In a recording from a nerve conduction velocity (NCV) study, decreased amplitude of recorded potentials, combined with slowing of NCV, indicates which of the following?
A. Myelinopathy
B. Myopathy
C. Myasthenia gravis
D. Upper motor neuron lesion
E. Axonopathy
ANS: E
Rationale: Axonopathy reduces both the amplitude and velocity of recorded potentials during a nerve conduction velocity study. Traumatic myelinopathy causes decreased velocity but usually not amplitude of recorded potentials. Myopathy only affects muscle and so amplitude of recorded potentials is decreased but velocity of conduction is normal. Myasthenia gravis damages ACh receptors on the muscle membrane, so conduction velocity is normal but recorded amplitude decreases with repeated muscle contractions. Because NCV studies only test peripheral nerves, NCV studies are normal in UMN lesions.
You might also like to view...
There are two basic types of medications used in _____ treatment: steroids and other anti-inflammatory medications and bronchodilators
A) asthma B) bronchitis C) COPD D) cystic fibrosis
What is an example of an immovable joint?
A) suture B) sulcus C) symphysis
Health ________ are differences in quality of health among various segments of the population
A) competencies B) variants C) disparities D) incidences
Discuss the impact that the Affordable Care Act has had on access to medical care