The Role of Interventional Procedures in Postherpetic Neuralgia
In this segment, moderator Peter Salgo, MD, inadvertently launches a verbal sparring session with Charles E. Argoff, MD, concerning a pain physician's ability to parse out peripheral and centralized pain experienced by a patient with postherpetic neuralgia (PHN) in order to form an effective interventional therapy strategy.
After Salgo poses a question on the degree to which peripheral versus centralized pain experienced by a patient dictates treatment course, Argoff asks Salgo to pinch himself and points out that "after you pinch yourself and you’ve experienced pinch, you’ve had both a peripheral and a central nervous system activity." Though injecting lidocaine or applying a topical numbing cream beforehand would have prevented Salgo from feeling the pinch, Argoff says one group of investigators at the University of California, San Francisco, failed to subtype PHN according to response to local anesthetic injection versus other approaches.
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"The fascinating but challenging and complex nature of taking care of somebody with PHN is that there are certainly peripheral and central components, and we don’t yet know even though the gold standard is 'let’s figure out the mechanisms and target the mechanisms in our treatment' we don’t yet know that a person has primarily peripheral and primarily central," Argoff explains. "So we usually approach our patients with PHN under the assumption and I think it’s a great educated assumption that there are both peripheral and central components, and we take that into account when we not only evaluate them, but when we treat them."
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On the topic of interventional approaches to treating PHN patients, Argoff notes that most medical literature has deemed nerve blocks or injection therapy to be most helpful in patients with acute herpetic neuralgia or PHN for three months or less not in the person who’s had PHN for six, 12, 18, 21 months." However, Argoff mentions that he has essentially eliminated pain through deeper brain stimulation in select PHN patients who otherwise didn't respond to treatment.
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"Counter stimulation has always been know especially in the acute pain setting to dampen the experience of pain," Argoff explains. "We know that the circuitry that helps to facilitate pain transmission is complex, but we also know that touch ... actually can dampen the experience of painful sensation."
