The Gate Control Theory of pain, published by Ronald Melzack and Patrick Wall in Science (1965), fundamentally changed our understanding of pain modulation and remains the foundational framework for TENS therapy. The theory proposes that a neural 'gate' in the substantia gelatinosa of the dorsal horn of the spinal cord controls the flow of pain signals to the brain. Large-diameter, myelinated A-beta fibres (which carry touch, pressure, and vibration signals) can 'close' this gate when stimulated, preventing smaller C-fibre and A-delta fibre pain signals from ascending to the thalamus and cortex. High-frequency TENS (80–150 Hz) specifically targets A-beta fibre recruitment, producing the characteristic comfortable tingling sensation that 'overrides' pain — explaining why pain relief is felt almost immediately during treatment but typically wears off within 30–60 minutes of cessation.

Low-frequency TENS (1–4 Hz), known as Acupuncture-Like TENS or AL-TENS, operates through a completely different neurochemical mechanism. At these low frequencies, the electrical stimulus produces visible muscle twitching (motor point stimulation) and triggers the release of beta-endorphins in the periaqueductal grey matter and enkephalins at the spinal level. These endogenous opioids produce analgesic effects that are longer-lasting — often persisting for 2–4 hours after treatment ends — but require a higher intensity (to motor threshold) and take longer to build (15–20 minutes of stimulation before peak analgesia). At Curis 360's Banashankari and Jayanagar clinics, Dr. Ponkhi Sharma and her team select between high and low frequency TENS based on the patient's pain profile: high-frequency for acute pain requiring immediate relief; low-frequency for chronic pain requiring sustained analgesia for home exercise programme participation.

TENS effectiveness is critically dependent on parameter selection — a one-size-fits-all approach produces suboptimal results. The three primary parameters are: Frequency (Hz) — the number of electrical pulses per second; Pulse Width (μs) — the duration of each individual pulse (the most important determinant of which nerve fibre type is recruited, since A-beta fibres require narrow pulse widths of 50–80 μs while motor fibres require wider pulse widths of 150–300 μs); and Intensity (mA) — the amplitude of current, which determines how strongly the patient feels the stimulation. For conventional high-frequency TENS: frequency 80–150 Hz, pulse width 50–80 μs, intensity to strong-but-comfortable tingling (sensory threshold, below motor threshold). For AL-TENS: frequency 1–4 Hz, pulse width 150–300 μs, intensity to comfortable muscle twitch (at or just above motor threshold).

A frequently overlooked parameter is the electrode placement, which is as important as the machine settings. At Curis 360 Physiotherapy's Vasanthapura and Jayanagar clinics, we use three evidence-based placement strategies: (1) Paravertebral placement — electrodes at the relevant spinal level (e.g., L3–S1 for sciatica, C5–C7 for cervicobrachialgia) to achieve segmental modulation; (2) Peripheral nerve placement — electrodes along the course of the affected nerve (e.g., along the sciatic nerve from the gluteal fold to the popliteal fossa); (3) Local/Periarticular placement — electrodes immediately around a painful joint (knee, shoulder, ankle). Gel quality and electrode size also matter: larger electrodes (5×5 cm or 7×5 cm) are used for large muscle groups; smaller electrodes (3×3 cm) for precise placement over specific nerves or joints. Electrode gel must be re-applied before each session to maintain impedance.

Lumbar Back Pain & Sciatica: Two pairs of electrodes (4 total for dual-channel TENS). Pair 1: bilateral paraspinal muscles at L3–S1 (approximately 2 cm lateral to the spinous processes). Pair 2: along the sciatic nerve path — one electrode in the gluteal fold, one in the posterior thigh. Frequency: 80 Hz (conventional) for immediate relief; 2 Hz (AL-TENS) for chronic sciatica with night pain. Duration: 25 minutes. The patient should feel a comfortable tingling that covers the area of pain without any muscle twitch for conventional TENS.

Knee Osteoarthritis: Four electrodes in a quadripolar arrangement — two medial (one above the medial joint line, one below) and two lateral (above and below the lateral joint line) — creating cross-fire stimulation through the joint. Frequency: 100 Hz, pulse width 60 μs. Evidence: A systematic review (Vance et al., 2014, Physical Therapy) confirmed significant immediate pain relief from TENS in knee OA, with additive effects when combined with exercise. At Curis 360 Banashankari, TENS is routinely applied immediately before supervised knee strengthening exercises to enable better pain-free exercise performance in patients with moderate-to-severe knee OA. Frozen Shoulder: One electrode over the anterior shoulder (acromioclavicular area), one over the posterior capsule (infraspinatus area). Frequency: 80–100 Hz for 20 minutes before joint mobilisation — the analgesia window allows the physiotherapist to perform Grade III–IV mobilisations that would otherwise be too painful for the patient to tolerate.

