Ultraviolet Radiation (UVR) in Physiotherapy - Complete Notes

1. Introduction

2. Classification of UVR (Wavelength Bands)

• Narrowband UVB (NB-UVB): 311 nm - this specific wavelength is the most therapeutically effective for psoriasis and other skin conditions
• Broadband UVB (BB-UVB): 280-315 nm full range

From Harrison's: "The outermost epidermal layer, the stratum corneum, is a major absorber of UV-B, and less than 10% of incident solar UV-B wavelengths penetrate from the epidermis to the dermis. Approximately 3% of radiation below 300 nm, 20% of radiation below 360 nm, and 33% of short visible radiation reach the basal cell layer in untanned human skin. UV-A readily penetrates to the dermis." - Harrison's Principles of Internal Medicine 22E

3. Physical Properties of UV Sources

Sources Used in Physiotherapy

4. Physiological Effects of UVR

A. Erythema (Redness)

• UVR causes vasodilation of superficial capillaries in the skin
• Results from release of histamine, prostaglandins, and other vasoactive substances
• Onset: UVB erythema peaks at 6-24 hours after exposure
• UVA erythema peaks at 4-8 hours and appears more rapidly but is less intense

B. Pigmentation (Tanning)

• Immediate pigment darkening (IPD): occurs within minutes of UVA exposure; represents oxidation of pre-existing melanin; fades within 20-30 minutes; provides no photoprotection
• Delayed tanning: visible within 24-72 hours after UVB and UVA; represents new melanin synthesis via increased tyrosinase activity; provides photoprotection
• Chronic UVR exposure increases melanocyte density up to 2x at sun-exposed vs. non-exposed sites

C. Epidermal Thickening (Hyperplasia)

• Repeated exposure stimulates keratinocyte proliferation
• Thickening of stratum spinosum and stratum corneum
• Increases photoprotection naturally

D. Vitamin D Synthesis

• UVB converts 7-dehydrocholesterol in skin to pre-vitamin D3
• This then isomerizes to vitamin D3 (cholecalciferol)
• UVA does not drive vitamin D synthesis

E. Bactericidal Effect

• Particularly UVC (253.7 nm) - damages bacterial DNA
• Used in wound treatment with cold quartz lamps
• Effective against MRSA and other pathogens on open wounds

F. Immunological Effects

• UVR depletes Langerhans cells from epidermis
• Impairs antigen presentation in skin-draining lymph nodes
• Expands regulatory T-cells (Treg) - key mechanism in treating psoriasis
• Shifts T-helper cell responses (Th1 -> Th2 shift)

G. Photochemical Effects

• UVB causes formation of cyclobutane pyrimidine dimers and 6,4-photoproducts between adjacent thymine/cytosine bases in DNA
• These are potentially mutagenic
• Relevant to both therapeutic and harmful effects

5. The Minimal Erythema Dose (MED)

MED Grading / Classification of UVR Doses

MED Testing Protocol (Standard)

1. Expose 6 areas of 1 cm² on the inner forearm or lower back
2. Give increasing doses of UV to each area
   • NB-UVB: 200, 400, 600, 800, 1000, 1200 mJ/cm²
   • BB-UVB: 20, 40, 60, 80, 100, 120 mJ/cm²
3. Read at 24 hours
4. MED = smallest dose producing uniform erythema over the entire exposed area
5. Start treatment at 50-70% of MED

6. Therapeutic Uses in Physiotherapy / Dermatology

A. Psoriasis

• Narrowband UVB (NB-UVB, 311 nm) is first-line phototherapy
• NB-UVB: 2-5 treatments/week; dose increased by 10-20% per session
• Goeckerman regimen: UVB + tar application
• Long-term NB-UVB found to carry NO significantly increased skin cancer risk (unlike PUVA)

B. PUVA (Psoralen + UVA) Photochemotherapy

• Combines oral 8-methoxypsoralen (8-MOP) + UVA
• 8-MOP dose: 0.4-0.6 mg/kg taken 90 minutes before UVA exposure (dissolved form) or 0.6 mg/kg 120 minutes before (micronized form)
• UVA fluorescent lamps with emission peak at 352 nm (near psoralen absorption maximum)
• Treatment frequency: 2-4 times/week, NOT on consecutive days
• Used for: psoriasis, vitiligo, mycosis fungoides (cutaneous T-cell lymphoma), atopic dermatitis
• Minimum Phototoxic Dose (MPD) is used instead of MED; read at 72 hours
• Long-term PUVA carries dose-related risk of SCC (adjusted RR = 8.6 for 100-337 treatments)

C. Vitiligo

• Narrowband UVB or PUVA
• Stimulates melanocyte proliferation and migration from follicular reservoirs

