Neurological Complications following SCI
William McKinley MDDirector, SCI Rehabilitation Medicine
Associate Professor PM&RVCU / MCV
Overview of Spinal Cord Function / Injury
• Movement (Weakness)
• Sensation (Sensory loss, Pain)
• Muscle tone (Spasticity)
• Bladder/bowel (Neurogenic B/B)
• Sexuality (Sexual dysfunction)
Syringomyelia
• Syrinx = fluid filled cavity (cyst) within the spinal cord
• Syringomyelia = neurological symptoms due to syrinx– incidence - 3-10%– etiology - trauma, tumor, congenital
• area of tissue damage / inflammation
• can expand, elongate, cause pressure
Syringomyelia: symptoms
• Pain (radicular)
• Sensory loss
• weakness
• Spasticity
• Hyperhydrosis
• Bladder / bowel
Syringomyelia Diagnosis / Treatment
• Dx: – clinical findings / suspicion, physical exam
– MRI (CT/myelogram, U/S)
• Rx– surgical shunt / drainage to “low” pressure points
• syrigopleural, syringoperitoneal)
– pain management
SCI PAIN
• Challenging issue– Physiologically & psychologically
• Incidence 15 - 85 %
• Etiology– Spinal cord pain– Radicular– Muscuoskelletal
Factors associated with SCI Pain
• Level of Injury (LOI)
• Complete vs Incomplete
• Time since injury
• Type of injury (GSW, trauma)
• Psychological factors
Classification of SCI PAIN
• Central Pain– Central Pain - below LOI, symmetrical
(burning, tingling)
• Radicular Pain– At the LOI, asymmetrical (aching, stabbing)
• Musculoskelletal Pain– localized MS structures (aching, tender)
Mechanism of Neurogenic SCI Pain
• largely unknown
• Irritation / abnormal firing of damaged nerve axons or roots
• Loss of descending inhibition
management of SCI Pain
• Pharmacological - neuropathic pain meds
• Surgery
• Adjunctive treatments
• Psychological Rx
Neuropathic meds
• Anticonvulsants (nerve membrane stabilization)– Neurontin, Tegretol, Dilantin
• Antidepressants (increase Seritonin levels)– Elavil, Trazadone
• Others : Mexiletine• Epidural agents
– Morphine, Clonidine, baclofen
Non-pharmacologic Rx
• Spinal cord stimulation– ? effectiveness
• Surface TENS– best with radicular pain incomplete injuries
• Surgery– Dorsal Root Entry Zone (DREZ)
Spasticity
• Definition: “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
• Ashworth Scale• 1= no increased tone
• 2= slight “catch” in ROM
• 3= moderate tone, easy ROM
• 4= marked tone, difficult ROM
• 5= 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%)
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
• 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?
Other Considerations ITB
• Test dosing / trial dose via intrathecal lumbar puncture
• Pump re-programming via radio-telemetry and computer
• Maintenance follow-up: Q 4-12 weeks