Anesth Analg 2007;105:286-287
© 2007 International Anesthesia Research Society
doi: 10.1213/01.ane.0000263024.41266.2e
LETTER TO THE EDITOR
Lateral or Posterior Popliteal Approach for Sciatic Nerve Block: Difference is Related to the Anatomy
Xavier March, MD,
Olga Pineda, MD,
Dolores Caramés, MD,
Antonio Villalonga, PhD, and
Dr Joseph Trueta
Servei d'Anestèsia; Reanimació i Terapèutica del Dolor; Hospital Universitari de Girona (March, Pineda, Caramés, Villalonga)
Girona, Spain; ane.xmarch{at}htrueta.scs.es (Trueta)
In Response:
We thank Risch et al. (1) and Palmisani et al. (2) for their comments on our article. In response to Risch et al., we clearly state that nerve stimulation of the sciatic nerve was performed 10 cm from the popliteal skin crease, after the recommendations made in the study of Vloka et al. (3) in cadavers.
As Vloka et al. show, injection at this point ensures placement of the needle in the vicinity of, or proximal to, the separation of the sciatic nerve. Although Borgeat et al. (4) have found a high level of clinical efficacy in using the apex of the popliteal fossa as the injection site, we believe that anatomic confirmation should be sought from cadavers that this point corresponds to the division of the sciatic nerve. Our study (5) which compared a single- versus a double-injection technique, must be based on a reference point validated by anatomical observation. The time between the two injections in the double stimulation group is not recorded but the total performance time, which is provided, is low. In practice, when the first injection is completed, the second injection is begun immediately.
Although it is true that multiple nerve stimulation theoretically has a greater risk of injury, in practice this has not been demonstrated (6).
Despite the comments by Palmisani et al. (2) we believe that the single-injection technique is as successful using a posterior approach as a lateral approach. For example, Borgeat et al. (4) use only the posterior approach, in their study of 500 patients, and had a 94% success rate. The difference in efficacy in single injection between the studies of Borgeat et al. (4), Arcioni et al. (7), and our own may well be explained by the difference in dose. While we used 25 mL of mepivacaine 1%, Arcioni et al. used 30 mL of ropivacaine 0.75% and Borgeat et al. used 40–50 mL of ropivacaine 0.5%.
The tibial response, plantar flexion or inversion, should be considered as the motor response of choice when a single injection sciatic nerve block in the popliteal fossa is performed. This is supported by the most recent clinical studies (8) and through the magnetic resonances of two volunteers in the study of Arcioni et al. (7).
We believe that, as our study shows, the use of a double injection of the sciatic nerve has advantages when working with low doses.
REFERENCES
- Risch M, Blumenthal S, Borgeat A. Is the double-injection technique really needed? Anesth Analg 2007;104:285–6.
- Palmisani S, Ronconi P, De Blasi RA, Arcioni R. Lateral or posterior popliteal approach for sciatic nerve block: difference is related to the anatomy. Anesth Analg 2007;104:286.
- Vloka JD, Hadzic A, April E, Thys DM. The division of the sciatic nerve in the popliteal fossa: anatomical implications for popliteal nerve blockade. Anesth Analg 2001;92:215–7.[Abstract/Free Full Text]
- Borgeat A, Blumenthal S, Karovic D, et al. Clinical evaluation of a modified posterior anatomical approach to performing the popliteal block. Reg Anesth Pain Med 2004;29:290–6.[Web of Science][Medline]
- March X, Pineda O, Garcia MM, et al. The posterior approach to the sciatic nerve in the popliteal fossa: a comparison of single- versus double-injection technique. Anesth Analg 2006;103:1571–3.[Abstract/Free Full Text]
- Fanelli G, Casati A, Garancini P, Torri G. Nerve stimulator and multiple injection technique for upper and lower limb blockade: failure rate, patient acceptance, and neurologic complications. Anesth Analg 1999;88:847–52.[Abstract/Free Full Text]
- Arcioni R, Palmisani S, Della Rocca M, et al. Lateral popliteal sciatic nerve block: a single injection targeting the tibial branch of the sciatic nerve is as effective as double-injection technique. Acta Anaesthesiol Scand 2007;51:115–21.[Web of Science][Medline]
- Taboada M, Cortes J, Rodriguez J, et al. Lateral approach to the sciatic nerve block in the popliteal fossa: correlation between evoked motor response and sensory block. Reg Anesth Pain Med 2003;28:450–5.[Web of Science][Medline]
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