The monikers “new mother’s thumb” or “mother’s wrist” stem from the increased incidence of this disorder seen during the third trimester of pregnancy and in the first few months after delivery, especially if breastfeeding.
A 28-year-old woman presents 3 months postpartum complaining of left wrist pain. She localizes the pain to the radial aspect of her left nondominant wrist and reports radiation into the thumb. Nonsteroidal antiinflammatory drugs (NSAIDs) provide limited relief and the pain is exacerbated with lifting or breastfeeding. The pain started in her third trimester of pregnancy and has gradually worsened.
De Quervain tenosynovitis—actually a misnomer since the condition lacks any true inflammatory component—is the clinical manifestation of stenotic changes to the tendon sheath surrounding the abductor pollicis longus and extensor pollicis brevis tendons as they pass over the radial styloid toward their insertion points at the base of the thumb metacarpal and the proximal phalanx, respectively. Believed to be induced by increased pressure or friction between the tendons and the inner tendon sheath, the sheath undergoes myxoid degeneration and can become grossly thickened (up to 5 times the normal sheath wall thickness).1
The monikers, “new mother’s thumb” or “mother’s wrist,” stem from the increased incidence of this disorder seen during the third trimester of pregnancy and in the first few months after delivery, especially if breastfeeding.2 Repetitive lifting and the extreme wrist positioning necessary to support the newborn baby’s head during breastfeeding subject the affected tendon sheath to abnormal stresses, which certainly could explain the pathologic changes. Fluid retention and even a hormonal component (possibly related to prolactin)2-4 have been proposed as additional etiologies and offer a more likely mechanism for women who develop antepartum symptoms.
Pain localized over the radial styloid with radiation both proximally and distally into the thumb is the most common presentation.
Patients will sometimes report stiffness or a catching sensation coming from the radial side of the wrist. Paresthesia affecting the dorsal proximal thumb skin is an occasional complaint, most likely due to irritation of the nearby superficial branch of the radial nerve; this should not be confused with sensory disturbances confined to the fingertips, which is more indicative of gestational carpal tunnel syndrome.
Patients often will have focal swelling (Figure 1) and point tenderness on the radial aspect of the wrist. Pain associated with provocative maneuvers supports the diagnosis by either stretching the involved tendons or straining the tendons against the tendon sheath.
Many of these patients will respond to conservative treatment including NSAIDs, temporary thumb spica splint immobilization (Figure 4), and ice application. Topical anti-inflammatory agents can be effective as well.
A common mistake is to apply a wrist splint, which does not immobilize the thumb and can actually exacerbate the condition as the thumb struggles to work around the splint! Often, symptoms will spontaneously resolve within a few months of delivery or after the patient discontinues breastfeeding. Patients with persistent symptoms (especially if significant swelling is noted) will benefit from referral to a hand surgeon for additional treatment options. These can include steroid injections or, in some cases, surgical release—both of which have high rates of success.8