Ultrasound-guided Precise Superficial Cervical Plexus Block

Study Overview
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Brief Summary
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This prospective, randomized, observer-blinded study compared ultrasound-guided superficial cervical plexus block positioned by the great auricular nerve or conventional landmark technique.

Detailed Description
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Ultrasound guidance has become a reliable adjunct for brachial plexus, femoral, and sciatic nerve blocks. Furthermore, US can also be used to anesthetize purely sensory nerves such as the lateral femoral cutaneous and saphenous nerves. The superficial cervical plexus (SCP), a sensory neural plexus, supplies the skin overlying the ear, neck, angle of the mandible, shoulder, and clavicle. Traditionally, the SCP is blocked using a subcutaneous infiltration of local anesthetics along the posterior border of the sternocleidomastoid muscle. Unlike brachial plexus, sciatic nerve, etc., the SCP often cannot be displayed directly under ultrasound. The purpose of ultrasound guidance was to inject the local anesthetic solution into the correct intermuscular plane between the sternocleidomastoid and scalene muscles. In previous studies, the midpoint of the posterior border of the sternocleidomastoid muscle was often selected as the puncture point. Studies of ultrasound-guided superficial cervical plexus block are mostly unsatisfactory. Ultrasound guidance does not increase the success rate of SCP block compared with traditional technique. The conventional landmark ultrasound guidance technique (LM group) selects the midpoint of the posterior border of the sternocleidomastoid muscle as the puncture point, but the anatomical difference of the individual cannot be considered. It may be the reason why ultrasound guidance cannot improve the success rate of the SCP block. The great auricular nerve is the largest branch of the SCP and can be identified under ultrasound. This study intends to indirectly locate the SCP by ultrasound scanning of the point where the great auricular nerve emerges the posterior border of the sternocleidomastoid muscle (GAN Point). The method of precise SCP block at GAN Point under ultrasound guidance (GAN Group) was explored and compared with the LM Group.

Official Title
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A Randomized Controlled Clinical Trial of Ultrasound-guided Superficial Cervical Plexus Block Positioned by the Great Auricular Nerve or Conventional Landmark Technique

Conditions
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Superficial Cervical Plexus Block

Intervention / Treatment
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* Procedure: Conventional landmark technique
* Procedure: Precise block technique


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients of American Association of anesthetists（ASA）Grade 1、2 or 3 Patients undergoing neck and shoulder surgery Exclusion Criteria: Communication barriers, unable to objectively describe symptoms Nerve block contraindicated

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Randomize, double blind, prospective
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: LM group<br>LM group use conventional landmark technique, which selects the midpoint of the posterior border of the sternocleidomastoid muscle as the puncture point of superficial cervical plexus block | Procedure: Conventional landmark technique<br>* inject at the midpoint of the posterior border of the sternocleidomastoid muscle<br>|
| Experimental: GAN Group<br>This group firstly locate the superficial cervical plexus by ultrasound scanning of the point where the great auricular nerve emerges the posterior border of the sternocleidomastoid muscle (GAN Point). GAN Group apply the precise block technique, selects the GAN Point as the puncture point of superficial cervical plexus block | Procedure: Precise block technique<br>* inject at the point where the great auricular nerve emerges the posterior border of the sternocleidomastoid muscle<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of block success rate in each group | Sensory blockade of the lesser occipital, greater auricular, transverse cervical, and supraclavicular nerves was graded according to a 3-point scale using a pinprick test: 2 = no block, 1 = analgesia (patient can feel touch, not pain), 0 = anesthesia (patient cannot feel touch). We considered a block to be successful if, at 15 mins, a score of 0 or 1 was achieved for each of the 4 nerves. | up to 15minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of onset time of success block in each group | onset time means time interval from completion of injection to block score of 0(patient cannot feel touch) or 1(patient can feel touch, not pain) | up to 15minutes | 
| Comparison of pain score after surgery at PACU in each group | Use NRS score to assess pain level, The Numeric Rating Scale (NRS-11) is an 11-point scale for patient self-reporting of pain. 0 means no pain, 1-3 means mild pain, 4-6 means moderate pain, 7-10 means severe pain. | Day of surgery, Arrival time of PACU | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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great auricular nerve, sternocleidomastoid muscle, ultrasound guidance