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