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DOI: 10.1186/1749-7221-5-2
Saphenous neuropathy in a patient with low back pain[*]
Verantwortlicher Herausgeber dieser Rubrik:
Publikationsverlauf
28. August 2009
16. Januar 2010
Publikationsdatum:
19. September 2014 (online)
- Background
- Case presentation
- Conclusion
- Consent
- Competing interests
- Authors’ contributions
- References
Abstract
Saphenous nerve, a pure sensory nerve, may compromise as a result or complication of a surgical procedure or secondary to trauma or insidiously. We present a male patient with low back pain concomitant with pain in medial portion of left thigh in addition to pain and numbness in medial part of leg and inferior part of patella after a strenuous activity. Preliminary diagnosis suggested that the patient had radiculopathy but electrodiagnostic tests revealed the absence of left saphenous response both in medial leg and infrapatellar region, while normal findings were recorded from right side. Needle electromyography in L4 innervated muscles were normal. The patient had saphenous nerve entrapment in left thigh. Two months later symptoms relieved with conservative therapy.
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Background
Saphenous nerve is a pure sensory nerve that is made up of fibers from L3 and L4 spinal segments [[1]]. Because of its long course, it can become entrapped in multiple locations but mostly in two sites: the first site is in adductor canal after the saphenous nerve has split from the femoral artery and courses independently through the fascial channel in the adductor canal, the second site is at the exit point of the saphenous nerve distally in the thigh, where it penetrates the fascial tissue between the sartorius and gracilis muscles [[2]]. This problem may arise as a result or complication of a surgical procedure or secondary to trauma or it may arise insidiously. Primary saphenous neuropathy is uncommon [[3]]. The differential diagnoses of saphenous entrapment are: patellofemoral disorders, suprapatellar plica, tear of medial meniscus, pes tendonopathy, osteochondritis dissecans, nonspecific synovitis and reflex sympathetic dystrophy [[4]]. We present a patient with low back pain that received recommendation for surgery of radiculopathy but had saphenous nerve entrapment in left thigh.
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Case presentation
The patient is a 32-year old athlete man who complained of low back pain concomitant with pain in medial portion of left thigh in addition to pain and numbness in medial part of leg and inferior part of patella. After a strenuous activity, he felt pain in low back area and severe local pain in midportion of thigh accompanied by numbness of infrapatellar area and medial part of leg. His low back pain was reduced after consumption of NSAIDs but numbness continued. In physical examination, sensation to light touch and pinprick in infrapatellar and medial part of left leg was impaired. Manual muscle test and muscle stretch reflexes were normal, and the patient had no pain in straight as well as reversed straight leg raise. MRI of lumbosacral region showed bulging of the L4, L5 and S1 discs.
With impression of radiculopathy, surgical intervention for discopathy was recommended for the patient. Electrodiagnostic tests performed in standard protocol [[5]] by first and second author revealed absence of left saphenous response both in medial leg and infrapattellar region while normal findings were recorded from right side. Needle electromyography was normal in all tested muscles including quadriceps and paraspinal muscles. Neural block was recommended to the patient but he did not accept. Conservative management including Gabapentin was prescribed. Patient’s symptoms relieved after 2 months, and six months later he had no symptom. He refused another Electrodiagnostic study.
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Conclusion
Clinical symptoms and electrodiagnostic findings revealed saphenous nerve entrapment at adductor canal or above this region. Saphenous neuropathy usually presents with pain[[4]] however, sensory complaints may be the presenting symptom. If L4 radiculopathies is caused by far lateral disc protrusion, sensory evoked response of saphenous nerve may be absent due to pressure on sensory ganglion [[6]]. In such cases, needle electromyography in L4 innervated muscles can differentiate between radiculopathy and saphenous neuropathy.
A thorough physical examination is mandatory in patients with low back pain and uncommon neuropathies like saphenous nerve entrapment must be considered.
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Consent
Written informed consent was obtained from the patient for publication of this case report.
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Competing interests
The authors declare that they have no competing interests.
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Authors’ contributions
TA and GR contributed in electrodiagnosis testing. All authors contributed in taking patient history. Physical exam and preparation of the paper. All authors read and approved the final manuscript.
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Cite this article as: Ahadi et al.: Saphenous neuropathy in a patient with low back pain. Journal of Brachial Plexus and Peripheral Nerve Injury 2010 5:2.
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*This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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References
- 1 Dumitru D, Amato AA, Zwarts MJ. Electrodiagnostic medicine. Hanley & Belfos; Philadelphia: Second edition 2002: 843-845 869-870
- 2 Edwards JC, Green TC, Riefel E. Neurilemoma of the saphenous nerve presenting as pain in the knee: a case report. J Bone joint Surg Am 1989; 71: 1410-1 2793898
- 3 Mozes MM, Ouaknine G, Nathan H. Saphenous nervous entrapment simulating vascular disorder. Surgery 1975; 77: 299-303 1129703
- 4 Worth RM, Kettlecamp DB, Defalque RJ, Duane KU. Saphenous nerve entrapment: a cause of medial knee pain. AM J Sports Med 1984; 12: 80-83 10.1177/036354658401200114 6703186
- 5 Wainapel S, Kim OJ, Ebel A. Conduction studies of the saphenous nerve in healthy subjects. Arch Phys Med Rehabil 1978; 59: 316-319 210740
- 6 Locketz AJ. Saphenous nerve conduction studies in suspected L4 radiculopathies: Friend or foe? Case report and literature review. Arch Phys Med Rehabil 2004; 85 9, e23
Corresponding author
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References
- 1 Dumitru D, Amato AA, Zwarts MJ. Electrodiagnostic medicine. Hanley & Belfos; Philadelphia: Second edition 2002: 843-845 869-870
- 2 Edwards JC, Green TC, Riefel E. Neurilemoma of the saphenous nerve presenting as pain in the knee: a case report. J Bone joint Surg Am 1989; 71: 1410-1 2793898
- 3 Mozes MM, Ouaknine G, Nathan H. Saphenous nervous entrapment simulating vascular disorder. Surgery 1975; 77: 299-303 1129703
- 4 Worth RM, Kettlecamp DB, Defalque RJ, Duane KU. Saphenous nerve entrapment: a cause of medial knee pain. AM J Sports Med 1984; 12: 80-83 10.1177/036354658401200114 6703186
- 5 Wainapel S, Kim OJ, Ebel A. Conduction studies of the saphenous nerve in healthy subjects. Arch Phys Med Rehabil 1978; 59: 316-319 210740
- 6 Locketz AJ. Saphenous nerve conduction studies in suspected L4 radiculopathies: Friend or foe? Case report and literature review. Arch Phys Med Rehabil 2004; 85 9, e23