intrathecal baclofen pump & other management strategies for spasticity william o mckinley md...
TRANSCRIPT
Intrathecal Baclofen Pump & other management strategies for
Spasticity
William O McKinley MDDirector, SCI Rehabilitation Medicine
Dept. PM&RVCU / MCV
What is Spasticity ?
• Abnormal, velocity-dependent increase in resistance to passive movement of peripheral joints due to increased muscle activity.
Spasticity: Etiology (Diagnosis)
• Spinal Cord Injury
• Traumatic Brain Injury
• Stroke
• Multiple Sclerosis
• Cerebral Palsy
Pathophysiology
• Intrinsic hyperexcitability of alpha motor neurons within the spinal cord secondary to damage to descending pathways– cortico, vestibulo, reticulospinal
• CNS modification– neuronal sprouting– denervation hypersensitivity
Symptoms of Spasticity
• NEGATIVE SX’s• Weakness• Function• Sleep• Pain• Skin, hygiene• Social, Sexuality• contractures
• USEFUL SX’s• Stability• Function• Circulation• Muscle “bulk”
Spasticity: Treatment Decisions
• Is Spasticity:– Preventing function?, Painful?– A result of underlying treatable stimulus– A set-up for further complications?
• What Rx has been tried?
• Limitations and SE’s of Rx…
• Therapeutic goals
Goals of Therapy
• Ease function (ambulation, ADL)
• Decrease Pain, contracture
• Facilitate ROM, hygiene
Spasticity Scales
• “Modified” Ashworth• 0= no increased tone
• 1= slight “catch” in ROM
• 1+= minimal resistance
• 2= moderate tone, easy ROM
• 3= marked tone, difficult ROM
• 4= Rigid in flexion or extension
• Spasm Frequency Scale
• 0= none
• 1= mild
• 2= infrequent
• 3=> 1 per hour
• 4= > 10 per hour
Rehab Evaluation (con’t)
• Gait patterns
• Transfer abilities
• Resting positioning
• Balance
• Endurance
Management Options
• Physical interventions
• systemic medications
• chemical denervation
• Intrathecal agents
• orthopedic interventions
• neurosurgical interventions
Rehabilitation Interventions
• Positioning (bed, wheelchair)• Modalities
– heat (relaxation)– cold (inhibition)
• Therapeutic Exercise– inhibitory to spastic muscles– facilatory to opposing muscles
• Orthotics
Non-Conservative Treatment Options
• Oral Medications
• Injections (Phenol , Botox)
• ITB (Intra-Thecal Baclofen)
• Surgical (nerve, root, SC)
• Spinal Cord Stimulator
Oral Antispasticity Medications
• Baclofen
• Dantrium
• Diazepam
• Clonidine
• Tizanidine
• (limitations: non-selective, side effects)
Baclofen (Lioresal)
• GABA-B analogue; binds to receptors
• inhibits release of excitatory neurotransmitters (spasticity control)– Ca++ (pre-synaptic inhibition)– K+ (post-synaptic inhibition)
• may also decrease release of substance P (pain control)
Dantrium
• Inhibits Ca++ release at muscle level
• Preferred : TBI, CVA, CP
• SE’s - weakness, GI
• Hepatotoxicity (<1%)
Diazepam
• GABA “potentiation”
• Usage : SCI, MS
• SE’s - CNS depression, dependence,
Clonidine
• Alpha-2 receptor blockage
• Usage : SCI
• Max dose - .4mg/d (oral & patch)
• SE’s - OH, syncope, drowsiness
Tizanidine (Zanaflex)
• 1996 - Approved for SCI, MS, CVA
• Alpha-2 agonist (pre-synaptic inhibition)
• 1/10 potency of Clonidine In lowering BP
• Dose: T1/2: 2-5hr, begin 4 mg qhs (max 36 mg)
• SE’s - Sedation, nausea, LFT’s
Chemical Neurolysis
• Phenol 5-7%- Motor Point/Nerve block
• Non-selective destruction of axons/myelin
• Inds: Local (not general) spasticity
• Duration: 3-6 months
• SE’s - dysesthetic pain
Botulinum Toxin
• 1989 FDA approved for strabismus & blepherospasm
• Botox-A inhibits Ach Release at NMJ
• Dose: 300-400u total (50-200/muscle)
• Onset: 2-4 hours, Peak : 2-4 weeks
• Duration: 3-6 months
• ? Immunoresistance w/repeated inj’s
Spasticity: Surgical Management
• Rhizotomy (posterior)
• Cordotomy
• Tendon Release
– (limitations: invasive, bowel/bladder changes, irreversible, effectiveness varies)
Intrathecal Baclofen and Spasticity
• Intrathecal delivery of baclofen via an inplantable pump is a safe and effective therapy for the management of spasticity !
