Sequelae of head and neck positions on auditory performance.
Stapedius reflex level, slow auditory evoked potential (AEP), and hearing threshold level of 18 normal adult probands (11 female, 7 male) as well as of 14 normal hearing cerebral palsied children between 4 and 12 years of age (5 female, 9 males)--were determined in different postures which correspond to the influence of tonic reflex activities in supine and prone, and in the so-called "reflex inhibiting pattern" (Bobath) and in a symmetrical relaxed position of neck, trunk and extremities in supine (the last one could only be maintained by the normal volunteers). Influence of the postures was small but significant for all parameters in the volunteers group as well as for AEP in the patients group. In the latter group the influence of tonic reflex activities on auditory evoked potential was independent from their strength. The strength of tonic reflex activity had been graded from 1-5 as judged from clinical impression by observation and palpation.