calf area, the clinical evaluation was considered as indicative for SN injury. Pain alone was not considered as evidence for SN injury. ENG was performed with the distal technique (Wainapel's method), by an independent neurologist.¹³ In brief, two recording electrodes were placed; one just above the higher predominance of medial malleolous, between the malleolous and the tendon of tibialis anterior (reference electrode), and a second proximal and slightly medial to the tibialis anterior tendon (active electrode). The stimulation point was consisted from a cathode electrode which was placed 14 cm proximal to the active electrode deep to the medial border of the tibia, and an anode electrode proximal to it. A ground electrode was placed between recording electrode and cathode. After an electric stimulation by the proximal electrodes the nerve response was recorded by the distal electrodes at the medial malleolous in an antidromic fashion. Sensory nerve action potential (SNAP), nerve conduction velocity (NCV) and latency time were measured. Two microvolts were considered as the lower limit for SNAP amplitude, 3.8 millisecond as the upper limit for onset latency and 36.8 m/second as the lower limit for NCV.¹⁴ Any value out of the above limits was considered as positive for SN injury (Table 2). It has to be mentioned that SN voltage responses may not be always detectable in normal subjects.¹⁵ To deal with this limitation and avoid false-positive for SN injury results, we excluded patients with undetectable nerve responses preoperatively, and furthermore we performed averaging of several voltage responses during ENG procedures.

Table 2

Clinical and electrophysiological criteria for saphenous nerve injury

Clinical symptom	Injury positive when
Pain	Exists with another clinical criterion
Numbness	Mentioned by patient
Tingling	Mentioned by patient
Hypoesthesia	Mentioned by patient
Touch test	Positive
ENG measurement
SNAP	<2 μV
NCV	<36.8 m/second

ENG, electroneurogram; SNAP, sensory nerve action potential; NCV, nerve conduction velocity

The study had 80% power to detect more than 30% differences between groups A and B as computed by IBM Sample Power 3 (IBM Corporation, Armonk, NY, USA). This power level was considered as adequate, taking into account the already published differences on SN injury between downwards and upward GSV stripping in studies comparing these two methods.^9,16,17 Summarizing the results of these studies, the mean value of positive cases for SN injury was 49% for the upwards stripping and 11% for the downwards stripping at three months follow-up. The results were statistically analysed with the IBM SPSS Statistics 20 software (IBM Corporation, Armonk, NY, USA) using cross-tabulation and non-parametric statistics. P value of less than 0.05 was considered significant.

Results

No patient had injury positive or undetectable ENG measurements before surgery. All 50 patients had a typical total GSV saphenectomy, without any need of staged stripping. None had bilateral limb surgery. There were not any periprocedural complications and all patients were dismissed ambulatory the next day of surgery. The results on SN injury are shown on Table 3 and Figures 1 and 2.

Table 3

Saphenous nerve injury as detected by electroneurogram and clinical examination

	Saphenous nerve injury
Group/weeks	ENG positive, n (%)	Clinically positive, n (%)
Group A/2w	8 (32%)	7 (28%)
Group B/2w	9 (36%)*	6 (24%)**
Group A/12w	2 (8%)^†	2 (8%)^††
Group B/12w	1 (4%)^‡,§	1 (4%)^‡‡,§§

ENG, electroneurogram

*P = 0.765 and **P = 0.747 when compared with A/2w, ^†P = 0.034 and ^††P = 0.06 when compared with A/2w, ^‡P = 0.552 and ^‡‡P = 0.552 when compared with A/12w, ^§P = 0.005 and ^§§P = 0.04 when compared with B/2w (Pearson's chi-squared test)

Figure 1

Charts showing the time course of saphenous nerve (SN) injury during follow-up, (a) after upwards stripping, (b) after downwards stripping and (c) for the whole cohort. *P < 0.05 when compared with two weeks follow-up for the same stripping group. Clinical evaluation (grey bars) compared with electroneurogram (ENG) measurements (black bars) underestimates SN injury at two weeks in all groups

Figure 2

Chart showing the incidence and time course of each type of saphenous nerve (SN) injury as a percentage of the whole patient cohort. Neuropraxia is completely abolished during the first 12 weeks after surgery, while mixed injury is reduced by 50%

With regard to ENG studies at two weeks, pathological measurements were found in 32% (8/25) of group A patients and 36% (9/25) of group B patients. At 12 weeks, ENG studies revealed SN injury in 8% (2/25) of group A patients and in 4% (1/25) group B patients. Statistical analysis found no significant differences between groups A and B both at two and at 12 weeks follow-up (P = 0.765 and P = 0.552, respectively, Pearson's chi-squared test). ENG measured nerve function showed statistically significant improvement from two to 12 weeks with both methods of stripping (Table 3).

