Week 2 Cases Flashcards
Proximal weakness is seen in disorders of _____ and _____.
muscle and NMJ
Distal weakness is seen in disorders of ____.
peripheral nerves
Tensilon test
The tensilon test is an old fashioned but simple diagnostic test for myasthenia gravis. Tensilon (edrophonium hydrochloride) inhibits the enzyme acetylcholinesterase, which is responsible for the breakdown of acetylcholine in the synaptic cleft. By prolonging the presence of acetylcholine at the neuromuscular junction in this way, Tensilon causes a very brief increase in strength in muscles affected by disorders of the neuromuscular junction.
- not specific for myasthenia gravis
What is CPK? What does an elevated serum CPK level suggest?
Elevation of serum CK is a nonspecific indication of damage to the muscle membrane, such as trauma to muscle tissue (rhabdomyolysis), muscle inflammation (like in this case), toxic and inherited muscle disorders.Elevations can be extremely high in disorders of skeletal muscle. CPK can be mildly elevated (<1000) in conditions where muscle damage occurs secondary to peripheral nerve or anterior horn cell denervation, like a peripheral neuropathy or amyotrophic lateral sclerosis. Intramuscular injections and trauma can also cause a mild rise in CK.
What information does NCS provide?
information about the health of the nerve (both axon and myelin).
What information does EMG provide?
determines if weakness is due to nerve disease or muscle disease
The presence of fibrillation potentials in a resting muscle is found in what kind of disorders?
Normal muscle should be electrically silent at rest. The presence of fibrillation potentials in a resting muscle is a nonspecific abnormality that can be seen in both nerve and muscle disease.
Decreased amplitude and duration of motor unit action potential suggests what disorders?
disease of muscle. The amplitude and duration of the MUAP is proportional to the size of the
Brain and Behavior 2013 2D (Answers)-3
2D-Sections: Neurology Small Group #1: Nerve & Muscle 11:00 AM-12:30 PM B&B Staff 02/18/2013
motor unit. The motor unit is composed of the motor neuron, its axon, neuromuscular junctions, and the muscle fibers that it innervates. When there is muscle damage, some of the muscle fibers drop out and the size of the motor units (and the MUAP) is reduced.
In what disorders is there early recruitment?
In the setting of myopathy, where the motor units are small (and thus generate less force), the muscle fires all available motor units in order to generate adequate force. Thus, the orderly progression is lost and the oscilloscopic screen fills up with small myopathic motor units “early” (ie – with minimal generation of force as perceived by the examiner).
Albumino- cytologic dissociation is characterized by ….
significantly elevated protein and little or no cellular reaction. This combination is typical but not diagnostic of the Guillian-Barre syndrome (GBS), an autoimmune reaction to peripheral nerve tissue. If the cell count had been elevated a diagnosis of GBS would be doubtful.
