Basic Human Neuroanatomy
A Clinically Oriented Atlas 
Case 67 Answers

1.  Is this patient’s weakness of the upper motor neuron (UMN) or lower motor neuron (LMN) type?

Lower motor neuron (weakness with atrophy, diminished muscle tone, possible fasciculations of the thenar eminence muscles, and diminished deep tendon reflexes)

2.  Are the motor signs and symptoms in this case due to spinal cord, spinal nerve, brachial plexus, or peripheral nerve involvement?  Cite the evidence in support of your choice.  Indicate the specific levels of involvement or peripheral nerves involved by the pathologic process.

Spinal cord (patchy, multifocal involvement of the anterior horns bilaterally, involving C5 partially, C6, C7 partially, C8 partially, and T1 spinal cord segments).

3.  The findings in this case represent a classic neurologic syndrome.  What is the name of this syndrome?

Motor neuron disease:  Progressive muscular atrophy (PMA) type

4.  In general, what type of pathologic process is involved in this case? 

Neurodegenerative process involving loss of LMN cell bodies in the anterior horns of the spinal cord (as indicated above). The brisk deep tendon reflexes in both lower limbs may suggest eventual involvement of UMNs and evolution of the disease process to ALS.

5.  What diagnostic procedure(s) would you undertake at this point?


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