Asleep DBS

Walk into room
Anesthesia does their thing
Retape eyes with tegaderm
Turn bed 90 degrees so head is facing ceretom
Pin with doro frame (radiolucent head holder) - shoulders may get in the way - pad shoulders with foam
Fix Mayfield on inner side of head holder
Bottom of Mayfield has to be angled back towards patient's feet - if its angled forward, it will hit CT scanner and you won't be able to get entire head in scan
Shave head
Prep with chloraprep then chlorhexidine then alcohol
Put in 5 fidicuial screws - 2 frontal, 1 left posterior (above/behind L ear), 2 right posterior (one by bregma, one above/behind R ear), roughly in a circle - bias screw 3 (posterior L screw) medial to allow for tunneling
CT scan
Put suction-cup registration device on head, non-sterile registration of fiducial screws with blue thing
Use stealth to determine optimal entry points
Mark entry holes with pen. Draw upside down U-shaped incision lines approx 1 cm radius around point
Prep again
Hand drill to mark entry points
Drape - body drape, 4 drapes in square on head - include fiducial screws in field. Ioban.
Incision
dissection between galea and periostium around incision and in flap. Or subperiosteal. depends on who you ask.
Hemostasis
On L side, dissect posteriorly to form pocket
Burr holes
Hemostasis
Screw in stimlock - do not strip screws - screws on both side, slit pointing down
Screw in base - two screws that are closer together approx 10 o'clock and 2 o'clock, the one pointing down at 6 o'clock. do not strip screws. Base has to be tight, all things are registered off base.
Make sure clip fits
Attach dome
Attach other registration device to left dome.
put steatlh probe into dome, find optimal trajectory and depth. tell scrub tech so they can set the cannula.
Attach nexdrive micropositioner
Then put in cannula
Figure out where it will enter dura. Bipolar dura at that point. a lot. Cruciate incision with 11-blade
Attempt to pass cannula - if any resistance, bipolar + 11 blade again. you need to get through Pia.
push in cannula to pre-determined depth into center hole
remove stylet
Place extender
Pass electrodes
remove cannula
apply clip to base of electrode
mark electrode where its coming out of the clip
Tisseal into burr hole
CT scan - merge with preop MRI with plan. deviation of <2mm is acceptable. More requires electrode replacement
Remove everything
close - do not hit the electrode with your needle. electrode is very sensitive and fragile.

DBS generator

pocket - incision 1 finger breath below clavicle approx 5-6 cm long. Cut down until you get deep to fascia into fat layer but above muscle, make a pocket deep enough to fit finger to knuckle.

ear incision - far down enough to be over the curve of skull (sucks to tunnel over the curve), but high up enough to access leads. bovie to bone. Look up to find leads, flip them out. use heavy scissors to start tunneling process to get through neck fascia, open them, then pull them back out. LEFT lead has tie on it. Use tunneler to get to pocket. go above the clavicle. anesthesia gets upset if you tunnel into subclavian artery. screw extension leads onto tunneler and pull back to incision (L and R extension leads are the same).

connect extension leads to head leads-- white = right, blue = left. Starting with left, remove plastic coverings off head lead, wipe lead with blood, put raytech below for clean field, put new clear plastic covering thingy on (skinny side first) connect extension lead on; when you screw the leads on, you must hold the lead by contact 1 tightly  (i.e. provide counter-torque) otherwise you risk breaking the electrode. if you break the electrode, you're fired. screw to 1 click of tightness. Repeat with right electrode - only use white covering instead of clear.

connect leads to generator (for medtronic, left is contacts 1-7, right is 8-15, left goes in front, right in back, front is the brand name side). screw to 3 clicks of tightness. tuck generator into pocket, rep checks impedance. very high impedance = suboptimal contact between electrode contacts. very low = concern for short circuit i.e. electrode breakage. If all goes well, pull the electrodes straight. close pocket and head.


DBS generator replacement

Knife through skin, then continue with knife while feeling with your fingers. the only way you screw this up is by cutting the leads. cut towards the generator. Cut through capsule with knife, make sure to turn the corners around both edges. Pull out generator with kocher. unscrew/remove leads one at a time! front/left lead first. correction, the other way you screw this up is by mixing up L and R leads. Connect leads to new generator first left, then right - put the leads all the way in, make sure good contact, screw to 3 clicks of tightness. put generator back into pocket, brand name side up. Test generator to check impedances. If good, anchor with non-absorable suture if needed, close.

ACDF 

Head towards anesthesia. towel roll under shoulders horizontally. head taped down - straight (important bc you don't want to fuse them turned, also helps identify midlines structures during surgery). arms tucked. 

Mark midline cartilagenous structures, SCM, sternal notch. Use fluoro to localize your levels 

- FYi - hyoid is approx C3, thyroid cartilage is approx C4-5, cricoid cartilage is approx C6

Small horizontal incision for 1-2 levels, big horizontal incision for 3 level, at 4+ levels you probably need CEA style vertical incision. 

Dissect through skin to fat - once you approach platysma, put scissors underneath to elevate it and cut through it horizontally with bovie. Then dissect rostral and caudal in a sub-platysmal plane. 