Clinical evaluation at two weeks detected sensory deficits in 28% (7/25) of group A and 24% (6/25) of group B patients. At 12 weeks the detected sensory deficits were 8% (2/25) and 4% (1/25) for groups A and B, respectively. Deficits at 12 weeks were seen as hypoesthesias with positive touch tests in all patients, while one additionally suffered from occasional pain. Statistical analysis found no significant differences between groups A and B both at two and at 12 weeks follow-up (P = 0.747 and P = 0.552, respectively, Pearson's chi-squared test). All clinical positive cases were also ENG positive; however, clinical examination failed to detect four cases at two weeks. Significant improvement in clinical symptoms was detected from two to 12 weeks in group B and marginally insignificant, possibly due to underestimation of injury, in group A (Table 3).

With regard to the quality of the ENG results, 11 (5 upwards, 6 downwards) of the 17 recorded pathological cases at two weeks had characteristics of predominant neuropraxia (normal or slightly reduced SNAP, but with significant lowering of NCV). The remaining six cases (3 upwards, 3 downwards) showed mixed injury results of both neuropraxia and axonal damage (significantly reduced or absent SNAP and NCV). At 12 weeks, three (2 upwards, 1 downwards) of the six mixed injury cases were still detectable, while none of the 11 cases of predominant neuropraxia did. No significant differences were found when compared group A with group B for each type of SN injury at both time points.

Discussion

The direction of total GSV striping has been examined in several studies to its relation with the SN injury. Some authors have found that downwards stripping results in lower incidence of postoperative lower calf sensory deficits compared with upwards stripping.^9,16,17 This was attributed to the inverted V formation of the SN branches that cross directly the saphenous vein at the lower calf, which predisposes to their entrapment by the striper head and avulsion when the latter is pulled in an upwards manner.^9,16 However, and in contrast to the above findings and suggestions, a number of other authors have concluded in their studies that the direction of stripping does not affect the incidence of postprocedural sensory neurological impairment.^10,11 Our clinical findings are in agreement with the latter. Moreover, and apart from the clinical symptoms which may sometimes be misjudged, we have reliably shown that the incidence of true SN injury as this can be determined through functional ENG studies by measuring the SNAP, NCV and latency times, does not differ significantly between upwards and downwards stripping. The fact that previous studies of histological examinations of stripped saphenous veins have shown that nerve fragments can be also found in a significant number of downwards stripped veins could additionally support these findings.¹⁸ The assumption that downwards stripping is an atraumatic method may not be valid in the clinical setting. When the stripper is pulled in a downwards manner, after passing the level of the knee, already carries a large segment of GSV and avulsed tributaries, which significantly increase its head diameter. In that way its passage through the calf, a region with far lower compliance than thigh, requires a significant amount of strength and leads to an extensive subcutaneous trauma, which undoubtedly may injure the crossing SN branches. Passage through calf might be easier when the striper is pulled upwards.

The objectively recorded SN injury using ENG, was found to be higher than the clinically detected neurological deficit at two weeks. These findings suggest that the difference between clinical and ENG studies could be a result of either borderline severity of the injury, with subsequent subclinical effect, or misjudgments of the aetiology of the symptoms by the examiner. In any case it seems that not all of the functional deficits can be detected or are revealed clinically, especially at the first weeks of follow-up where additional clinical situations (e.g. presence of haematoma and oedema) may outshine them. The overall ENG-detected SN injury in our study was 34% at two weeks. This finding is well correlated with recent histological results of dissections, where in one-third of individuals the SN was very close to the GSV wall; a fact that could be a possible cause of injury in cases of total GSV stripping.¹⁹ Similarly to the mechanical damage of stripping, endovenous ablation may result in thermal nerve injury when it is extended to below knee GSV. Thus, tumescent-dilute anaesthesia should be applied into the below knee saphenous compartment in order to increase the distance of GSV from the nerve and prevent neurological injury.^20,21

In both upwards and downwards stripping, sensory impairment was significantly ameliorated and the clinical symptoms tended to be relieved during the first 12 weeks after surgery. This injury and symptom relief supports the low clinical impact of SN injury and could be explained by the detected type of neurological damage. Most of the positive cases consisted of predominantly neuropraxic injury, which is generally a mild nerve injury with a benign clinical course. Neuropraxic injury is usually self-resolved within a time of several weeks.¹⁷ All such injuries in the present series were disappeared between two to 12 weeks. Apart from neuropraxia, almost one-third of the positive patients had characteristics of mixed type of injury. Mixed nerve injury, which includes axonal damage in addition to neuropraxia, is considered as a more severe injury. Usually two to six months are needed for this injury to be resolved in cases of limited axonal loss.²² In our series 50% of mixed injuries were resolved during the first 12 weeks, which suggests that axonal nerve damage during GSV stripping is usually limited and of low clinical importance. It has to be mentioned that no differences were recorded between upwards and downwards stripping in terms of the type of nerve injury.