D. Wound Healing

• UVC (cold quartz/Kromayer lamp) used for:
  • Infected wounds and pressure sores
  • Ulcers (venous, diabetic)
  • Burns
  • Sinuses and body cavities (using Kromayer with quartz rod)
• Bactericidal effect is primary mechanism

E. Atopic Dermatitis (Eczema)

• NB-UVB and UVA1 are effective
• UVA1 (340-400 nm) penetrates deeper than UVB; useful for lichenified/thickened eczema

F. UVA1 Phototherapy

• Wavelength: 340-400 nm; penetrates deeper into dermis than UVB
• Dosing regimens: Low dose (10-30 J/cm²), Medium dose (40-70 J/cm²), High dose (130 J/cm²)
• Start at 20-30 J/cm², increase to full dose within 3-5 treatments
• Frequency: 3-5 times/week
• Lower burn risk than UVB or PUVA
• Used for: morphea, localized scleroderma, atopic dermatitis

G. Other Indications

• Jaundice of the newborn (phototherapy)
• Mycosis fungoides
• Uremic pruritus
• Pityriasis rosea
• Lichen planus

7. Contraindications to UVR Therapy

Absolute Contraindications

• Xeroderma pigmentosum (defective DNA repair)
• Lupus erythematosus (photosensitive)
• Active tuberculosis of the skin
• History of melanoma
• Existing skin malignancy
• Porphyria

Relative Contraindications

• Previous extensive PUVA therapy (cumulative dose concern)
• Photosensitive conditions (certain drug ingestion - tetracyclines, thiazides, phenothiazines)
• Recent radiotherapy to skin
• Basal cell naevus syndrome
• Very fair (Type I) skin with history of multiple sunburns
• Pregnancy (relative)

8. Precautions and Safety

• Eye protection: UV-opaque goggles must be worn by BOTH patient and therapist
• Genitalia shielded unless being treated
• Sunscreen may be applied to normal skin areas adjacent to treated zones
• Gradual dose increments prevent burns
• A burn reported by the patient at the next visit (even if no longer visible) must be managed as still-visible

Dose Adjustment After Missed Treatments (Fitzpatrick protocol)

9. Adverse Effects

Short-term

• Erythema, burning, pain
• Blistering (severe burns)
• Photokeratitis (UV burns to cornea - "arc eye") - prevented by goggles
• Systemic toxicity with large area burns (fever, malaise)
• PUVA: nausea from psoralen (take with food)

Long-term

• Photoaging: premature skin aging, wrinkling, solar elastosis (primarily UVA)
• Non-melanoma skin cancer (NMSC): dose-related; PUVA carries SCC risk (RR 8.6 at high cumulative dose); chronic UVB also carries risk
• Melanoma risk: slight increased risk with prolonged PUVA
• Cataract formation: without adequate eye protection
• Immunosuppression: persistent reduction in skin immune surveillance

10. Skin Phototypes (Fitzpatrick Classification)

• Fitzpatrick's Dermatology - Phototherapy chapter (Broadband/Narrowband UVB and PUVA protocols)
• Harrison's Principles of Internal Medicine 22E - UV Radiation and Skin Structure and Function
• Dermatology 2-Volume Set 5e - UVR and Melanogenesis

Infrared Radiation (IRR) in Physiotherapy - Complete Detailed Notes

1. Definition

• Wavelength range: 760 nm to 1 mm (1,000,000 nm)
• Also called thermal radiation because it transfers heat energy
• IRR is produced by any body whose temperature is above absolute zero (0 K / -273°C)
• The higher the temperature of the emitting body, the higher the frequency and the shorter the wavelength of emitted IRR

2. Classification of IRR

Note: Some older physiotherapy texts use a simpler two-category division: Near (short) IR = 760-1500 nm and Far (long) IR = 1500 nm-1 mm. Both systems are in use.

3. Sources / Generators of IRR

A. Luminous (Light-emitting) Lamps

• Produce short IR (IR-A) predominantly
• Emission spectrum: ~70% short IR, 24% long IR, 5% visible light, 1% UVR (absorbed by glass)
• Example: Tungsten filament bulb (incandescent lamp, 250W-1500W)
• No warm-up time required - can be switched on when patient is ready
• Produce more heat with deeper penetration
• Tungsten filament glows red/orange - hence "luminous"
• Placed at 40-60 cm from skin

B. Non-luminous (Non-light-emitting) Lamps

• Produce long IR (IR-B) predominantly
• Emission spectrum: mainly 3000-4000 nm long IR, ~10% between 1500 nm and visible
• Example: Heated coil/element (carbon rod, Nichrome wire, 250W-1000W) that does NOT glow visibly
• Requires 10-15 minute warm-up before treatment (to reach maximum emission)
• Less heat output; more superficial penetration
• Placed at 65-80 cm from skin

