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.