Effective Treatment of Fibromyalgia Comorbid With Premenstrual Dysphoric Disorder With a Low Dose of Venlafaxine

Sir: Fibromyalgia and premenstrual dysphoric disorder (PMDD) are common psychosomatic disorders in women. Fibromyalgia is characterized by chronic widespread pain, and tenderness at specific muscle-tendon sites. Estimates of lifetime prevalence are 3.4% for women and 0.5% for men.¹ We report the case of a 39-year-old woman with both conditions treated successfully with only 75 mg daily of venlafaxine, a dosage much lower than that used in previously published studies. To our best knowledge, no instances of fibromyalgia comorbid with PMDD have been reported.

Case report

Ms. A, a 39-year-old married Asian woman, had a history of marked pain and tenderness in the neck, shoulders, hands, and occipital and sacral areas for more than 10 years. The symptoms would worsen before menstruation. She visited various orthopedic outpatient clinics repeatedly, and high daily doses of nonsteroidal anti-inflammatory agents were prescribed. Other medical conditions included peptic ulcers, duodenal polyps, chronic pharyngitis, migraine, and irritable bowel syndrome. PMDD was diagnosed by DSM-IV research criteria and the Prospective Record of the Impact and Severity of Menstrual Symptomatology (PRISM) calendar for 2 menstrual cycles after other psychiatric diagnoses and possible organic contributions were ruled out in the premenstrual syndrome specialty clinic at Chang-Gung Hospital, Taoyuan, Taiwan.^2,3

Ms. A sought help from the departments of gastroenterology, gynecology, rheumatology, rehabilitation, and neurology of Chang-Gung Hospital; the diagnosis of fibromyalgia without active pain symptoms and impaired occupational function was confirmed. She received treatment of physical rehabilitation, acupuncture, local steroid injections, yoga, and Chinese qi training, with little improvement.

Venlafaxine 75 mg was prescribed with PRISM calendar recording and assessment of pain severity with a visual analog scale. Ms. A reported that the pain was decreased at least 50% after 4 weeks' treatment. Further improvement was reported in the following 8 months. The severity of PMDD decreased 72%, as assessed with the PRISM calendar.

The average dosage of venlafaxine for fibromyalgia is 75 mg to 225 mg daily. In this case, a low dosage had significant effectiveness. A randomized, controlled trial of 90 patients with fibromyalgia found that venlafaxine (75 mg daily) was not significantly different from placebo.⁴ Venlafaxine at a higher dosage was found useful in 2 small, open-label studies.⁵

Venlafaxine for PMDD has had some clinical trials.^6,7 The average dosage in one double-blind, placebo-controlled study in the West was 75 to 112.5 mg daily.⁶ To our best knowledge, this is the first report to discuss the role of antidepressants in fibromyalgia comorbid with PMDD. The presenting case improved markedly with a dosage of 75 mg daily. I conclude that both fibromyalgia and PMDD impair women's mental health significantly, and more clinical trials of antidepressants are needed.