Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.319213
Source of Support: None, Conflict of Interest: None
Keywords: Case report, craniovertebral junction, neoplasms, neuroendoscopy, spinal neoplasms, spineKey Message: Endoscopic-assisted minimally invasive approach is an excellent alternative to the traditional anterior retropharyngeal approach. Good visualization through an endoscope enables preservation of the normal anatomy and complete excision of the lesion.
Spinal exostoses are rare lesions accounting for 4–7% of all benign spinal tumors. High cervical is the commonest region of both solitary and multiple exostoses. They develop during the period of skeletal growth and are symptomatic according to their intra/extra canalicular location. Surgical excision of these tumors is the treatment; however, it may be challenging if critical structures surround them. Common pathological diagnosis is an osteochondroma, and removal of the cartilaginous cap is essential. Endoscopic approaches are minimally invasive, safe, and effective for a majority of craniovertebral junction lesions.,
This article describes excision of a C2 transverse process osteochondroma through an endoscopic-assisted anterior retropharyngeal approach (ARPA). A step-by-step technical report with video is presented.
A 14-year-old girl presented with right-sided neck pain without neurological deficits for 6 months. Her computed tomography (CT) cervical spine revealed a 6.5 cm3 mass in the right transverse process extending into the lateral mass of the C2 vertebra [Figure 1]a and [Figure 1]b. The tumor was extracanalicular and away from neural structures. The vertebral artery was in direct contact and lying posterior. A right-sided endoscopic ARPA was planned as the lesion was placed anterior to the vertebral artery [Figure 1]c. Institutional ethics committee approval was taken. The patient was operated under general anesthesia in a supine position with head extension. The nasotracheal intubation was done to permit mouth closure. Oral packing was avoided to prevent downward bulging of the pharynx. During initial exposure, her head was turned @10 degree to the left side, which was later turned to a neutral position for orientation. Intraoperative fluoroscopy, neuronavigation, or cavitron ultrasonic aspirator was not utilized.
Detailed operative steps can be seen in Video 1. The patient's consent was taken for this report. A 4 cm length incision was marked 2 cm inferior to the mandible on the right side [Figure 2]a. The platysma was dissected both in supra and subplatysmal plane to open the middle (visceral) fascial layer and the superficial layer of the deep cervical fascia [Figure 2]b. The wide opening of each fascial layer permitted adequate retraction and visualization of the submandibular gland [Figure 2]c. The inferior edge of the gland was elevated cranially and the fascial capsule was opened. The facial vein may be transected if it courses through the operative corridor; however, it was not needed in the present case. The fascial sling of the digastric tendon was detached from the hyoid bone [Figure 2]d and retracted cranially by releasing the bellies both medially and laterally. The hypoglossal nerve was dissected from the fascia around it [Figure 2]e and retracted cranially. Medial retraction of the constrictor muscles opened the prevertebral space [Figure 2]f. The prevertebral fascia and longus colli muscles were coagulated and cut. Cranially, the joining of both longus colli muscles marked the C1 anterior tubercle. Gauge piece packs were inserted to retract the soft tissues. The rest of the procedure was done under endoscopic visualization.
A 23 mm diameter outer sheath of the EasyGo system (Karl Storz, Tuttlingen, Germany) was utilized. The soft tissue over the C1 tubercle, C1 arch, lateral mass of C1 and C2, and transverse process of C2 were coagulated and cut to identify the landmarks [Figure 3]a, [Figure 3]b, [Figure 3]c. The right-sided C2 transverse process had punctate bleeding points. Using a combination of drill, Kerrison punch, and curette, the tumor was identified and excised [Figure 3]d. The cartilaginous cap was present around the tumor, which helped to dissect the tumor from the vertebral artery [Figure 3]e. Post resection, the vertebral artery could be seen in the bed [Figure 3]f. Hemostasis was achieved by using oxidized regenerated cellulose (Surgicel, Ethicon, J and J, USA). Fusion was not necessary as joints were intact. The closure was done in layers.
Video link: https://youtu.be/ZXQr3eBMwf8
Video timeline with audio transcript (Minutes):
00–00:06 – This video demonstrates endoscopic excision of a right-sided C2 transverse process mass.
00:10-00:18- The patient was a 14-year-old girl presenting with right-sided neck pain without neurological deficits for last 6 months.
00:20–00:31 – A 2 × 2 cm mass can be seen over the right transverse process of C2 vertebra in axial, and coronal CT scans. The mass was abutting and lying anterior to the vertebral artery.
00:33–00:45 – The patient was positioned supine with head extension and turned approximately 10 degrees to the left side. A 4 cm incision was made @2 cm inferior to the mandible.
00:46–0:55 – The platysma was dissected both in supra and subplatysmal plane to open the middle (visceral) fascial layer and superficial layer of the deep cervical fascia.
00:56–1:08 Wide opening of fascial layers permitted adequate retraction and visualization of the submandibular gland. The inferior edge of the gland was elevated cranially and the white fascial capsule was opened to expose the underlying digastric muscle.
1:09–:15 – The fascial sling of the digastric tendon was detached from the hyoid bone and retracted cranially by releasing the bellies.
1:20–1:30 – As the digastric tendon was retracted cranially, the hypoglossal nerve with overlying fascia could be seen. It was dissected and retracted cranially.
1:37–1:55 – Medial retraction of the constrictor muscles opened the prevertebral space. The prevertebral fascia was cut and longus colli muscles were retracted. Gauge piece packs were inserted to retract the soft tissues. The EasyGo endoscopic system by KarlStorz was inserted thereafter.
1:57–1:60 – Orientation can be seen.
02:01–2:10 – The right-sided longus colli muscle was coagulated and cut to expose the C1 arch, C1–C2 facet, and C2 transverse process.