In conclusion, the present study has shown that there are no significant differences between upwards and downwards total GSV striping in terms of incidence, time course and type of SN injury, as confirmed by electrophysiological nerve studies and clinical examination. The ENG-recorded incidence of SN injury after total GSV striping is 34% at two weeks but is ameliorated to 6% after three months. The predominant type of nerve injury is neuropraxia, which is totally abolished after 12 weeks. Further studies that will examine the occurrence of SN injury after invaginated or short stripping with the use of electrophysiological methods, may offer additional important information for the current clinical practice.

Footnotes

Acknowledgements

We would like to thank Dr Alexis Martzoukos for his excellent assistance on electrophysiological nerve studies.

Competing interest: None.

Funding: University of Ioannina.

Ethical approval: Ethics Committee of the University Hospital of Ioannina.

Guarantor: MM.

Contributorship: JCP: protocol development, data analysis, literature search, writing of the first draft of the manuscript. ED: protocol development and patient recruitment. IS: protocol development, data collection and data analysis. SA: data collection and data analysis. AK: conceived the study and critical revisions. MM: conceived the study, protocol development and critical revisions. All authors reviewed and edited the manuscript and approved the final version of the manuscript.

References

Flu

Breslau

Hamming

Lardenoye

. A prospective study of incidence of saphenous nerveinjury after total great saphenous vein stripping. Dermatol Surg 2008;34:1333–9

Holme

Skajaa

Holme

. Incidence of lesions of the saphenous nerve after partial or complete stripping of the long saphenous vein. Acta Chir Scand 1990;156:145–8

Morrison

Dalsing

. Signs and symptoms of saphenous nerve injury after greater saphenous vein stripping: prevalence, severity, and relevance for modern practice. J Vasc Surg 2003;38:886–90

Scheltinga

Wijburg

Keulers

de Kroon

. Conventional versus invaginated stripping of the great saphenous vein: a randomized, double-blind, controlled clinical trial. World J Surg 2007;31:2236–42

Durkin

Turton

Scott

Berridge

. A prospective randomised trial of PIN versus conventional stripping in varicose vein surgery. Ann R Coll Surg Engl 1999 81:171–4

van Neer

Kessels

Estourgie

de Haan

Neumann

Veraart

. Persistent reflux below the knee after stripping of the great saphenous vein. J Vasc Surg 2009;50:831–4

Kostas

Ioannou

Veligrantakis

Pagonidis

Katsamouris

. The appropriate length of great saphenous vein stripping should be based on the extent of reflux and not on the intent to avoid saphenous nerve injury. J Vasc Surg 2007;46:1234–41

Subramonia

Lees

. Sensory abnormalities and bruising after long saphenous vein stripping: impact on short-term quality of life. J Vasc Surg 2005;42:510–4

Cox

Wellwood

Martin

. Saphenous nerve injury caused by stripping of the long saphenous vein. Br Med J 1974;1:415–7

10.

Jacobsen

Wallin

. Proximal or distal extraction of the internal saphenous vein? Vasa 1975;4:240–2

11.

Gasser

Pohl

Mildner

. läsionen des nervus saphenus in abhängigkeit von der teknik des strippings. Phlébologie 1995;24:76–7

12.

Eklöf

Rutherford

Bergan

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;40:1248–52

13.

Wainapel

Kim

Ebel

. Conduction studies of the saphenous nerve in healthy subjects. Arch Phys Med Rehabil 1978;59:316–9

14.

Buschbacher

. Sural and saphenous 14-cm antidromic sensory nerve conduction studies. Am J Phys Med Rehabil 2003;82:421–6

15.

Chiodo

Spiegelberg

Tong

. Comparing saphenous nerve conduction study techniques at the knee and at the ankle and their relationship to body mass index. Arch Phys Med Rehabil 2007;88:477–80

16.

Docherty

Morrice

Bell

. Saphenous neuritis following varicose vein surgery. Br J Surg 1994;81:698

17.

Ramasastry

Dick

Futrell

. Anatomy of the saphenous nerve: relevance to saphenous vein stripping. Am Surg 1987;53:274–7

18.

Aigner

Hellerer

Haberkorn

Brückner

. Sensation disorders following saphenous vein excision. Munch Med Wochenschr 1980;122:1305–7

19.

Veverková

Jedlicka

Vlcek

Kalac

. The anatomical relationship between the saphenous nerve and the great saphenous vein. Phlebology 2011;26:114–8

20.

Beale

Mavor

AID

Gough

. Heat dissipation during endovenous laser treatment of varicose veins – is there a risk of nerve injury? Phlebology 2006;21:32–5

21.

Golan

Glenn

. Laser and radiofrequency endovenous ablation of venous reflux. Perspect Vasc Surg Endovasc Ther 2008;20:75–9

22.

Quan

Bird

. Nerve conduction studies and electromyography in the evaluation of peripheral nerve injuries. UPOJ 1999;12:45–51