Cervical SCS trial tips

[Nonphysiologic]

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Hey, got my first cervical scs trial coming up...I could have sworn as a fellow my attending and I would enter the space at L1/2. My rep keeps telling me though C7/T1....I obviously haven't done a cervical scs in like 6 mo or so


I'm not gonna lie I'm a little concerned about entering at C7/T1 mostly because I'll be using a 14G needle and it'll be a little weird for me to get LOR up there with that...any tips?

I was thinking of using curved needle tip also I was thinking of not relying on LOR so much and instead relying on contralateral oblique view and if im able to pass through the lead....

What do you guys think of that strategy and any other tips?

Thanks





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[Aether2000]

I have done both. Using the curved tip Tuohy contralateral oblique needle placement method at C7T1, confirmed with contrast, it is fairly safe if you advance millimeter by millimeter and use the posterior facet line.

 

[unchockey21]

Hey, got my first cervical scs trial coming up...I could have sworn as a fellow my attending and I would enter the space at L1/2. My rep keeps telling me though C7/T1....I obviously haven't done a cervical scs in like 6 mo or so


I'm not gonna lie I'm a little concerned about entering at C7/T1 mostly because I'll be using a 14G needle and it'll be a little weird for me to get LOR up there with that...any tips?

I was thinking of using curved needle tip also I was thinking of not relying on LOR so much and instead relying on contralateral oblique view and if im able to pass through the lead....

What do you guys think of that strategy and any other tips?

Thanks





Sent from my iPhone using SDN mobile

You probably did enter L1/2. We had some attendings enter low and some enter high. They both have pros and cons. Easier entry lower but can have a harder time driving the lead or get bowing. Bottom line is do it the way that you feel comfortable. Don’t let some rep with a music degree talk you into doing something different. Personally, I like entering high but that’s just me. As long as the leads end up in the right spot who cares how they get there. If you do end up going high, I agree with using CLO but I’d still use LOR. I can’t quote a paper, if one even exists, but I’ve been told by multiple people that complications are higher using a lead for loss.

 

[Orin]

The rep may not have the long leads for you to drive up from the lumbar space, so if you have the usual size lead, you may not be able to get there from L1-L2. You can enter anywhere below your target level, with the caveat of lead length, but I would generally aim for anything between T1 - T7 if you have space between the processes. You want a little bit of landing space on the cord prior to your target level, but you just need to have enough wire to reach.

When I don't have a LOR syringe or higher up when I don't have great visualization, I go with CLO and verify with the lead gently. Using the lead or the manufacturer's supplied stylet for loss is a bit unnerving as they're stiff but the lead is less pierce-y.

One of my attendings was a fan of dropping down and touching the lamina below the target level first, and then sloping off of it into the space, but I find that fulcrums my Tuohy away from the epidural space in the thoracic spine especially. I just end up taking the curved needle and having a steeper angle of attack. Driving it is a bit harder though then.

Regardless of the approach, that case lives/dies by the initial positioning on the table so open up those spaces and get the patient comfortable. Get a shot in AP and CLO before you prep/drape.

 

[Ducttape]

i usually will look at T1-2 initially and do a fairly severe cephalad obliquity, more than one would expect.

 

[emd123]

Hey, got my first cervical scs trial coming up...I could have sworn as a fellow my attending and I would enter the space at L1/2. My rep keeps telling me though C7/T1....I obviously haven't done a cervical scs in like 6 mo or so


I'm not gonna lie I'm a little concerned about entering at C7/T1 mostly because I'll be using a 14G needle and it'll be a little weird for me to get LOR up there with that...any tips?

I was thinking of using curved needle tip also I was thinking of not relying on LOR so much and instead relying on contralateral oblique view and if im able to pass through the lead....

What do you guys think of that strategy and any other tips?

Thanks





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If you haven't done a cervical in a while, I'd say err on the side of entering much lower, and deal with the longer thread distance, until you're more comfortable going higher up. Seems dealing with a longer steering distance is a better downside than dinging the cord at c7/T1, if you're not confident the the more aggressive (higher) entry point.

 

[Nonphysiologic]

Thanks everyone ...hmm yeah I'm still debating which method to use...i feel like if I use the CLO lead for loss method up at T1 it should be pretty straight forward and the tunnel will be way easier....


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[Tapspatellas]

Thanks everyone ...hmm yeah I'm still debating which method to use...i feel like if I use the CLO lead for loss method up at T1 it should be pretty straight forward and the tunnel will be way easier....


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I like any between C7-T5, find T1-2 used most frequently, but if I have a nice wide open looking interlaminar space below I take that. I like to get a nice wide interlaminar view, then go 45 deg and contact edge of lamina with modified touhy. Switch to CLO and walk off with LOR. Very often quite soft up there due to the small size with that big scooped out bevel not being fully occluded. I will try to gently pass the lead several times while accessing typically, I take my sweet time.

Edit:should have read between C7-T5, not just C7-T1

 

[Nonphysiologic]

So I did them today...went ok. The first one the ligament was super thick at c7/T1. I did gently push the lead to confirm but it didn't work as well as I thought it would mainly because ultimately you still need to pass through ligament and I was just more comfortable advancing with an LOR syringe on.

I think I have a couple issues with entering cervical:

1. The 14g + sometimes thick ligament can some times require you to really push hard through ligament which is kind of scary in the neck because I don't want to put all this force down and then nick the cord....I've been looking for answers on this online maybe someone can help me out: how big is the epidural space in c7/t1 on average. I see a lot of literature in skin to epidural but not the depth of the epidural space itself. Honestly I'm not worried really about wet tap I just don't want to hit the cord.

2. I can see how it is much harder to steer up to cervical from lumbar but I also believe in keeping things consistent. Because then when you do implant for cervical or lumbar you will always go to the flank. Also, trial wise you don't have to worry as much about the external leads and can also place by the flank.

