Function Preserving Surgery for Brachial Plexus Fibromatosis with Mediastinal Extension
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.355151
Source of Support: None, Conflict of Interest: None
Key Message: Functional resection provides optimal results in symptomatic desmoid lesions involving vital neurovascular structures.
Desmoid tumors or fibromatosis is a benign but locally aggressive and infiltrative disease with origin attributed to musculoaponeurotic fibrous tissue. Despite being a locally aggressive tumor, infrequent mitosis, absence of necrosis, and absence of metastasis reconfirm its benign nature. Fibromatosis in general is a rare entity comprising 0.03% of all tumors in humans. Most cases of fibromatosis are intra-abdominal and extra-abdominal fibromatosis is less common. Head and neck are also an uncommon locations making up to 7%–25% of extra-abdominal desmoid tumors. The precarious location in the head and neck combined with aggressive nature of these tumors often causes involvement of vital neurovascular structures ranging from involvement of the frontal bone and palate to extension into the mediastinum being reported., In this article, we describe a case of neck fibromatosis involving the brachial plexus in a 24-year-old female that was associated with motor and sensory deficit in the ipsilateral upper limb. We discuss the operative technique and associated nuances of the case, highlighting the multidisciplinary surgical approach to achieve maximal safe resection while preserving neurological function.
In this video, we aim to describe the operative technique and nuances associated with maximal safe resection of a brachial plexus fibromatosis extending into the mediastinum while preserving neurological function.
A 24-year-old female presented to us with a right-sided swelling in the supraclavicular region, which was first noticed 1.5 years back and was gradually increasing in size. It was associated with right-sided weakness and sensory loss for the past 1.5 months. There was no history of symptoms in any other limbs. On examination, the tone was normal in all four limbs. The power in the right shoulder, elbow, and wrist was 3/5 (MRC grading) and the hand grip was 30%–40%. The power in other limbs was normal. Magnetic resonance imaging (MRI) was suggestive of a large paravertebral lesion on the right side with homogeneous hyperintensity on STIR images, and encasing the brachial plexus, the subclavian vessels, and extending into the mediastinum. The lesion showed homogeneous contrast enhancement on contrast imaging and was isointense on T2 images. The patient was planned for maximal safe debulking surgery after multiple failed attempts at reaching tissue diagnosis on percutaneous fine-needle aspiration cytology (FNAC) tests. The patient was positioned supine on the operating table with the neck tilted to the left side. The draping was done in standard fashion with the whole neck, right shoulder, right chest till the xiphisternum (including axillary region) was included in the draping field. The right upper limb was draped free in sterile drapes with the hand and forearm being draped in a sterile transparent polybag to see movements on nerve stimulation. A curvilinear incision was planned along the lateral border of sternocleidomastoid and inferior border of clavicle. A subfascial flap was raised and the tumor was exposed. This was followed by splitting the omohyoid muscle in the middle and tagging both the ends. The medial two-thirds of the clavicle was exposed subperiosteally and resected by osteotomy of the midpoint of the clavicle and disarticulation of sternoclavicular joint by the orthopedic team.
The subclavian vessels were seen to be encased by the tumor. The cardiothoracic surgical team achieved the proximal and distal control for subclavian vessels. They also identified and tagged other important vascular structures like carotid artery, brachiocephalic trunk, and internal jugular vein in close proximity to tumor capsule. [Figure 1] A nerve stimulator was used to identify functional neural tissue around the lesion. There was stimulation present on the superior and lateral aspect of the tumor. A safe zone for entry into the lesion was identified from the ventral aspect of the lesion and an intra-lesional debulking of the tumor was started. The tumor was yellowish in color, firm in consistency, and moderately vascular in nature. A combination of cavitron ultrasonic surgical aspirator (CUSA), loop cautery, knife, curettes, and biopsy forceps were used for tumor resection. Nerve stimulation was used frequently as and when required to ensure safe margins of resection. After internal debulking of the tumor an extracapsular plane could be identified on the superior and lateral aspect of the tumor and dissection was continued. The mediastinal part of the tumor was separated using blunt dissection and piecemeal resection was carried out to prevent any iatrogenic injury to segmental vessels. The tumor capsule of the mediastinal part was adherent to the parietal pleura and an inadvertent pleural tear occurred while resection. An intercostal drain (ICD) was readily inserted in the fifth intercostal space along the anterior axillary line. The part of the tumor encasing the subclavian artery was further resected carefully. The tumor tissue was also seen extending along the neural foramina medially, which was carefully removed with the help of CUSA. The tumor capsule adherent to functional nerves was identified with a nerve stimulator and left behind as further dissection would have resulted in a possible neurological deficit. Hemostasis was achieved and the resected clavicle was fixed back with a 3.5-mm locking anatomical plate and multiple K wires. [Figure 2] A romovac drain was placed in the operative cavity and layered skin closure was done.
