Neuromuscular Junction Disorders Flashcards
Botulism (Etiology)
- Neurotoxin produced by clostridium botulinum
- Affects the PREsynaptic cell terminal
- Anaerobic, Gram positive rods
- Found in improperly preserved/canned foods & contaminated wounds.
Botulism (Classification/Mode of Acquisition)
- Food borne
- Wound
- Unclassified
Botulinum Mechanism (General Overview)
- Toxin enters PREsynaptic Terminals
- Block the fusion of the ACh vesicles with the presynaptic membrane. (myoneural junction)
- It inhibits ACh release into the NMJ
- Nerve fails to send an impulse across the NMJ
- Muscle Paralysis
Botulinum Mech (specifics)
SNARE protein that helps the vesicle fuse to the membrane is cleaved by the light-chain of the toxin. Without the SNARE protein the vesicle cannot fuse to the membrane.
Incidence of Botulinum
- 10 adult and 100 infant cases each year in the US
- 8-20% overall mortality rate (fatal if not seen within 24 hours, secondary to respiratory failure)
Botulinum- S & S
S & S
- Develop within 12-36 hours following ingestion of food
- Flaccid Symmetrical paralysis
- Blurred & Double vision, photophobia, ptosis
- Dry mouth, nausea, vomiting
- Difficulty swallowing/speech
- Can involve muscles of respiration. (respiratory failure in 6-8 hours)
- NO sensory or autonomic involvement
Prevention of Botulinum
- Boil food x10 mins will destroy the toxin
- Avoid honey for children under 1yr
- Take care of wounds and use sterilized equipment.
Interventions to Treat Botulinum
-ABE serum antitoxin
- Debridement & Antibiotics for wound
- Removal of toxin from GI tract (pumping the stomach)
Supportive Measures:
- IV
-Mechanical Vent
Botulinum: Recovery
Recovery
- Gradual recovery over weeks and months
- Typically get fill recovery in both infant and adult.
- recovery is more about sprouting new terminal nerve filaments and formation of new synapses.
- NOT repair of the old, MAKING of the new.
BoTox- Treatment for Individuals with….
- Spinal Cord Injury
- MS
- Dystonia
- Cerebral Vascular Accident
- Traumatic Brain Injury
How does Botox work?
- It’s injected intramuscularly (goes through muscle barrier) into specifically selected muscles to generate highly focal weakness.
- It’s prevents the release of Ach from the PRE-synaptic nerve terminal. Thus blocking Ach transmission at the NMJ.
- It’s Dose-dependent, and causes a reversible reduction in muscle power.
- Effects are temporary and muscle weakness resolves over three to four months.
Botulinum: Administration, Determining injection sites
- Larger superficial muscles (ID’d via surface anatomy knowledge).
- EMG, Nerve or muscle stimulation, ultrasound may be needed for smaller less accessible muscles, or when the muscle is deformed because of fat.
- Best sites for injection are the nerve end-plate zones deep in muscle bulk.
- Small and moderate sized muscles will usually respond to BT injected into their belly.
Duration of Effects of BT
- Taken into the NMJ within 12 hours
- Clinical effect occurs gradually over 4-7 days
- BT interferes with NMJ synaptic for about 12-16 weeks
- which causes muscle weakness for 3-4 months.
Post-Injection Management
- PT is mandatory as soon as BT takes effect.
- Assess the need for orthotics/splints or review existing ones to assess pt compliance
- Provide pt education on stretching
- Do not over stretch weakened muscles, stretches should be graded over time to prevent intramuscular hematomas.
- Increase muscle strength of the opposing muscle groups
- Consider other treatments that could enhance the effects of the BT (constraint therapy/ electrical stimulation of antagonist)
Botox Side-Effects KNOW
- Problems swallowing, speaking, or breathing due to weakness in associated muscles. (Can be severe and result in loss of life)
- Most issues stem from inappropriate dose, and bt affecting areas away from injection site.
- double vision,
- blurred vision
- drooping eyelids,
- hoarseness or change or loss of voice (dysphonia),
- trouble saying words clearly (dysarthria),
- loss of bladder control,
