Managing neuropathic pain in cancer

“Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.” – IASP Definition of Pain - 1994

After several recent consultations for pain, may I present a few thoughts for when you are considering treatment options.

Remember that acute pain and chronic pain are vastly different entities. Acute pain (minutes/days) implies an acute cause and, when possible, correcting the cause will provide analgesia. Chronic Pain (months/years) is the disease and presents with a spectrum of associated symptoms, resulting in a negative impact on life and function.

There are many neuropathic pain syndromes seen in cancer patients:

Paraneoplastic sensorimotor neuropathy
Postherpetic neuropathy
Post-radiation plexopathies
Surgical neuropathies
- Phantom pain
- Post-mastectomy syndrome
- Post-thoracotomy syndrome
Brachial plexus neuropathies
Cachexia-induced
Cranial neuropathies
Chemotherapy-induced neuropathy
- Platinum agents
- Taxanes
- Vinca alkyloids
- Thalidomide
- Bortezomib

First, a few principles regarding neuropathic pain:

1. A careful assessment of the pain is critical using history, verbal scales, and physical exam. Diagnostic tests may be necessary.
2. Analgesics (often opioids) are required.
3. Co-analgesics are often added to analgesics and may provide additional benefit.

When treating neuropathic pain, titrate one drug at a time and start with an analgesic. I often start with a strong opioid (morphine, oxycodone, hydromorphone) and use a liquid preparation to allow careful and conservative titration.

Then add a co-analgesic agent. Remember, there are more than just anti-convulsants (e.g. gabapentin or pregabalin).

Anticonvulsants: e.g. pregabalin, gabapentin, carbamazepine, topiramate, etc.
Corticosteroids: e.g. dexamethasone
Local anesthetics: e.g. lidocaine
Tricyclic antidepressants: e.g. nortriptyline
Functional restoration: e.g. physical therapy, rehabilitation

Here is a recent reference with particular regard to chemotherapy-induced neuropathic pain.