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[Adult polysaccharide storage myopathy]
Rinsho Shinkeigaku = Clinical Neurology
|October 1, 1989
Summary
This study reports the first Japanese case of adult polysaccharide storage myopathy (APSM) in a 30-year-old male presenting with progressive limb weakness. Muscle biopsy revealed vacuolar myopathy with unusual polysaccharide accumulation, distinct from typical glycogen storage diseases.
Area of Science:
- Neurology
- Muscle Physiology
- Biochemistry
Background:
- Adult Polysaccharide Storage Myopathy (APSM) is a rare neuromuscular disorder.
- Understanding its genetic and biochemical basis is crucial for diagnosis and treatment.
Observation:
- A 30-year-old Japanese male presented with progressive lower limb weakness starting at age 23.
- Neurological examination revealed proximal muscle weakness, reduced vibratory sense, and a waddling gait.
- Electromyography (EMG) showed mixed myopathic and neurogenic features, with myotonic discharges.
- Muscle biopsy demonstrated vacuolar myopathy with unique, filament-composed polysaccharide deposits.
Findings:
- The storage material was PAS-positive, diastase-resistant, and Lugol's iodine-negative, located sub-sarcolemmally and within myofibrils.
- Type 1 fiber predominance was observed, but vacuoles were primarily in type 2A fibers.
- Biochemical analysis excluded enzymatic defects typical of glycogen storage diseases.
Implications:
- This case expands the known spectrum of APSM and highlights the diagnostic challenges posed by unusual polysaccharide accumulations.
- Further research is needed to elucidate the specific nature and metabolic pathway of this polysaccharide.
- Early identification and characterization of such myopathies are vital for patient management.