Transoral Odontoidectomy for Pediatric Craniovertebral Junction Anomaly: Is It Redundant Now?

The novel conceptualization of C1–C2 joint distraction by Goel[12] revolutionized the surgical management of craniovertebral junction anomaly (CVJA). It would be not be untrue, if I say that the future generation of neurosurgery residents will not even assist a single case of transoral odontoidectomy (TOD) in their curriculum. Will the art of Odontoid drilling sojourn only in operative atlases or endure in the hands of few neurosurgeons? We did a literature search with word “TOD” in PubMed and Scopus search engines, and found that majority of reported cases were operated as a rescue effort after posterior fixation and clinical deterioration. In one of our previous article, 28 patients (of 154) required second-stage TOD following posterior distraction-and-fusion due to neurological non-improvement.[3] Therefore, I believe that the “kairotic moment” has come, for the neurosurgeons to unite, and revisit the radiological indications of TOD in present era.

Although the TOD procedure was first described by Kanavel,[4] for the indication of an entrapped bullet removal between skull base and C1, it was Scoville and Sherman[5] who successively described the technique for basilar impression (BI). Thereafter, Fang and Ong[6] popularized the approach for traumatic Cl–C2 instability and tuberculosis of the upper cervical spine. As the “change” is inevitable, so is the evolution of CVJ surgery being a dynamic process. The modern indications of TOD in pediatric neurosurgery subspecialty includes (a) as a rescue procedure after posterior fixation - Herein, the word “over-distraction” and “hyper-mobile AAD” needs to be mentioned and understand.[7] Wang et al.[8] reported four cases of vertical atlantoaxial dislocation (AAD) and BI with postoperative neurological deficit after undergoing anatomic reduction. He proposed that the posterior fixation done in the over-distracted position, to treat vertical AAD, may displace the brainstem caudally, leading to traction injury to the lower cranial nerves. Actually the suitable distance of distraction for achieving adequate decompression still remains unknown.[9] Therefore, the patients who deteriorate post-posterior fixation, warrants either re-exploration and re-fixation in partially distracted state; or TOD.[10]

(b) A second indication may be the patients with anomalous vertebral artery course, either over the C1–C2 joints or high riding V1–V2 loop with a thin pars inter-articularis. Although these cases are a real challenge for an experienced neurosurgeon, I would rather say captivating or enrapturing, it is always safe to do occipitocervical fixation along with TOD in the same sitting. At the end of surgery, the only thing matters is your patient, and it is esteem pleasure to see child being discharge from hospital happily. To my young fellows, I always insist that “a new surgical technique” or “devise” may look mesmerizing, but not to follow these arbitrarily. (c) Bony tumors of odontoid such as osteoblastoma, chordoma, and aneurysmal bone cyst are although rare, but may occur in pediatric age and warrant a ventral corridor. (d) Abnormal deposition anterior to odontoid as in the Morquio’s syndrome still remains as an important indication of TOD. The posterior distraction or reduction can never address the mucopolysaccharide deposited ventral to the odontoid process. (e) Anterior ligamentous hypertrophy or inflammatory pannus (in the context of rheumatoid arthritis). The incidence of pannus formation is decreasing due to better disease control with biologic medication. Some authors believe that proper distraction may buy time for the pannus to resolve. Moreover, this arthritis is rare below 18 years of age. Still, few cases have been reported, where pannus was the only cause of irreducibility and needs utmost surgical addressal.[1112] Figures 1–3 show several representative patients operated through TOD and had a remarkable improvement in follow-up.

Figure 1

A 9-year-old child presented to us with progressive spastic quadriparesis (Nurick grade IV) and the CT (A) sagittal image showed AAD with basilar invagination. There was severe canal compromise at foramen magnum and posterior arch of atlas was occipitalized. We did transoral odontoidectomy followed by posterior fixation (O-C1-C2). The postoperative (B) axial and (C) sagittal CT-scan shows ventral decompression and adequate funneling of craniovertebral junction. The child improved in postoperative period and after a follow-up of 3-years, the patient is able to walk without support

Figure 3

A case of anterior compressive myelopathy due to thick hypertrophied tectorial membrane. (A) Magnetic resonance imaging sagittal T2-weighted sequence of a child operated through posterior fixation and deteriorated (Nurick grade IV, on ventilator). C1–C2 joints were manipulated, reoriented and instrumentation was done. (B, C) After 24 h of the first surgery, excision of hypertrophied tectorial membrane was done and patient improved significantly

An 11-year-old child presented with acute spastic quadriparesis (Nurick grade III) after a trivial trauma. Radiology showed evidence of atlantoaxial dislocation (A). The patient was operated from posterior approach and occipital-atlas (lateral mass) and axis (pars inter-articularis) fixation was done (C) but the child deteriorated in immediate postoperative period and his ventilator requirement kept on persisting. On the third postoperative day, we did transoral odontoidectomy (B) and patient improved thereafter (D). The child was discharged on the 14th postoperative day and is able to so all his routine activities after 2 years of follow-up

NEED FOR PALATE INCISION AS AN EXTENSION TO PHARYNGEAL WALL EXPOSURE

Menezes believe that soft palate incision is only required in the cases, wherein exposure of the clivus is needed.[9] This includes the case of severe BI with proximal migration of the odontoid. Other reported indication includes the rare cases of rheumatoid arthritis with mandibular joint involvement, where mouth opening becomes a limiting factor. Some surgeons believe that TOD in a patient, wherein, posterior fixation is already done in the extended neck position, is technically difficult.[10] However, we never felt need of palatal incision or used endoscopic assistance in our experience of more than twenty years.

Infection: It is a popular belief that the contaminated oral or nasal cavity gets communicated with retropharyngeal space and may infect the implant or predispose osteomyelitis. None of the patients, neither from series of Sonntag (n = 29, 10 years), Crockard (n = 22), and Elbadrawi (n = 20, 5 years), and nor in our experience (except two cases where wound dehiscence occurred had such infection.[131415]

Cerebrospinal fluid (CSF) leak and meningitis: The CSF leak occurs as a result of technical failure or superadded infection. The problem denotes a significant risk to the patient and need utmost addressal. Various treatment options include dural patching, re-repair, and placement of a lumbar drain.

Dysphagia and velopharyngeal insufficiency: The mal-closure of the velopharyngeal sphincter during speaking or swallowing may lead to hypernasal voice and nasal regurgitation. The pathogenesis proposed is postoperative fibrosis of the soft palate or pharyngeal wall.

FACTORS COMPLICATING THE TECHNIQUE OF TRANSORAL ODONTOIDECTOMY

The art of TOD should not remain in books or atlas. Majority of patients with craniovertebral anomaly can be dealt with posterior approach, but still, TOD is necessary in a subset of patients. One should not be obsessed with a particular surgical approach, and rather think about his surgical experience or expertise and patient-related outcome.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.