Different responses to auditory and somaesthetic stimulation in patients with an excessive startle: a report of pediatric experience

Objectives: Children with cerebral injury often exhibit brief muscle contra ction to a variety of stimuli. However, it remains to be determined whether or not the pattern of the reaction is stereotypical irrespective of the si te stimulated. To answer this question, we studied electromyographic (EMG) responses to three types of stimuli in children. Methods: The EMG responses of cranial and limb muscles were recorded after acoustic or somaesthetic stimulation in 6 patients and 23 control subjects. Results: Acoustic stimuli evoked patterned motor activity with a rostrocaud al progression. Nose-tapping stimuli elicited reflex EMG activity in the VI Ith cranial muscles that was similar to the R1 component of the electrical blink reflex. Sternum-tap stimuli evoked motor activity in the sternocleido mastoid and arm muscles, and this reflex was probably mediated through the cervical cord (H-reflex). Moreover, late reflexes were evoked following the se early reflexes in the patients. In particular, atypical forms of myoclon ic jerks were evoked on sternum-tap stimuli. Conclusions: Many types of primitive reflexes were evoked following three t ypes of stimuli. These reflexes included startle reflex, trigeminomotor ref lex, H-reflex and atypical forms of myoclonus, and they were enhanced in th e patient group. There are many startle mimicking reflexes. (C) 2001 Elsevi er Science Ireland Ltd. All rights reserved.