Original research| Volume 96, ISSUE 12, P2112-2119, December 2015

Increased Lower Limb Spasticity but Not Strength or Function Following a Single-Dose Serotonin Reuptake Inhibitor in Chronic Stroke

Published:September 13, 2015DOI:



      To investigate the effects of single doses of a selective serotonin reuptake inhibitor (SSRI) on lower limb voluntary and reflex function in individuals with chronic stroke.


      Double-blind, randomized, placebo-controlled crossover trial.


      Outpatient research setting.


      Individuals (N=10; 7 men; mean age ± SD, 57±10y) with poststroke hemiplegia of >1 year duration who completed all assessments.


      Patients were assessed before and 5 hours after single-dose, overencapsulated 10-mg doses of escitalopram (SSRI) or placebo, with 1 week between conditions.

      Main Outcome Measures

      Primary assessments included maximal ankle and knee isometric strength, and velocity-dependent (30°/s–120°/s) plantarflexor stretch reflexes under passive conditions, and separately during and after 3 superimposed maximal volitional drive to simulate conditions of increased serotonin release. Secondary measures included clinical measures of lower limb coordination and locomotion.


      SSRI administration significantly increased stretch reflex torques at higher stretch velocities (eg, 90°/s; P=.03), with reflexes at lower velocities enhanced by superimposed voluntary drive (P=.02). No significant improvements were seen in volitional peak torques or in clinical measures of lower limb function (lowest P=.10).


      Increases in spasticity but not strength or lower limb function were observed with single-dose SSRI administration in individuals with chronic stroke. Further studies should evaluate whether repeated dosing of SSRIs, or as combined with specific interventions, is required to elicit significant benefit of these agents on lower limb function poststroke.


      List of abbreviations:

      5-HT (5-hydroxytryptamine (serotonin)), MG (medial gastrocnemius), MVC (maximum volitional contraction), SCI (spinal cord injury), 6MWD (6-minute walking distance), SSRI (selective serotonin reuptake inhibitor), TA (tibialis anterior), UMN (upper motor neuron)
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