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  • A disorder characterized by velocity-dependant increase in the tonic stretch reflex (muscle tone) with exaggerated tendon jerks resulting from hyperexcitability of the stretch reflexes The stretch Reflex Arc Nerve fibers from various tract converge and synapse in the anterior horn, maintaining segmental muscle tone by modulating the stretch reflex arc, which is basically a negative feedback loop in which muscle stretch (stimulation) cause reflexive contraction (inhibition), thus maintaining muscle length and tone. Damage to certain tracts results in loss of inhibition and a disruption of the stretch reflex arc. Uninhibited muscle stretch produces exaggerated, uncontrolled muscle activity stressing the reflex arc and resulting in spasticity.
  • Jagatsinh Due to increased Gamma motor neuron activity Due to impaired descending influence on segmental input or structural reorganization of the propriospinal input Resulting in increased responsiveness of alpha and gamma motor neurons to the input from muscle afferents On alpha motor cells and consequently hyperactivity of alpha motor cells
  • Dystonia can manifest in many forms including adult-onset focal forms: writer's cramp is the most common form of dystonia ( a ). It is task specific and begins when the repetitive task of handwriting is undertaken. The hand, finger and forearm muscles contract into an abnormal posture making writing difficult. Torticollis refers to a condition in which the muscles around the neck contract in a sustained or intermittent manner forcing the head to turn to one side with the chin thrust upward ( b ). This condition is also referred to as wry neck or cervical dystonia. Other forms of dystonia have a childhood/adolescent-onset. For example, early-onset generalized dystonia is the most severe and common of the hereditary dystonias. Symptoms usually begin in childhood with onset in a leg or arm, manifesting as muscle contractions and twisting ( c ). It progresses to other body parts forcing them into abnormal positions, which can be painful. This condition is also referred to as dystonia musculorum deformans and Oppenheim's disease. Rapid-onset dystonia-parkinsonism is a hereditary condition with sudden onset of dystonic symptoms within hours to weeks after physical or mental stress. Symptoms can manifest as dystonic spasms in the upper limbs with facial grimacing, but can also include parkinsonian symptoms such as slowness of movement and postural instability ( d ). The pathophysiological basis of dystonias Xandra O. Breakefield, Anne J. Blood, Yuqing Li, Mark Hallett, Phyllis I. Hanson & David G. Standaert Nature Reviews Neuroscience  9 , 222-234 (March 2008) doi:10.1038/nrn2337
  • Used primarily in the calf muscles to treat dynamic equinus of the ankle Injected several areas of the muscle Repeated every 3-8 months to maintain its effect Most evidence is for Equinus varus**
  • CBA: range of motion, strength, assessment of selective motor control, muscle tone and function
  • Serum Baclofen virtually undetectable
  • Cleared at CSF clearance rates CSF elminiation t ½ = 1.5hrs CSF clearance 30ml/hr
  • $70 for the initial test bolus 20ml refill ~$425 40ml Refill ~$850
  • Severe spastic hemiplegia: benefits the affected area without making the unaffected area hypotonic Spastic diplegia related to Cerebral Palsy Patient (usually don’t show benefit from ITB) Use selective dorsal rhizotomy, first line Primary Dystonia’s tend not to respond well to ITB, these are associated with gene involvement
  • Traditionally inserted subfascially on the right side, and catheter inserted obliquely in the lumbar region Kroin JS, Ali A, York M, Penn RD: The distribution of medication along the spinal canal after chronic intrathecal administration. Neurosurgery 33:226-230, 1993
