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Table of Contents    
NI FEATURE: CENTS (CONCEPTS, ERGONOMICS, NUANCES, THERBLIGS, SHORTCOMINGS) - COMMENTARY
Year : 2019  |  Volume : 67  |  Issue : 2  |  Page : 510-515

Endoscopic single stage trans-oral decompression and anterior C1 lateral mass and C2 pedicle stabilization for atlanto-axial dislocation


1 Department of Neurosurgery, NSCB Medical College, Jabalpur, Madhya Pradesh, India
2 Department of Radiology, MP MRI Centre, Jabalpur, Madhya Pradesh, India

Date of Web Publication13-May-2019

Correspondence Address:
Dr. Yad R Yadav
105 Nehru Nagar Opposite Medical College, Jabalpur - 482 003, Madhya Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.257989

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 » Abstract 


Although most of the cases of atlanto-axial dislocation (AAD) and basilar invasion can be managed by posterior approaches in the recent times, anterior decompression with stabilization is required in selected patients who persist with irreducible AAD even after manipulation of the C1-C2 facet joint under general anesthesia. A single stage endoscopic trans-oral decompression and stabilization can be used in such patients. It has not been described so far to the best of authors' knowledge. This is indicated in irreducible AAD with the mandibular angle lying below the C2-C3 disc space. It is not a proper choice when the mandibular angle is above the C2-C3 disc space, there is involvement of the facet joint by trauma or any other pathologies, and if a posterior compression at the cervicomedullary junction persists. All patients should undergo pre-operative radiographs, computed tomography (CT) scan and magnetic resonance imaging with angiogram of the cranio-vertebral region. Utilizing this technique, an intra-operative satisfactory reduction of the dislocation with C1-C2 stabilization could be achieved in 3 patients, and 7 required an additional odontoid excision. Post- operative plain radiographs should be performed to assess for C1- C2 alignment and fusion at 3 and 12 months after surgery. All 10 patients of our series had an irreducible AAD and two had an additional basilar invasion. All patients improved from the pre-operative Ranawat grade 3A (n = 8) and 3B (n = 2) to post-operative grade 1 (n = 9) and 2 (n = 1) at a 3–12- month follow-up assessment. The average duration of the procedure and blood loss was 145 minutes and 75 ml, respectively. Endoscopic trans-oral single stage decompression and stabilization seems to be an effective and safe alternative in selected patients with AAD and basilar invasion.


Keywords: Atlantoaxial joint, endoscopic surgical procedure, endoscopy, minimally invasive surgical procedure, surgical decompression


How to cite this article:
Yadav YR, Parihar VS, Ratre S, Dubey A, Jindel S, Dubey MN. Endoscopic single stage trans-oral decompression and anterior C1 lateral mass and C2 pedicle stabilization for atlanto-axial dislocation. Neurol India 2019;67:510-5

How to cite this URL:
Yadav YR, Parihar VS, Ratre S, Dubey A, Jindel S, Dubey MN. Endoscopic single stage trans-oral decompression and anterior C1 lateral mass and C2 pedicle stabilization for atlanto-axial dislocation. Neurol India [serial online] 2019 [cited 2019 May 22];67:510-5. Available from: http://www.neurologyindia.com/text.asp?2019/67/2/510/257989

Key Message: An endoscopic single.stage trans.oral decompression and C1 lateral mass to C2 pedicle stabilization is an effective and safe alternative in selected patients having AAD and basilar invasion. It can be used in irreducible AAD with the mandibular angle lying below the C2.C3 disc space where the trans.cervical approach is not possible. It is the most direct approach, and provides a better visualization of the operative area compared to that achieved with a microscope. An avoidance of palatal incision, the possibility of carrying out the procedure even if the mouth opening as small as 1.5 cm, the minimal tissue dissection, and the preservation of posterior tension bands are some of the advantages of this technique. Surgery can be performed in any position (flexion or extension) of the neck. There is good screw purchase at the C1 lateral mass and C2 pedicle. Although we did not come across any infection, there is, however, a risk of contamination by oral bacterial flora.




