Schwannoma in head and neck: preoperative imaging study and intracapsular enucleation for functional nerve preservation

Abstract

Purpose: In treating schwannoma patients, it is critical to determine the origin of the tumor to preserve nerve function. We evaluated the validity of preoperative imaging studies in distinguishing the neurological origin of the schwannomas of the head and neck, and the efficacy of intracapsular enucleation in preserving nerve function.

Materials and methods: In 7 cases of schwannomas in the head and neck region, we predicted whether the tumor originated from the vagus nerve or the cervical sympathetic chain through imaging studies including computed tomography (CT) and magnetic resonance imaging (MRI). All patients were performed intracapsular enucleation, and the function of the vagus nerve and the sympathetic nerve was evaluated preoperatively and postoperatively.

Results: Preoperative imaging studies showed 6 cases where the tumor was located between the carotid artery and the internal jugular vein, and 1 case where the tumor was located posteriorly, displacing the carotid artery and the internal jugular vein anteriorly. At the time of operation, we confirmed schwannoma originating from the vagus nerve on the first 6 cases, and schwannoma originating from the sympathetic nervous system on the last case. All patients went through successful intracapsular enucleation, and of the seven schwannoma cases, 6 patients maintained normal postoperative neurological function (85.7%).

Conclusion: Preoperative imaging studies offer valuable information regarding the location and origination of the tumor, and intracapsular enucleation helped us to preserve the nerve function.

Fig. 1

Neck CT image of a vagal schwannoma patient. Tumor (asterisk) is separating the common carotid artery (white arrow) anteriorly and internal jugular vein (arrow head) posteriorly.

Fig. 2

Neck CT image of a sympathetic schwannoma patient. Tumor (asterisk) is anteriorly displacing the common carotid artery (white arrow) and internal jugular vein (arrow head) together without separating them.

Fig. 3

Operative findings (A and B) and specimen (C) of a vagal schwannoma patient. (A) A vagal schwannoma that surrounded the capsule exposed. (B) After confirming that the nerve fibers surrounded the tumor, intracapsular enucleation was performed as the tumor was carefully dissected from the capsule without any damages given to the nerve fibers. (C) A photograph of the schwannoma specimen. About 1cm sized rounded mass without the capsule is observed.

Fig. 4

Operative findings (A-C) and specimen (D) of a sympathetic schwannoma patient. (A) A sympathetic schwannoma that surrounded the capsule exposed. (B) A vertical incision parallel to the direction of the nerve was made on the capsule. (C) Tumor was enucleated by preserving the neural pathway using the microsurgical technique. (D) A photograph of multiple schwannoma specimens. About 6 cm sized yellowish mass like fat tissue without the capsule is observed.