  • If child is unresponsive to 50 μ cg then increase bolus to 75 to 100 μ cg the next day. (Spasticity) **There is enough evidence to disregard these test doses, literature points out that more than 90% of patients who were screened have decrease dystonia scores after pump implantation**** Albright AL, Gilmartin R, Swift D, Krach LE, Ivanhoe CB, McLaughlin JF: Long term intrathecal baclofen therapy for severe spasticity of cerebral origin. J Neurosurg 98:291-295, 2003
  • Key points of the low complication implant technique include: Paramedian oblique entry Helps stabilize the catheter against dislodgement Reduced wear on catheter compared to midline entry V-wing anchor at spinal entry point Reduces catheter dislodgements Catheter connector/primary anchor Reduces catheter dislodgements Strain-relief sleeve on catheter tubing Reduces catheter kinks and holes Loop of catheter under pump Reduces catheter kinks Slack in catheter by connector Reduces catheter kinks Thick wall proximal catheter Reduces catheter kinks and holes Pump anchor using suture loops or mesh pouch Reduces catheter kinks and dislodgements
  • * Find out why
  • Most commonly S. Aureus Treat by removing the pump, and IV antibiotics for 14 days 5-15% prevalence Most prevalent the first two week after implantation
  • Subdural catheter placement: drug infuses into the subdural space and accumulates and then upon patient repositioning the accumulation is released into the intrathecal space Baclofen is not neurotoxic Half-life: 4-5 hours
  • Occurs much more commonly than overdosage
  • Mild to moderate: enteral Baclofen If NPO  IV Diazepam Follow the flow of medication through the catheter in real-time
  • Other Citations Anne-Berit Fjelstad,  R.N.,  Jorunn Hommelstad,  R.N., M.S., and  Angelika Sorteberg,  M.D., Ph.D.. (2009) Infections related to intrathecal baclofen therapy in children and adults: frequency and risk factors.  Journal of Neurosurgery: Pediatrics   4 :5, 487-493 Online publication date: 1-Nov-2009.

Transcript

  • 1. Trey Rumph Mercer University 4 th year Student
  • 2.
    • What is spasticity?
    • Current treatments for spasticity
    • How does Baclofen work?
    • How is Intrathecal Baclofen used in the clinical setting?
  • 3.
    • Modified Ashworth Scale
    • Penn’s Spasm Score
    • Spasticity
    • Dystonia
  • 4. Score Ashworth Scale  (1964) Modified Ashworth Scale  Bohannon & Smith (1987) 0  (0) No increase in tone No increase in muscle tone 1  (1) Slight increase in tone giving a catch when the limb was moved in flexion or extension Slight increase in muscle tone, manifested by a catch and release or by minimal resistance at the end of the range of motion when the affected part(s) is moved in flexion or extension. 1+ (2) Slight increase in muscle tone, manifested by a catch, followed by minimal resistance throughout the reminder (less than half) of the ROM (range of movement). 2  (3) More marked increase in tone but limb easily flexed. More marked increase in muscle tone through most of the ROM, but affected part(s) easily moved. 3  (4) Considerable increase in tone - passive movement difficult. Considerable increase in muscle tone passive, movement difficult. 4  (5) Limb rigid in flexion or extension. Affected part(s) rigid in flexion or extension.
  • 5. Penn spasm frequency scale Score Spasm frequency score No spasms 0 No spasms Mild spasms at stimulation 1 One or fewer spasms per day Irregular strong spasms less than 1 time/[sol]/h 2 Between 1 and 5 spasms per day Spasms more often than 1 time/[sol]/h 3 Five to less than 10 spasms per day Spasms more than 10 times/[sol]/h 4 Ten or more spasms per day, or continuous contraction
  • 6.
    • Sustained stiff or rigid muscles with exaggerated deep tendon reflexes
  • 7.
    • Proposed Mechanisms
      • Muscle spindle hyperactivity
      • Decreased pre-synaptic inhibition
      • Alteration in segmental reflex mechanisms
      • Impaired suprasegmental influence
  • 8.  
  • 9.
    • Movement disorder which causes involuntary contraction of one’s muscle/s
      • Typically twisting and repetitive movements
  • 10.
