MUSCLE SPASTICITY AND INFECTIOUS DISEASE Flashcards
Muscle Spasticity:
A velocity-dependent increased resistance to passive stretch
Pathophysiology is poorly understood, but end result:
· Over activity of the alpha motor neuron
· Results from a lesion along the path of the corticospinal tracts
(Motor pathways of cortex, basal ganglia, thalamus, cerebellum, brainstem, central white matter, and spinal cord)
Symptoms of Spasticity:
· Hypertonia
· Hyperreflexia
· Spasms or involuntary movements
· Clonus
· Pain
· Difficulties with ADLs
· Contractures
· Bone and Joint deformities
Disorders associated with spasticity:
· MS (multiple sclerosis)
· Stroke
· SCI (spinal cord injury)
· TBI (traumatic brain injury)
· CP (cerebral palsy)
Treatment of Spasticity:
· PT/OT
· Orthotics
· Aids
· Medication
· Surgery
4 approved medications to treat chronic spasticity:
· Diazepam
· Dantrolene
· Tizanidine
· Baclofen
Other options include:
· Gabapentin
· Botox
Medication related facts for treatment of spasticity:
- Only a few options can reduce disability
- Many adverse effects associated with medications to reduce spasticity
- Start with lowest dose and gradually increase dose to optimal effect
Diazepam
(Benzodiazepine)
- Intermediate to long-acting half-life of 20-80 hours
- Acts on the GABA channels in spinal pathways
Dose: 2mg twice daily or 5mg at bedtime
· May titrate up to 40-60mg/day in 3-4 doses
ADRs:
· Drowsiness
· Ataxia
· Fatigue
· Cognitive slowing - Should not be stopped abruptly
Dantrolene
- Acts peripherally at skeletal muscle
- Interferes with calcium influx at skeletal muscle to reduce excitation of muscle
- Dose increased gradually every 7 days to desired effect
Starting dose: 25mg once daily
Titrate to 100mg three times a day (max 100mg four times a day)
ADRs: (·Generally early in treatment and develop tolerance)
- drowsiness
- dizziness
- generalized weakness
- MINIMAL COGNITIVE EFFECTS
-Withdrawal of treatment could result in exacerbation of symptoms
Tizanidine
- Central acting alpha 2 receptor agonist
- Peak effect: 1-2 hours after dosing
- Absorption increased by 20% when taken with food
Dose: 2mg once daily at bedtime; max 36mg per day in 2-4 divided doses - Gradually taper when discontinuing (Rebound symptoms: hypertension, tachycardia, hypertonia)
ADRs:
- Sedation
- weakness
- hypotension
· Sedation seen 30 min after administration and peaks in 1.5 hours
· Hypotension can be seen 1 hour after administration and peak in 2-3 hours
- BETTER TOLERATED THAN BACLOFEN AND DIAZEPAM
- Less likely to weaken muscles
Baclofen
- Binds to a GABA receptor (GABA-B)
· Reduces neurotransmitter release → reduces neuron firing - Available orally or Intrathecal Baclofen Pump (ITB)
· Oral is dosed three times daily
· Max 80 mg daily orally
· Intrathecal dose is about 1% of oral dose
Requires titration until optimal effect achieved
· May be increased every 3 days
ADRs: (CNS effects)
- SEDATION, ataxia (loss of control of bodily movement), cardiac and respiratory depression
- Should NOT be stopped abruptly
Intrathecal Baclofen Pump (ITB)
Treats spasticity of spinal cord origin
· Used in patients who do not respond well to oral therapy or whose CNS effects are intolerable
· Must demonstrate positive response to ITB screening trial
- Pump is placed subcutaneously in abdominal wall, tip of the catheter in subarachnoid space usually between T12 and L1
- Onset of action peaks at 4 hours and lasts 4-8 hours
- If dose suddenly needs increased → kink or catheter/pump malfunction
- Reservoir usually refilled every 3 months (takes about 30-45 min)
- Battery usually lasts 4-5 years
Therapeutic Concerns with ITB
Problems with pump:
· Infection, dislodgement, kinking or blocking of catheter, and pump failure
Signs of overdose:
· Sedation, confusion, respiratory depression, coma
Signs of withdrawal:
· Spasticity, agitation, hallucinations, and death (rare)
Assess Balance as patient adjusts to new muscle tone
Botulinum Toxin
- Neurotoxin produced by Clostridium botulinum, spore-forming anaerobic bacillus
- Appears to affect only the presynaptic membrane of the neuromuscular junction in humans
- Prevents calcium-dependent release of acetylcholine and produces a state of denervation
- Muscle inactivation persists until new fibrils grow from the nerve and form junction plates on new areas of the muscle cell walls
- Blocks the release of Acetylcholine from nerve terminals
- Injections into affected muscles muscle weakness in area of injection – use caution if targeting therapy in injected area
ADRs:
* Swelling at the injection site: treat with cold compress and elastic wrap
* Weakness
Why do we use Botox (Botulinum Toxin)
- Relax a muscle that is too tense (dystonic)
- Contracting when it should be relaxed
- Lower extremities
- Relax calf muscle
- Fit for brace
- Upper extremities
- Free up movements of arm
- Improved function
- Increase in independence and ADLs
Therapeutics Concerns with Botox
- May have diminished function initially after injection
(Weakness in antagonist muscles uncovered) - Ensure safety as patient adjusts to reduced muscle tone
- Avoid therapy modalities over the injection site for at least 10 days
- Patients may develop antibodies
Skeletal Muscle Relaxant
Cyclobenzaprine: used to treat spasms associated with musculoskeletal injury without interfering with muscle function (ineffective at treating spasms of CNS origin)
ADRs:
- drowsiness
- dizziness
- dry mouth
Indicated for short-term use of 2-3 weeks
Antimicrobials:
Bacterial Infections/Bacteria
- Gram-positive, Gram-negative (commonly bacillus), or anaerobic (different stain effect)
- Common misconception that antibiotics work on viral infection
· They DO NOT kill viruses - Bacteria have a rigid cell walls – provides target for antibiotics
(Antibiotic will have little effect on the host since human cells do not have rigid cell walls)
Antibiotics
- Antibiotic Target bacteria NOT viruses
- What they do:
· Bacteriostatic → inhibit growth of bacteria but do not kill them – depend on our own immune system to kill them
· Bactericidal→ kill the bacteria
(Concentration dependent, Time dependent) - Type of antibiotic chosen depends on the organism you are trying to get rid of and the patient’s immune function
How to choose an antibiotic:
*Broad Spectrum vs. Narrow Spectrum
Choice based on organism you are treating
· Certain antibiotics work better on Gram-positive than Gram-negative
· Resources (Sanford’s Guide and Antibiograms) designed to guide antibiotic selection
*Patient factors:
· Allergies to antibiotics
· Liver and Kidney function of the patient
· Age of the patient (especially infant and young children)
· Pregnancy
· Site of the infection (brain/CSF harder to treat)
Bacterial Cell Wall Inhibitors:
Bactericidal, time-dependent killing
β-lactams
· Penicillins
· Cephalosporins
· Carbapenems
· Monobactams
Glycopeptides
Bacitracin
