Late-Onset Pompe's Disease
Late-Onset Pompe's Disease
A 21-year-old man presented for evaluation complaining of difficulty climbing stairs. He notes that he becomes very short of breath with only one flight, and has to use the handrail to assist in climbing toward the end of a flight. On one occasion recently, he noted difficulty placing a small box onto an overhead shelf. He works as a web page designer and admits that he is physically inactive. He recalls having difficulty keeping up with his peers in junior high school gym class, and never participated in any competitive sports. He reports no episodes of very dark urine, and reports no pain. He reports no numbness. He does not have difficulty chewing or swallowing. He denies diplopia or ptosis. He believes the weakness has been insidiously worsening, and that the shortness of breath with minimal activity is what is causing him to seek medical attention at this time. He also reports that he has not been sleeping well, and is not rested upon awakening. He has one healthy, active sister and knows of no weakness in extended family members.
On examination, there is 4+/5 weakness of deltoid and infraspinatus muscles bilaterally. Hip flexion and abduction has four-fifth strength. Distal limb and facial strength is normal. Sensory examination is normal and reflexes are easily elicited and symmetric. There is no rash, joint swelling or muscle tenderness. No percussion myotonia is noted. There does appear to be mild scoliosis. General examination is otherwise unremarkable. Laboratory testing reveals the serum creatine kinase (CK) to be elevated at 900 IU/L.
Electrodiagnostic studies reveal normal nerve conduction amplitudes and velocities in nerves of the right arm and leg. No decrement is noted on repetitive stimulation of the facial and spinal accessory nerves. Needle examination reveals profuse p-waves and fibrillation potentials as well as complex repetitive discharges in the deltoid, gluteus medius, and iliopsoas muscles. Recruitment is early, and the motor units are small, brief, and polyphasic. Similar abnormal spontaneous activity is present in the thoracic paraspinal muscles, except that true myotonia is also present.
A biopsy of the right vastus lateralis muscle was performed. Muscle fiber diameter varied prominently. Vacuoles were present in many fibers and these stained positive for acid phosphatase. Glycogen content was increased in the muscle. Frozen muscle was sent for biochemical testing of glycolytic enzyme function. Acid maltase activity was reduced to 18% of normal.
Typical Case
A 21-year-old man presented for evaluation complaining of difficulty climbing stairs. He notes that he becomes very short of breath with only one flight, and has to use the handrail to assist in climbing toward the end of a flight. On one occasion recently, he noted difficulty placing a small box onto an overhead shelf. He works as a web page designer and admits that he is physically inactive. He recalls having difficulty keeping up with his peers in junior high school gym class, and never participated in any competitive sports. He reports no episodes of very dark urine, and reports no pain. He reports no numbness. He does not have difficulty chewing or swallowing. He denies diplopia or ptosis. He believes the weakness has been insidiously worsening, and that the shortness of breath with minimal activity is what is causing him to seek medical attention at this time. He also reports that he has not been sleeping well, and is not rested upon awakening. He has one healthy, active sister and knows of no weakness in extended family members.
On examination, there is 4+/5 weakness of deltoid and infraspinatus muscles bilaterally. Hip flexion and abduction has four-fifth strength. Distal limb and facial strength is normal. Sensory examination is normal and reflexes are easily elicited and symmetric. There is no rash, joint swelling or muscle tenderness. No percussion myotonia is noted. There does appear to be mild scoliosis. General examination is otherwise unremarkable. Laboratory testing reveals the serum creatine kinase (CK) to be elevated at 900 IU/L.
Electrodiagnostic studies reveal normal nerve conduction amplitudes and velocities in nerves of the right arm and leg. No decrement is noted on repetitive stimulation of the facial and spinal accessory nerves. Needle examination reveals profuse p-waves and fibrillation potentials as well as complex repetitive discharges in the deltoid, gluteus medius, and iliopsoas muscles. Recruitment is early, and the motor units are small, brief, and polyphasic. Similar abnormal spontaneous activity is present in the thoracic paraspinal muscles, except that true myotonia is also present.
A biopsy of the right vastus lateralis muscle was performed. Muscle fiber diameter varied prominently. Vacuoles were present in many fibers and these stained positive for acid phosphatase. Glycogen content was increased in the muscle. Frozen muscle was sent for biochemical testing of glycolytic enzyme function. Acid maltase activity was reduced to 18% of normal.
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