    • Types
      • Focal —limited to one area of the body
      • Segmental —affecting 2 or more nearby or contiguous areas of the body
      • Multifocal —involving 2 or more distant regions of the body
      • Hemidystonia —affecting one half of the body
      • Generalized —leg involvement plus eventual involvement of another region or regions of the body
  • 11.
    • Injectables*
    • Oral Antispasmodics*
    • Surgical Treatment
      • Selective dorsal rhizotomy
    • Orthopedic interventions
      • Muscle-tendon surgery
    • Physical Therapy
    • Constraint Therapy
    • Electrical Stimulation
  • 12.
    • Botulinum toxin (BTX A) injected into the affected muscle blocks the presynaptic release of acetylcholine from the motor endplates of the motorneural junction decreasing tone by limiting muscle contraction
        • **3-10 percent develop antibodies to the toxin and no longer will receive benefit from the medication
  • 13.
    • Treatment:
      • Complete Baseline assessment
      • Dosing is based on body weight as well as the muscle being treated by the toxin
      • No reliable potency standard amongst the different preparations so each dosing scheme is unique to the manufacturer brand
      • Re-evaluate the patient six week post-treatment, effect typically last for 3 to 8 months  re-dose
  • 14.  
  • 15.
    • Zanaflex
      • In the spinal cord : primary action is on polysynaptic pathways to reduce release of excitatory neurotransmitters and reduce the sensitivity of the post-synaptic neuron to excitatory neurotransmitters
    • Dantrolene
      • Inhibits release of calcium ions from the sarcoplasmic reticulum
    • Benzodiazepines
      • Increases presynaptic inhibition due to binding of the BZD receptors that are linked to the receptors for GABA located on the primary afferent fibers  increased affinity of GABA to its receptor
    • Baclofen
      • GABA analog
      • Oral availability is limited due to poor lipid solubility resulting in low levels in the CSF
  • 16.
    • Pharmacology
      • 4-amino-3-(4-chlorophenyl)-butanoic acid
      • Oral baclofen is absorbed well via the GIT, but doesn’t cross the BBB (low lipophilicity)
        • Oral dose: 30-60mg  CSF level: 12 to 96 μ cg
        • Onset 30min to 1hr
        • Peak: ~4hrs
        • DOA: ~8hrs
        • Renal clearance 10-85%
  • 17.
    • Baclofen given via intrathecal administration achieves much higher CSF concentrations
            • BLACK BOX WARNING : Don’t abruptly stop medication due to high fever, altered mental status, exaggerated rebound spasticity, and muscle rigidity, which in rare cases has advanced to rhabdomyolysis, multiple organ-system failure, and death
            • Intrathecal dose: 400 μ cg  CSF level: 400 μ cg/ml
            • Onset 30 min to 1hr
            • Peak: ~4hrs
            • DOA: ~8hrs
            • CSF Clearance
  • 18.
    • Patient Selection
    • Pumps Implantation
    • Dosing Schemes
    • Side Effects
    • Complications
      • Overdose
      • Baclofen Withdrawal
    • Outcomes
  • 19.
    • Four Indications
      • Spinal cord injuries or Familial paraparesis related spasticity
      • Secondary Dystonia (brain lesion)
      • Hemidystonia
      • Spastic hemiparesis
  • 20.
    • Kroin, observed that CSF concentration varied along a gradient in the spinal canal. Drug concentrations at the foramen magnum were ¼ those in the lumbar region.
      • T10-11: familial spastic paraparesis
      • C6-T2: spastic quadriparesis
      • C1-4: generalized secondary dystonia
  • 21.
    • Screening
      • “ virtually all patients with spasticity respond to bolus doses…”
      • “ The great majority of children who ‘do not respond’ to bolus doses have dystonia , which takes higher dose and often require continuous infusion”
  • 22.
