What could be causing a freezing sensation and coolness to the touch in the buttocks of an adult with possible underlying health conditions?

Freezing Sensation and Coolness in the Buttocks: Differential Diagnosis and Management

This presentation most likely represents either peripheral vascular insufficiency, peripheral neuropathy, or non-freezing cold injury, and requires immediate assessment of skin temperature, color changes, sensation, and pulses to differentiate between vascular compromise (requiring urgent intervention) and neuropathic causes.

Immediate Assessment Priorities

Rule Out Vascular Emergency First

• Check for tissue viability immediately: Assess skin color progression from pale to hardened and dark, which indicates advancing frostbite or severe ischemia 1, 2
• Measure skin temperature bilaterally and compare to other body regions to determine if this is localized vascular compromise 3
• Palpate pulses and assess capillary refill in the affected area and lower extremities 3
• If tissue appears pale, hardened, or darkened with absent sensation, this constitutes a vascular emergency requiring immediate medical facility transport 4, 1

Environmental Exposure History

• Determine if there has been recent cold exposure, as frostbite can affect any body part with prolonged exposure, not just traditional extremities like fingers and toes 4, 2
• Ask about duration of cold exposure and whether the area was in contact with cold surfaces (sitting on cold ground, metal surfaces) 5, 6
• Do not attempt rewarming if there is any chance of refreezing or if close to a medical facility 4, 1

Primary Differential Diagnoses

1. Peripheral Vascular Disease (Most Urgent)

• Digital blood pressure measurement is essential to differentiate arterial occlusion from vasospastic disorders 3
• Unilateral coldness suggests arterial occlusion or steal syndrome and requires urgent vascular evaluation 3
• Risk factors include diabetes, hypertension, or history of peripheral vascular disease 3
• Presence of tissue necrosis, ulceration, or gangrene requires immediate vascular surgery referral 3

2. Peripheral Neuropathy with Cold Hypersensitivity

• Chronic non-freezing cold injury results in neuropathic pain with cold hypersensitivity, numbness, and paradoxical cold sensation even without ongoing cold exposure 7
• The "triple cold syndrome" describes cold hyperalgesia (pain with cold), cold hypoesthesia (reduced cold sensation), and abnormally cold skin due to sympathetic denervation causing vasospasm 8
• This occurs from small fiber nerve damage affecting both sensory A-delta fibers and sympathetic efferents 8
• Patients may report burning pain triggered by cold exposure despite having objectively cold skin 9

3. Non-Freezing Cold Injury (Trench Foot Variant)

• Develops after sustained exposure to cold but non-freezing temperatures, particularly in damp conditions 5, 6
• Results in persistent sensory disturbance including numbness, paresthesia, and chronic pain 7
• Can affect any body part subjected to prolonged cold exposure, including buttocks from sitting on cold surfaces 5
• Intraepidermal nerve fiber density is markedly reduced (90.5% of patients at or below 0.05 centile) 7

4. Raynaud's Phenomenon (Secondary)

• While classically affecting hands and feet, secondary Raynaud's can involve other body areas 3
• Secondary forms involve entire regions rather than individual digits and can progress to tissue damage 3
• Associated with connective tissue diseases like systemic sclerosis or lupus 3

Critical Red Flags Requiring Emergency Evaluation

Immediate transport to emergency department if any of the following:

• Complete inability to sense touch in the affected area 2
• Skin color changes: pale, white, blue, or darkened/blackened tissue 1, 2
• Hardened skin texture 2
• Any signs of tissue necrosis, ulceration, or gangrene 3
• Bilateral symptoms suggesting systemic hypothermia 4, 2

Diagnostic Workup

Initial Assessment

• Core body temperature measurement with low-reading thermometer to rule out systemic hypothermia 5
• Complete neurological examination focusing on sensory testing (light touch, pinprick, temperature discrimination, vibration) 7
• Vascular examination including pulses, capillary refill, and skin temperature mapping 3

Laboratory and Imaging Studies

• Digital blood pressure measurement to assess arterial perfusion 3
• Complete blood count and inflammatory markers 3
• Antinuclear antibody (ANA) testing if connective tissue disease suspected 3
• Nerve conduction studies if neuropathy suspected (though small fiber neuropathy may have normal large fiber studies) 7
• Skin biopsy for intraepidermal nerve fiber density assessment if chronic neuropathic pain present 7

Management Based on Etiology

If Frostbite or Acute Cold Injury

• Remove from cold environment immediately and prevent further heat loss 4, 1
• Remove any constricting materials (tight clothing, belts) 1
• If moderate to severe hypothermia present, prioritize core rewarming before treating peripheral frostbite 1, 2
• Protect tissue from further injury; avoid walking or pressure on affected area 1
• For severe frostbite requiring rewarming: immerse in warm water at 37-40°C (98.6-104°F) for 20-30 minutes 1, 6
• Never use water above 40°C as this causes additional tissue damage 1
• Do not use chemical warmers directly on tissue 4, 1
• Administer ibuprofen to prevent further tissue damage and treat pain 1

If Peripheral Neuropathy

• Recognize this as definite neuropathic pain using validated tools like DN4 questionnaire 7
• Initiate neuropathic pain treatment algorithms (gabapentinoids, tricyclic antidepressants, or SNRIs) 7
• Avoid further cold exposure as this exacerbates symptoms 7

If Vascular Insufficiency

• Urgent vascular surgery consultation 3
• Do not delay definitive care with attempted rewarming 4

Common Pitfalls to Avoid

• Do not assume absence of pain means absence of injury: Patients with diabetes or pre-existing neuropathy may have impaired sensation masking cold injury 1
• Do not rewarm if refreezing is possible: Freeze-thaw-refreeze cycles cause exponentially worse tissue damage 6
• Do not rewarm extremities before core in hypothermic patients: This can cause core temperature to drop further 2
• Do not debride tissue in first aid setting: Wait for clear demarcation of viable versus necrotic tissue, which takes 1-3 months 6
• Do not dismiss unilateral symptoms as benign: Unilateral coldness suggests arterial pathology requiring urgent evaluation 3