Name of Lecture: …Pathophysiology and Modulation of Pain

Name of Speaker: … Dr RM Kaushik, MD, FICP, Professor of Medicine, HIMS, HIHT, Dehradun, India

Program Time: …230-3:00

Name of Reporter: …Peter Fabian

Main Points of the Lecture: ....

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Pain is a person’s experience.  It is what he says and what he experiences.  Pain has a personal meaning for the patient.  It is real.  It is difficult to measure.  There are three types of pain: sensory, cognitive, and behavioral pain.  They differ in their location, duration, intensity and etiology.  Pain can also be referred (i.e. coming from a site distant from the current symptom).  Pain can be acute (less than 6 months), chronic (more than 6 months, often duller), or cancer pain.

We can measure pain on scales of intensity, i.e. analogue scale, numeric scale, descriptive scale.  He spoke about various concepts including pain threshold and pain tolerance.

He described the neurophysiology of various pain pathways to include: ascending pain pathways from the spinal cord to higher centers, descending pathways and other spinal pathways.  There was a review of the chemical mediators of pain like histamine, endorphins and enkephalins for example.

Nocioceptors perceive and transmit pain.  Different fiber types of the nervous system transmit different information.  There are four processes that can be viewed in relation to the nocioceptors.  There is transduction (conversion of the mechanical, thermal or chemical stimulation into the nervous system for transmission), transmission (movement of the information from the peripheral to central nervous system), perception (CNS response, either brief or prolonged), and modulation (internal and external ways of increasing or decreasing the pain).

The Gate Theory (a gate in the spinal cord that determines what information goes to higher centers) proposed by Melzak and Wall in 1965, has been significantly expanded to include other areas in the brain that can modulate pain not just the spinal cord). 

Many influences on pain by cognitive processes as well as mediated chemically.  Endogenous opiates play an important role.  Also many other neurotransmitters can affect neurotransmission of the pain pathway.  A review of common drug approaches was stated.  He listed many non-drug management categories: meditation, asanas, progressive relaxation, biofeedback, exercise, transcutaneous nerve stimulation, thermal modalities, and others.