[Note: Propranolol is a nonselective “beta blocker” drug. It blocks the action of the hormone epinephrine by blocking Beta 1 and 2 adrenergic (epinephrine) receptors, and is employed to reduce blood pressure – helps blood vessels open up and heart to beat more slowly, with less force. Epinephrine is the short-term "fight or flight" hormone.]
In patients with fibromyalgia syndrome (FMS) and temporomandibular disorder (TMD), stress and pain may chronically enhance sympathetic activity, altering cardiovascular responses and worsening pain.
This study examined cardiovascular, epinephrine (EPI), norepinephrine (NE), cortisol and clinical pain responses in 54 female patients with these disorders and 34 controls.
In a subsample of 10 FMS, 10 TMD patients and 16 controls, using a counterbalanced, double-blind, crossover design, the same responses were assessed after intravenous administration of low dose propranolol vs placebo. Testing included baseline, postural, speech and ischemic pain stressors.
• FMS patients showed:
– Lesser heart rate (HR) increases to posture challenge
– But greater blood pressure (BP) increases to postural and speech tasks than controls,
– As well as higher overall BP and greater total vascular resistance (TVR) than TMDs or controls.
• TMDs showed higher overall cardiac output and lower TVR than controls.
• Both FMS and TMD groups showed lower baseline norepinephrine than controls,
• And TMDs showed lower overall epinephrine and norepinephrine levels.
• Group differences in HR, EPI and NE were abolished after propranolol although BP, CO and TVR differences persisted.
• In both FMS and TMD, the number of painful body sites and ratings of total clinical pain obtained 4 times during each session were significantly lower after beta-blockade vs. placebo.
Perspective: These findings support the hypothesis that both FMS and TMD may frequently involve dysregulation of beta-adrenergic activity that contributes to altered cardiovascular and catecholamine responses and to severity of clinical pain.
Acute treatment with low-dose propranolol led to short-term improvement in all these domains.
Source: Journal of Pain, May 2009;10(5):542-52. PMID: 19411061, PMID: 19411061. Light KC, Bragdon EE, Grewen KM, Brownley KA, Girdler SS, Maixner W. Health Sciences Center, University of Utah, Salt Lake City, Utah, USA. [E-mail: Kathleen.C.Light@hsc.utah.edu]