Case Study #5_5
A 43-year-old right-handed man presents to the clinic with gradual onset of right hand and arm
weakness. He had been in good health and an avid golfer until a few weeks ago when he noted
that he was having trouble keeping his club steady during his swing. His driving distance has
markedly decreased, and he would drop things that he would be holding with his right hand.
There is no numbness or other sensory symptoms. On physical examination, he appears well and
has normal vital signs. He has mild wasting and fasciculations along his right brachioradialis
muscle. His grip strength is 4 out of 5 on the right and 5 out of 5 on the left. He has absent
reflexes in his right arm and 1+ reflexes on the left. An electromyelogram shows features of
denervation, including increased numbers of spontaneous discharges in resting muscle, and a
reduction in the number of motor units detected during voluntary contraction. A diagnosis of
amyotrophic lateral sclerosis (ALS) is entertained.
1. What are the presenting clinical symptoms and progression of the clinical course in ALS?
2. Which cells are affected in ALS?
3. What are some possible molecular mechanisms responsible for the pathologic changes?