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Intrathecal Baclofen Pump & other management strategies for Spasticity William O McKinley MD Director, SCI Rehabilitation Medicine Dept. PM&R VCU / 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 longterm 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