Intrathecal Baclofen
• Indicated for patients unresponsive to oral meds or with SE’s
• Delivered directly to intrathecal space affording much higher drug concentration
• Implantable system allows non-invasive monitoring & adjustments
ITB: Successful Outcomes
• Study results since 1984 demonstrate reduction of Ashworth spasticity scores and spasm scales
• Other results include improvements in:– pain– bladder function– chronic drug side effects– quality of life for patient & caregiver
ITB: Outcome Studies
• “Intrathecal baclofen for spasticity of spinal origin: seven years of experience”…Penn* (J. neurosurg 77:236-40, 1992)– 66 patients with intractable spasticity– followed for 30 months
– “It is suggested that long term control of spinal spasticity by intrathecal baclofen can be achieved in most patients”
ITB: Outcome Studies
• “Intrathecal baclofen for intractable spasticity of Spinal of spinal origin: a long-term multicenter study”…..Coffe* (J. Neurosurg 78; 226-32, 1993)– 93 patients with intractable spasticity– followed 19 months
– “Results indicate intrathecal baclofen can be safe and effective for long term management in SCI or MS”
Outcome Studies: Meta Analysis
• *Dijkers- Meta analysis of 37 studies– 77% positive response to bolus dose– 91% of whom opted for implant– 84% of whom had benefit w/o SE’s– Avg Dec’d Ashworth: 3.95-1.53 (P<.0001)– negligible effect of LOI
• * J.Spinal Cord Med:19(2), 138, 1996
ITB
• 1992 - FDA Approved ITB for spinal Spasticity
• 1996 - FDA Approved for Cerebral Etiologies (BI and CP)
ITB: Pharmacokinetics
• Baclofen: GABA-b agonist; inhibits neuronal firing
• ITB (Lioresal)– preservative-free; stable for 90 days– half-life 1.5 hours– typical dose: 1/100 of oral dose– average daily dose: 300-800ug– lumbar/cervical ratio 4:1
Decision to Treat w/ ITB
• Have oral antispasticity meds truly failed?
• Are their SE’s too great?
• Can a single definitive surgical procedure accomplish similar goals?
• Is precise control necessary for functional gains?
• Does gain in function / comfort justify invasive procedure & maintenance?
Exclusion Criteria
• Severely impaired renal function
• Pregnancy / nursing mothers
• Severe Aut. Dysreflexia
• Hx of Hypersensitivity to baclofen
• Hx of Noncompliance to regimens or follow-up
Trial Dose
• Trial dose via intrathecal lumbar puncture
• Begin with 50 ug (if no response, 75-100 ug)
• Observe 2-8 hrs
• Positive response = decrease in spasticity
• also access functional abilities
ITB: Surgical Phase
• Subcutaneous abdominal placement
• Catheter tunneled to mid-lumbar region below L3 and advanced 10 cm
• Intra-operative fluoroscopy confirms catheter placement without twisting
• Total time: 1-2 hours
Post-Operative Phase
• Pump programming via radio-telemetry and computer begins day one post-imp;ant
• ITB concentration: 500mcg/ml
• ITB rate: 2 X bolus response (less if patient had prolonged (>12 hrs) response)
• Can increase 10-15% every 24 hrs
• maintenance follow-up: 1-4 weeks
Post-Implant Clinical Care
• Post-Operative Adjustments
• Pump Dosing Adjustments
• Taper Oral Meds
• Pump Refills
• Patient Education
ITB: Maintenance Phase
• scheduled follow-ups for pump reassessment, refill and reprogramming– percutaneous refill into “port” (template)
– dose adjustment: portable computer/telemetry
– calculate next refill date
• if sudden changes in spasticity occurs, assess for potential infection, bowel/bladder regimen, before increasing dosage
• consider “drug holiday”
Pump Adjustments
• Adjustment parameters include:– drug name and concentration– reservoir status ( __ ml)– alarms (low battery; low reservoir)– infusion rate– infusion pattern (continuous, intermittent,
complex)– may increase by up to 15% per adjustment
Infusion Modes
• Continuous: drug delivered at continuous specified rate
• Continuous-complex: step-wise increases/decreases at specified times
• Bolus-delay: drug delivered intermittently at specific intervals
ITB Side Effects
• Drowsiness
• Dizziness
• Blurred Vision
• Slurred Speech
• Nausea
• Orthostasis
• Confusion
Potential Pump Complications
• Drug over-infusion - somnolence, coma – no antidote– Physostigmine 1-2mg IV (.02 mg/kg) over 5-10 min– titrate ITB
• Pump / Catheter malfunctions (kinking, disconnection, breaks)…often readily correctable under local anesthesia
• Infections
Pump /System Complications & Trouble-shooting
• r/o volume discrepancy– check pump setting– empty & compare fluid reservoir
• r/o catheter kink, occlusion, disconnection– X-Ray catheter / CT intrathecal catheter– dye/ contrast study to check patency– bolus/infusion w/sereal scans over 12-24 hr
• r/o pump underinfusion– X-Ray “roller” pre/post bolus
Pocket Complications
• seroma, hematoma, infection
• Causes– post-op swelling– inadequate fixation– infection– pocket too small– drug extravasation
Suspected CSF Leak
• headache, dizziness, N/V, spinal swelling / redness
• RX:– X-Ray / CT– culture of fluid– blood patch– surgical revision
Advantages of Programmable System
• Consistent optimal dosage
• can be programmed to decrease or increase spasticity at certain times during the day
• reduces adverse drug effects