Video timeline and audio transcript
0.04–0.24: A 24-year-old female presented to us with a right supraclavicular swelling for the past 1.5 years and weakness (MRC grade ⅗, hand grip 40%) and 20%–30% sensory loss to all modalities in right C7-T1 dermatomal distribution since 1.5 months.
0.25–0.37: The coronal and sagittal MRI scans show a large paravertebral lesion with homogeneous hyperintensity on STIR images, encasing the brachial plexus, the subclavian vessels, and extending into the mediastinum.
0.38–0.39: The axial T2 scan.
0.44–0.49 The coronal and sagittal T1 post gadolinium contrast scans.
0.50–0.56 The axial T1 post gadolinium contrast scan showed homogeneous intense enhancement and encasement of subclavian vessels.
0.57–1.17 CT scan shows the mediastinal part of the tumor extending below the level of clavicle. So the clavicle resection was considered necessary for better visualization and removal of the tumor.
1.17–1.24 3D reconstruction VRT images of CT angiography showing narrowing of the right subclavian artery.
1.24–1.34 The patient was positioned supine with neck tilted to the left. A curvilinear incision was planned along the lateral border of sternocleidomastoid and inferior border of clavicle.
1.34–1.38 A subfascial flap was raised.
1.38–1.42 The tumor was exposed.
1.42–1.53 Omohyoid muscle was further cut and tagged; and medial two-thirds of the clavicle was resected by the orthopedic team for better access to the upper mediastinum and deep vascular structures.
1.53–2.04 With the help of cardiothoracic and vascular surgeons the proximal and distal control for subclavian vessels was achieved and other vascular structures were identified and tagged.
2.04–2.24 A nerve stimulator was used to identify functional neural tissue along the tumor capsule. Safe zone for entry into the lesion was identified and an intralesional decompression of the tumor was started.
2.24–2.30 Nerve stimulation was used at regular intervals to preserve neurological function.
2.30–2.43 A combination of cavitron ultrasonic surgical aspirator (CUSA), loop cautery, knife, curettes, and biopsy forceps were used for tumor dissection and excision.
2.43–2.48 Tumor debulking using loop cautery.
2.48–3.03 After internal debulking of the tumor, an extracapsular plane was identified and dissection was continued. Nerve stimulation was used intermittently during extracapsular dissection.
3.03-3.15 The tumor was removed piecemeal using loop cautery and CUSA
3.15–3.25 The nerve stimulator played a key role during extracapsular dissection in preserving the neural structures.
3.15–3.37 After careful dissection of the tumor capsule, it was removed using loop cautery, CUSA, and biopsy forceps.
3.37–3.54 Blunt dissection of the tumor from its capsule was done along the mediastinal part to prevent iatrogenic injury to segmental vessels. Tumor was resected piecemeal with the help of a biopsy forceps, CUSA, and curettes.
3.54–4.12 The tumor capsule of the mediastinal part was adherent to the parietal pleura and an inadvertent pleural tear occurred. Such an occurrence was anticipated and an ICD was kept on standby, which was readily inserted.
4.12–4.23 The tumor was encasing the subclavian artery and careful dissection was done around the vessel.
4.23–4.31 Further the tumor tissue extending along the cervical neural foramina was removed carefully to avoid an intraoperative cerebrospinal fluid leak.
4.31–4.43 The nerves in the tumor bed were starting to get stimulated marking the near end of resection.
4.43–4.51 The tumor capsule adherent to functional neural tissue was identified with a nerve stimulator and preserved.
4.51–4.58 Hemostasis was achieved using surgicel and floseal, and all neurovascular structures were preserved.
4.58–5.07 The resected clavicle was fixed back with a 3.5 mm locking anatomical plate and multiple K wires, and confirmed on intraoperative radiograph.
5.07–5.11 A subcuticular closure was done for optimal cosmesis.
5.11–5.32 A comparison of pre- and postoperative MRI scans showed significant reduction in size of the lesion.
5.32–6.07 A follow-up at 4 months showed objective improvement in power of the upper limb across all joints (MRC grade ⅘, hand grip 70%). The patient is currently on Sorafenib as maintenance chemotherapy to halt further tumor progression.