Although most of the patients with an atlanto-axial dislocation (AAD) or basilar invasion can be managed by posterior approaches in recent times, anterior decompression with stabilization is required in selected patients. Atlanto-axial dislocation in such patients remains irreducible even after manipulation of the C1-C2 facet joints under general anesthesia. These patients need anterior surgical corridors such as the trans-oral,[1],[2] trans-nasal,[3] and extra-oral trans-cervical retropharyngeal approach.[4],[5],[6],[7]

The narrow and oblique corridor and the difficulty in approach to the lower part of the C2 body are some of the major limitations of the trans-nasal approach, whereas obstruction by angle of mandible and an obliquity of approach are the limitations of a trans-cervical approach.[7] The trans-oral technique remains an appropriate approach in selected patients. It is the most direct approach for ventral cranio-vertebral junction lesions. Trans-oral decompression and fusion using a microscope has been reported to be safe and effective, although the procedures have been done in a small number of patients.[6],[8],[9],[10],[11] The trans-oral mini-plate fixation for mandibular angle fracture has been found to be safe and effective.[12] Anterior fixation has been found to be a viable option for atlantoaxial stabilization with a longer screw purchase for better atlantoaxial stability.[13] Although microscopic trans-oral reduction and stabilization has been described,[8],[9],[10],[11] a single stage endoscopic decompression and fusion has not been reported so far, to the best of the authors' knowledge. Besides describing the the technique, we also report our preliminary experience of operating upon 10 patients with irreducible AAD and/or basilar invagination utilizing a single stage endoscopic trans-oral decompression as well as fusion.

Indications and contraindications

This approach is indicated in patients with irreducible AAD, after an attempt at reduction of the AAD under general anesthesia has not been successful. Patients with a large mandible, and those with a very high basilar invagination, in whom the mandibular angle is lying below the C2-C3 disc space even after extension of neck, are proper candidates for this approach. Such patients are difficult to approach by the trans-cervical approach. Although patients with a reducible AAD and patients with the mandibular angle above the C2-C3 disc space can also be operated by this technique, the trans-cervical approach is preferred in such patients because of a clean, and potentially non-infected corridor available with this approach. Patients with involvement of the facet joint by trauma or by any other pathologies that do not permit joint manipulations are not good candidates for this technique. This approach should be avoided in AAD with associated posterior compression at the cervicomedullary junction, such as Chiari malformation.

Pre- operative assessment and work up

Reduction is attempted pre-operatively with a skeletal traction in all cases and during surgery under general anesthesia. The pre- operative clinical status using Ranawat grading should be recorded. All patients should undergo a plain radiograph and computed tomography (CT) scan of the cranio-vertebral region [Figure 1]. Pre-operative magnetic resonance imaging with angiogram should be done to assess for the degree of cord compression and the course of the vertebral artery [Figure 1]. Relevant blood investigations should be done as a part of the pre-anesthetic work up in all these cases. Post-operative X-rays should be performed to access for C1-C2 alignment. Proper alignment of these joints and fusion should be assessed at 3 and 12 months after surgery. Post-operative CT scan should be done to assess for the amount of decompression and the status of stabilization [Figure 2]. Post-operative MRI scans should be done to better estimate the amount of decompression.
Figure 1: Pre-operative midsagittal T1 (a) and T2 weighted (b) MRI showing significant compression at the cranio-cervical junction; mid sagittal CT scan image (c) showing the fused C1 anterior arch to the occiput; right (d); left (e) parasagittal; and, coronal (f) images showing an abnormally vertical right C1-C2 facet joint, while the left side joint is horizontal

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Figure 2: Post-operative midsagittal (a); and coronal (b) images showing the removal of the odontoid process and part of C2 body and the screw position in the lateral mass of C1 and C2; the parasagittal (c); and, reconstructed (d) images showing the well placed C1-C2 screws

