Unilateral anatomical variation of the ansa cervicalis

Ansa cervicalis: a comprehensive review of its anatomy, variations, pathology, and surgical applications

The ansa cervicalis is a neural loop in the neck formed by connecting the superior root from the cervical spinal nerves (C1-2) and the inferior root descending from C2-C3. It has various anatomical variations and can be an important acknowledgment in specific operations of the neck region. This is a review the anatomy, variations, pathology and clinical applications of the ansa cervicalis.

Intraoperative Hypoglossal Nerve Mapping During Carotid Endarterectomy: Technical Note

BACKGROUND

Hypoglossal nerve deficit is a possible complication caused by carotid endarterectomy (CEA). The accidental injury of the hypoglossal nerve during surgery is one of the major reasons for permanent hypoglossal nerve palsy. In this study, we investigated the usefulness of intraoperative mapping of the hypoglossal nerve to identify this nerve during CEA.

METHODS

Five consecutive patients who underwent CEA for the treatment of symptomatic or asymptomatic carotid artery stenosis were studied. A hand-held probe was used to detect the hypoglossal nerve in the operative field, and the tongue motor evoked potentials (MEPs) were recorded.

RESULTS

The tongue MEPs were obtained in all the patients. The invisible hypoglossal nerve was successfully identified without any difficulty when the internal carotid artery was exposed. Intraoperative mapping was particularly useful for identifying the hypoglossal nerve when the hypoglossal nerve passed beneath the posterior belly of the digastric muscle. In 1 of 2 cases, MEP was also elicited when the ansa cervicalis was stimulated, although the resulting amplitude was much smaller than that obtained by direct stimulation of the hypoglossal nerve. Postoperatively, none of the patients presented with hypoglossal nerve palsy.

CONCLUSIONS

Intraoperative hypoglossal nerve mapping enabled us to locate the invisible hypoglossal nerve during the exposure of the internal carotid artery accurately without retracting the posterior belly of the digastric muscle and other tissues in the vicinity of the internal carotid artery.

Descendens vagohypoglossi: rare variant of the superior root of ansa cervicalis

Knowledge of variants in the formation and position of the ansa cervicalis is important in head and neck surgery, specifically in reconstructions of the tongue that use the infrahyoid muscles, and in the anastomosis of the ansa cervicalis to the recurrent laryngeal nerve when the laryngeal muscles have been paralysed. We describe a rare variant of the superior root of the ansa cervicalis, which had a contribution from the vagus and hypoglossal nerves. The inferior root was formed by the C2 and C3 ventral rami, but it passed medial to the internal jugular vein before it joined the superior root to form the loop.

A case report of complex auricular neuralgia treated with the great auricular nerve and facet blocks

BACKGROUND

The great auricular nerve is a cutaneous branch of the cervical plexus originating from the C2 and C3 spinal nerves. It innervates the skin over the external ear, the angle of the mandible and the parotid gland. It communicates with the ansa cervicalis. Great auricular neuralgia is rarely diagnosed in clinical practice and can be refractory. We present a new approach using ultrasound-guided nerve blocks.

CASE

We present a case of a 41-year-old female with paroxysmal ear pain accompanied by dysautonomia, tingling in the tongue, dysphagia, dysarthria and abdominal symptoms. No significant findings were found on cervical and brain imaging. The patient responded partially to a great auricular nerve block. A combined approach using this block with facet block of C2 and C3 induced a more pronounced and prolonged benefit.

CONCLUSION

Great auricular neuralgia is not often encountered in practice and can be accompanied by symptoms originating from the ansa cervicalis network. A combined approach of nerve blocks can be considered in refractory cases.

Sternocleidomastoid innervation from an aberrant nerve arising from the hypoglossal nerve: a prospective study of 160 neck dissections

BACKGROUND

Anatomical variants of the spinal root of the accessory nerve and cervical plexus are well known but other variants are exceptionally rare.

METHODS

A prospective study of 160 selective neck dissections was undertaken following an index case, where a presumed C1 nerve (travelling with the hypoglossal nerve) was found to innervate sternocleidomastoid (SCM). A search was subsequently made for this variant while not compromising the neck dissection surgery itself. Eight cases could not be included due to metastatic disease precluding safe dissection in this area. A nerve stimulator was used to confirm the motor supply to SCM.

RESULTS

This nerve variant was found in 4/160 necks (2.5 %). In all cases, it originated directly from the hypoglossal nerve and stimulation resulted in isolated SCM contraction. No accessory nerve anomalies were found.

CONCLUSION

This finding adds to the knowledge of variants in this area. Meticulous dissection and preservation of all nerves, where possible, is important for optimising functional outcomes following surgery.