Neuropathic pain — characterised by burning, electric shock sensations, allodynia (pain from non-painful stimuli), and hyperalgesia — is one of the most challenging pain presentations in physiotherapy, and one where TENS provides significant clinical benefit. In diabetic peripheral neuropathy (affecting an estimated 50% of people with long-standing diabetes mellitus), TENS applied to the plantar surface of the foot and lower leg has been shown in multiple RCTs to reduce pain intensity by 30–50% compared to sham TENS. At Curis 360's Vasanthapura and Banashankari clinics, where we manage a significant caseload of diabetic patients requiring home physiotherapy, we prescribe AL-TENS (2 Hz, motor threshold intensity) applied to the tibial nerve at the medial ankle — a point corresponding to the acupuncture point SP-6 — for 30 minutes daily, with careful instruction on skin inspection before and after, given the sensory deficits in this population.

Complex Regional Pain Syndrome (CRPS) — formerly known as RSD (Reflex Sympathetic Dystrophy) — is a particularly challenging neuropathic condition characterised by disproportionate pain, allodynia, oedema, vasomotor instability, and trophic changes following limb injury or surgery. TENS for CRPS requires specialised parameter selection: electrodes are placed proximal to the affected area (to avoid the hypersensitive zone of allodynia), using high-frequency (80–100 Hz), low intensity (well below sensory threshold — subsensory TENS) to avoid triggering pain flares. At Curis 360, TENS for CRPS is always combined with graded motor imagery, desensitisation techniques, and graduated active exercise — the electrotherapy alone is insufficient without the neuroplasticity-based rehabilitation approach.

Physiotherapy patients in Bangalore often ask why one clinic uses TENS while another uses IFT (Interferential Therapy) or Ultrasound — and wonder which is 'better'. The answer depends entirely on the treatment goal and tissue target. TENS is optimal for: (1) surface-level pain modulation, (2) neuropathic pain along peripheral nerve distributions, (3) home-based self-management (portable TENS units are available for patient purchase), and (4) conditions where drug-free analgesia for exercise is the primary goal. IFT penetrates deeper than TENS (due to medium-frequency carrier wave design) and is superior for: deep joint pain (hip, shoulder, spine), large muscle spasm, and post-surgical visceral or periarticular pain. Therapeutic Ultrasound targets the tissue level — accelerating soft tissue healing via thermal and mechanical mechanisms — and is the choice for tendinopathy, plantar fasciitis, and scar tissue remodelling. All three modalities are available at Curis 360's clinics in Banashankari, Jayanagar, and Vasanthapura, and their selection is based on a structured assessment protocol rather than convenience.

In practice, combination electrotherapy is often more effective than any single modality. A typical Curis 360 treatment session for chronic low back pain might involve: (1) Hot pack (15 minutes) to increase tissue extensibility and prepare the paraspinal musculature; (2) IFT (15 minutes) for deep paraspinal muscle spasm and facet joint pain; (3) Therapeutic exercise (20 minutes) with the TENS unit running during the exercise session to enable better pain-free range of motion and loading; (4) Patient education and HEP (home exercise programme) prescription with a take-home TENS protocol for self-management on non-clinic days. This structured combination approach — not passive reliance on electrotherapy alone — is the hallmark of evidence-based physiotherapy practice at all three Curis 360 clinics.

One of TENS therapy's greatest advantages is its portability — professional-grade portable TENS units allow patients to receive the benefits of clinic electrotherapy at home, especially valuable for patients with limited mobility, elderly patients, post-surgical patients, and those in severe pain who cannot travel to a physiotherapy clinic. Curis 360 Physiotherapy's home visit team in Bangalore carries professional TENS units to patient homes across Banashankari, Jayanagar, Vasanthapura, Koramangala, JP Nagar, Electronic City, Whitefield, HSR Layout, Sarjapur Road, and all Bengaluru areas. Our home physiotherapy physiotherapists apply TENS as part of a comprehensive home visit session, assess the patient's response, and — where appropriate — recommend purchase of a suitable home TENS unit with written and demonstrated instructions for self-application.

For patients across India who wish to optimise their TENS home programme remotely, Curis 360 offers online physiotherapy consultations. During a video call, Dr. Ponkhi Sharma or one of our senior physiotherapists will: (1) conduct a detailed pain and functional assessment; (2) identify the optimal TENS parameters (frequency, pulse width, intensity guidance) for your specific condition; (3) demonstrate electrode placement on camera using anatomical landmarks; (4) provide a written TENS protocol with dosing schedule; and (5) coordinate with your local physiotherapist or orthopaedic surgeon to ensure TENS is appropriately integrated with your overall treatment plan. Online consultations are available for patients in Karnataka, Tamil Nadu, Maharashtra, Telangana, Kerala, and all Indian states, as well as for the Indian diaspora internationally.