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Surgical procedure

Most of the surgical steps are same as described earlier in the endoscopic trans-oral technique.[2],[6],[14] The neck is positioned in slight extension position. The tongue is retracted by a Dingman retractor. A 4-mm diameter and 30 cm long endoscope is used. A 0-degree endoscope is positioned in the center, while a 30-degree scope (if needed) is kept in the corner of the operative field. A 30-cm long scope allows for the unobstructed use of instruments. The uvula is retracted into the nasopharynx with the help of an infant feeding tube passed through the nose [Figure 3]. The uvula is fixed to the end of the infant feeding tube by a suture and is pulled gently into the nasal cavity. This helped in increasing the cranial exposure. Lidocaine and adrenaline is used for infiltration of the posterior pharyngeal wall [Figure 4]. A cut is made in the midline of the posterior pharyngeal wall [Figure 5]. The pharyngeal wall is retracted using a pharyngeal retractor [Figure 6]. The upper border of the odontoid process and the intervertebral disc between C2 and C3 vertebrae is identified using fluoroscopy. Longus coli muscle is detached from the C1 anterior arch. A cut is placed in the articular capsule of the C1-C2 facet joint. The anterior constricting tissues are released between C1 and C2 vertebrae and between the anterior arch of atlas and the odontoid process [Figure 6]. C1-C2 facet joint is opened and margins are prepared for fusion [Figure 7] and [Figure 8]. Reduction of C1-C2 is tried by introducing a curette into the atlantoaxial facet joint and by employing fluoroscopic control. Autologous bone graft is packed into the joint space [Figure 9] and [Figure 10] and stabilization of C1 lateral mass and C2 pedicle is performed, if there is proper realignment. Removal of the anterior arch, [Figure 11] odontoid, and part of C2 body [Figure 12] is performed to decompress the cord if the dislocation could not be reduced. Part of the anterior arch of the atlas can be spared, if possible, in some patients. Wide decompression is achieved [Figure 13]. The existence of adequate dural pulsations implies a satisfactory decompression. Titanium plates and screws are used for C1 lateral mass- C2 pedicle stabilization [Figure 14] and [Figure 15]. The posterior pharyngeal wall is sutured [Figure 16]. Ryle's tube is kept for oral feeding. The endotracheal tube is removed after the careful assessment of airway. The endotracheal tube can, however, be left in situ for 1 or 2 days if there is any doubt about the airway patency or tongue edema is present, although we did not come across any such problems. All the instruments are passed by the side of endoscope. The amount of excision of the C2 base is decided by the preoperative MRI utilizing the Wackenheim line. Palatal splitting or self-retracting retractors for the soft palate were not required in any case. The palate could be further pushed upwards by suction or any other micro-instrument used during the dissection. Oral feeding is initiated 5 days after the surgery.
Figure 3: The uvula (arrow to the right) was retracted (a and b) into the nasopharynx with the help of infant feeding tube (arrow down)

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Figure 4: The posterior pharyngeal wall (arrow down) was infiltrated with lidocaine and adrenaline (a and b) with the help of a lumbar puncture needle (arrow to the left)

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Figure 5: A midline incision (arrow up) was made in the posterior pharyngeal wall (a and b)

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Figure 6: The pharyngeal wall was retracted (a) using a pharyngeal retractor (arrow to left); Anterior constricting tissues were released (a and b) between the C1 anterior arch (arrow up) and at C2 shown as arrow pointing down (c)

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Figure 7: Right sided C1-C2 facet joint (arrow to the right) was opened and margins were prepared for fusion (a-c)

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Figure 8: Left side C1-C2 facet joint (arrow to the right) was made bare for fusion (a and b)

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Figure 9: Autologous bone graft (arrow to the left) was packed into the left sided joint space (a and b) with the help of an impactor (arrow up)

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Figure 10: Autologous bone graft (arrow to the left) filled into the right facet joint space (a); both side facet joints (arrow to the right) packed with bone grafts (b)

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Figure 11: The anterior arch of the atlas (a-c) was drilled (tubercle of C1 is shown by the arrow to the left)

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Figure 12: Odontoid process and part of C2 body was removed (arrow down) with the help of a drill, curette and fine Kerrison punch (a-d)

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Figure 13: Well decompressed cord (arrow down) after removal of the odontoid and part of C2 body (a and b); Surgicel (arrow to the left) was used for hemostasis (c)

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Figure 14: Titanium plates and screw were placed on the C1-C2 lateral mass for stabilization (a-d) on the left side. Please note the drill hole on C1 (arrow up) and on C2 (arrow down)

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Figure 15: Bilateral titanium plates and screws were in place (a-d). Well decompressed thecal sac (arrow down) was seen

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Figure 16: Posterior pharyngeal wall was sutured (a-c)

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Our experience with this technique

