Auditory brainstem responses in preterm neonates: maturation and follow-up.

Seventy-five neonatal intensive care unit patients with given auditory brainstem response screening tests at 40 db and 70 db above the normal adult hearing threshold. The presence of wave V, the criterion for pass, was strongly related to postconceptual age: It appeared at 70 db in 50% of the infants tested at 32 weeks' PCA and at 40 db in 50% of the infants tested at 40 weeks' PCA. Forty-four infants failed the last test before NICU discharge (15 at 70 db and 29 at 40 db), but most infants were discharged at a PCA of less than 40 weeks. No significant correlation appeared between ABR test failure and intraventricular hemorrhage, hyaline membrane disease, perinatal asphyxia, hyperbilirubinemia, or aminoglycoside therapy. Follow-up information was obtained in 23 of the 36 "failing" infants who survived (8 died). This consisted of definitive hearing tests in ten patients and historical information supporting normal auditory function in 13 patients. One case of severe hearing loss was confirmed. Thus, most failures of the ABR screen apparently resulted from immaturity. These data raise doubts regarding the effectiveness of ABR screening in the NICU.

The cricopharyngeus in the neonate.

The cricopharyngeus muscle in neonates and infants has not been well established. It is found, like other laryngopharyngeal structures in infants, to be relatively much larger than its counterpart in the adult but not large enough to correlate with the total length of reported sphincter function. It also varies significantly in size, and therefore probably does not contribute completely to the function of the upper esophageal sphincter. Its relationship to airway protection, regurgitation and respiration needs to be more thoroughly studied.

Intramembranous and mesotympanic cholesteatomas associated with an intact tympanic membrane in children.

A series of 15 intramembranous (IMTC) and mesotympanic (MTC) cholesteatomas associated with intact tympanic membranes in children is presented. Clinical observations, audiometric and radiographic data, and surgical findings are correlated. A history of recurrent otitis media was obtained in 85% (13/15) of the cases, differentiating them from the usual congenital cholesteatomas. The possibility that many of these are indeed "acquired" lesions is emphasized. Hypothetical pathogenetic mechanisms are discussed. The basal cell papillary proliferation theory is considered the most attractive explanation of the development of both IMTCs and MTCs. The need for careful, prolonged, follow-up otoscopic examination of children with recurrent otitis media is stressed, if more of these lesions are to be recognized early.

Auditory function in newborn intensive care unit patients revealed by auditory brain-stem potentials.

The relations between clinical illness and auditory response (as revealed by auditory brain-stem potentials) were prospectively studied in a neonatal intensive care unit. Forty-nine tests were performed on 29 infants with gestational age 24 to 43 weeks and birth weight 530 to 3,380 gm. Auditory test results were classified as pass or fail, depending on the presence or absence of wave V at a latency of 7 to 11 ms in response to clicks 60 dB above the normal adult threshold. Six patients failed and 23 patients passed. The failures were not correlated with excessive noise exposure or ototoxic medication. Five of the patients who failed had intracranial hemorrhage. Routine screening of infants in the NICU for auditory impairment is a clinically feasible and useful procedure.

Dilation of the eustachian tube by electrical stimulation of the mandibular nerve.

The recent studies of the anatomy of the eustachian tube and related structures in the Rhesus monkey (Macaca mulatta) have shown that the monkey tubal system is similar to the human. This investigation in Rhesus monkeys was an attempt to verify previous studies in other animals that the tensor veli palatini muscle was the only dilator of the eustachian tube. Two unipolar stimulating electrodes were introduced into the foramen ovale, and the mandibular branch of the trigeminal nerve was electrically stimulated. Simultaneously, pressure-flow recordings through the eustachian tube were monitored. Stimulus-response relationships were obtained for five Rhesus monkeys. The degree of tubal dilation by the tensor veli palatini muscle contraction was shown to be a function of stimulating current levels. Artifically induced dilations were quite similar to the physiological dilations during swallowing when these animals were tested alert. Following complete transection of the tensor muscle, regardless of the stimulus level, no tubal dilations were observed. Stimulation of the nerve to the internal pterygoid and stimulation of the levator veli palatini muscle induced only constrictions of the tube. The tensor veli palatini muscle is the only paratubal muscle responsible for active dilation of the eustachian tube in the Rhesus monkey, and its motor innervation is the mandibular division of the trigeminal nerve.

Respiratory obstruction and apnea in infants with bilateral abductor vocal cord paralysis, meningomyelocele, hydrocephalus, and Arnold-Chiari malformation.

This report describes 21 infants and children with bilateral abductor vocal cord paralysis and associated meningomyelocele, Arnold-Chiari malformation, and hydrocephalus. Two life-threatening forms of respiratory distress are distinguished: (1) upper airway obstruction due to bilateral abductor cord paralysis and (2) apnea. Clinically significant episodes of apnea were documented in 13 infants. Ten infants had evidence of aspiration and dysphagia. Vocal cord paralysis, apnea, aspiration, and dysphagia were frequently temporally related to increased intracranial pressure.

Congenital cricopharyngeal achalasia.

Fifteen infants with congenital cricopharyngeal achalasia are reviewed. Although most of the patients had symptoms at birth, the diagnosis was frequently not confirmed until later in the first year of life. While four of the infants had only cricopharyngeal achalasia, 11 had associated diseases related to the central nervous system. Those patients without associated diseases improved spontaneously with conservative management; most of the infants with other abnormalities also improved, although their clinical progress was slower and more complicated. In three of the patients, the symptoms were persistent and there were two deaths related to associated diseases. Cricopharyngeal myotomy was performed on two children with only moderate improvement in symptoms. Congenital cricopharyngeal achalasia is more common than formerly recognized. When suspected, an esophagram with tele- or cineradiography is essential to confirm the diagnosis. Esophageal motility studies will quantify changes and also evaluate lower esophageal dysfunction not easily identified on esophagrams.