• Anatomy & Physiology - bones, muscles, nerves, joints, organ systems
• Biomechanics - movement analysis, forces, posture
• Pathology & Kinesiology - conditions, movement disorders
• Pharmacology - drugs used in PT practice
• Clinical topics - assessment, rehabilitation, therapeutic exercises
• Study help - explanations, summaries, flashcards, diagrams

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TENS (Transcutaneous Electrical Nerve Stimulation)

Complete Exam Notes - BPT 2nd Year

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1. Definition

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2. Equipment

• Pulse generator (battery-operated, hand-held)
• Amplifier
• Electrodes (carbon-impregnated rubber or carbon-filled silicone)
• Connecting wires

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3. Mechanism of Action (VERY IMPORTANT FOR EXAMS)

A. Gate Control Theory (Melzack & Wall) - PRIMARY THEORY

• Pain (nociception) is transmitted via T-cells to higher brain centres
• These T-cells are presynaptically inhibited by interneurons in the substantia gelatinosa (dorsal horn, spinal cord)
• TENS bombards these interneurons, blocking/modulating pain transmission
• Think of it as: TENS "closes the gate" on pain signals

B. Endogenous Opioid Theory

• TENS (especially low-frequency) stimulates release of endorphins and enkephalins
• These natural opiates bind to opioid receptors and reduce pain perception

C. Other Theories

• Acupuncture effect - stimulation at acupuncture points
• Direct local vasodilation - reduces relative ischemia, which reduces pain

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4. Types of TENS (EXAM FAVOURITE)

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5. Treatment Parameters

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6. Electrode Placement

• Over trigger points, dermatomes, myotomes, or along specific nerve distributions
• Electrodes placed at least 2 inches apart (closer = burning sensation)
• The perimeter of the painful area should be surrounded by electrodes
• Patient must feel paresthesia in the area of pain (not motor stimulation)
• Skin prep: trim hair, clean with 70% isopropyl alcohol before placement

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7. Indications

• Chronic pain
• Acute pain
• Musculoskeletal pain
• Neurological pain (e.g., herpes zoster)
• Phantom limb pain
• Post-operative pain
• Obstetric pain (after 1st trimester)
• Pain before/after another procedure (to elevate pain threshold)

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8. Contraindications (VERY IMPORTANT)

• Demand-type pacemakers (check with cardiologist)
• First-trimester pregnancy
• Known cardiac dysrhythmias
• Mentally incompetent/uncooperative patients
• Undiagnosed pain syndromes

• Carotid sinuses
• Chest in patients with cardiac history
• Head/neck in epileptic patients
• Laryngeal/pharyngeal muscles
• Broken/irritated skin
• Mucosal surfaces
• Eyes

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9. Complications

• Skin irritation under electrodes
• Contact dermatitis from electrode gel
• Pacemaker malfunction (older pacemakers)
• Unwanted muscle twitch (if motor nerve stimulated)

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10. Quick Revision - Key Points for Exams

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11. TENS Unit Setup - Step-by-Step (Technique)

1. Prepare skin - trim hair, clean with alcohol
2. Select appropriate electrodes
3. Attach electrodes to treatment site
4. Set amplitude to zero first, then connect wires
5. Turn on unit, increase amplitude slowly until patient feels paresthesia
6. Adjust settings if desired result not achieved
7. Treat 30-60 min, once/twice daily
8. On completion: turn off, return settings to zero, remove electrodes

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TENS Electrode Placement - Condition-Wise Guide

BPT 2nd Year | Electrotherapy Exam Notes

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General Rules of Electrode Placement (ALWAYS APPLY)

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Methods of Electrode Placement

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Condition-Wise Electrode Placement

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1. Low Back Pain (LBP)

• Place 2 electrodes on either side of the lumbar spine (paravertebral) at the level of pain
• For bilateral pain: one pad each side of spine
• For unilateral pain: both pads on the same side, one above and one below the pain
• Never directly on the spine
• Square formation if using 4 electrodes

  [Pad]  Spine  [Pad]
  [Pad]         [Pad]

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2. Neck Pain (Cervicalgia)

• Place 2 electrodes on either side of the cervical spine, just below the skull (high up)
• Place the other 2 electrodes approximately 5 cm below the first pair
• Never directly on the front of the neck (carotid sinus/larynx risk)

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3. Shoulder Pain

• One electrode on the bulk of the trapezius muscle (close to neck)
• Other electrode closer to the edge of shoulder (over shoulder blade - NOT over the bone/acromion)

• Both upper electrodes on the painful side, plus two more over the shoulder blade muscles
• Aim for soft muscle tissue, not bony prominences

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4. Knee Pain

• Place pads above and below the knee (2 electrodes)
• Or: one pad on the front (anterior/medial) and one on the back (posterior) of the knee
• For 4-electrode setup: bracket the knee - 2 above, 2 below
• Do NOT place directly over the joint/bone

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5. Sciatica (Sciatic Nerve Pain)

• Along the nerve method is most effective
• Trace the path of the sciatic nerve: from lower back → buttock → back of thigh → back of leg
• Place electrodes at intervals along the path of the sciatic nerve
• One pad in the lumbar region (L4-S1 level), one in the gluteal region, one on the posterior thigh

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6. Hip Pain

• Place 2 electrodes on the upper part of the buttocks
• Place 2 more electrodes just below the first pair
• All electrodes in the gluteal region, surrounding the painful area

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7. Shoulder/Upper Arm Pain (Arm Pain)

• Two electrodes on either side of the elbow on the back of the arm
• One electrode higher on the lateral arm
• One electrode below on the lateral arm
• Forms a surrounding pattern around the elbow/arm

