Chronic neurogenic quadriceps amyotrophies

Area of Science:

• Neurology
• Muscle Diseases
• Neurophysiology

Background:

• Chronic quadriceps amyotrophy presents diagnostic challenges, often mimicking other neuromuscular disorders.
• Understanding its varied presentations is crucial for accurate diagnosis and management.

Observation:

• Two cases of quadriceps amyotrophy are detailed, one with diminished knee jerks, hypertrophic calves, and elevated creatine kinase.
• Electromyography (EMG) revealed neurogenic abnormalities in the quadriceps of the first case.
• Muscle biopsies and CT scans indicated neurogenic origin and widespread muscle involvement, including gastrocnemius, sartorius, and gracilis muscles.

Findings:

• The first case showed histological evidence of neurogenic atrophy with hyalinized hypertrophic fibers.
• The second case initially suggested myogenic origin but later presented as neurogenic atrophy, resembling focal spinal amyotrophy.
• Diagnostic differentiation from Becker dystrophy and other conditions like muscular dystrophy, spinal atrophy, polymyositis, or metabolic disorders proved difficult.

Implications:

• Chronic quadriceps amyotrophy is not a distinct entity but a potential manifestation of various underlying neuromuscular conditions.
• Widespread muscle involvement influences diagnostic classification.
• These cases align with literature describing "forme fruste" of chronic spinal amyotrophy.