    • Test Doses (spasticity):
      • <40lbs  25 μ cg
      • > 40lbs  50 μ cg
    • Test Dose (dystonia):
      • <7 years old, < 40lbs  50 to 100 μ cg bolus
      • > 7 years old, > 40 lbs  continuous infusions
        • Begin @ 200 μ cg /day
        • Increase by 50 μ cg every 8 hours until desired effect is reached
          • Look for the following: 1) dystonia improvement; 2) unacceptable side effects; 3) no significant response at 900 μ cg/day
  • 23.
    • Dosing for Spasticity
      • 100 μ cg/day (a dose twice the test dose)
        • Can adjust daily, often increasing 5-10% a day
    • Dosing for Dystonia
      • 200-300 μ cg/day
        • Can adjust daily, often increasing 50 -100 μ cg/day
  • 24. Source: Data on file at Medtronic.
  • 25.
    • Common Early Side Effects
      • Hypotonia, somnolence, headache, convulsion, urinary retention, dizziness and nausea
    • Common Chronic Side Effects
      • Hypotonia, somnolence, nausea and vomiting, headache, urinary retention
  • 26.
    • Three most common:
      • Infections
      • Catheter Problems (breaks, kinks, migration)
      • CSF leaks
  • 27.
    • Presentation
      • Hypotonia, decreased alertness, depressed respiration, bradycardia and coma
    • Treatment
      • Turn off the pump, support oxygenation and respiration until the drug has metabolized
      • If significant overdose: CSF barbotage can speed up recovery
  • 28.
    • Presentation
      • Mild
        • Characterized by pruritus (without exanthem), agitations, diaphoresis and increased tone
      • Moderate
        • Fever, tachycardia, spontaneous clonus and painful muscle spasms
      • Severe
        • Worsening of the following sx: seizures, hallucination, delirium, rhabdomyolysis and death
  • 29.
    • Treatment
      • Administration of GABAergics
      • Enteral Baclofen: 10mg TID  30mg Q4h
        • If NPO  IV Valium
    • Differential
      • Malfunctioning Pump*
        • Fluoroscopic study or Radionuclide instillation
      • Tachyphylaxis to ITB (no reported cases)
        • Give “meaningful” bolus: 50 - 150 μ cg through pump in shortest interval
  • 30. Intrathecal Baclofen Therapy
    • SynchroMed II (20ml, 40ml)
        • $11,000/unit
      • Battery Life: 6-7 years
        • 20ml refill ~$425
        • 40ml Refill ~$850
    • SynchroMed EL (10ml, 18ml)
      • Battery Life: 3-7 years
    • Intrathecal Test Dose
      • $70 for the initial test bolus
  • 31.
    • ITB has been proven efficacious in decreasing spasticity in the upper and lower extremities
    • ITB treats spasticity for at least 17 years and is effective for dystonia for at least 10 years
  • 32.  
  • 33.
    • Albright, A. Leland, Ferson, Susan S. Intrathecal baclofen therapy in children. Neurosurgical FOCUS 2006 21:2, 1-6 
    • Albright AL, Gilmartin R, Swift D, Krach LE, Ivanhoe CB, McLaughlin JF: Long term intrathecal baclofen therapy for severe spasticity of cerebral origin. J Neurosurg 98:291-295, 2003
    • Francesco Motta, M.D., Vincenzo Buonaguro, M.D., and Cecilia Stignani, P.T.. (2007) The use of intrathecal baclofen pump implants in children and adolescents: safety and complications in 200 consecutive cases.  Journal of Neurosurgery: Pediatrics   107 :1, 32-35 Online publication date: 1-Jul-2007.
    • Jagatsinh Y. Intrathecal baclofen: Its effect on symptoms and activities of daily living in severe spasticity due to spinal cord injuries: A pilot study. Indian J Orthop [serial online] 2009 [cited 2009 Dec 13];43:46-9. Available from:  http://www.ijoonline.com/text.asp?2009/43/1/46/45323
    • Kroin JS, Ali A, York M, Penn RD: The distribution of medication along the spinal canal after chronic intrathecal administration. Neurosurgery 33:226-230, 1993