Nociceptive Specific cells (NS) are in high concentration in lamina I & V – receive excitatory input from HTM,MMT and CPM.
Some NS cells receiving input only from HTMs.
Wide Dynamic Range (WDR) neurons in lamina V – Receive convergent input.
Glutamate and Aspartate are the major excitatory neurotransmitters of CNS.
Bundles of nerve fibers whose cell bodies are located in the gray matter of spinal cord or brain stem and terminate by synapsing with cells in the brain, usually in the reticular formation or in the thalamus.
Each structure below the brain that projects to the cortex receives descending fibres from the cortex that can influence transmission in the thalamus, reticular formation, trigeminal system and spinal cord.
Cortical & diencephalic systems.
Mesencephalic periaqueductal grey matter (PAG) & periventricular grey matter (PVG)- rich in enkephalins and opiate receptors.
Parts of rostroventral medulla- the nucleus raphe magnus (NRM).
The spinal and medullary dorsal horn.
These axons are prominently seratonergic terminating on cells in the laminae I,II & V and selectively inhibit nociceptive neurons and interneurons.
Descending anlagesic system
Assessment and recognition of pain
Most important step.
Absence of verbal communication
Key source- Interpretation of behavioural and physiologic responses.
Latest - Power Spectral Encephalogram analysis.
Physiologic Signs of pain
Result of catecholamine release and activation of the sympathetic nervous system.
Cardiovascular system - heart rate & BP.
Pulmonary sys - resp. rate, shallow breathing.
Musculoskeletal sys - tense muscles, M. tremors.
Immune sys - resistance, stress leukogram.
Neuroendocrine sys - catabolism, anabolism.
Digestive sys - Inappetence, vomiting, diarrhoea.
Urinary and bowel habits
Guarding and self-mutilation
Degree of Pain
It is the common degree of pain that is treated.
it is intolerable
chance of self mutilation
Why pain management ?
Physiologic changes that accompany pain
Should be able to eliminate pathologic pain
Pain free sleep
12 – 24 hr post operative pain management is important.