Does Interneural Local Anesthetic Spread at the Site of Sciatic Nerve Bifurcation Shorten Block Onset Time?

Following foot and ankle surgery, ultrasound-guided sciatic nerve block (SNB) at the popliteal fossa decreases post-operative pain and opioid consumption. At the popliteal fossa, the sciatic nerve bifurcates to form the Common Peroneal Nerve (CPN) and Tibial Nerve (TN). Studies have shown that when both branches are blocked separately distal to the bifurcation site, block onset time is reduced by 30%. Through clinical observation, the investigators found that onset time is further shortened when ultrasound-guided SNB is performed at the site of bifurcation. This is because the local anesthetic spreads interneurally. The purpose of this study is to compare the block onset time of an ultrasound-guided sciatic nerve block at the site of nerve bifurcation with the blockade of each terminal nerve separately (TN and CPN) distal to sciatic nerve bifurcation.

Study Overview

• Status: Completed
• Conditions: Post Operative Analgesia; Regional Anesthesia; Sciatic Nerve Block
• Intervention / Treatment: Procedure: Distal; Procedure: Interneural

• Study Type: Interventional
• Enrollment (Actual): 88
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5T 2S8
      • Toronto Western Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• ASA physical status I-III
• 18-85 years of age, inclusive
• 50-120 kg, inclusive
• 150 cm of height or greater

Exclusion Criteria:

• Contraindications to sciatic nerve block (e.g., allergy to local anesthetics, coagulopathy, malignancy or infection in the popliteal area)
• Significant peripheral neuropathy or neurological disorder affecting the lower extremity
• Pregnancy
• History of alcohol or drug dependency/abuse
• History of significant psychiatric conditions that may affect patient assessment

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Distal; Blockade of both terminal branches of Sciatic nerve separately, distal to bifurcation	Procedure: Distal; Blockade of both terminal branches of Sciatic nerve separately, distal to bifurcation
Active Comparator: Interneural; sciatic nerve blockade at the site of bifurcation	Procedure: Interneural; Sciatic nerve blockade at the site of bifurcation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Block onset Time	We aim to compare the block onset time of an ultrasound-guided sciatic nerve block at the site of nerve bifurcation resulting in interneural spread of local anesthetic with that of blockade of each terminal nerve separately (TN and CPN), distal to sciatic nerve bifurcation. We hypothesize that sciatic nerve blockade at the site of bifurcation with interneural local anesthetic spread within a common epineural sheath results in shorter onset time compared to blockade of each terminal nerve distal to sciatic nerve bifurcation.	every 5 minutes up to 45 minutes of the block or until surgery starts

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Extent of longitudinal local anesthetic solution spread		starting at block administration till 5 minutes after complete injection
Nerve diameter prior to and following injection		starting at block administration till 5 minutes after complete injection
Block procedure time		starting at block administration till complete injection(up to 10 minutes)
Number of skin punctures required.		starting at first attempt of block administration till complete injection(up to 10 minutes)
Block success rate		starting after complete injection up to 45 minutes
Incidence of block-related complications	Incidence of block-related complications (vascular puncture, hematoma formation, intravascular injection and post-operative neurologic deficit) will be documented, but due to the very low incidence in all block-related complications, this study is not powered to show a difference in safety	immediately , at 24 hours and Post operative day 7
Postoperative pain	Postoperative pain: Postoperative pain using a verbal rating score (0-10, where 0= no pain, 10=excruciating pain) at 0, 30, 60, 90 and 120 min upon admission to post-anesthetic care unit.	starting at patient's arrival at post-anesthetic care unit till 120 minutes

Collaborators and Investigators

• Sponsor: University Health Network, Toronto
• Investigators: Principal Investigator: Anahi Perlas, MD, FRCPC, University of Toronto

Study record dates

Study Major Dates

• Study Start: July 1, 2011
• Primary Completion (Actual): June 1, 2013
• Study Completion (Actual): June 1, 2013

Study Registration Dates

• First Submitted: March 6, 2012
• First Submitted That Met QC Criteria: March 29, 2012
• First Posted (Estimate): April 2, 2012

Study Record Updates

• Last Update Posted (Actual): December 5, 2017
• Last Update Submitted That Met QC Criteria: December 1, 2017
• Last Verified: December 1, 2017

More Information

Terms related to this study

• Keywords: Regional anesthesia; Sciatic nerve block; foot surgery; ankle surgery; Interneural local anesthetic
• Other Study ID Numbers: 11-0059-A