Large branchial arch cyst excision using superficial and deep cervical plexus blocks in a patient with severe comorbidities

Summary

Branchial arches are embryologic structures that develop between the fourth and seventh gestational week. Anomalies may form if these structures fail to develop. The majority of cases are diagnosed during childhood, with surgical excision recommended to prevent risk of infection, growth or malignancy. We report an unusual case of a 72‐year‐old man with severe cardiac comorbidities who presented with a large second branchial arch cyst extending into the oropharynx. General anaesthesia to facilitate surgical excision was deemed too risky. Therefore, we performed successful ultrasound‐guided superficial and deep cervical plexus blocks as a sole mode of anaesthesia. This case highlights how regional anaesthesia can be utilised to facilitate surgery in high‐risk patients, as well as presenting an alternative for general anaesthesia.

Introduction

Branchial arches, also known as pharyngeal arches, are embryologic structures that develop between the fourth and seventh gestational week. They comprise of an external layer of ectoderm and an internal layer of endoderm, called the pharyngeal cleft and pharyngeal pouch respectively. The pharyngeal cleft and pouch will eventually form parts of the face, neck and pharynx. Failures in development of these complex embryologic structures may give rise to anomalies, such as cystic masses of the neck which while uncommon can present in any age group [1]. Complete surgical excision is the recommended treatment option to prevent cystic infection, growth or malignant change. The majority of cases are diagnosed and treated in childhood, and therefore general anaesthesia is usually performed to facilitate surgery.

We present an unusual case of an adult patient with severe cardiac comorbidities requiring surgical excision of a growing branchial cyst. We believe this is the first report of a branchial cyst excision in an adult patient where superficial and deep cervical plexus blocks were used as the sole method of anaesthesia.

Report

A 72‐year‐old man presented with an incompressible, tender mass on the left side of his neck anterior to the sternocleidomastoid. Medical history included severe ischemic cardiomyopathy secondary to a myocardial infarction and atrial fibrillation. Echocardiogram demonstrated regional wall abnormalities, severely dilated left atrium and 25% ejection fraction. Neck computed tomography (CT) scan revealed a second branchial arch cyst close to the external carotid artery, external jugular vein and hypoglossal nerve (Fig. 1). Five months before surgical excision, the patient developed bilateral pulmonary emboli and a lower gastrointestinal bleed. During recovery from these events, the cyst increased in size and repeatedly recurred despite cyst drainage and doxycycline monohydrate treatment. Considering the patient's clinical condition, we offered a regional anaesthesia technique of superficial and deep cervical plexus block.

Figure 1.

Computed tomograph scans demonstrating a 2.9 × 2.3 × 2.2 cm well‐circumscribed mass in the left cervical area in the anterior triangle of the neck, anterior to the sternocleidomastoid (SCM), lateral to external carotid artery (Ext CA) and posterior to external jugular vein (Ext JV). Both superficial and deep cervical plexus blocks were performed in the posterior triangle of the neck.

Block placement was performed in the supine position under aseptic conditions. Ultrasound was performed (Sonosite^® X‐Porte, Bothell, WA, USA) and a linear high frequency probe (13–6 MHz) was used for its high frequency and resolution. Standard monitoring included ECG pulse oximetry and non‐invasive blood pressure monitoring.

The superficial cervical plexus block was performed using ultrasound guidance. The probe was placed at the C6 level on a transverse lie using the cricoid cartilage as a landmark and was slid laterally along the neck until the sternocleidomastoid muscle was identified. A 22 G 50 mm echogenic neurostimulating needle (Pajunk^®, Geisingen, Germany) was inserted until the tip of the needle was deep to the sternocleidomastoid muscle. Twenty millilitres of a eutectic mixture of 10 ml bupivacaine 0.5% and 10 m; mepivacaine 1.5% in a 20 ml syringe was injected in four divided doses over 3–5 minutes.

The deep cervical plexus block was performed using landmarks. The lateral border of the sternocleidomastoid muscle was identified and a line from the mastoid to the clavicle was drawn. The C6 level was identified by palpating the cricoid cartilage and drawing a line laterally until it intersected with the line that connected the mastoid with the clavicle. Marks were made at 2 cm, 4 cm and 6 cm caudal to the mastoid process along the same line representing the C2, C3 and C4 levels respectively. A 25g 90 mm pencil point needle (B.Braun^®, Bethlehem, PA, USA) was introduced at each level until a transverse process was palpated. The needle was withdrawn slightly and 5 ml of a eutectic mixture of mepivacaine 1.5% with bupivacaine 0.5% was injected at each level. Fifteen millilitres of local anaesthetic was injected at all three levels.

Block checks were performed and the procedure was uneventful. The patient was in the supine position for the 1‐h long surgery and did not complain of any pain during the operation. The cyst was completely excised, with histology confirming the branchial arch cyst diagnosis. The patient was observed 3 h post‐surgery and remained stable. He received no sedation throughout the entire case. The patient was discharged on the same day without any pain, nausea or vomiting. In the follow‐up visits, patient reported complete cyst resolution, no clinical complaints and expressed satisfaction with the results and choice of anaesthesia.

