Date post: | 01-Jun-2015 |
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MANAGEMENT OF PAIN
BYDR. OFOEGBU J.I
INTRODUCTION
Pain is a warning that something is wrong. It pre empts other signals.
Pain by Sherrington is “the physical adjunct of an imperative protective reflex”.
It is a subjective term and can be defined as a sensory and emotional experience
PHYSIOLOGIC OVERVIEW
• The sense organs for pain are the naked nerve endings found in almost every tissue of the body.
• The pain impules are transmitted to the CNS by 2 fiber systems;
• Small myelinated Ad fibers {fast pain fibers}
• Unmyelinated C fibers { Slow pain fibers}
PHYSIOLOGIC OVERVIEW CONTD
• The neurotransmitters for both include glutamate and Substance P respectively.
• Both fibers terminate on the dorsal horn.Some of the axons of the dorsal horn neurons end in the spinal cord and brainstem while others ascend in the lateral spinothalamic tract and a few in the dorsal portion of the cord.
PHYSIOLOGIC OVERVIEW CONTD
• The lateral spinothalamic tract fibers project to the ventral posterior nuclei of the thalamus.
• From here to the cerebral cortex. As such, pain activates cortical areas( post central gyrus) on the side opposite the stimulus.
MANAGEMENT
• The key to accurate diagnosis is a comprehensive history and detailed physical examination.
HISTORYa) Explore the painb) Review the systemsc) PMH and SHd) Drug history
HISTORY CONTD
e) Family and Social history EXAMINATIONGeneral Physical ExaminationSystemic Examination
INVESTIGATIONS
1) Diagnostic Imaging • a) Plain film radiology• b) Fluoroscopy• c) Computed Tomography Scan• d) Magnetic Resonance imaging• e) Myelography• f) Bone Scans
INVESTIGATIONS CONTD
• 2) Urinalysis• 3) S E/U/C• 4) FBC + ESR
TREATMEMT
a) Pharmcologicb) Neurosurgical Interventionc) Other non-conventional methods
PHARMACOLOGIC:CLASSES OF PAIN MEDICATIONS1) Non Steroidal Anti inflammatory drugs[NSAIDS] E.g Aspirin, Diclofenac, Apazone, Ibuprofen,
Celecoxib e.t.c MECHANISM OF ACTION • Inhibition of biosythesis of prostaglandins by
inhibiting cyclo-oxygenase isoforms• Inhibition of Chemotaxis• Downregulation of IL-1 production• Decreased production of free radicals and
superoxide• Interference with calcium mediated intracellular
events.
INDICATIONS
• Acute pains;inflammatory conditions like tendonitis, bursitis and arthritis.
• Pain from bone metastases in cancer patients.
• Others are rheumatic fever, transient ischaemic attack,coronary artery thrombosis
SIDE EFFECTS
• Gastric upsets, peptic ulcer disease,Elevated liver enzymes and Hepatitis e.t.c
2) Acetaminophen
MECHANISM OF ACTION• Weak inhibitor of Cox-1 and Cox-2
in peripheral tissues• Has no significant anti
inflammatory effects• Has antipyretic activity
INDICATIONS
• Mild to moderate pains as in headache, myalgia
SIDE EFFECTS Dizziness, Hepatotoxicity with
high doses etc
3) Opioids
• E.g Morphine, Codeine, Methadone, Fentanyl, Pentazocin, e.t.c
MECHANISM OF ACTION Bind to specific G-proteins coupled
receptors in the brain and spinal cord regions involved in transmission and modulation of pain.
INDICATIONS
Pains associated with cancer SIDE EFFECTS Behavioural restlessness,
respiratory depression, nausea, vomiting, constipation e.t.c
4) Corticosteroids
• E.g Prednisolone, Cortisone etc MECHANISM OF ACTION Phospholipase inhibitor INDICATIONS Acute pain and flare-ups of
chronic inflammatory conditions like vasculitis, SLE, Sarcoidosis etc
SIDE EFFECTS
Insomnia, behavioural changes, acute pancreatitis etc
5) Anticonvulsants E.g Neurontin (Gabapentin),
Lyrica (Pregabalin) INDICATIONS Neuropathic pain, Fibromyalgia
Local anaesthetics
• A) Nerve blocks• B) Epidural anaesthesia ; Patient
controlled Epidural anaesthesia (PCEA)
NEUROSURGICAL INTERVENTONS
• A) ABLATIVE PROCEDURES• a) Peripheral neurectomy• b) Myelotomy• c) Cordotomy• d) Sympathectomy• e) Dorsal root ganglionectomy
B) AUGMENTATION PROCEDURES
• a) Peripheral nerve stimulation• b) Spinal cord stimulation• c) Deep brain stimulation• d) Implantable infusion systems
OTHER METHODS
• Radiotherapy• Acupuncture• Use of ice• Rest• Elevation
Follow up
• Chronic pain can be managed but not cured; the majority of patients will require careful and regular follow up indefinitely. Periodic review of medications and careful evaluation of the progression of any underlying disease are important.
CONCLUSION
• It is natural to have pains. Medications are a key part of recovery and can speed healing and lead to fewer complications.