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LETTERS TO THE EDITOR

Inadvertent Femoral Nerve Impalement and Intraneural Injection Visualized by Ultrasound

Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, San Francisco, CA

To the Editor:

We present a case of femoral nerve impalement and subtotal intraneural injection during femoral nerve block (Fig. 1) that was recognized in retrospect after review of the recorded ultrasound imaging (see videos available at www.anesthesia-analgesia.org). A total of 35 mL mixture of 0.5% mepivacaine and 0.25% levobupivacaine was administered via a 22-gauge blunt Quincke tip needle. On follow-up 24 h later, quadriceps function was intact, but sensory block remained, resolving the following day.

View larger version (106K): [in this window] [in a new window]   Figure 1. Short Axis (transverse cross-sectional) ultrasound scan of the inguinal region (left) and the corresponding labeled image (right). (A) The femoral nerve (Femoral Nerve) is shown impaled by a 22-gauge blunt Quincke tip needle (solid line, Needle Path) with the needle tip (Tip) appearing at the underside of the nerve. Local anesthetic spread around the nerve is shown between the large arrowheads. (B) Intraneural injection is shown between small arrowheads. The femoral nerve lies on top of the psoas muscle (Psoas Muscle). Tick marks are spaced 10 mm. Supplemental material available at www.anesthesia-analgesia.org.

The sonographically measured cross-sectional area of the intraneural injection was 7.3 mm² (only 22% of the femoral nerve cross-sectional area). Therefore, the increase in intraneural pressure due to injection likely was within the tolerable pressure range (6,7). Moreover, the femoral nerve increases in caliber along its course in the inguinal region (8), indicating dispersion of nerve fibers within the femoral nerve before separating into its cutaneous and muscular branches. This polyfascicular architecture may have prevented a significant increase in intraneural pressure in our patient.

The present case demonstrates that femoral nerve impalement and intraneural injection of local anesthetic may occur without major adverse sequelae. We hope this report will serve to improve the understanding of these potentially harmful events.

References

1. Frerk CM. Palsy after femoral nerve block. Anaesthesia 1988; 43: 167–8.
2. Rice AS, Andreev NY, McMahon SB. The consequences of microneurography electrode-induced injury of peripheral nerves observed in the rat and man. Pain 1994; 59: 385–93.[Medline]
3. Inglis JT, Leeper JB, Wilson LR, et al. The development of conduction block in single human axons following a focal nerve injury. J Physiol 1998; 513: 127–33.[Abstract/Free Full Text]
4. Noseir RK, Ficke DJ, Kundu A, et al. Sympathetic and vascular consequences from remifentanil in humans. Anesth Analg 2003; 96: 1645–50.[Abstract/Free Full Text]
5. ISO 9626: Stainless steel needle tubing for the manufacturer of medical devices. 1st ed. Geneva: International Organization for Standardization, 1991: 1–2.
6. Gelberman RH, Yamaguchi K, Hollstien SB, et al. Changes in interstitial pressure and cross-sectional area of the cubital tunnel and of the ulnar nerve with flexion of the elbow: an experimental study in human cadavera. J Bone Joint Surg Am 1998; 80: 492–501.[Abstract/Free Full Text]
7. Okutsu I, Hamanaka I, Chiyokura Y, et al. Intraneural median nerve pressure in carpal tunnel syndrome. J Hand Surg [Br] 2001; 26: 155–6.[Medline]
8. Gruber H, Peer S, Kovacs P, et al. The ultrasonographic appearance of the femoral nerve and cases of iatrogenic impairment. J Ultrasound Med 2003; 22: 163–72.[Abstract/Free Full Text]

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				I. Schafhalter-Zoppoth, I. D. Zeitz, and A. Gray Ultrasound Evidence of Intraneural Injection Anesth. Analg., August 1, 2005; 101(2): 611 - 611. [Full Text] [PDF]

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This Article Full Text (PDF) VIDEOS Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schafhalter-Zoppoth, I. Articles by Gray, A. T. Search for Related Content PubMed PubMed Citation Articles by Schafhalter-Zoppoth, I. Articles by Gray, A. T.

Anesthesia & Analgesia® is published for the International Anesthesia Research Society® by Lippincott Williams & Wilkins with the assistance of Stanford University Libraries' HighWire Press®. Copyright 2006 by the International Anesthesia Research Society. Online ISSN: 1526-7598   Print ISSN: 0003-2999