Non-familial stiff baby syndrome cases in the northern central area of Puerto Rico.

Hyperekplexia or Stiff Baby Syndrome is an uncommon disorder of non-epileptic movements with an autosomal dominant inheritance pattern. Neonates present exaggerated startle response to sensory stimuli and temporary muscular rigidity. We report two neonates from the northern center of Puerto Rico who presented involuntary movements, hypertonia and apnea during first days of life, being treated with anticonvulsants without improvement. Both were diagnosed with hyperekplexia due to the clinical evolution associated to normal EEG and head radiologic studies. Electromyography showed persistent muscular activity with periods of rest. Both were managed with clonazepam satisfactorily. We emphasized prompt recognition to prevent seizures misdiagnosis and administering appropriate treatment due to complications of sudden death secondary to stiffness and apnea.