Author(s): Alexander M Senk, MD, Mark Volker, MD, Grant Gustafson, DO, Dillon Welch
Originally published: October 22, 2013 Last updated: December 29, 2022
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Disease/ Disorder

Definition

The lower abdominal wall, hip, thigh and knee are affected by neuropathies of the iliohypogastric, ilioinguinal, genitofemoral, femoral, lateral femoral cutaneous, and obturator nerves.

Etiology, Epidemiology including risk factors and primary prevention

Proximal-Lower-Extremity-Mononeuropathies-Table-1Download

Patho-anatomy/physiology

Proximal-Lower-Extremity-Mononeuropathies-–-Table-2Download

Specific secondary or associated conditions and complications

Proximal muscle weakness can cause instability around the hip and knee, resulting in falls. Progression of mobility after a trauma may be delayed because of unrecognized neurologic lesions. Protective postures because of neuropathic pain may lead to hip flexion contractures. Complex regional pain syndrome may develop.

Essentials of Assessment

History

Patients often present with an acute pelvic fracture, blunt trauma around the ASIS or groin, or after inguinal herniorrhaphy, hip surgery, pelvic surgery, obstetric surgery, or vascular catheterization. Injury may not initially be identified because of acute injury or surgery. Patients present with numbness or weakness in the anatomic nerve distribution.

Patients with meralgia paresthetica present with numbness, paresthesias and pain in the anterolateral aspect of the thigh as a result of damage to the lateral femoral cutaneous nerve.

Physical examination

Generally, mononeuropathies of these nerves will result in pain or abnormal sensation in the cutaneous distributions listed above. Other physical exam findings are as follows:

Proximal-Lower-Extremity-Mononeuropathies-–-Table-3Download

Functional assessment

Pain from traumatic injury, such as fractures and orthopedic restrictions, may initially mask nerve injury symptoms. As recovery ensues, symptoms become apparent. A persistent forward-flexed posture may be observed because of pain from neural tension. Internal hip rotator weakness may cause extremity to externally rotate during ambulation and cause a circumducted gait. Femoral and obturator weakness interferes with transfers, such as lifting the limb in and out with bed, bathtub, and stair use.

Imaging

Plain radiographs should be obtained in traumatic injury to assess for fractures of the pelvis or proximal femur, to detect bony exostosis, heterotopic ossification, or tumor that impinges on the course of the nerves. Computerized tomography can show bony lesions in greater detail. Magnetic resonance imaging provides detailed visualization of anatomic structures, such as tumor and hematoma, along with direct visualization of nerves and signal change associated with denervated muscle or nerve injury.15 Ultrasonography can visualize nerves and help localize injury location. An injured lateral femoral cutaneous nerve will show significantly larger diameter on ultrasound than on the asymptomatic side.16

Considerations in MRI and US evaluation:

Proximal-Lower-Extremity-Mononeuropathies-–-Table-4Download

Supplemental assessment tools

Electrodiagnostic testing is very useful in identifying the lesion, localizing level of injury, assessing the severity and chronicity, and is critical in evaluating plexus or root lesions in trauma or iatrogenic injury.

Proximal-Lower-Extremity-Mononeuropathies-–-Table-5Download

Professional issues

Iatrogenic injury to proximal nerves is very common in many pelvic and orthopedic procedures. Patients can be reassured that in most cases good recovery can be expected. Discussion of the possibility of such injuries should be part of routine discussion of operative risks. Recurrent injuries, however, warrant examination of intraoperative procedures, particularly in the employment of self-retaining retractors and patient positioning.

Rehabilitation Management and Treatments

Available or current treatment guidelines

  • Typically treated conservatively with activity modification, bracing, physical therapy, and pain control.25
    • Bracing: When quadriceps weakness is severe, a knee-ankle-foot orthosis with a few degrees of ankle plantar flexion can assist the extension moment at the knee.
    • Physical Therapy: To compensate for quadriceps weakness, the patient can be trained to activate the gluteus maximus, hamstring muscles, and the gastroc-soleus muscles during stance phase to assist knee extension.
    • Pain control: Medications, such as tricyclic antidepressants and anticonvulsants, and topical agents, such as lidocaine and capsaicin, can be prescribed. Transcutaneous electrical nerve stimulation or acupuncture may be useful.
  • If not responding to conservative management, US guided perineural injections can be diagnostic and therapeutic.4,24
    • In the case of lateral femoral cutaneous nerve, US guided hydrodissection has been shown to be equally effective as surgery.26
  • Surgical exploration and neurolysis should be considered if there is no improvement after 3 to 6 months of conservative management.10,27
  • If due to a compressive lesion from tumor/mass, consider surgical decompression. Hematoma may require correction of anticoagulation and urgent drainage. Correction of hernias can relieve compression.

Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills

  • When assessing a patient with a traumatic injury to the pelvis, keep a high index of suspicion for neurologic injury, particularly because such injuries can easily be masked by pain, orthopedic restrictions, and altered mental status or sedation.
  • Likewise, in patients who have had lower abdominal, obstetric, or pelvic surgeries, any unexpected pain, weakness, or delay in progress should raise suspicion for nerve damage.
  • EMG can aid in differentiating neurologic injury from deficits because of orthopedic injury. It can also assist in localizing the level of the lesion, severity, and prognosis.

Cutting Edge/ Emerging and Unique Concepts and Practice

Computed tomography (CT)-guided diagnostic and therapeutic perineural injections are becoming increasingly common for chronic pelvic pain.28

Radiofrequency ablation and peripheral nerve stimulation are being explored as alternative interventions for proximal lower extremity nerve entrapments.29,30

Gaps in the Evidence-Based Knowledge

Imaging of peripheral nerves around the hip and pelvis is challenging due to their small size, variable course and the complexity of the associated anatomy. Additionally, electrophysiologic studies are challenging due to the depth of the nerves and their complex and variable courses. Ultrasound and magnetic resonance imaging (MRI) are currently used to visualize these nerves but the results remain operator dependent.

References

  1. Bohrer, J., Walters, M., Park, A., Polston, D., & Barber, M. (2009). Pelvic nerve injury following gynecologic surgery: A prospective cohort study. American Journal of Obstetrics and Gynecology, 201(5), 531.e1-531.e7.
  2. Cardosi, R., Cox, C., & Hoffman, M. (n.d.). Postoperative neuropathies after major pelvic surgery. Obstetrics and Gynecology, 100(2), 240-244.
  3. Shin, J., & Howard, F. (n.d.). Abdominal wall nerve injury during laparoscopic gynecologic surgery: Incidence, risk factors, and treatment outcomes. Journal of Minimally Invasive Gynecology, 19(4), 448-453.
  4. Matičič, U.B., Omejec, G., Salapura, V., & Snoj, Ž. (2021). Ultrasound-guided injections in pelvic entrapment neuropathies. Journal of Ultrasonography, 21(85), 139-146.
  5. Zannoni, M., Luzietti, E., Viani, L., Nisi, P., Caramatti, C., & Sianesi. (n.d.). Wide resection of inguinal nerves versus simple section to prevent postoperative pain after prosthetic inguinal hernioplasty: Our experience. World Journal of Surgery, 38(5), 1037-1043.
  6. Elkins, N., Hunt, J., & Scott, K. (n.d.). Neurogenic Pelvic Pain. Physical Medicine and Rehabilitation Clinics of North America, 28(3), 551-569.
  7. Yang, I. (n.d.). Neurovascular Injury in Hip Arthroplasty. Hip & Pelvis, 26(2), 74-78.
  8. Clarke-Pearson, D., & Geller, E. (n.d.). Complications of hysterectomy. Obstetrics and Gynecology, 121(3), 654-673.
  9. Gibelli, F., Ricci, G., Sirignano, A., Bailo, P., & De Leo, D. (2021). Iatrogenic femoral nerve injuries: analysis of medico-legal issues through a scoping review approach. Annals of Medicine and Surgery, 72, 103055.
  10. Craig, A., Richardson, J., & Ayyangar (2016). R. Braddom’s Physical Medicine and Rehabilitation, 41, 907-942.e4
  11. Craig, A. (n.d.). Entrapment neuropathies of the lower extremity. PM&R: The Journal of Injury, Function and Rehabilitation, 5(5 Suppl), S31-S40.
  12. Triplett, J.D., Robertson, A., & Yiannikas, C. (2019). Compressive Lateral Femoral Cutaneous Neuropathy Secondary to Sartorius Muscle Fibrosis. JAMA Neurology, 76(1), 109-110.
  13. Hayat, G., & Calvin, J.S. (2021). Electrodiagnostic Assessment of Uncommon Neuropathies. Neurologic Clinics, 39(4), 957-981.
  14. Refai, N.A., & Tadi, P. (2020). Anatomy, Bony Pelvis and Lower Limb, Thigh Femoral Nerve.
  15. Stoller, D.W., Rosenberg, Z.S., Cavalcanti, C., et al. (2007) Entrapment neuropathies of the lower extremity. Magnetic Resonance Imaging in Orthopaedics and Sports Medicine, 1051-1098.
  16. Aravindakannan, T., & Wilder-Smith, E.P. (2011). High-resolution ultrasonography in the assessment of meralgia paresthetica. Muscle Nerve, 45, 434-435.

Original Version of the Topic

Anita S.W. Craig, DO. Proximal lower extremity mononeuropathies. 10/22/2013

Previous Revision(s) of the Topic

Brionn K. Tonkin, MD, Deborah Hudleston, MD, Alexander M Senk, MD. Proximal lower extremity mononeuropathies. 9/6/2018

Author Disclosure

Alexander M Senk, MD
Nothing to Disclose

Mark Volker, MD
Nothing to Disclose

Grant Gustafson, DO
Nothing to Disclose

Dillon Welch
Nothing to Disclose