Pain_Gate_Theory__Electrotherapy

Pain gate theory Pain in detected by nociceptors: A delta and C fibres | | | |A delta fibres – sharp pain |C fibres – throbbing dull ache | |Large in diameter, myelinated |Small in diameter, unmyelinated, slow | |Conduction velocity 6-30 m/sec |More than Aδ x 2 | |Mechanical & thermal stimuli |1% speed of Aδ | |“transitory” pain |Conduction velocity 0.5-1.7 m/sec | |salutatory conduction |polymodal - Chemical, thermal & mechanical stim. | | |2o pain | . Melzack & wall, 1965 With grade one and grade two we are stimulating the A-beta fibres which travel through the dorsal root ganglia into the dorsal horn of the spinal cord at the level of lamina 2 in the substantia gelatinosa, with the purpose of closing down the pain gate ahead of any nociceptive signals by the A-delta and C fibres that travel up the afferent pathways in the spinothalamic and spinoreticular pathways. A-beta fibres ■ The largest peripheral nerve fibre ■ Large diameter ■ Myelinated ■ Respond to low stimuli (and are therefore ‘low threshold’) such as light touch, pressure and proprioception. ■ Impulses transmitted 30-100m/sec to the CNS ■ Normally relate non-noxious ‘mechanical’ Polysynaptic inter neurones Transcutaneous electrical nerve simulation You get hit, you get a sharp pain and dull ache, you rub it, tens mimics the sensory input of rubbing so your brain feels that type of tingling and not the pain, so your using an electrical stimulation to stimulate the A-beta fibres and dampen down any pain signals. Used for pain relief • Need to do a sensation test - sharp and blunt test | | | |Traditional or Hi or Normal TENS |Acupuncture or low TENS | | | | |High frequency pulses (90-130Hz) |Low frequency (2-5Hz) | |( narrow pulse width |( Wider Pulses | |Normal intensity |Stronger intensity | |Limited carryover |Pain relief lasts longer, even when the machine is off | |Pain Gait Theory |Opioid theory – simulating a painful fiber | ■ Opioid theory - it makes the brain and spinal cord produce its own natural pain killers, Stimulates the periquaduacal gray matter in the midbrain to release the body’s own natural opiates such as endorpins ■ This nociceptive modulatory system projects to the spinal cord via the dorsalateral funiculus, in which neurons of the NRM make inhibitory connections with laminae I, II and V of the dorsal horn. ■ Therefore, there is inhibition of the dorsal horn neurons including those of the spinothalamic tract neurons that respond to noxious stimulation. Intensity and Treatment duration Increase the current / intensity (mA) until the patient feels a mild tingling – because you are stimulating a painful fiber to stimulate pain, e.g get slapped and get pain and dull aches, sharp pain is transmitted by a-delta nerve fibre to get opioid release ➢ Accommodation - as the tissues get used to the current, the intensity may have to be increased, or change pulse width, continuous (C) or modulated (M) settings ➢ Treatment times: Acute ~ 10mins, Chronic ~ 20-30 mins Interferential • Difference between 2 medium 2 frequency currents with the net effect of a low frequency, the higher the frequency the lesser the resistance of the tissue • The currents are slightly out of phase i.e one starts and then the other, the difference between the currents is the beat frequency (which is the frequency/dosage we set on the machine) • Check sponges for dark patches as they are dead skin, • When using Interferential- Turn on the machine, ensure the output is zeroed, test on yourself by putting the pads in between the webbing of fingers - then back to zero before putting the electrodes on patient • Teach the patient the settings of the dial, increase intensity if they feel it • Give pt bell or buzzer, check half way through at least once, • After treatment, take the electrodes off patient then power line off | | |4 pole method | |Paired electrodes MUST be diagonally opposite to ensure currents interfere | |2 pole method | |1 pair of electrodes placed diagonally | |Current interferes within machine | |stronger sensation at tissue interface, | ➢ Pain relief: • Pain Gate Theory 90-130 Hz • Opioid Theory-Stimulation of Aδ fibres (2-5 Hz) • ➢ Decrease swelling: • Increased circulation • increases the amount of tissue fluid in a swollen area, which helps the ‘harmful’ plasma proteins flow off to the lymph glands ( 0-100 Hz) | | | |CONTRAINDICATIONS |PRECAUTIONS | | | | |Poor understanding patients/non co-operative patients |Decreased skin sensation | |Cardiac pacemakers |Don’t place over the eye | |Dermatological conditions (eg eczema, dermatitis) |Epiphyseal growth plates | |Open wounds |Pregnancy during 1st trimister | |Thrombosis | | |Recent Haemorrhage/vascular dysfunction | | |Infection | | |Malignancy-unless palliative | | |Metal work | | |Uncontrolled epilepsy | | |Cervical spine- Vagus nerve or Carotid Sinus | | Not give TENS to pt with uncontrolled epilepsy, decrease mental capacity, poor RA of the hand, pregnancy during 1st trimester, malignancy active implants, pacemaker, active tissue bleeding, PRECAUTION – metal implants, local circulatory insufficiency,