Wiki source code of EEA Odontoidectomy

Last modified by XWikiGuest on 2023/10/09 14:28
Show last authors
1 = Preop =
2
3 Know the course of the carotids, especially:
4
5 Where they run anterior to the C1 and C2 vertebral bodies. The carotids often course medially in this area and occasionally will come together or "kiss" anterior to C1. In the image below the carotids do "kiss" but at the level of the C2/3 disk space.
6
7 Pay attention to the inferior extent of the clivus and know whether you will have to take some clivus to facilitate the decompression.
8
9
10 [[image:1695383650986-764.png||height="307" width="599"]]
11
12 = Monitoring =
13
14 SSEPs, BSERs, usually bilateral CN12 especially if there is some congenital fusion or bony assimilation
15
16 = Medications =
17
18 Dexamethasone 10 mg, Ancef
19
20 = Positioning =
21
22 Typical [[EEA positioning >>doc:Notes By Procedure.Skull Base.EEA.WebHome]]with the following exceptions:
23
24 1. Place a bump lengthwise under the left shoulder
25 1. Leave the head entirely neutral - no extension, rotation, or lateral tilt
26
27 = Procedure =
28
29 As for all EEAs, ENT will start, but there is significantly less for them to do in these cases so they will be ready for neurosurgery to scrub in within 20-30 minutes.
30
31 === Posterior septostomy ===
32
33 Navigate along the nasal floor to the choana. Begin at the superior edge of the choana and draw a line anteriorly, angled down to the nasal floor. Draw a second line from the inferior edge of the choana along the nasal floor, to meet the first line at the anterior extent. This defines the septostomy.
34
35 Use the needle-tip Bovie to cut the mucosa along the red lines, then elevate with a cottle. Use a backbiter to bite away the outlined septostomy.
36
37 **Right side**
38
39 [[image:1695479096032-383.png||height="304" width="229"]][[image:https://s6.gifyu.com/images/S4r99.gif||alt="Recording 2023-09-23 at 10.10.00" height="306" width="330"]]
40
41 **Left side**
42
43 [[image:1695478865460-276.png||height="352" width="224"]][[image:https://s6.gifyu.com/images/S4r3V.gif||alt="Recording 2023-09-22 at 14.08.28" height="351" width="416"]]
44
45 === Maxillary crest drilling ===
46
47 The curved white line demarcates the edge of the posterior septostomy. The maxillary crest needs to be drilled down so you can reach low enough in the back.
48
49 [[image:1695479803327-981.png||height="393" width="419"]][[image:https://s6.gifyu.com/images/S4r9h.gif||alt="Recording 2023-09-23 at 10.41.48" height="393" width="418"]]
50
51 Use image guidance to make sure you're low enough at the back of the field to reach the inferior aspect of the C1 anterior arch.
52
53 Run the drill from right to left over the stump of the maxillary crest to see if there is still a "hump" of crest that your instrument bumps over. If there is, you need to drill more.
54
55 Be careful with drilling lest you create a palatal fistula which is really bad.
56
57 [[image:https://s6.gifyu.com/images/S4r9q.gif||alt="Recording 2023 09 23 at 10.48.57" height="420" width="447"]]
58
59 === Raising the retropharyngeal flap ===
60
61 The classic RP flap is an inverted "U" shape along the back of the retropharynx, demarcated as a white line. The arrows mark the location of the Eustachian tubes. The top of the RP flap is at the angle between the back of the retropharynx and the floor of the sphenoid sinus.
62
63 When the carotids are potentially at risk due to medial deviation, a "T" shaped incision is used instead.
64
65 [[image:1695486319994-710.png||height="317" width="371"]][[image:1695481101110-944.png||height="319" width="374"]]
66
67 In this case, we began intending to do a traditional "U" shaped incision, but changed course midway through in favor of the "T" shape.
68
69 The **rectus capitis anterior, longus capitis** and **longus colli **muscles are visible between the clivus and nasopharyngeal fascia.
70
71 The **supracondylar groove** is the bony landmark for the hypoglossal nerve on the ventral surface of the occipital bone. It is formed by the insertion of rectus capitis anterior.
72
73 [[image:https://s6.gifyu.com/images/S4r9n.gif||alt="Recording 2023-09-23 at 11.09.58" height="282" width="314"]]
74
75 [[image:1695605793571-545.png]]
76
77 Schematic demonstrating relevant anatomy. PS:** rectus capitis anterior, longus colli **and** longus capitis **muscles; OC: occipital condyle; D: dens; R: midline raphe; FM: foramen magnum.
78
79 From Kassam, Amin B., et al. "The expanded endonasal approach: a fully endoscopic transnasal approach and resection of the odontoid process: technical case report." //Operative Neurosurgery// 57.suppl_1 (2005): E213-E213.
80
81 === Drill the C1 anterior arch ===
82
83 Left arch. We started with a diamond bit and later transitioned to an M8.
84
85 [[image:https://s6.gifyu.com/images/S4r9V.gif||alt="Recording 2023-09-23 at 11.31.00"]]
86
87 Right arch.
88
89 [[image:https://s6.gifyu.com/images/S4r9a.gif||alt="Recording 2023-09-23 at 11.35.23"]]
90
91 Use a Kerrison and straight Thru-cut to cut the ligamentous attachments of the arch and remove it.
92
93 === Odontoidectomy ===
94
95 Use a straight Thru-cut to bite away the ligamentous attachments and pannus overlying the odontoid.
96
97 Drill the odontoid from top to bottom.
98
99 [[image:https://s6.gifyu.com/images/S4r9f.gif||alt="Recording 2023-09-23 at 11.41.39"]]
100
101 Switch to a diamond bit again when you reach the posterior cortex of the odontoid. When it's thin, the posterior cortex will move when you push on it with the drill bit.
102
103 [[image:https://s6.gifyu.com/images/S4r95.gif||alt="Recording 2023 09 23 at 11.46.22"]]
104
105 Use a Kerrison to remove the final piece of posterior cortex
106
107 [[image:https://s6.gifyu.com/images/S4r9G.gif||alt="Recording 2023-09-23 at 11.54.24"]]
108
109 === Pannus resection ===
110
111 Remove the pannus with Kerrisons and Thru-cuts
112
113 [[image:https://s6.gifyu.com/images/S4r9P.gif||alt="Recording 2023-09-23 at 11.57.44"]]
114
115 Usually, you will stop once you see pulsations in the tectorial membrane. In this case, the tectorial membrane was hypertrophic and compressive, so the resection was carried to the dura.
116
117 [[image:https://s6.gifyu.com/images/S4r9e.gif||alt="Recording 2023-09-23 at 12.03.31"]]
118
119 = Closure =
120
121 Use a 3-0 V-loc suture to close the descending limb of the RP flap. Start at the bottom and work up. ENT will usually pack with an absorbable packing like Posisept.
122
123 [[image:https://s6.gifyu.com/images/S4rES.gif||alt="Recording 2023-09-23 at 12.06.27"]]
124
125 = Orders =
126
127 1. EEA order set
128 1. ICU admission
129 1. Dexamethasone 4q6 for 24 hours
130 1. CTA head and neck
131
132 = Follow-up =
133
134 Two weeks for a wound check, usually with AP and lateral x-rays, sometimes with an MRI c spine
135
136 Dr. Okonkwo will review images when the patient comes to Gardner's clinic but does not need to see the patient
137
138 Second visit is in 6 months with AP lateral c spine films with Okonkwo and in 1 year with MRI c spine with Gardner