Discussion

Branchial arch cysts are the second most common cause of congenital neck masses in childhood. With second arch malformations being the most common, forming up to 95% of all cases [2]. History, examination and imaging are used to aid in diagnosis. Ultrasound usually shows a well‐circumscribed, round to ovoid, anechoic compressible mass with a thin peripheral wall with or without septations which displaces surrounding soft tissues. Computed tomography and magnetic resonance imaging scans demonstrate a well‐circumscribed low‐density mass with a thin uniform wall [1]. The most effective treatment available is complete surgical excision of the cyst. Recurrence is unlikely if the excision is complete, but incision and drainage or inflammatory processes may increase recurrence rates. Currently, cervical plexus blocks are commonly used for carotid endarterectomies, but may also be used to provide analgesia for thyroidectomy, parathyroidectomy, tympanomastoid surgery, cervical discectomy and fusion, oral and maxillary surgery, lymph node dissection, excision of branchial defects and thyroglossal cysts, external ear surgery and vascular access placement [3].

The cervical plexus is formed by the anterior division of cervical spinal nerves from C1 to C4. The superficial branches travel through the deep cervical fascia of the neck at the posterior margin of the sternocleidomastoid muscle and divide into three directions: cephalic, forming the small occipital and great auricular nerves; anterior, forming the transverse cervical nerve; and caudal, forming the suprasternal, supraclavicular and supra‐acromial nerves. The deep branches innervate cervical muscles with the lateral group innervating sternocleidomastoid, trapezius, scalenus medius and levator scapular muscles. The medial group innervates the rectus capitis lateralis, longus capitis, longus colli, rectus capitis anterior and diaphragm [4].

The superficial cervical plexus block is usually placed through a subcutaneous injection of local anaesthetic along the posterior border of the sternocleidomastoid muscle with distribution of local anaesthetic to the ipsilateral side of the neck from the mandible to the clavicle, affecting the supraclavicular, transverse cervical, greater auricular and lesser occipital nerves. The intermediate cervical plexus block is performed by injection of local anaesthetic behind the sternocleidomastoid muscle anterior to the prevertebral fascia, with distribution of local anaesthetic to the ipsilateral side of the neck from the mandible to the clavicle and sternocleidomastoid muscle, involving the supraclavicular, transverse cervical, greater auricular and lesser occipital nerves. Deep cervical plexus blocks are performed by injecting local anaesthetic inside the prevertebral fascia in close proximity to the transverse process of C2–C4 with distribution to the ipsilateral side of the neck from the mandible to the clavicle and the cervical muscles (geniohyoid, sternocleidomastoid muscle, levator scapulae, scalenes and trapezius).

Superficial and deep cervical plexus blocks were placed due to operator preference. The neck was scanned after the superficial cervical plexus block was placed and the local anaesthetic tracked medially and deep to the carotid artery in the plane where the intermediate cervical plexus block would have been performed.

Complications of cervical plexus block include paroxysmal coughing, anxiety, shortness of breath, agitation, hemidiaphragmatic paresis, airway obstruction, seizures and tachycardia as a result of intravascular injection and local anaesthetic toxicity. Additionally problems of hoarseness, dysphagia, stellate ganglion block and Horner's syndrome have been highlighted [5]. Phrenic nerve paralysis may occur following deep cervical plexus block due to spread of local anaesthetic into the prevertebral fascia and ventral rami of C3, C4 and C5. Another possible complication is paralysis of the vagus or hypoglossal nerve causing mechanical obstruction of the airway [3]. Complications of the technique are more related to the deep cervical plexus block when compared with the superficial or intermediate blocks. These complications include intrathecal or intravascular injection, respiratory problems due to phrenic nerve paralysis or local anaesthetic toxicity. A systematic review comparing superficial vs. deep cervical plexus block complications concluded that the deep block is more than twice as likely to yield life‐threatening complications, although the incidence of block‐related complications is low for all blocks [6].

Cervical plexus blocks can be performed expeditiously using minimal resources and is safe and effective [7]. Regional anaesthesia also allows for day case procedures and quicker recovery. Limitations of cervical plexus block include that the patient must have the ability to stay still for the duration of the procedure. The patient is usually in a supine, semi‐sitting (with head turned to the contralateral side) or lateral decubitus position. The patient's comfort and limitations must be taken into consideration during positioning. In obese patients, the posterior border of the sternocleidomastoid muscle can be difficult to identify. Additionally, deep cervical plexus block can be technically demanding since the needle is advanced close to critical anatomical structures, such as the spinal canal and the vertebral vessels [7].

Cervical plexus blocks should be considered when patients are deemed to be high risk for general anaesthesia. In this case, the patient had a history of severe ischaemic cardiomyopathy secondary to a myocardial infarction, atrial fibrillation, bilateral pulmonary emboli and a lower gastro‐intestinal bleed. This technique was successful in removing a branchial arch cyst in a patient who was multimorbid. The superficial and deep cervical plexus blocks were a safe and reliable method for excision of a branchial arch cyst.

In conclusion, we report the first case of a multimorbid adult patient undergoing branchial arch cyst excision using superficial and deep cervical plexus blocks as the sole method of anaesthesia. We have demonstrated the versatile use of regional blocks. We encourage anaesthetists to undertake appropriate training in order to increase their skill mix, allowing more patients to undergo selected surgery with regional anaesthesia as the sole mode of anaesthesia.