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Biomedical subjects

W D Goldie

Publications and source records attributed to W D Goldie.

9 recordsLinked to original sources

The brainstem auditory evoked potential in infants and children.

The brainstem auditory evoked potential (BAEP) is a neurophysiological study that provides functional information about the auditory system and brainstem. It provides information that is different from any other form of evaluation. This report tries to summarize technical and clinical information that will make the BAEP more meaningful for the practicing technologist and clinician. Attention is focused on the BAEP as it is used in infants and children, starting with a brief review of auditory physiology, then progressing to normative data, clinical utility, physical setup, preparing the patient, comments on technique, and comments on interpretation. This is not an exhaustive review of the topic, and many important elements of clinical utility had to be left out. This review tries to focus on recent references and on practical issues, and it relies on the experience and opinions of the author. Emphasis has been placed on the use of the BAEP by the neurologist, but an attempt has been made to acknowledge the importance of audiology and otolaryngology as well as speech and language science. Particular emphasis has been placed on the use of the BAEP in assessing the premature infant and young infant at risk for neurological and audiological injury. An enormous amount of published data is available in the literature, and much of it had to be left out of this review. However, the reader is encouraged to develop an enthusiasm for the BAEP and to further explore the broad range of its clinical uses.

Acoustic Stimulation

Rhythmic coma in children.

We describe a syndrome of rhythmic coma in children that consists of an invariant, nonreactive, diffuse cortical activity of a specific frequency, such as alpha, beta, spindle, or theta, recorded from a comatose child. We report 11 cases of children who were found to be in rhythmic coma during their acute illnesses. Their ages ranged from 2 to 15 years, and their diagnoses included encephalitis, head trauma, seizures, near drowning, brain tumors, stroke, and metabolic derangements. The specific frequency of the electroencephalographic pattern, ie, alpha, beta, spindle, or theta, did not influence the outcome. The clinical outcome appeared to depend on the primary disease process rather than the electroencephalographic finding. The prognosis of alpha-frequency rhythmic coma as well as of rhythmic coma in general was better in children than in adults. The pathophysiology in children may be similar, ie, the interruption of reticulothalamocortical pathways by metabolic or structural abnormalities, but the expression of this deafferentation may be more varied in the developing brain. Thus, we propose the term rhythmic coma as a unified concept for alpha, beta, spindle, and theta coma in children.

Adolescent

Neurological basis of respiratory complications in achondroplasia.

Evaluation of 32 individuals with achondroplasia revealed that 28% had a history of apnea and 22% had respiratory abnormalities on polysomnography. In those patients requiring posterior fossa decompressive surgery, improvement was noted in follow-up polysomnograms. Multimodality studies suggested that brainstem compression was common in achondroplasia and could account in part for the abnormal respiratory function in this disorder, including obstructive apnea, central apnea, and hypoxemia.

Achondroplasia

Brain stem auditory evoked potentials as a tool in the clinical assessment of children with posterior fossa tumors.

The use of brain stem auditory evoked potentials (BAEP) as a diagnostic modality in children with posterior fossa neoplasms is described. Thirty-one patients were examined; their diagnoses were medulloblastoma (12), brain stem glioma (9), cerebellar astrocytoma (6), and ependymoma (4). Distinct differences in the type and severity of waveform abnormalities were observed among the different tumor types, possibly related to location and invasiveness. Medulloblastomas frequently demonstrate normal waveforms, while brain stem gliomas demonstrate severe disruption of BAEP patterns. Ependymomas may result in a variety of abnormal studies, while cerebellar astrocytomas induce mild abnormalities or result in a normal exam. The use of brain stem auditory evoked potentials in the diagnosis of pediatric brain tumors, as well as the underlying mechanisms of the abnormalities, is discussed.

Adolescent

Postoperative neurological deficits may occur despite unchanged intraoperative somatosensory evoked potentials.

We describe 6 patients who demonstrated postoperative neurological deficits despite unchanged somatosensory evoked potentials during intraoperative monitoring. Although there is both experimental and clinical evidence that somatosensory evoked potentials are sensitive to some types of intraoperative mishap, the technique should be employed with an awareness of its possible limitations.

Adolescent

Foramen magnum stenosis in homozygous achondroplasia.

A 4-month-old female with homozygous achondroplasia and daytime apnea was found to have a small foramen magnum by computerized tomography. Following suboccipital craniectomy and C1-C2 laminectomy respiratory problems did not recur during a 7 month post-operative period. We suggest that the respiratory problems in homozygous achondroplasia may be due to brainstem compression from an abnormally small foramen magnum.

Achondroplasia

The 40 Hertz auditory event-related potential: normal values and effects of lesions.

A model of the 40 Hz auditory event-related potential (40 Hz AERP) was developed and evaluated in a group of normal subjects and two patient groups. The model views the 40 Hz AERP as a combination of the brain-stem auditory evoked potential (BAEP) and a sinusoidal component presumed to arise from structures rostral to the brain-stem. Fourier analysis techniques were used to quantify changes in the sinusoidal component. The results obtained demonstrated that the phase of the sinusoidal component was quite stable in normal subjects, but was predictably altered as a consequence of thalamic or midbrain lesions. Lesions of the temporal lobe did not alter the phase of the sinusoidal component. These results were interpreted as being consistent with the model developed and suggesting a midbrain or thalamic origin for the 40 Hz sinusoid.

Acoustic Stimulation

The spectrum of congenital facial diplegia (Moebius syndrome).

The Moebius syndrome consists of congenital facial diplegia with associated anomalies. No single pathophysiologic hypothesis accounts for all aspects of the syndrome. We present six cases which manifest a very broad spectrum of associated neurologic anomalies. Postmortem examination was performed on two cases. Midline brainstem necrosis was evident in one while the other had subtle brainstem hypoplasia. The four other patients have demonstrated fixed deficits on follow-up examinations. Improvement in brainstem evoked potential waveforms has occurred in three cases, but the significance is uncertain. Many of the cases were delivered by caesarean section because of failure of labor to progress, and had associated polyhydramnios and arthrogryposis. These features suggest that a defect is established in utero. Only one infant, born prematurely, may have suffered some perinatal brainstem insult. Congenital facial diplegia is a heterogenetic entity which can affect the nervous system in many different ways.

Abnormalities, Multiple