We use the case of a mildly affected GBS patient with severe neuropathic pain to discuss the latter’s pathophysiology in general and the treatment for neuropathic pain in particular.
There is an excellent review article in BMJ 2014 which hints at the various drugs on the horizon, including some known substances whose application in neuropathic pain seems feasible (see below).
- Prophylaxis: in order to reduce the occurrence of neuropathic pain there is a good rationale for prophylactic treatment in certain cases, such as amputation, Zoster and nerve surgery, although not much good data has been published.
- Classify: distinguish NP with autonomic features from that without, central versus peripheral (the latter often with autonomous signs)
- Diagnosis: recognize the core features of pain character with good PPV (radiation, allodynia, hyperalgesia, autonomous sign if present, distribution along affected nerve structures)
- Basic treatment
- Stick to the basics: Despite the fact, that we Neurologists tend to think that NP is so special, we forget that basic nonsteroidal analgesics do work in NP; there is even a good pathophysiologic reason for that, since local cytokine production is influenced by at least the antiinflammatory substances (not acetaminophen, though).
- Opiates: next is opiates, most often as a bridge to other approaches – still highly effective and reasonably well tolerated
- alpha 2 delta blockers (gabapentinoids) work on the dorsal root ganglion and have been shown to be effective in many prototypical diseases
- Na blockers (carbamazepine, phenytoin, lidocaine, lamotrigine)
- NASRIs including tri- and tetracyclics and mirtazapin, as well as venlafaxine and duloxetine
- Local treatment: only if the pathophysiological proces is focal – capsaicin and lidocain patch
- Advanced treatment: for more advanced NP, ketamine seems to be the agent of choice as an NMDA blocker with all the problems arising. Further ideas could be: Baclofen, Clonidin. Many anticonvulsants (apart from those above) have been tested, not many survived, except in some diseases (trigeminal neuralgia for instance -> topiramate)
- Experimental or future therapies: Allopurinol (ADP antagonist), Aprepipant (NK1 blocker), Memantine, Amantadine (both mild NMDA blockers), Cannabinoids (good preclinical data, moderate effect), cytokine inhibitors, NGF blockers
Pain in Guillain-Barré-Syndrome
I hesitate to repeat all the information to be found in the literature. Still it has to be said that pain is very prevalent, often preceding and also often following GBS, can take several forms (backache, interscapular, distal, skin, myalgia, …) and is often severe enough to run through the above list. Here is a good review article in Neurologia on this from 2015. The best case series has been published in Neuroloy in 2010.