Basic Human Neuroanatomy
A Clinically Oriented Atlas 

Case History #67

Date of Consultation: 1-12-1984


This 39-year-old right-handed white male art designer was referred for neurologic consultation because of weakness in the upper limbs.  Approximately one year prior to consultation, the patient noted the gradual onset of weakness in both upper limbs.  The most profound weakness was in the distal muscle groups, with the muscles in the mid-arm region being less involved.  The proximal musculature was even less involved than the more distal muscle groups.  The overall course of this problem was a steady, slow progression.  He noted no fasciculations or atrophy, although occasionally he noted an uncontrollable small twitching movement of the thumbs.  The patient indicated that for the past 10 years he had used paint containing lead in his occupation as a sign painter and art designer. 


Mental Status Exam:  Intact.

Cranial Nerves:  Intact.

Motor System:  There was a mild to moderate degree of wasting of the forearm muscles, interosseous muscles, thenar eminence muscles, and hypothenar eminence muscles bilaterally.  This was essentially symmetric.  There was no atrophy in the lower limbs.  Fasciculations were not seen.  Muscle tone was normal in all 4 limbs, except for diminished tone with elbow flexion-extension.  Muscle power was normal in the lower limbs.  In the upper limbs, muscle power was normal (5/5) at the shoulder girdle and in the deltoid muscles, triceps, finger flexors, and grip.  Thenar eminence muscles, hypothenar eminence muscles, interosseous muscles, wrist extensors, and elbow flexors were all profoundly weak, in the range of 2 to 3/5. 

Reflexes:  Deep tendon reflexes were absent to trace bilaterally at the biceps and brachioradialis tendons.  Triceps jerks were 1/4 bilaterally.  Knee jerks and ankle jerks were slightly brisk (3/4) and symmetric.  There was no ankle clonus present.  Plantar reflexes were flexor bilaterally. 

Sensory System:  Intact.

Cerebellar Function:  Intact.

Gait and Stance:  Intact.


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

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.  

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

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

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

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