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Intrathecal Baclofen for Spasticity

Intrathecal Baclofen for Spasticity. George Jallo MD, Division of Pediatric Neurosurgery Johns Hopkins University. Spasticity. Spastikos - “to draw or tug” Motor disorder Velocity-dependent increased resistance to passive stretch Exaggerated tendon jerks

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Intrathecal Baclofen for Spasticity

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  1. Intrathecal Baclofen for Spasticity George Jallo MD, Division of Pediatric Neurosurgery Johns Hopkins University

  2. Spasticity Spastikos - “to draw or tug” • Motor disorder • Velocity-dependent increased resistance to passive stretch • Exaggerated tendon jerks • Hyperexcitability of the stretch reflex

  3. DescendingInhibition Sensory Excitation Pathophysiology of Spasticity Theory • Imbalance between excitatory and inhibitory impulses to the alpha motor neuron • Due to a lack of descending inhibitory input to the alpha motor neuron

  4. Pathophysiology of Cerebral Origin Spasticity Normal brain delivers inhibitory neural signals to the spinal cord Damaged brain fails to generate or sends inadequate inhibitory signals Inhibitory signals modulate reflex signals–tone remains normal Lack of neural inhibition leads to spasticity

  5. Pathophysiology of Spinal Origin Spasticity Normal Damaged Inhibitory neural signals sent to the alpha motor neuron Damaged spinal cord fails to relay adequate inhibitory signals Inhibitory signals modulate reflex signals–tone remains normal Lack of neural inhibition leads to spasticity

  6. Possible Advantages of Spasticity • Maintains muscle tone • Helps support circulatory function • May prevent formation of deep vein thrombosis • May assist in activities of daily living

  7. Consequences of Spasticity • May interfere with mobility, exercise, joint range of motion • May interfere with activities of daily living • May cause pain and sleep disturbance • Can make patient care more difficult

  8. Measuring Spasticity • Ashworth and Modified Ashworth scales • Spasm and reflex scales • Passive quantitative tests • Active tests of movement

  9. Uncontrollable Urinary tract infection Kidney stones Menses Bowel impaction or gas Deep vein thrombosis Pneumonia Wounds or infections Progression of disease Controllable Stress Ingrown nails Restrictive clothing Fatigue Psychological factors Change in temperature or humidity Factors That May Increase Spasticity

  10. Spasticity Associated with Cerebral Palsy (CP) • Disorders affecting • movement • posture • balance • Injury to the developing brain • Permanent and non-progressive • Developmental disability

  11. Classifications of Cerebral Palsy • Location of brain lesion • pyramidal, extrapyramidal, mixed • Type of movement disorder • spastic, dystonic, athetoid, ataxia, mixed • Extent and location of limb involvement • monoplegia, diplegia, hemiplegia, paraplegia, tetraplegia

  12. Conditions Associated withCerebral Palsy • Mental retardation, learning disabilities • Seizures • Gastrointestinal difficulties • Urinary infections • Respiratory problems • Hearing/vision impairment • Orthopedic problems

  13. Goals of Spasticity: Management • Decrease spasticity • Improve functional ability and independence • Decrease pain associated with spasticity • Prevent or decrease incidence of contractures • Improve ambulation • Facilitate hygiene • Ease rehabilitation procedures • Save caregivers’ time

  14. Spectrum of Care forManagement of Spasticity PreventNociception IntrathecalBaclofen(ITB™)Therapy RehabilitationTherapy OralDrugs Patient OrthopedicTreatments InjectionTherapy Neurosurgery

  15. Traditional Step-Ladder Approach to Management of Spasticity Neurosurgical Orthopedic Neurolysis Oral medications Rehabilitation Therapy Remove noxious stimuli

  16. Stretching Weight bearing Inhibitory casting Vibration of the antagonist Pool therapy EMG biofeedback Electrical stimulation Positioning and rotary movements Rehabilitation Therapy

  17. Oral Medications • Baclofen • Diazepam • Dantrolene Sodium • Tizanidine

  18. Drug Baclofen: Diazepam: Dantrolene Sodium: Tizanidine: Site of action GABAb receptors in spinal cord Central nervous system Skeletal muscles beyond the myoneural junction Central acting (spinal and supraspinal) at alpha2 – adrenergic receptor sites Site of Action for Oral Drugs

  19. NeurosurgerySurgical Treatments Neurodestructive Procedures • Neurectomy • Myelotomy • Rhizotomy • Cordectomy • Selective Dorsal Rhizotomy

  20. Selective Dorsal Rhizotomy • Two primary goals: • facilitate patient care • sitting, dressing, transfers • improve function • walking Surgical procedure where the dorsal (sensory) nerve roots are severed

  21. Orthopedic Surgeries Soft Tissue Procedures • Tenotomy • Tendon lengthening • Myotomy • Tendon transfers

  22. Baclofen Injection Baclofen injection is delivered to the CSF and thought to act at GABAb receptor sites at the spinal cord Lower doses than those required orally Potential for fewer systemic side effects Oral Baclofen Low blood/brain barrier penetration, with high systemic absorption and low CNS absorption Lack of preferential spinal cord distribution Some patients experience unacceptable side effects at effective doses Why Intrathecal vs. Oral?

