Neuromuscular Diseases Flashcards
(43 cards)
Gower’s sign
a characteristic feature of neuromuscular disease or myopathy. Involves having to use your hands to get off the floor and then climbing over your legs.
Ptosis
muscle fatigue…present in diseases such as myasthenia gravis where pts presesnt with “lid Lag” where the eyelids become tired
He wants us to know the anatomical location of different neuromuscular diseases
ok
Anterior Horn is affected in:
SMA and ALS….spinal muscular atrophy, amytrophic lateral sclerosis
Peripheral nerves (peripheral neuropathy)
Demyelinating neuropathies or axonal neuropathies
In polyneuropathy, there is distal muscle wasting and weakness. These patients also typically have decreased sensation and depressed reflexes.
In contrast, patients with motor neuron diseases typically do not have sensory deficits
Mononeuropathy
a disorder that affects an individual nerve.
Slide numer seven is bigtime
ok
Normal shape of muscle fibers?
polygonal
What is electromyography
Detects the number and size of motor unit action potentials. close to a needle electrode inserted into a muscle.
Motor neurons innervate either type one or type 2 muscle fibers. Each motor neuron only innervates one type of fiber.
yup
Type 1 muscle fibers stain
pale
Type II muscle fibers stain
dark
Most muscles exhibit a checkerboard type pattern which shows a mixture of type one and type two muscles
yeah
When a muscle loses its innervation due to some injury, muscle fibers become atrophic and angulated (do not retain the polygon shape). How do these fibers stain?
They stain dark on most stains
What is fiber type grouping?
This is a process that occurs when certain nerves have been damaged and can no longer innervate muscle fibers. Axons from other intact neurons sprout and reinvervate these fibers. Because of this, you get groups of muscle fibers innervated by the same motor neuron. This manifests on EMG as a larger action potential, but fewer action potentials
What does fiber type grouping look like on histo?
Checkerboard lost. More areas of dark fibers and light fibers clumped together
What is the problem in myopathies?
Muscle fibers themselves are ill or non-functional.
Know this….
In myopathies, the number of motor units is not decreased because the number of motor neurons or axons is normal. It is the number of individual fibers of the motor unit that are nonfunctional or dead.
In myopathies, what do the sick muscle fibers do>
Leak enzymes like creatinine kinase. Common blood test for Serum CK
Myopathies are characterized at the most basic level by:
a decrease in the numbe rof muscle fibers per motor unit and, thus, small action potentials!!
In myopathy, during voluntary activity:
- potentials are small and short
- In creased number of unit potentials relative to the strength of contraction since a seemingly easy movement requires the participation of tons.
- the number of fibers per motor unit is decreased because some fibers are sick
conduction velocity calculation
distance between the two electrodes/ (latency 1- latency 2)
Signs and symptoms of myopathies
proximal weakness, normal sensation, normal reflexes, elevated muscle enzyme in serum, small motor unit potentials but normal number of motor units activated (this is because the number of motor neurons and their axons are not reduced, there is just less functional muscle fiber).
