The Efficacy of Intermediate Cervical Plexus Block Versus Cutaneous and Thyroid Capsular Blocks

Regional techniques of anesthesia may help to decrease post-operative pain and reduce systemic analgesic requirement. Classically, the cervical plexus is considered to have two distributions, the superficial cutaneous and the deep motor nerves.

Anatomically, the thyroid gland has an inner true capsule which is thin and adheres closely to the thyroidal tissue [Fancy et al., 2010]. External to this is a false capsule formed by the middle layer of the deep cervical fascia, which splits anterolaterally to ensheathe the thyroid gland, thus forming the thyroid sheath [Bliss et al., 2000]. In this fashion, the potential space called the capsule-sheath space is formed. It contains also loose connective tissue, blood vessels, nerves and parathyroid gland. Anesthetic deposited in this space would block the surface of thyroid gland and permeate directly into the parenchyma producing effective local anesthesia for thyroid surgical procedures. It is supposed also to involve autonomic nerve block of the thyroid gland [Fliers et al., 2010]. Additionally, a subcutaneous injection along the sternocleidomastoid muscle (SCM) would also enhance effective local anesthesia for the initial skin incision and further contribute to a more ideal working environment for the surgeon. Therefore, anesthetic technique termed ultrasound-guided capsule-sheath space block (CSSB) combined with anterior cervical cutaneous nerves block (CCNB) for thyroidectomy is done [Wang et al., 2015] .

Our hypothesis is that a combination of simple dual techniques including superficial cutaneous block to provide sensory blockade, and surgeon mediated capsular block may afford autonomic thyroid blockade. In comparison, ultrasound guided intermediate cervical plexus block may provide these blocks but using a machine and deep penetration possibly involving unwanted blocks for phrenic and recurrent laryngeal nerves. So, if the simple safe technique can provide the same intra and postoperative anesthetic conditions it will be preferred.

Inclusion criteria

• American Society of Anesthesiologists physical status grade I and grade II.
• Euthyroidism after thyroid function tests

Exclusion criteria

• Patient refusal.
• Thyroid gland more than 5 cm size.
• Retrosternal extension.
• Planned block neck dissection.
• Neuromuscular diseases
• Hematological diseases.
• Bleeding diseases.
• Coagulation abnormality.
• Psychiatric diseases.
• Drug abuse.
• Local skin infection
• sepsis at site of the block.
• Known intolerance to the study drugs.
• Body Mass Index > 40 Kg/m2.
• Known diaphragmatic motion abnormalities
• major respiratory disease.
• Previous history of cervical surgery.