Cryotherapy Masterclass: Principles & Practice MCQs

Cryotherapy Masterclass: Principles & Practice

💡 The Core Concept: Cryotherapy is the therapeutic application of cold (0°C to 18°C) to body tissues. It works on the principle of Heat Abstraction (removal of heat) rather than adding cold.

1. Basic Principles (Physics of Cold)

To cool a tissue, heat must be transferred from the body to the cooling agent. This happens via:

• Conduction: Direct contact (Ice packs, Ice massage).
• Convection: Movement of fluids (Cold whirlpool, Cryo-cuff).
• Evaporation: Liquid to gas state change (Vapocoolant sprays like Fluori-Methane/Ethyl Chloride).

Latent Heat of Fusion: Melting ice absorbs a significant amount of heat to change state (solid to liquid) without changing temperature (0°C), making it more effective than cold water alone.

2. Physiological Effects

A. Hemodynamic Effects (Blood Flow)

• Initial Vasoconstriction: Direct action on smooth muscle and activation of sympathetic nerve fibers reduces blood flow to limit bleeding and edema.
• Lewis Hunting Reaction (Cold-Induced Vasodilation - CIVD):
  • Occurs after prolonged exposure (>10-15 mins) or extreme cold (<10°C).
  • It is a protective cyclic mechanism: Vasoconstriction followed by temporary Vasodilation to prevent tissue damage (frostbite).
  • Primarily seen in "acral" regions (fingers, toes, nose, ears).

B. Neuromuscular Effects

• Nerve Conduction Velocity (NCV): Decreases. Both sensory and motor NCV slow down.
  • Key Value: Conduction block can occur below 12°C.
• Pain Threshold: Increases. Cold acts as a counter-irritant (Gate Control) and reduces nerve transmission speed.
• Spasticity: Decreases. Cold reduces the activity of Gamma Motor Neurons and muscle spindle sensitivity.
• Muscle Strength:
  • Short duration (1-5 mins): Increases strength (facilitation).
  • Long duration (>10 mins): Decreases strength initially, but strength may increase 1 hour later.

C. Metabolic Effects

• Metabolic Rate: Decreases. Lowers oxygen demand of tissues, reducing "Secondary Hypoxic Injury" after trauma.
• Enzyme Activity: Inhibits collagenase activity (useful in inflammatory joint diseases like RA).

3. Therapeutic Uses (Indications)

• Acute Soft Tissue Injury: (e.g., Ankle Sprain) - Reduces bleeding, edema, and pain (R.I.C.E protocol).
• Spasticity Management: Upper Motor Neuron (UMN) lesions (e.g., CP, Stroke). Application for 15-20 mins reduces clonus/resistance.
• Muscle Spasm: Breaks the "Pain-Spasm-Pain" cycle.
• Post-Surgical Pain: Reduces narcotic use (e.g., after TKR/ACL surgery).
• Myofascial Trigger Points: "Spray and Stretch" technique.

⚠️ Dangers & Contraindications

Absolute Contraindications:

• Cold Hypersensitivity: Cold Urticaria (hives), Cryoglobulinemia (blood proteins clump), Paroxysmal Cold Hemoglobinuria.
• Raynaud's Disease/Phenomenon: Digital cyanosis and pain.
• Regenerating Peripheral Nerves: Cold delays regeneration.
• Peripheral Vascular Disease (PVD): Compromised circulation cannot re-warm the tissue, leading to gangrene.

Risks/Dangers:

• Frostbite: Freezing of tissue fluids (avoid temps < 0°C or direct ice contact for too long).
• Nerve Palsy: Specifically the Common Peroneal Nerve (at fibular head) and Ulnar Nerve (at elbow). Avoid ice over superficial nerves.
• Ice Burn: Chemical-like burn from direct salt-ice mixtures or gel packs.

🏆 AIIMS "Golden Points"

• Hunting Reaction Time: Starts after 10-15 minutes of cold exposure.
• Sensation Stages: Patient feels: Cold → Burning → Aching → Numbness (CBAN).
• Exercise: Cryotherapy is best used after exercise for recovery (DOMS), or before stretching (Spray and Stretch) for trigger points.

📝 20 High-Yield MCQs (Practice Now)

Click an option to check your answer immediately.

Q1. The "Lewis Hunting Reaction" (Cold Induced Vasodilation) typically begins after how many minutes of cold application?

A. 1-2 minutes B. 10-15 minutes C. 30 minutes D. Immediately

Rationale: The initial vasoconstriction gives way to vasodilation after approximately 10-15 minutes to prevent tissue damage (frostbite) from prolonged ischemia.

Q2. Which nerve fibers are affected first and most significantly by cold application?

A. A-delta and C fibers (Pain & Temp) B. A-alpha fibers (Motor) C. A-beta fibers (Touch) D. All are affected equally

Rationale: Small, myelinated (A-delta) and unmyelinated (C) fibers transmitting pain and temperature are most sensitive to cold, leading to the analgesic effect.

Q3. Cryotherapy reduces spasticity primarily by:

A. Increasing Alpha motor neuron activity B. Decreasing Gamma motor neuron activity C. Increasing muscle temperature D. Decreasing Golgi Tendon Organ sensitivity

Rationale: Cold decreases the discharge of afferent spindles and reflex activity by inhibiting the Gamma motor neurons, which lowers muscle tone and spasticity.

Q4. Which of the following is an ABSOLUTE contraindication for Cryotherapy?

