medial branch nerve question

[ctts]

I just saw a patient, new to me, with T12 compression fracture, I assume chronic, who then underwent T10-L2 fusion with pedicle screws and rods (no screws in T12). Surgery was on 6/6/14, about 4-5 months ago. She has two pains. One is in the middle of the surgical area, approximately T12, that she describes as a deep ache, and she and her surgeon are operating under the assumption that this is post-surgical pain that may take 1 year from time of surgery to resolve, so taking a wait and see approach. In addition, she has allodynia around the T10-11 level, fairly localized to the area of the surgical scar, maybe extending 2-3 inches lateral from midline. This is a what bothers her more. The surgeon sent her to me with request/recommendation for "T11-L1 facet injection/MBB" (this is literally what he wrote). I have no idea what to make of this... First who knows if the medial branch nerve is still intact from the pedicle screws going in. Even if it were, it innervates the facet joint and multifidus…as far as I am aware, it is not involved in cutaneous sensation. Is there any rationale for MBB to address cutaneous allodynia? First of all, she is so sensitive in the area, I am afraid that a procedure could just make things worse. So we are trying lidocaine patch or cream, and will work on increasing Lyrica.

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[powermd]

I just saw a patient, new to me, with T12 compression fracture, I assume chronic, who then underwent T10-L2 fusion with pedicle screws and rods (no screws in T12). Surgery was on 6/6/14, about 4-5 months ago. She has two pains. One is in the middle of the surgical area, approximately T12, that she describes as a deep ache, and she and her surgeon are operating under the assumption that this is post-surgical pain that may take 1 year from time of surgery to resolve, so taking a wait and see approach. In addition, she has allodynia around the T10-11 level, fairly localized to the area of the surgical scar, maybe extending 2-3 inches lateral from midline. This is a what bothers her more. The surgeon sent her to me with request/recommendation for "T11-L1 facet injection/MBB" (this is literally what he wrote). I have no idea what to make of this... First who knows if the medial branch nerve is still intact from the pedicle screws going in. Even if it were, it innervates the facet joint and multifidus…as far as I am aware, it is not involved in cutaneous sensation. Is there any rationale for MBB to address cutaneous allodynia? First of all, she is so sensitive in the area, I am afraid that a procedure could just make things worse. So we are trying lidocaine patch or cream, and will work on increasing Lyrica.

Why do you assume the fracture was chronic? A patient with pain in the vicinity of a compression fracture is active as far as I'm concerned until the fat suppressed MRI says otherwise. And why did she have a fusion around the fracture level? It sounds like the surgeon was taking a very expensive alternative to a cement injection. I would get a MRI with fat suppressed sequences to see if that T12 fracture really is quiescent. If it's active, you may be able to do an extrapedicular approach around the hardware and fix her. It seems way too early for her to develop facet syndrome secondary to the fusion, but whatever. Do the blocks in the meantime to see.

 

[ctts]

That's a fair question and criticism, in regards to assuming fracture is chronic. I do not have the original MRI images, but notes from surgeon states "sequential imaging studies demonstrated that this fracture was chronic in nature and not active." Also, his note states, "She had seen multiple surgeons, most of which did not recommend surgical intervention. She felt that she could not live with her pain as it is worse." So might be fair to question whether she should have been operated on in the first place. I will get prior MRI records, and possibly consider re-imaging as per your suggestion.

Nonetheless... I want to point out again that her primary concern is the allodynia around the upper part of the surgical scar. As far as I know, even if T12 compression fracture was active, it would not cause allodynia. And to be clear about the nature of her allodynia, she flinches when I lightly brush my fingers on her skin in this area, but if I do the same in the mid or lower portion along the surgical scar, she does not flinch. In the lower part, she can tolerate palpation with moderate pressure, although it also causes some pain. I agree it is too early to develop adjacent level facet syndrome secondary to fusion, but we are not talking about facet pain anyway, as facet pain also should not cause allodynia. The allodynia is a new pain after surgery.

So my question really is this: Does it make any sense to do medial branch blocks for this allodynia (and presumably RF ablation if good response)? Is there any anatomical basis to explain why it could help with cutaneous allodynia type pain?

 

[epidural man]

The medial branch does get a small patch of the skin.

Also, if the pedicle screw went through the medial branch (very likely in my mind), possibly caught the intermediate branch (does cutaneous) and maybe even lateral branch.

 

[powermd]

I'm not sure what to make of cutaneous allodynia in this case, although it sounds like a form of medial or lateral branch neuritis as EM said. PHN is another possibility, although this doesn't sound dermatomal. Allodynia around a surgical scar is not uncommon, but is usually self limiting. Could be a neuroma, and these often respond to injections into and around the painful scar region. You can even RF these (be careful how close to skin you get).

Is this patient kind of a needy whiner? I've seen patients with what amounts to postural muscle pain end up with surgery because they complained loudly enough.

 

[lobelsteve]

Surgery not indicated. Mbb contra indicated at site of fusion.

Why are you not reviewing the MRI images yourself?

Why did several other surgeons say no?

What drugs is she on?

WHERE is post op MRI?

How about topicals or scar injection? Lidocaine injection and if not lasting then Botox.

 

[ctts]

Thanks for the replies.

I will try to address some of the specific questions from Steve.

Surgery not indicated. Mbb contra indicated at site of fusion.

I can understand that MBB usually not indicated at site of fusion if treating facet pain...but I am talking about treating the allodynia, not facet pain.

Why are you not reviewing the MRI images yourself?

Outside MRI, I don't have direct access to images. We ask our patients to bring imaging, so she probably forgot or was unable to get it in time for appointment. Will ask her again next time.

Why did several other surgeons say no?

I don't know, but can look into this.

What drugs is she on?

Unfortunately, she is on chronic oxycodone 10 mg Q4-6 prn and Butrans 10 mcg/hr, since prior to surgery. Since surgery, she is now on MS Contin 30 mg Q8, Lyrica 25 mg daily (working on increasing), and tizanidine 8 mg TID. Also on lorazepam 1 mg QID. Also on Forteo. Yes, it is too much...and certainly complicates the picture, but her complain is very localized, in regards to the allodynia, so I still feel there is still a better explanation than generalized hyperalgesia from opioids. She did not strike me as a drug seeker, and certainly did not ask me for more.

WHERE is post op MRI?

What would be looking for? I am not sure how it would help in regards to the allodynia? I suppose we would look for edema around the pedicle screws, which would be hard to see anyway due to artifact? We can consider this, but I am skeptical that it is going to show us anything helpful, especially in regards to the allodynia.

How about topicals or scar injection? Lidocaine injection and if not lasting then Botox.

I have started topical lidocaine (patch or cream). I have not tried scar injection, but it seems powermd is also suggesting this, so may give it a try.

 

[Taus]

I'm not sure what to make of cutaneous allodynia in this case, although it sounds like a form of medial or lateral branch neuritis as EM said. PHN is another possibility, although this doesn't sound dermatomal. Allodynia around a surgical scar is not uncommon, but is usually self limiting. Could be a neuroma, and these often respond to injections into and around the painful scar region. You can even RF these (be careful how close to skin you get).

This. More likely in upper lumbar w/ location of intermediate and lateral branches in closer proximity to medial. (per one of my fellowship attendings who's on ISIS standards...I haven't seen the lit on this myself vs lower lumbar). Similar to what you may often see post cervical RF. Would treat as you are... neuropathic orals, topicals, possible scar neuroma injection.