After surgery, the postoperative course was uneventful. The patient was given an arm pouch sling for support and shoulder pendulum range of motion exercises were started on postoperative day 1. The patient was also allowed elbow and wrist range of motion exercises. However, overhead abduction of the right arm was restricted. The ICD drain was removed on the fourth postoperative day. The histopathology report revealed the diagnosis of fibromatosis. Follow-up MRI done at 3 months, showed significant reduction in size of lesion compared with preoperative MRI. Clinical examination at 3 months showed objective improvement in power of upper limb to ⅘ (MRC grading) power across all joints. The hand grip also improved to 70% from 30% preoperatively. This patient was initiated on oral therapy with sorafenib.
Pearls and pitfalls
The resection of large head and neck tumors encasing brachial plexus and vital neurovascular structures in the neck and upper mediastinum can be a daunting task. A thorough study of the preoperative imaging is pivotal to plan and anticipate intraoperative and postoperative complications. A multidisciplinary approach and involvement of colleagues from other specialties are very helpful. The orthopedic team in this case resected the clavicle, which greatly improved the surgical access to the upper mediastinum. The cardiothoracic team achieved proximal and distal control of vascular structures, which is important to control intraoperative bleeding and perform vascular repair in case of inadvertent injury to these structures. The use of nerve stimulation can act as a savior in such cases, as differentiation of plane between functional neural tissue and fibromatosis tumor tissue can often be difficult. Functional maximal safe resection instead of complete radiological clearance should be the aim in such cases, to optimize a patient's quality of life. Patient counseling regarding this aspect is a must preoperatively, and the role of medical oncologists in maintenance chemotherapy and radiological surveillance after debulking surgery cannot be overstated.
Fibromatosis despite being a benign lesion is a locally aggressive tumor. Tumors arising from the neck region are often symptomatic due to involvement of vital neurovascular structures. Despite neck and supraclavicular regions being reported sites for extra-abdominal desmoid tumors, involvement of brachial plexus is uncommon. In the present case, the tumor involved the brachial plexus, the subclavian vessels and even extended into the mediastinum.
The optimal treatment strategy for such tumors is still a bone of contention. Although gross total resection with negative margins is considered the best, these tumors are plagued with a very high incidence of recurrence (40%–70%) despite negative margins. Hence, in cases where neurovascular structures are involved functional resection has gained popularity instead of attempting gross total excision and compromising vital structures and functional aspect.[6–8] Tools to aid function-preserving surgery in such cases include the use of sensory and motor evoked potential and nerve stimulators to check for functional neural tissue. In the present case, we utilized a nerve stimulator which was very helpful as the tumor capsule was adherent to functional neural tissue partly encasing it on the superior, dorsal, and inferior surfaces with no clear delineation of a working plane between tumor capsule and neural tissue.
Radiotherapy as an adjunct has been used in desmoid tumors with limited success especially those with positive margins and those which cannot be surgically resected. However, skin necrosis, fibrosis, cancers, and sarcomas secondary to radiation have raised questions on its relevance in this benign disease, especially in the younger patient population.
Chemotherapy has been an adjunct that has been often used for disease stabilization in desmoid tumors. It has been noted that around two-thirds of the patients may achieve disease stabilization with chemotherapy. Various agents like NSAIDs, hormonal agents (tamoxifen), sorafenib, methotrexate with vinblastine, and various other agents are used for the treatment of extra-abdominal desmoid tumors. Sorafenib has been shown to provide clinical improvement in around 70% of patients with progressive disease of imaging. Good response rates have been noted with the combination of methotrexate and vinblastine also. However, there is no current consensus on the optimal chemotherapeutic regimen for the treatment of extra-abdominal desmoid tumors.
Fibromatosis of desmoid tumors involving the brachial plexus is a rare entity. In symptomatic lesions involving vital neurovascular structures, functional resection should be the goal of surgery as recurrence rates are high even after gross total excision and achieving negative margins. A tailored multidisciplinary function preserving surgical approach with maintenance chemotherapy is an acceptable management strategy in preserving a patient's quality of life for such infiltrating desmoid tumors encasing brachial plexus with mediastinal extension.
We thank the neurosurgery technicians team for their assistance and technical support during intraoperative neurophysiological monitoring and video recording.
The patient's identity has been adequately anonymized. If anything related to the patient's identity is shown, adequate consent has been taken from the patient/relative/guardian. The journal will not be responsible for any medico-legal issues arising out of issues related to patient's identity or any other issues arising from the public display of the video.
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Conflicts of interest
There are no conflicts of interest.
[Figure 1], [Figure 2]