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8. Headache / Migraine

• 2 electrodes on the upper neck (suboccipital region)
• 1 electrode on the upper shoulder beside the neck on the affected side
• 1 electrode on the temple of the affected side
• Keep intensity LOW - high intensity worsens headache

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9. Knee Osteoarthritis

• 4-electrode technique: bracket the knee
• Medial and lateral to the joint, above and below
• Surround the joint without placing on the patella/bony area directly

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10. Stomach / Abdominal Pain

• 2 electrodes on the affected side of the abdomen (between belly button and nipple level)
• 2 electrodes on the back (posterior) directly opposite the anterior electrodes
• Front and back electrodes at same level (transcutaneous effect)

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11. Chest / Thoracic Pain

• Electrodes placed paravertebrally (either side of thoracic spine) at the level of pain
• One under the shoulder blade, one at the level of the bottom of the ribs
• Someone else should assist with posterior placements

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12. Phantom Limb Pain

• Electrodes placed on the stump (residual limb) to stimulate the proximal nerve
• Or placed along the nerve root supplying the amputated limb

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13. Post-Operative Pain

• Electrodes placed around the surgical incision (not directly over)
• At least 2 cm away from the wound edges

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Summary Table - Quick Revision

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Areas to NEVER Place Electrodes (Exam MCQ)

• Directly over the spine
• Over eyes
• In the mouth
• Front of neck (carotid sinus)
• Carotid sinuses
• Over tumors/malignancy
• On broken/damaged skin
• Over a pacemaker or cardiac monitoring leads
• On the abdomen or lower back in pregnancy

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Key Exam Points to Remember

1. Gate control theory - electrodes surround the pain to block the gate
2. Paresthesia is the target sensation, NOT motor contraction
3. 2 inches minimum between pads
4. Placement over soft tissue, never directly over bone
5. Bracketing method is the most commonly used technique
6. For radiating/nerve pain - use the along the nerve method
7. Do NOT place directly over the spine - always paravertebral

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TENS Electrode Placement - Visual Guide

Condition-by-Condition Images

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Master Reference Chart (All Conditions)

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1. Low Back Pain (LBP)

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2. Neck Pain (Cervicalgia)

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3. Shoulder Pain

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4. Neck & Shoulder Combined

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5. Knee Pain

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6. Sciatica / Hip & Gluteal Pain

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7. Hip Pain

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Quick Summary - Key Rules from All Images

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Burst Mode TENS

BPT 2nd Year | Electrotherapy Exam Notes

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1. Definition

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2. How Burst TENS Works - The Waveform

Normal (Conventional) TENS:
||||||||||||||||||||||||||||||||  → continuous high freq pulses

Burst TENS:
||||  ||||  ||||  ||||  ||||     → packets (bursts) of pulses
 2-4 bursts per second
 Each burst = ~100 Hz internally

• Each burst = a train of ~7-10 high-frequency pulses
• Burst rate = 2-4 Hz (low frequency)
• Internal carrier frequency = ~100 Hz (high frequency)
• Pulse width = 150-250 µs (long - similar to acupuncture TENS)
• Intensity = at motor threshold (produces visible, rhythmic muscle twitch with each burst)

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3. Mechanism of Action - DUAL MECHANISM (MOST IMPORTANT)

Key exam point: Burst TENS combines the fast relief of conventional TENS (gate control) with the longer-lasting relief of acupuncture TENS (opioid release) - giving benefits of BOTH.

Neurotransmitters Released:

• Enkephalins - released at spinal cord level (substantia gelatinosa)
• Beta-endorphins - released at supraspinal level (midbrain)
• Both reduce pain perception centrally and peripherally

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4. Parameters - Exam Table

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5. Accommodation (IMPORTANT CONCEPT)

• With conventional TENS, the nervous system adapts (accommodates) and the tingling fades during the session - so effectiveness reduces over time
• Burst TENS reduces accommodation because:
  • The on-off nature of the bursts provides variation
  • The nervous system does not get used to it as quickly
  • This is a major clinical advantage of burst mode

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6. Indications

• Chronic pain where conventional TENS has lost effectiveness (due to accommodation)
• Musculoskeletal pain - back pain, neck pain, joint pain
• Neurogenic/neuropathic pain - when both gate and opioid pathways need targeting
• Patients who cannot tolerate the continuous tingling of conventional TENS
• Post-operative pain (less commonly)
• Conditions requiring longer-lasting relief beyond the treatment session

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7. Advantages of Burst TENS

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8. Disadvantages / Limitations

• Muscle twitch may be uncomfortable for some patients (especially over sensitive areas)
• Slower onset than conventional TENS (not ideal for acute pain)
• Not suitable over areas where muscle contraction is contraindicated (post-fracture, acute inflammation with swelling)
• Requires proper intensity calibration to achieve motor threshold without pain

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9. Contraindications (Same as all TENS, plus)

• Demand-type pacemakers
• Over the carotid sinus, larynx, eyes
• First trimester pregnancy
• Over areas of active inflammation where muscle contraction is harmful
• Epilepsy (head/neck area)
• Undiagnosed pain

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10. Comparison - All 5 TENS Types (Master Table for Exams)

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11. Quick Revision - 5 Bullet Points for Exams

1. Burst TENS = high freq carrier (100 Hz) + low burst rate (2-4/sec)
2. Produces a rhythmic muscle twitch with each burst
3. Dual mechanism - gate control AND endorphin/enkephalin release
4. Main advantage = less accommodation + longer lasting relief
5. Best for chronic pain where conventional TENS has stopped working

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