title: Effect of concentration and mode of intrathecal baclofen administration on soleus H-reflex in patients with muscle hypertonia.
abstract: OBJECTIVE
  Assess spinal reflex excitability after increasing intrathecal baclofen (ITB) flow by manipulation of drug concentration and mode of administration.
  
  
  METHODS
  The effect of concentration was assessed by comparing changes in H-reflex (H/M ratio) 1-6h after a 50μg ITB bolus at 50μg/ml concentration administered manually via lumbar puncture (LP, duration 1-2min, n=27) to a 50μg bolus at 500μg/ml concentration programmed through the pump and delivered via intrathecal catheter (IC, duration 10min) above simple continuous dose (25-100μg/day, n=16). The effect of mode of administration was assessed by comparing peak changes in H/M ratio after 50μg IC bolus above simple continuous dose (complex continuous mode, n=27) to simple continuous mode only (n=22) at equivalent daily doses (75-150μg/day).
  
  
  RESULTS
  H/M decrease was faster and overall greater after LP than IC bolus (mean 1-h 77% vs. 63%, p=0.012; 1-6h 91% vs. 82%, p<0.001, respectively). H/M ratio also decreased significantly more with complex (91%) than simple continuous mode of administration (78%, p=0.025).
  
  
  CONCLUSIONS
  Lower ITB concentration and complex continuous mode of administration lead to greater decrease in H/M ratio.
  
  
  CONCLUSIONS
  Decreased spinal reflex excitability after adjustment of drug and pump parameters to increase ITB flow may result in better clinical response.
authors.affiliation: Center for Neuroscience and Neurological Recovery, Methodist Rehabilitation Center, Jackson, MS, USA. dstokic@mmrcrehab.org
authors.forename: Dobrivoje S
authors.initials: DS
authors.lastname: Stokic
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Yablon
mesh_terms: D000328:Adult; D001418:Baclofen / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006181:H-Reflex / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007260:Infusion Pumps; D060186:Infusions, Spinal; D007278:Injections, Spinal; D008297:Male; D008875:Middle Aged; D009122:Muscle Hypertonia / Q000188:drug therapy* / Q000503:physiopathology; D009125:Muscle Relaxants, Central / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D018482:Muscle, Skeletal / Q000294:innervation*; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D009125:Muscle Relaxants, Central; D001418:Baclofen