Spinal muscular atrophy diagnostic difficulties

OBJECTIVE: To describe the clinical findings of patients with spinal muscular atrophy (SMA) with survival motor neuron (SMN) gene deletion. METHOD: Descriptive study of SMA cases confirmed with the deletion of the SMN gene. Frequency determination of positive clinical and laboratory revised diagnostic criteria. RESULTS: All of the 22 included patients had symmetrical muscle weakness, which was diffuse in those with onset of symptoms up to 6 months of age (75%), and either proximal or predominant in lower limbs in the remaining group (67%). Fasciculations and atrophy were both frequent findings (82%). Laboratory tests findings were variable, with a positivity of 57% for electrophysiology and of 58% for muscle biopsy. CONCLUSION: The presence of a deletion in the SMN gene can help to confirm this diagnosis in unclear presentations.