Find plane medial to SCM - and go straight through to to vertebrae. if you need to cut omohyoid, you can. SCM and carotid should be lateral, esophagus and trachea should be medial. If it doesn't dissect easily, you are in the wrong plane. Put in retractors (we often use clowards). 

Use kittners to get all the fascia off the spine. Mountains are disks, valleys are vertebrae. Localize your operative level -  recommend caspar pin into one of the vertebrae you are fusing; some people do needle into disc but this can theoretically poke a hole in the wrong annulus (does this increase risk of future disk hernation?) and then you have to pull it out and mark that level somehow and your mark could come off or it could slip out etc. To avoid adjacent segment disease, expose only the operative levels (ie. if you are doing 4-6 ACDF, expose only the bottom of 4 and the top of 6, only enough to get your plate in. 

Once your level is confirmed, use bovie to elevate longus coli off just to the uncovertebral joints - don't go more lateral than that - you risk injury to sympathetic chain under longus coli, you also risk injury to verts. Your cloward (or whatever) retractors should be flush all the way to the vertebrae while doing this - otherwise if your bovie slips and there is no retractor stopping it, you will run into the carotid/IJ laterally or the esophagus medially. That is bad. 

Measure depth and put in your color-coded retractor system of choice - Trimline, phantom, etc. Put in the remaining caspar pins, make sure they are all midline and lined up neatly. Use knife to cut square into your disk. Don't cut too aggressively lateral, thats where the vert lives. 

Use a combination of curette (straight and curved), pituitary, kerrison and drill to remove the disk. Use the straight curette against the endplates to prepare them to receive fusion graft. you know you are at PLL when you feel the posterior edge of the disks. if there are osteophytes at the posterior aspect, drill them down. 

Taking of PLL is controversial - some people always do it, some people rarely do it, some people say do it only if there is significant central stenosis/myelopathy (i.e. may not be needed if you are only doing foraminotomy). If you take PLL, then use nerve hook to get under PLL and flick towards center to get it away; you are done only when the shiny pretty dura is visible the entire length of the disk. 

Make sure to run nerve hook at either edge to ensure the foramina are open and free. if they are not, take a kerrison and bite stuff off until they are open. 

Make sure your endplates are prepared! Free of cartilage. That will prevent fusion. However do not be too aggressive, otherwise if you have no endplate then your graft will subsist (i.e. sink into cancellous bone) 

Put in your sizing tool - it should fit very snug. determine appropriate size of graft. Then put in graft. it is our humble opinion that PEEK cages with tiny-ass bone insert fail more often than all-bone allografts. Whatever. something to ensure fusion. certainly do not leave in an all-metal/all-PEEK construct with no bone/fusion material. That is just silly. Hammer it in; ideal graft placement is relatively anterior, but fully flush at the anterior edge. 

Plate over the system - screws should angle towards the center of each vertebrae (i.e. at bottom edge of bone screws will be angled inferior and medial. 

Two view XR at the end. 

Thoughts: 

- A fast surgeon can complete a 1 level ACDF in 45 mins and a 2 level in 90. This is the goal to shoot for. 

- if you ever do skip-level ACDFs (i.e you fuse 4-5 and 6-7), the intervening levels will fail and they will fail soon. additionally - if you fuse 5-6, because there is limited movement at 7-1 -- 6-7 may fail. 

- when to do ACDF rather than PIF - when compression is mostly anterior rather than from ligamentum/uncovertebral hypertrophy, or when there is a kyphotic deformity you are trying to correct by jamming in a wedged graft 

- if the disk is herniated such that it's in the middle of the vertebrae - consider corpectomy instead

- if there are many (i.e. entire subaxial cervical spine) levels of significant disk herniation causing bad cervical stenosis, and you don't want to do a 5 level ACDF, can consider big posterior lami and fusion instead. can also consider multi-level laminoplasty, either swing-door or french door. Risk for worsening of kyphosis, but typically not a problem unless >5 degrees of kyphosis already. Laminoplasty at C2 and C7 tend to cause a lot of pain but not so much in between (consider laminoplasty for C3-C6 + laminectomy C7 if needed). Can still do foraminotomy. 

- if there are many (i.e. entire subaxial cervical spine) levels of significant disk hernation causing bad cervical stenosis, and the person is 90 years old or a medical train wreck and you want to get them off the table as fast as possible, then consider big posterior lami without fusion - although the risk of subsequent kyphotic deformity will be high 

- if there is mostly uncovertebral disease and/or the patient is mostly having radiculopathy symptoms - consider posterior foraminotomy only. 

original scan on bottom, new scan 1 year later on the top 

- on original scan - L4-5 foraminal stenosis- you would expect an L4 radiculopathy since foraminal stenosis affects the exiting nerve root, and the L4 nerve root exist at L4-5. 

- on new scan - now stenosis is at the lateral recess, you an see from the different slices that the traversing nerve roots get crushed by the disk. You would expect an L5 radic since the L5 nerve roots are passing by at this level.