Pain and the Treatment of Fibromyalgia and Functional Somatic Syndromes

• What is pain?
• “Normal” pain and the activation of nociceptive nerve fibers
• Nociceptive pathways to the spinal cord
• Nociceptive pathways from the spinal cord to the brain
• Neuropathic pain
• Peripheral mechanisms
• Central mechanisms
• Incoming synapses from peripheral neurons (primary afferents)
• Descending spinal synapses in the dorsal horn
• Here today and not gone tomorrow: the curse of chronic pain and other central sensitization syndromes
• Can pain gates be opened from the inside and cause pain in affective spectrum disorders and functional somatic syndromes?
• Pain in affective spectrum disorders and functional somatic syndromes
• The spectrum of mood and anxiety disorders with pain disorders
• Does depression or anxiety hurt?
• Fibromyalgia
• Gut feelings about irritable bowel syndrome
• Pain in other functional somatic syndromes
• Summary

Pain and the Treatment of Fibromyalgia and Functional Somatic Syndromes

This chapter provides a brief overview of a relatively new area in psychopharmacology – namely, the management of various chronic pain conditions associated with different psychiatric disorders and treated with psychotropic drugs. Included here are discussions of the symptomatic and pathophysiological overlap between disorders with pain and many other disorders treated in psychopharmacology, especially those with depression and anxiety. Clinical descriptions and formal criteria for how to diagnose painful conditions are only mentioned here in passing. The reader should consult standard reference sources for this material. The discussion here emphasizes how discoveries about the functioning of various brain circuits and neurotransmitters – especially those acting upon the central processing of pain – have affected our understanding of the pathophysiology and treatment of many painful conditions that may occur with or without various psychiatric disorders. The goal of this chapter is to acquaint the reader with ideas about the clinical and biological aspects of the symptom of pain, how it can be hypothetically caused by alterations of pain processing within the central nervous system, how it can be associated with many of the symptoms of depression and anxiety, and finally, how it can be treated with several of the same agents that can treat depression and anxiety.

Many of the treatments discussed in this chapter are covered extensively in previous chapters. For details of mechanisms of pain treatments that are also used for the treatment of depression, the reader is referred to Chapter 12; for those pain treatments also used as mood stabilizers, the reader is referred to Chapter 13. The discussion in this chapter is at the conceptual level, not at the pragmatic level. The reader should consult standard drug handbooks (such as Essential Psychopharmacology: Prescriber’s Guide) for details of doses, side effects, drug interactions, and other issues relevant to the prescribing of these drugs in clinical practice.