Power Ratings

4. Physics of Infrared - Key Laws

The Inverse Square Law

• Doubling the distance reduces intensity to 1/4
• Halving the distance increases intensity 4 times
• This is why distance control is the primary means of adjusting dose

Cosine Law (Lambert's Law)

• Maximum absorption occurs when radiation falls perpendicular (90°) to the skin surface
• Oblique angles reduce the intensity of absorbed energy

Inverse Square Law in Practice

• Increasing distance = less intense, safer, more comfortable
• Decreasing distance = more intense, deeper, potentially burning

5. Absorption and Penetration

• IRR is strongly absorbed near the skin surface
• Heat is then conducted to deeper tissues via conduction and circulating blood/fluids
• IRR is considered a superficial heating modality overall

1. Wavelength - shorter wavelengths penetrate deeper (IR-A > IR-B)
2. Skin structure - thickness of stratum corneum
3. Vascularity - well-vascularised tissue dissipates heat faster (more heat can be safely applied)
4. Skin pigmentation - darker skin absorbs more radiation
5. Water content - water strongly absorbs IR-B wavelengths

6. Physiological Effects of IRR

A. Cutaneous Vasodilatation (Primary Effect)

1. Axon Reflex Mechanism:
   • Cutaneous thermoreceptors (free nerve endings) are stimulated by heat
   • Afferent impulses travel to the spinal cord
   • Some impulses are carried antidromically back toward skin blood vessels
   • Vasoactive mediator (substance P) is released, causing vasodilation of arterioles
2. Release of Chemical Mediators:
   • Heat causes release of prostaglandins, histamine, bradykinin
   • The enzyme kallikrein released from sweat glands acts to release bradykinin, which increases capillary and venule permeability
   • These act directly on vessels to produce vasodilation
3. Local Spinal Cord Reflexes:
   • Heat stimulates cutaneous receptors
   • Reflex arc via spinal cord produces vasodilation in the treated segment

• Increased local blood flow (hyperaemia)
• Skin appears pink/red (mottled erythema - normal expected finding)
• Increased delivery of oxygen and nutrients to tissues
• Increased removal of waste products and inflammatory mediators
• Slight rise in local tissue temperature (1-3°C typically)

B. Increased Metabolism

• Elevated temperature increases cellular metabolic rate
• Follows the Q10 rule: for every 10°C rise, metabolic rate approximately doubles
• Enhanced cellular activity promotes healing

C. Increased Tissue Extensibility

• Heat reduces viscosity of collagen and ground substance
• Decreased joint stiffness
• Increased muscle flexibility and extensibility
• Reduced resistance to passive stretch
• Infrared should be used in conjunction with stretching and ROM exercises to capitalise on this effect

D. Pain Control

1. Counter-irritant effect (IR-A / near IR): Stimulation of large sensory nerve fibres (A-beta fibres) activates gate control mechanism, inhibiting pain transmission at spinal cord level
2. Sedative effect (IR-B / far IR): Gentle warming produces a sedative/soothing effect on peripheral sensory nerves, reducing pain perception
3. Decreased activity of muscle spindle: Reduced gamma motor neuron activity leads to decreased muscle spindle sensitivity, breaking the pain-spasm cycle
4. Increased pain threshold: Thermal stimulation raises overall pain threshold
5. Removal of waste products: Improved circulation removes algogenic substances (bradykinin, prostaglandins, lactic acid) responsible for pain
6. Endorphin modulation: IR-associated increase in nitric oxide (NO) and reduced oxidative stress may modulate endorphin pathways

E. Molecular and Cellular Effects (Modern Understanding)

• At molecular level: IR affects rotation of molecules in body fluids and tissues
• At cellular level: IR alters cell membrane potentials by raising intracellular Ca²+ levels
  • Increased membrane permeability for Ca²+
  • Increased Ca²+ release from endoplasmic reticulum in response to ROS generated by radiation
• Nitric Oxide (NO) production increases - promotes vasodilation, reduces oxidative stress, stimulates growth factor production and extracellular matrix deposition (tissue repair)
• Near-IR (photobiomodulation / LLLT): Stimulates cytochrome c oxidase in mitochondria, enhancing ATP production - this is distinct from pure thermal effects

7. Comparison: Luminous vs. Non-luminous in Clinical Use

8. Indications for IRR in Physiotherapy

Painful Conditions

• Muscle spasm and myofascial pain
• Osteoarthritis and joint stiffness
• Chronic low back pain and neck pain
• Fibromyalgia
• Myofascial pain syndrome

Inflammatory Conditions

• Sub-acute and chronic inflammation (not acute in most protocols)
• Sacroiliitis / ankylosing spondylitis
• Bursitis, tendinitis (sub-acute/chronic phase)

Healing and Tissue Repair

• Acceleration of wound healing (sub-acute stage)
• Pressure sores (early/healing stage)
• Post-surgical healing

Preparatory Treatments

• Prior to stretching, mobilisation and ROM exercises (to improve tissue extensibility)
• Warm-up before therapeutic exercise in stiff joints

Other

• Fungal skin conditions (mild)
• Chronic fatigue syndrome (far IR sauna)
• Gulf War Illness (IR therapy for pain and fatigue)
• Knee osteoarthritis
• Rehabilitation post-injury

Research note: A systematic review (PMC 2022) confirmed IR as a promising complementary treatment for musculoskeletal conditions including knee osteoarthritis, fibromyalgia, chronic low back pain, chronic myofascial syndrome, and sacroiliitis.