  23. Advantages of ITB™ Therapy • Reversible • Potentially fewer systemic side effects • Programmable • allows dose titration to give optimal benefit • Effective in reducing spasticity • upper and lower extremities1 • cerebral and spinal origin

  24. ITB™ Therapy Process • Stage 1: Patient Selection • Stage 2: Screening Test • Stage 3: Implant • Stage 4: Maintenance

  25. Efficacy in Adults and Children • 86% cerebral origin (screening test) • 97% spinal cord origin (screening test) • Upper and lower extremities • Both patients with functional goals and patients with goals of improving comfort and ease of care Albright, A. Leland. Baclofen in the Treatment of Cerebral Palsy, J Child Neurol 1996; 11:77-83. Becker, R., Alberti, O., and Bauer, B.L. Continuous intrathecal baclofen infusion in severe spasticity after traumatic or hypoxic brain injury, J Neurol 1997; 244: 160-166. Campbell, Susan K., Almeida, Gil L., Penn, Richard D., and Corcos, Daniel M. The Effects of Intrathecally Administered Baclofen on Function in Patients with Spasticity, Phys Ther 1995; 75: 352-362.

  26. Reported Outcomes in Patients with Spasticity of Cerebral Origin Method • 37 patients • Spastic quadriplegia • ITB Therapy received over a range of 3 - 48 months Results • 6 and 12 months post implant • muscle tone significantly decreased in lower and upper extremities • 25 children capable of self-care at start of study: • significant improvement in • ADL • upper extremity function • hamstring extensibility Albright AL, Barron WB, Fasick MP, et al. Continuous Intrathecal Baclofen Infusion for Spasticity of Cerebral Origin. JAMA 270(20):2475-77, Nov 24, 1993.

  27. Reported Outcomes in Patients with Spasticity of Spinal Origin Method • 20 patients • Diagnosed with spinal cord injury or multiple sclerosis • ITB Therapy received over a range of 10-33 months Results • Statistically significant decreases in muscle tone of hip, knee, and ankle musculature • based on Ashworth score • Statistically significant decrease in frequency of spasms • Functional status tracked in 8 patients (6 months duration): • improved ADL • improved bowel and bladder management programs Parke B, Penn RD, Savoy SM, et al. Functional Outcome after Delivery of Intrathecal Baclofen. Arch Phys Med Rehabil 70:30-32,1989. Penn RD, Savoy SM, Corcos D, et al. Intrathecal Baclofen for Severe Spinal Spasticity N Engl J Med 329:1517-21,1989.

  28. Drug Spinal level Excitatory neurotransmitters How Does Baclofen Injection Work? Spinal cord To brain Epiduralspace Dura-arachnoidmembranes Capillaryabsorption Intrathecalspace Catheter CSF Drug Vertebra Anatomic figure adapted from Kroin, JS. Intrathecal drug administration: present use and future trends. Clin Pharmacokinet 1992, 22:319-326.

  29. GABA • Gamma-butyric acid (GABA) • an inhibitory neurotransmitter • Baclofen • thought to act as a GABA agonist in the spinal cord, reducing positive input to the alpha motor neuron

  30. Pharmacokinetics of Baclofen Oral • 60 mg dose: 0.024 mcg/mL IT lumbar concentration • Half-life 3-4 hours Intrathecal • 600 mcg/day dose: 1.24 mcg/mL IT lumbar concentration • Lumbar to cervical concentration is 4:1 • Half-life 4-5 hours

  31. Pharmacodynamics ofBaclofen Injection Bolus • Onset of action is one-half hour to 1 hour after intrathecal bolus • Peak effect at 4 hours after dosing • Effects may last from 4 to 8 hours Continuous • Effects are first seen at 6 to 8 hours after initiation of continuous infusion • Maximum effect observed in 24 to 48 hours Onset, peak response, and duration of action may vary

  32. Interdisciplinary Team Assessment • Considers all facets of patient’s needs and resources • Considers the “whole” person • Provides optimal care for the patient

  33. Contraindications of ITB™ Therapy • Patient has a history of allergy (hypersensitivity) to oral baclofen • Infection is present at time of screening or implant

  34. Potential Risks of ITB™ Therapy • Common side effects: hypotonia, somnolence, nausea/vomiting, headache, dizziness • Overdose, although rare, could lead to respiratory depression, loss of consciousness, reversible coma, and in extreme cases, may be life-threatening • Catheter and procedural complications may occur

  35. Causes of Overdose • Dosing error • Pump malfunction • Programming error • Injecting catheter access port during refill • Filling catheter with syringe during surgery • Use of concomitant drugs

  36. + = Positive Response “Implant” = Negative Response “No Implant” - - - Screening Test Flow Chart Bolus: 50 mcg + 24 hrs after Bolus: 75 mcg + 24 hrs after Bolus: 100 mcg - + Not a Candidate Intrathecal Baclofen Therapy Clinical Reference Guide for Spasticity Management, Medtronic, Inc.

  37. Pump infuses drug Catheter delivers drug to the intrathecal (subarachnoid) space of the spinal cord Programmer allows for precise dosing easily adjustable dosing SynchroMed® System Components

  38. Battery life of approximately 7 years Flow rates down to48 microliters/day Four suture loops Matte finish No changes in clinical procedure or pump programming SynchroMed® EL Pump

  39. Two-piece catheter design Pre-attached pump connector Tapered, open tip InDura® IntraspinalTwo-Piece Catheter

  40. Insert the catheter through the introducer needle to the desired level (T10-T12) Verify catheter tip position through use of fluoroscopy and CSF backflow Catheter Implant Advancing catheter under fluoroscopy

  41. Pump Implant • Abdominal incision • make a pocket for the pump no deeper than 2.5 cm or 1 inch

  42. Titration Period After First 24-Hour Period • Increase dose slowly • Increase only once every 24 hours until desired clinical effect achieved • Adults with spasticity of spinal origin • 10-30% increments • Adults with spasticity of cerebral origin • 5-15% increments • Pediatrics • 5-15% increments

  43. Comparison of Techniques

  44. Conclusions • Intrathecal delivery is an alternative to rhizotomy procedures in children • Advantages: simple, adjustable, reversible • Disadvantages: cost, infection, toxicity

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