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)

Neurological Complications Following SCI

• Syringomyelia

• Pain

• Spasticity

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%)

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

• 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

THE END