Injury of cutaneous branches of the femoral nerve following varicose vein surgery

Abstract

The majority of operations carried out for varicose veins (VV) are entirely straightforward and complications are usually concentrated on minor vascular damage or nerve injury [1]. Injury to small sensory nerve branches in the skin is extremely common and largely unavoidable when veins are stripped or avulsed. This can result in small patches of numbness, burning or altered skin sensation close to surgical scars or where VVs have been avulsed. Here, we describe the neurophysiological and ultrasonographic findings in a patient with intermediate and medial femoralcutaneous nerves (IFCN and MFCN) damage following crossectomy and stripping of the great saphenous vein. The patient was a 40-year-old woman affected by VV in stage II according to Widmer clinical classification. Doppler ultrasound showed an incompetent sapheno-femoral junction and great saphenous veins reflux in right leg. She underwent crossectomy and stripping of the great saphenous vein from just below the knee to the inguinal area. Immediately after the surgical procedure, the patient reported numbness over the anterior-medial aspect of the right thigh. 6 months later, she was admitted to our department. Neurological examination showed sensory loss in the lower two-thirds of the anterior-medial thigh, but normal muscle strength. Electrodiagnostic study of the MFCN was performed according to the technique of Lee et al. [2] (Fig. 1a). The sensory action potential of the MFCN of the right thigh could not be elicited, whereas that of the left thigh had amplitude of 6.8 uV and conduction velocity of 67 m/s (Fig. 1b). There were no abnormalities of motor femoral and saphenous nerves conduction. Both IFCN and MFCN could be easily visualized by ultrasonography (fq 4–13 MHz linear probe) below the inguinal ligament (Fig. 1c). On both limbs, the cross-sectional area of the two nerves was 4 mm, whereas the echotexture of nerves was altered in the affected thigh. In particular, the IFCN and MFCN of the right limb were hypoechoic and the physiological fascicular echotexture appeared rarefied or almost lost. In the available literature, there are papers illustrating saphenous, peroneal, tibial or sural nerve damage after VV surgery. Really, nerves of the thigh are also at risk during VV surgery. Two studies were carried out with the aim to clinically evaluate the incidence and the extent of sensory abnormalities following VV surgery [3, 4]. Overall, numbness and paresthesia occurred in 7 out 63 and 8 out 62 limbs at the thigh, respectively. These results demonstrate a fairly frequent impairment of the cutaneous nerves of the thigh following VV surgery. IFCN and MFCN originate from the femoral nerve below the inguinal ligament. IFCN pierces the fascia lata about 7.5 cm below the inguinal ligament, and divides into two branches which descend in immediate proximity along the forepart of the thigh, to supply the skin as low as the front of the knee. MFCN crosses the femoral artery at the apex of the femoral triangle and divides into anterior and posterior branches. The anterior branch innervates the anterior medial thigh, and the posterior branch innervates the medial aspect. The distribution of cutaneous nerves in the thigh is important in the analysis of nerve injuries following VV surgery: in the groin and upper thigh, the ilioinguinal nerve (and to a lesser extent, the femoral branch of the genitofemoral F. Ginanneschi (&) A. Rossi Department of Neurological, Neurosurgical and Behavioural Sciences, Neurology and Clinical Neurophysiology unit, University of Siena, Viale Bracci 1, 53100 Siena, Italy e-mail: ginanneschi@unisi.it