2:16–2:29 – Punctate bleeding points over the C2 transverse process can be seen. Using a combination of Kerrison punch, drill, and curette, the tumor was identified and excised.
2:36–2:40 – The tumor was cartilaginous, resected in piecemeal.
2:51–3:00 – A cartilaginous cap is seen around the mass, which was utilized to separate it from the vertebral artery by using a blunt curette.
3:10–3:12 – Here, the vertebral artery is starting to appear.
3:21–3:24 – Using the same plane of dissection the tumor was lifted.
3:35–3:39 – Good visualization from the endoscope helped to preserve the normal anatomical structures.
3:53–3:56 – Here, the vertebral artery is clearly seen in the bed.
4:03–4:07 – Hemostasis was achieved using pieces of surgicel.
4:09–4:15 – Postoperative CT scan axial, sagittal, and coronal images showed total resection of the mass.
4:16–:20 – The patient had an uneventful recovery and her symptoms resolved.
4:26–4:28 – Thank you for your attention.
The postoperative course was uneventful. The postoperative CT showed complete excision of the mass [Figure 4]a, [Figure 4]b, [Figure 4]c. The patient became symptom free and is without recurrence till the last follow-up of 6 months. The biopsy came out to be osteochondroma.
Pearls and pitfalls
Nasotracheal intubation is preferable to permit complete mouth closure. This maneuver allows working at a lesser angle toward the craniovertebral junction. The avoidance of oral packing prevents downward bulging of the pharynx that in turn decreases the chances of a pharyngeal tear. The release of the digastric tendon from the hyoid bone is essential; otherwise, the release of the hypoglossal nerve is difficult and the operative corridor becomes very narrow. The head is made neutral after the initial exposure to maintain the orientation. In cases of distorted anatomy, the surgeons may use fluoroscopy or navigation to identify the landmarks. The plane of the cartilaginous cap should be utilized to separate the lesion from the critical structures.
Spinal exostosis may be solitary or multiple. C1 level is commonest for solitary and C2 for multiple hereditary exostoses. Majority of these lesions (88%) originate from the posterior elements., The cervical transverse process has vital structures around it, which makes the tumor's excision challenging. As the vertebral artery was lying posterior to the lesion, an anterior approach was chosen. It is critical to preserve the intricate neurovascular structures through this minimally invasive approach. The ARPA has been shown effective for high cervical discs, fractures, and dislocations. It also provides a clean path compared to the transoral or a transpharyngeal approach. Recently, the endoscopic approach has been shown for atlantoaxial dislocations (AADs) and parapharyngeal tumors.,, It provides excellent visualization and the ability to fuse the joints in cases of instability. This is the first report of an endoscopic ARPA for a high cervical transverse process mass.
The traditional ARPA might be associated with complications such as dysphagia, hoarseness of voice, hypoglossal nerve palsy, salivary fistula, injury to the marginal mandibular branch of facial nerve, and rarely carotid injury. Dysphagia and hoarseness of voice develop due to undue retraction of superior laryngeal nerve and generally resolves in 1–2 weeks. Hypoglossal nerve palsy is again due to excessive retraction but takes a longer time to recover. Though found on clinical examination, patients usually do not complain of glossal dysfunction. The release of the digastric tendon from the hyoid bone allows the operative corridor to become spacious and the retraction of the hypoglossal nerve without tension. The marginal mandibular branch of facial nerve is near the angle of the mandible. Making the incision @2 cm below the mandible, limiting the incision in the paramedian region, as shown in [Figure 2], and lifting the nerve with the platysma prevent its injury. Careful handling of the submandibular gland and avoidance of monopolar cautery prevent a salivary fistula. These complications are rare with an endoscopic minimally invasive approach as retraction is minimal here. Obliquity and large mandible are critical limitations. Maneuvers to move the mandibular angle up reduce the obliquity and provide additional working space. These include nasal intubation to allow jaw closure, avoidance of oral packing to prevent downward bulge of the pharynx, cervical traction, and using a short tubular retractor. With the undermining of fascial incisions, the need for retraction decreases further. Preoperative CT angiogram shows the positions of carotids and other vessels and helps to avoid their injury. Considering a transverse process mass, which requires extensive retraction to visualize the lateral extent, the endoscopic assistance provided adequate visualization without undue retraction. Authors have significant experience of this approach for AAD., The technique enables decompression and fixation in a single setting, fewer chances of injuring the vertebral artery, the ability to perform the bicortical purchase of screws, and easy positioning of the patient. In a series of 58 patients of AAD with a minimum follow-up of 1 year, we had four cases of transient dysphagia and hoarseness and no permanent morbidity. One can find a detailed endoscopic ARPA technique for AAD in our previous publications.,
Bimanual dissection is also possible through the endoscopic system. The insertion and intermingling of both longus colli muscles mark the C1 tubercle and authors have found this technique quite useful for localization. The C1 anterior arch, C1–C2 lateral mass and joint, and C2 transverse process were identified. C-arm help can be taken if there is any doubt. Using bimanual dissection and with the combination of drill, curette, and punch the tumor could be removed completely. Complete excision of spinal exostosis have a low recurrence; however, the follow-up of this patient is short and needs to be observed. The endoscopic ARPA requires good anatomical knowledge, and authors recommend adequate practice on cadavers before embarking on patients. A steep learning curve is associated, as is present with all endoscopic surgeries.
Endoscopic-assisted ARPA is a minimally invasive alternative to the traditional approach, and was found safe and effective for C2 transverse process exostosis.
Declaration of patient consent
A full and detailed consent from the patient/guardian has been taken. 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], [Figure 3], [Figure 4]