Numbness and tingling in Raynaud phenomenon

Why they occur

• Numbness, tingling and a sensation of cold are expected features of the pallor and cyanosis phases. Digital artery vasospasm causes ischemia, and the nerves in the fingertips are briefly under-perfused. (Harrison's Principles of Internal Medicine 22E, p. 2220)
• Classic descriptions put them in the first stage, "local syncope". The digits turn cold and white with tingling and numbness. - S Das, A Manual on Clinical Surgery, 13th Ed.
• Adams and Victor's Neurology says numbness, paresthesia and burning often accompany the color changes. - Adams and Victor's Principles of Neurology, 12th Ed.
• Tingling and swelling often return during the rewarming and reactive hyperemia phase. Rewarming is also when the painful, throbbing sensation appears. - Ganong's Review of Medical Physiology, 26th Ed.

What it means clinically

1. Typical pattern (reassuring). The symptoms:
   • come with cold or stress,
   • are limited to the fingers or toes,
   • are symmetric,
   • resolve completely within minutes of rewarming.
   This fits primary Raynaud. The physical exam is often normal, and pulses and nailfold capillaries are normal.
2. It does not separate primary from secondary Raynaud. Andrews' notes the attacks of pallor, cyanosis, hyperemia and numbness are identical in primary disease and secondary phenomenon. - Andrews' Diseases of the Skin.
3. In systemic sclerosis it can be an early symptom. Robbins describes Raynaud phenomenon, "manifested as numbness and tingling of the fingers and toes", as seen in virtually all patients with scleroderma. It may precede other symptoms. - Robbins, Cotran & Kumar Pathologic Basis of Disease.

Features that suggest something else

• Numbness or tingling between attacks, or without color change. Consider:
  • carpal tunnel syndrome, which is common in scleroderma, hypothyroidism and connective tissue disease,
  • cervical radiculopathy,
  • thoracic outlet syndrome,
  • peripheral neuropathy, such as diabetic, B12 deficiency, or vasculitic neuropathy.
• Persistent or asymmetric numbness, weakness, or a one-sided pattern. Look for a neurologic or large-vessel cause.
• Ischemic features:
  • digital ulcers or pitting scars,
  • gangrene,
  • severe pain,
  • onset after age 40,
  • an asymmetric or single-digit pattern.
• Features of connective tissue disease:
  • puffy fingers or sclerodactyly,
  • abnormal nailfold capillaries,
  • joint pain,
  • dysphagia or reflux,
  • dyspnea,
  • rash,
  • positive ANA.
• Triggers:
  • vibrating tools, which can cause hand-arm vibration syndrome with both vascular and neural damage,
  • drugs such as beta-blockers, ergots, stimulants (including ADHD medication), and chemotherapy,
  • cold agglutinins or cryoglobulins.

Suggested approach

• Ask whether the tingling happens only during attacks or also at rest.
• Examine the pulses, do an Allen test, and check for sclerodactyly, ulcers, and Tinel and Phalen signs.
• Look at the nailfold capillaries.
• If there are red flags, check ANA with ENA/anti-centromere/anti-Scl-70, CBC, ESR/CRP, TSH, glucose, B12, and consider nerve conduction studies.
• For simple primary Raynaud, treat with cold avoidance, warm gloves, and calcium channel blockers if needed.

The most likely reason: pregnancy vasodilation

• In normal pregnancy, systemic vascular resistance falls from about 5 weeks. This is driven by vasodilators, mainly progesterone, nitric oxide, relaxin and prostaglandins (prostacyclin). - Creasy & Resnik's Maternal-Fetal Medicine, "Systemic Vascular Resistance"; Comprehensive Clinical Nephrology, 7th Ed.; Miller's Anesthesia, 10th Ed.
• Raynaud's is a disorder of excess digital vasoconstriction. Part of the problem is thought to be too little vasodilator signaling, including nitric oxide, and excess vasoconstrictors such as endothelin-1 and alpha-2C adrenoceptor activity (from my knowledge and a Medscape review). A body flooded with vasodilators should therefore protect against vasospasm.
• Cardiac output and blood volume also rise, and peripheral blood flow and skin temperature increase. This makes cold-triggered digital ischemia less likely. Pregnant women often feel warm, and the textbooks note facial and palmar erythema from pregnancy-induced vasodilation. - Firestein & Kelley's Textbook of Rheumatology

Possible hormonal contribution

• Estrogen is linked to Raynaud's. It upregulates alpha-2C adrenoceptors, which mediate cold-induced vasoconstriction, and this may explain the female predominance.
• Progesterone is a vasodilator and may offset estrogen's effect. Progesterone dominance has been proposed as one reason some women improve. One small study reported improvement in only 6 of 23 pregnant women, so this is a hypothesis and not an established mechanism. These points come from web sources (Life Extension summary), not from the textbooks I searched.

Caveats

• The evidence is weak. My PubMed search found only small studies and case reports, such as Kahl 1990 on primary Raynaud's and pregnancy outcomes. I found no good controlled data showing consistent improvement. Other surveys report no change, or worse symptoms in some women.
• In systemic sclerosis, disease activity improved or stayed stable in most pregnant patients. - Creasy & Resnik's, "Systemic Sclerosis". This is about the disease overall and not specifically Raynaud's.
• Pregnancy can also cause problems in Raynaud's. Raynaud's of the nipple often starts in pregnancy or lactation. Secondary Raynaud's from scleroderma carries risks of miscarriage, pre-eclampsia, growth restriction and preterm birth. Scleroderma renal crisis can be hard to tell from pre-eclampsia. - Andrews' Diseases of the Skin; Firestein & Kelley's.
• Symptoms often return after delivery, as vascular resistance goes back to baseline. This is my clinical understanding, and I did not find a source for it.

Management in pregnancy