9. Contraindications to IRR

Absolute Contraindications

• Open wounds - excessive heating delays healing, promotes infection, causes tissue damage
• Impaired sensation - patient cannot detect burning; risk of thermal injury
• Impaired circulation - inability to dissipate heat, risk of burns
• Over pregnant uterus - teratogenic risk from heat to fetus
• Over malignant tissue - heat may promote tumour growth or spread
• Eyes - risk of photokeratitis, cataract formation (IR can damage the lens)
• Unreliable patients - cannot communicate discomfort
• Following deep X-ray / ionizing radiation therapy - impaired skin vascularity and sensation

Additional Precautions

• Haemorrhagic areas - heat increases bleeding
• Oedematous areas - risk of increased swelling
• Acutely inflamed joints - may exacerbate acute inflammation
• Sensitive skin types
• Areas with metal implants - caution (though IRR is superficial and less concern than TENS/ultrasound)

10. Dangers / Adverse Effects

Erythema ab igne (IRR-Specific Complication)

• Caused by chronic/repeated exposure to moderate heat (usually IRR)
• Presents as reticulate (net-like) tan-red-brown hyperpigmentation
• Common sites: thighs, lower legs, abdomen, back
• Histology: vasodilation, RBC extravasation, hemosiderin and melanin deposition in dermis
• Can become fixed and permanent in chronic cases; may develop epidermal atrophy, bullae, hyperkeratosis
• Check thyroid function (hypothyroid patients sit near heat sources for warmth)
• Modern causes: laptop on thighs, heating pads, hot water bottles, car heaters

11. Technique of Application

Step 1 - Preparation of the Patient

1. Perform a thermal sensation test (hot/cold discrimination with test tubes - vital to confirm intact sensation before applying heat)
2. Check patient for all contraindications
3. Explain the expected sensation: "mild to moderate comfortable warmth" - not hot or burning
4. Explain the procedure fully
5. Position patient in a comfortable, well-supported position with the treatment area exposed

Step 2 - Preparation of the Device

1. Choose the appropriate lamp (luminous vs. non-luminous based on condition)
2. If non-luminous: switch ON at least 10-15 minutes before treatment to reach maximum emission
3. Luminous lamps: no warm-up needed
4. Test heat output by holding the back of your hand near the lamp at treatment distance
5. Remove any superficial metal objects (jewelry) or tight clothing from the area

Step 3 - Setup and Application

1. Position lamp so that rays fall perpendicular (90°) to the skin surface (cosine law)
2. Set distance: luminous = 40-60 cm; non-luminous = 65-80 cm
3. Turn on lamp (if luminous) and immediately check patient's comfort
4. Instruct patient: do not look at the lamp, do not move toward the lamp, do not touch the lamp; report any burning sensation or discomfort immediately
5. Monitor the skin regularly during the session (every 3-5 minutes)
6. Dry the skin regularly during session to avoid pooled sweat causing burns

Step 4 - Session Parameters

Step 5 - End of Session

1. Turn off lamp; allow to cool
2. Check skin for mottled erythema (expected normal response - irregular pink/red blotchy erythema indicating vasodilation)
3. Ensure no blistering, excessive redness, or discomfort
4. Document treatment parameters (distance, duration, lamp type, skin response)

12. IRR vs. Other Heat Modalities - Key Comparisons

13. Modern Applications: Photobiomodulation (PBM) / Low-Level Light Therapy (LLLT)

• Primary chromophore: cytochrome c oxidase in mitochondria
• Stimulates ATP production, reduces oxidative stress
• Promotes wound healing, tissue regeneration, nerve regeneration
• Reduces inflammation
• Biphasic dose response: small doses stimulate; excessive doses inhibit (Arndt-Schulz law)
• Used for: wound healing, peripheral nerve injury, tendinopathies, neurological conditions

• Bailey and Love's Short Practice of Surgery 28th Ed. - Infrared radiation
• Fitzpatrick's Dermatology - Erythema ab igne (IRR complication)
• Cairo University Physical Therapy lecture notes - IRR physiotherapy (Aneis, PhD PT)
• PMC Systematic Review 2022 - IR in musculoskeletal conditions
• PMC Biological Effects Review 2017 - Biological effects and medical applications of IR