Neuromuscular Diseases Flashcards
What are upper motor neurons?
Motor neurons that originate in the cerebral cortex and carry motor information to a lower motor neuron
What is a lower motor neuron?
A motor neuron that connects upper motor neuron’s to the end muscle
How are upper motor neuron lesions characterized?
Spasticity
Paralysis
Weakness
Hyperactive reflexes
How are low work motor neuron lesions characterized?
Fasciculation Paralysis Weakness Atrophy Flaccid reflexes
What is the main difference between upper motor neuron lesions and lower motor neuron lesions in terms of paralysis
Upper motor neuron lesions cause spastic paralysis
Lower motor neuron lesions cause flaccid paralysis
What is the purpose of Myelin?
Speeds neuronal signal conduction
What is myelin?
And electrically insulating phospholipid layer that surrounds axons of neuron’s
What type(s) of cells supply the myelin for peripheral and central nerves?
Schwann cells = peripheral nerves
Oligodendrocytes = CNS
An auto immune disease with antibodies against the acetylcholine receptors of the motor end plate is known as…
Myasthenia gravis
What is the clinical hallmark of myasthenia gravis?
Skeletal muscle weakness worsens with activity and improves with rest
What does the severity of myasthenia gravis depend on (in terms of the antibodies)?
The ability of the antibodies to decrease the number of available acetylcholine receptors
The bulbar region has an effect on what parts/functions of the human anatomy?
Facial control
Airway control
Swallowing
Myasthenia gravis has a correlation with which gland?
Thymus glands are often hyperplastic in Myasthenia gravis patients
What are some of the exacerbating factors of myasthenia gravis?
Vaccinations Infection Stress Pregnancy Increased temperature
Are newborns of myasthenia gravis mothers at risk for respiratory failure? if so, why?
Yes. Acetylcholine receptor antibodies cross the placenta.
What are some of the anesthetic considerations for patients with myasthenia gravis?
-Bulbar involvement (Aspiration risk)
-Respiratory weakness
-Decreased response to succinylcholine
-Prolonged effects of nondepolarizing muscle relaxants
(Worse with inhaled anesthetics, Magnesium and Aminoglycosides)
List the four post op risk factors for mechanical ventilation in myasthenia gravis patients?
Having the disease > 6 years
Chronic respiratory disease
Pyridostigmine dose > 750 mg/day
Preop vital capacity < 2.9 L
What is a myasthenic crisis?
An exacerbation of myasthenia gravis characterized by muscle weakness and respiratory insufficiency
What type of test can differentiate between a cholinergic crisis and a myasthenic crisis and how does it work?
Tensilon test: Give a little anti-cholinesterase
Pt gets better = myasthenic
Pt gets worse = cholinergic
What is myasthenic syndrome and what is another name for it?
Myasthenic syndrome (Lambert Eaton syndrome) -Antibodies attack calcium gated channels at presynaptic nerve terminals to decrease the release of acetylcholine
Differentiate between the physical symptoms of myasthenia gravis and myasthenic syndrome
MG: Worse with activity
- Symptoms move from the top down
- Very sensitive to non-depolarizer’s
- Treated with anti-cholinesterase drugs
MS: Improves with activity
- Symptoms start in the legs and move up
- Sensitive to both depolarizer’s and non-depolarizer’s
- Anti-cholinesterase drugs have no benefit
Lou Gehrig’s disease is also known as
Amyotrophic lateral sclerosis (ALS)
Death in ALS usually results from what?
Pulmonary infections
What is ALS?
The loss of nerve cells in the anterior horn of the spinal cord and lower brainstem
(Effects MOTOR not SENSORY)
ALS is characterized by
Atrophy
Weakness
Exaggerated reflexes
Late stages–Pharyngeal, laryngeal, and respiratory muscles affected
What are some of the anesthetic considerations for an ALS patient?
High aspiration risk Abnormal PFTs No succ Sensitive to nondepolarizing agents Regional if possible
What is multiple sclerosis?
An autoimmune disease that results in the demyelination of neuron’s in the brain and spinal cord
What are some factors that increase the risk for multiple sclerosis?
Two times as common in females
20 to 40 years of age
Familial tendency
Increasing latitude
What are some of the anesthetic considerations for patients with multiple sclerosis?
Sensitive to local anesthetics No succ Don't overheat Autonomic lability Resistant to non-depolarizer's No spinal's
What is muscular dystrophy?
A hereditary disease caused by abnormality in dystrophin
-Muscle wasting without denervation
What is the most common form of muscular dystrophy and how is it contracted?
Duchenne’s muscular dystrophy is an X-linked recessive disease characterized by elevated creatinine kinase levels
Lab results will show an increase in what for Duchenne’s muscular dystrophy patients?
Creatinine kinase levels
What are the primary characteristics of Duchenne’s muscular dystrophy?
Presents 3 to 5 years of age Proximal muscle weakness pseudo-hypertrophy of calf muscles Abnormal gait Intellectual impairment Relentless progression Severe kyphoscoliosis Severe bulbar symptoms Pulmonary HTN due to OSA Death by 20 to 30 years of age
What are some important in aesthetic considerations for muscular dystrophy patients?
- Increased incidence of MH (no sux or inhalational agents)
- Respiratory issues (Bulbar symptoms and restrictive pulmonary disease)
List three other types of muscular dystrophy and one drug that should be avoided in all cases
Beckers
Facioscapulohumeral dystrophy
Limb-girdle dystrophy
NO SUCCINYLCHOLINE
Why is succinylcholine contraindicated in patients with neuromuscular diseases or those who have been immobile for extended periods of time?
These patients developed extra junctional receptors along the muscles
-More receptors for sux to bind to and cause hyperkalemia
Guillain-Barre syndrome is also known as?
ACUTE demyelinating polyneuropathy
How is Guillain-Barre syndrome characterized?
Sudden onset of ascending motor paralysis
Immune mediated against myelin of peripheral nerves
Severe autonomic dysfunction
What are some anesthetic considerations for Guillain-Barre?
Bulbar muscle involvement-Aspiration
Autonomic lability
No sux
Regional controversial
What is the recommended dose for succinylcholine in myasthenia gravis patients?
2x normal or 2.6x normal for intubation
What is the recommended dose for nondepolarizing agents in myasthenia gravis patients?
Not recommended (extreme sensitivity)
Discuss the role of temperature on nerve conduction in multiple sclerosis patients?
Increased temperature
decreases conduction
What is the abnormal protein in muscular dystrophy?
Dystrophin
What other disease has a similar defect to muscular dystrophy?
Malignant hyperthermia
Guillan-Barre Syndrome is usually seen after what type of illness?
Viral
-Also has an association with Hodgkin’s and HIV