A. Acute inflammation B. Raynaud's Disease C. Muscle Spasm D. Post-surgical edema

Rationale: Raynaud's is a vasospastic disorder where cold triggers severe vasoconstriction, leading to ischemia, pain, and potentially necrosis.

Q5. Vapocoolant sprays (e.g., Ethyl Chloride) cool the skin primarily by:

A. Conduction B. Convection C. Evaporation D. Radiation

Rationale: The liquid spray absorbs heat from the skin to change its state into gas (evaporate), causing rapid superficial cooling.

Q6. At what tissue temperature does nerve conduction failure (block) typically occur?

A. 20°C B. 15°C C. Below 12°C D. 0°C

Rationale: Cooling nerve fibers below 12°C (some sources say 10°C) blocks the conduction of impulses, leading to numbness and temporary paralysis.

Q7. Applying ice over the lateral aspect of the knee (fibular head) carries a risk of damaging which nerve?

A. Tibial Nerve B. Common Peroneal Nerve C. Sciatic Nerve D. Saphenous Nerve

Rationale: The Common Peroneal nerve is very superficial at the fibular head. Direct ice application can cause cryotherapy-induced nerve palsy (foot drop).

Q8. What is the correct sequence of sensations felt during ice application (CBAN)?

A. Cold -> Burning -> Aching -> Numbness B. Cold -> Numbness -> Burning -> Aching C. Burning -> Cold -> Numbness -> Aching D. Numbness -> Cold -> Aching -> Burning

Rationale: This is the standard progression of sensory changes (CBAN) experienced by patients during effective cryotherapy.

Q9. Why is cryotherapy indicated immediately after acute trauma (e.g., ankle sprain)?

A. To reduce secondary hypoxic injury B. To increase blood flow to the area C. To increase metabolic rate D. To speed up nerve conduction

Rationale: By lowering the metabolic rate and oxygen demand of cells surrounding the injury, cold prevents them from dying due to lack of oxygen (ischemia) caused by the swelling. This preserves viable tissue.

Q10. Which of the following methods uses "Convection" for heat transfer?

A. Ice Pack B. Cold Whirlpool / Agitated Water C. Cold Towel D. Ice Massage

Rationale: Convection involves heat transfer by the movement of a fluid (air or water) across a surface. An agitated whirlpool uses convection.

Q11. Cryoglobulinemia is a condition where:

A. Abnormal blood proteins clump/precipitate at low temperatures B. The skin turns red due to histamine release C. There is an allergy to ice D. Hemoglobin is excreted in urine

Rationale: Cryoglobulins are abnormal proteins that thicken or gel in cold temperatures, potentially blocking blood vessels. This is an absolute contraindication.

Q12. The "Spray and Stretch" technique is primarily used for:

A. Ligament sprains B. Myofascial Trigger Points C. Bone fractures D. Open wounds

Rationale: Vapocoolant spray is applied in sweeping strokes over a trigger point while passively stretching the muscle. The rapid cooling provides a sensory distraction (Gate Control) allowing a deeper stretch.

Q13. For a 10-minute ice massage, the treatment area should typically be:

A. 10 cm x 15 cm (Small areas) B. The entire back C. The whole quadriceps muscle D. Whole body

Rationale: Ice massage is an intense, localized treatment meant for small areas (e.g., muscle belly, tendon insertion). Treating a large area like the back is ineffective with a small ice cup.

Q14. Which of the following is NOT a physiological effect of cold?

A. Increased blood viscosity B. Increased collagen extensibility C. Decreased metabolic rate D. Decreased nerve conduction velocity

Rationale: Cold decreases collagen extensibility, making tissues stiffer. Heat is used to increase extensibility.

Q15. In the context of muscle performance, prolonged cooling (>15-20 mins):

A. Increases strength immediately B. Decreases strength/force production initially C. Has no effect on strength D. Increases agility

Rationale: Prolonged cooling reduces nerve conduction and muscle enzyme activity, leading to a temporary decrease in strength and agility immediately after application.

Q16. Why is cryotherapy used in the acute phase of burns (minor)?

A. To freeze the bacteria B. To dissipate heat and stop tissue destruction C. To increase bleeding D. To regenerate skin

Rationale: Immediate cooling removes the residual heat in the tissue, preventing the burn from deepening and spreading to surrounding cells.

Q17. During "Quick Icing" (Rood's Approach), the stimulus is used to:

A. Facilitate muscle contraction B. Inhibit muscle contraction C. Reduce pain only D. Reduce edema

Rationale: Quick swipes of ice are a facilitatory technique used to stimulate the A-alpha motor neurons and enhance muscle contraction in flaccid muscles.

Q18. A "Cold Urticaria" reaction is characterized by:

A. Blanching of skin B. Hives, itching, and wheals C. Cyanosis D. Muscle paralysis

Rationale: Cold Urticaria is a hypersensitivity reaction where histamine is released, causing itchy red patches (hives) on the skin exposed to cold.

Q19. Which modality utilizes the "Latent Heat of Fusion"?

A. Ice Massage / Ice Packs B. Cold Water Immersion C. Vapocoolant Spray D. Cryo-cuff

Rationale: Latent heat of fusion is the energy absorbed when a solid (ice) melts into a liquid (water). This allows ice to extract more heat from the body than cold water at the same temperature.

Q20. Cryotherapy is contra-indicated over a regenerating nerve because:

A. It increases pain B. It delays nerve regeneration/repair C. It causes neuroma D. It increases conduction velocity

Rationale: Cold slows down metabolic and enzymatic activity, which is essential for the healing and regeneration process of the nerve.