3. I tried using the curved initially but I switched over to the straight needle. Curved made it easier to access the space but I didn't like how I had to rotate it while in space to thread up the lead. I'd like to move that needle as little as possible once it's in the space like that.

4. I think from now on I'm just gonna stick with lumbar entry. I felt like I was too nervous. Maybe it's because I'm not used to loss with a 14G in the neck. Also i actually don't find steering it that bad for the most part and especially when using HF-10 the placement doesn't matter as much.


Thoughts?

Thanks


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[Aether2000]

Most of the time, the lumbar entry works just fine, especially in patients with limited thoracic and cervical mobility. The caveat is that if you meet significant obstruction on advancement in the thoracic or cervical spine, switch to a lateral or contralateral view frequently to assure the tip of the lead is not diving anteriorly (There are reports of the lead diving into the cord itself and then advancing cephalad within the cord).

HOWEVER, for patients who are active and mobile, there is significant lead cephalad-caudad movement due to thoracic spine flexion, resulting in erratic coverage of upper extremity and cervical spine pain or even overt shocking of the patient. This is due to the anchor point being 30-40cm away from the lead tip with the lead extending over a spinal segment that may have significant flexion/extension, causing distal migration of the lead tip in thoracic flexion. On occasion, I have seen distal migration of the leads requiring surgical revision (not easy given the fibrosis bands that are then present above the tip of the migrated leads).

Early on after implantation, there may be a greater tendency towards lateral migration of the lead tips especially if there is cephalocaudad movement of the lead during thoracic flexion since the bands of fibrosis tissue that forms over the posterior aspect of the leads may be delayed, or the linear channels in this fibrosis tissue may become elliptical shaped allowing slight lateral motion. This can partially be eliminated by crossing the lead several times back and forth across the midline during advancement through the plica medialis dorsalis, but if there are two leads advanced in this manner, there will be obligatory stacking of leads, and if they cross in a segment of the spine that has limited AP diameter, the cord may be impacted.

Finally, during such extended advancement of the leads, there is an inherently greater resistance encountered to advancement of the leads, sometimes causing buckling of the leads into the lateral gutter of the epidural space. If this is not corrected at the time of anchoring (by retraction of the lead until the lateral bowing is corrected), the patient may experience radicular pain at the area of lateral buckling of the lead. Routine use of a lead introducer can alleviate much of this (needle-lead blank/guidewire-remove needle-introducer advanced to full length into the epidural space-removal of lead blank/guidewire-advancement of the lead). One sign of migration of the cervical tip distally may be thoracic or lumbar radicular pain onset.

 

[Sparkymd]

Most of the time, the lumbar entry works just fine, especially in patients with limited thoracic and cervical mobility. The caveat is that if you meet significant obstruction on advancement in the thoracic or cervical spine, switch to a lateral or contralateral view frequently to assure the tip of the lead is not diving anteriorly (There are reports of the lead diving into the cord itself and then advancing cephalad within the cord).

HOWEVER, for patients who are active and mobile, there is significant lead cephalad-caudad movement due to thoracic spine flexion, resulting in erratic coverage of upper extremity and cervical spine pain or even overt shocking of the patient. This is due to the anchor point being 30-40cm away from the lead tip with the lead extending over a spinal segment that may have significant flexion/extension, causing distal migration of the lead tip in thoracic flexion. On occasion, I have seen distal migration of the leads requiring surgical revision (not easy given the fibrosis bands that are then present above the tip of the migrated leads).

Early on after implantation, there may be a greater tendency towards lateral migration of the lead tips especially if there is cephalocaudad movement of the lead during thoracic flexion since the bands of fibrosis tissue that forms over the posterior aspect of the leads may be delayed, or the linear channels in this fibrosis tissue may become elliptical shaped allowing slight lateral motion. This can partially be eliminated by crossing the lead several times back and forth across the midline during advancement through the plica medialis dorsalis, but if there are two leads advanced in this manner, there will be obligatory stacking of leads, and if they cross in a segment of the spine that has limited AP diameter, the cord may be impacted.

Finally, during such extended advancement of the leads, there is an inherently greater resistance encountered to advancement of the leads, sometimes causing buckling of the leads into the lateral gutter of the epidural space. If this is not corrected at the time of anchoring (by retraction of the lead until the lateral bowing is corrected), the patient may experience radicular pain at the area of lateral buckling of the lead. Routine use of a lead introducer can alleviate much of this (needle-lead blank/guidewire-remove needle-introducer advanced to full length into the epidural space-removal of lead blank/guidewire-advancement of the lead). One sign of migration of the cervical tip distally may be thoracic or lumbar radicular pain onset.

Very helpful and thoughtful. Thanks for taking the time!

 

[Sparkymd]

Algosdoc, it sounds like in most situations you prefer higher insertion. Any pointers for such an approach?

 

[Aether2000]

My approach depends on patient activity level. I prefer lumbar approach from a safety approach if the patients are relatively inactive. My cervical approach is parallel to the lamina if possible. This may place the entry point 1 or 2 vertebral levels inferior to the interlaminar entry level. The CLO view is imperative, esp. in thicker patients. The length of the incision depends on the anchor depth (posterior cervical fascia, interspinous ligament. The LOR technique may not work very well, giving a false loss of resistance in the interspinous ligament, or may give no LOR at all as the tip passes the discontinuity in the ligamentum flavum at the C7T1 level (common). The placement of a lead anterior to the ligamentum flavum may require either contrast injected through the Tuohy needle (causes the lead to become somewhat sticky) or attempted gentle advancement of the lead using only the CLO technique as your guide, given the inadequacy of the LOR technique using such a large needle diameter.