Review of Pain Management in Multiple Sclerosis (MS)
Pain, a common symptom estimated to affect as much as 65% of MS patients can be debilitating and significantly impair function and overall quality of life (QOL). Characterizing pain syndromes in MS is challenging, and may be dichotomized based on origin into central neuropathic pain (CNP) and nociceptive pain (NP). Despite the significant impact on patient’s QOL, pain is often overlooked and undertreated. Also, treatment options for pain in MS are not well delineated making its management a challenge.
To review current treatment modalities for MS-related pain.
A literature search was done using Pub-Med. Relevant articles were reviewed and significant findings synthesized.
Conventional analgesics such as NSAIDs and opioids, the most commonly used medications in pain management protocols, are not efficacious for MS pain.
Common first-line agents in managing MS-induced CNP include tricyclic antidepressants, serotonin norepinephrine reuptake inhibitors, topical lignocaine, and calcium channel α2-δ subunit ligands. These drugs disrupt pain impulse transmission, but their side effects limit use. The use of drug combinations may reduce side effects, improve tolerability, and enhance compliance.
Carbamazepine is the most effective agent for treatment of trigeminal neuralgia in MS. Again, its side effects are problematic. When combined with gabapentin, the dose can be reduced, and this improves tolerability.
Nociceptive pain is managed using anti-spastics, muscle relaxants, benzodiazepines and anticonvulsants. Spasticity, a common cause of NP in MS is effectively managed with anti-spastics such as baclofen, tizanidine and gabapentin administered orally. Refractive cases may require invasive therapies like intrathecal baclofen or botulinum toxin. Generally, anti-spastic agents have few disturbing side effects, although high doses may result in muscle weakness. Recently, the cannabinoid nabiximols, has demonstrated efficacy in long-term symptomatic management of MS spasticity.
Ancillary treatment options for MS-related pain include physical therapy, transcutaneous electrical nerve stimulation and acupuncture. Acupuncture is hypothesized to act via release of endorphin and serotonin, the body’s natural painkillers, in CNS pain pathways.
Current management guidelines recommend individualization of therapy for MS-related pain.
Adequate treatment of MS-related pain is important. Clinicians need to be acquainted with the various therapies, to enable them identify optimum therapy for individual patients.