Revisiting the surgical corridors for cervical Type IIb-c dumbbell neurofibroma: A series of two unconventional approaches and review of literature

Lateral Displacement of the Phrenic Nerve in C5 Tumors

BACKGROUND AND OBJECTIVES

Nerve sheath tumors of the brachial plexus frequently distort the local anatomy, increasing the difficulty of safe exposure and resection. However, lateral displacement of the phrenic nerve has not been previously described. The purpose of this study was thus to illustrate the abnormal lateral displacement of the phrenic nerve in 2 cases of patients undergoing brachial plexus tumor resection and provide a possible mechanism for this observation.

METHODS

Two patients underwent surgical resection of clinically progressing C5 schwannomas. During exposure, the phrenic nerve was found to be significantly more superficial and lateral than typical. This structural relationship persisted even after complete resection of the lesion. Both patients did well postoperatively.

RESULTS

The phrenic nerve traverses along the anterolateral aspect of the anterior scalene. However, in these 2 cases of C5 nerve sheath tumors, the phrenic was found to be significantly more lateral and superficial than usual, draping across the medial aspect of the tumor. We believe that the C5-phrenic communicating branch may act as a functional tether that mobilizes the phrenic nerve laterally as the tumor grows. The mass effect on the anterior scalene by the underlying C5 tumor may further contribute to the anterolateral and superficial displacement of the nerve.

CONCLUSION

The phrenic nerve may be seen markedly more laterally and superficially displaced in cases of C5 nerve sheath tumors. It is important for surgeons who operate on lesions of the brachial plexus to be aware of this phenomenon.

Vertebral artery is an anatomical landmark in the posterior unilateral resection of cervical benign nerve sheath tumors with dumbbell extension of Eden type 2 or 3

Background

In the cervical nerve sheath tumor (NST) surgery with dumbbell extension of Eden type 2 or 3, selection of anterior, posterior, or combined approach remains controversial.

Objectives

This technical note aimed to propose possible advantages of the posterior unilateral approach (PUA). Methods: Six patients who underwent the surgical treatment of cervical NSTs with dumbbell extension of Eden type 2 or 3 were included. The critical surgical steps included (1) complete separation of extradural and intradural procedures, (2) careful peeling of the neural membranes (epineurium and perineurium) from the tumor surface in the extradural procedure, (3) complete removal of the extradural tumor within the neural membranes, (4) intradural disconnection of tumor origin, and (5) intentional tumor removal up to the vertebral artery (VA), i.e., the VA line.

Results

The tumor location of dumbbell extension was Eden types 2 and 3 in two and four patients. Gross total resection was achieved in two patients and intentional posterior removal of the tumor to the VA line was achieved in the remaining four patients. No vascular or neural injuries associated with surgical procedures occurred. Postoperative neurological assessment revealed no symptomatic aggravation in all patients. No secondary surgery was performed during the study period.

Conclusion

PUA was safe and less invasive for functional recovery and tumor resection, if the anatomical relationship between the tumor and VA is clearly understood. The VA line is an important anatomical landmark to limit the extent of tumor resection.

Cervical Trident-Shaped Neurofibroma: A Rare Variant

Spinal nerve root tumors can arise throughout the spine and at multiple levels, likely representing plexiform neurofibromas that grow from the nerve root into the intraspinal space either intradurally or epidurally and exit through the neural foramen, producing a dumbbell-shaped appearance. Although many cases of dumbbell-shaped extramedullary neurofibromas in the cervical spine have been reported, to the best of our knowledge, there are no reports of trident-shaped extramedullary neurofibromas. A 26-year-old woman presented with swelling over the right side of her neck. Diagnostic workup included magnetic resonance imaging (MRI) and contrast-enhanced computed tomography (CECT) of the neck, which revealed an intradural, extramedullary tumor mass at the right C2-C6 level with an extraspinal extension. Spinal cord compression or canal compromise is the most reliable indication for surgery. The solitary cervical neurofibroma was treated surgically in a single stage through laminoplasty and excision of the intradural tumor along with that of the neck component. This was performed without any complications. A single-stage double approach was adopted in this case. After total excision, the shape of the tumor was found to be more like a trident than a dumbbell. Hence, here we would like to suggest a new nomenclature for this neurofibroma, the trident neurofibroma.