Results of 10 patients with a minimal follow up of 3 months is available. The patients were in the age group between 11 and 69 years. There were 6 male and 4 female patients. The duration of symptoms was between 5 and 17 months. There was a history of associated trauma in 2 patients. Neck pain was seen in 9 patients. All patients had quadriparesis and irreducible AAD with two cases having an additional basilar invasion. There were 8 and 2 patients in Ranawat grade 3A and 3B, respectively before surgery. Satisfactory intra-operative reduction of dislocation could be achieved in 3 patients, and 7 patients required an additional odontoiddectomy with part of the C2 body excision. Excellent visualization was achieved in all the patients. All patients improved after surgery to Ranawat grade 1 (n = 9) and grade 2 (n = 1), respectively at a follow up range of between 3–12 months. The duration of the procedure ranged from 105 to 185 minutes (average 145 minutes). Part of the anterior arch of the atlas was spared in 2 patients, apart from 3 more cases (total 5 patients) in which reduction could be achieved after joint manipulation and removal of the anterior constricting tissue. The blood loss ranged from 35 to 100 ml (average 75 ml) There was no permanent complication. Post -operative imaging showed a good decompression and C1-C2 alignment [Figure 2]. Postoperative swallowing difficulties were observed in 3 patients for 5–21 days after the surgery. There was no dural injury or CSF leak. There was no infection, significant tongue edema, or respiratory airway complication.


 » Discussion Top


Endoscopic procedures are being used in various cranial and spine pathologies such as abscess,[15] hydrocephalus,[16] arachnoid cyst,[17],[18] hematoma,[19] hydrocephalus secondary to tuberculous meningitis,[20] anterior,[21] and posterior cervical approaches,[22] and for cranio-vertebral junction[7],[14] etc. Results of surgery were good using the endoscopic trans-oral approach in the present study. Similar reports are available in the literature using the microscopic technique.[8],[9],[10],[11] Both decompression and fusion can be achieved using this technique. Intra- operative reduction of the dislocation could be achieved in 3 patients in our study due to removal of the anterior constricting tissue. Removal of the odontoid process with part of C2 body was done in 7 patients when there is no reduction of the C1-2 joints, which was a big advantage of this approach over the posterior approach.

There was a good visualization from the lower clivus to the C2 lower body in all cases in the present series. A similar experience of a good exposure from the lower clivus to the C2 lower body was observed in the studies by Yadav et al.,[2] and Pillai et al.[23] Although superior exposure is limited by the line drawn from the lower teeth and hard palate towards the cranio-vertebral junction (CVJ), and the inferior exposure is limited by a line joining the upper teeth, and the retracted tongue extending towards the vertebrae. The endoscope helps in a better visualization of this area. The use of angled tip instruments further help in achieving a better decompression and fusion in this endoscopic procedure. Instruments can be passed through the nose for facilitating a more cranial exposure, if needed.

Post-operative imaging showed a good decompression and C1-C2 alignment [Figure 2]. There was no permanent complication. The duration of procedure (an average of 145 minutes) and the amount of blood loss (average 75 ml) experienced was comparable to the other surgical procedures used for this pathology. Part of the anterior arch of the atlas could be spared in 2 patients, even when the odontoidectomy had been performed, a procedure which may be helpful in maintaining the stability of the region. The preservation of the anterior C1 arch can also help in avoiding cranial settling and also in avoiding an additional procedure for posterior fusion.[24],[25],[26],[27]

Advantages and limitations of the approach

Endoscopic trans-oral technique for anterior cranio-vertebral junction is the most direct approach to this region. It has the advantage of a better visualization of the posterior pharyngeal wall and the anterior bony structures at the foramen magnum from the lower part of the clivus to the C2 base, compared to operating using a microscope.[23] Palatal splitting could be avoided in all our patients. This procedure could be done when the mouth opening is even as small as 1.5 cm compared to at least a 2.5–3 cm mouth opening that is mandatory in microscopic excision. Surgery can be performed in any neck position (flexion or extension). There is minimal tissue dissection and the posterior tension band can be preserved. There is a good screw purchase in C1 lateral mass and the C2 pedicle. Both decompression of the anteriorly lying pathology and stabilization can be performed in a single stage.

A short follow up, and a small number of patients are the limitations of this study. Postoperative swallowing difficulties was observed in 3 patients from the 5th to the 21st day after surgery. Although we did not come across such complications, there may be a risk of dural injury, CSF leak, difficulty in closing the dura mater, and a risk of contamination by the oral bacterial flora. There is also a risk of tongue edema and respiratory airway complications. There may be difficulty encountered in removal of intradural lesions, and in approaching laterally lying pathologies using this technique. Patients with inflammation in the oral cavity, such as periodontitis and tonsillitis, and those with senile osteoporosis, should be excluded from the indications of this approach.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16]



 

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