E.J. Colon

The maturation of the central auditory conduction in preterm infants until three months post term. II: The auditory brainstem responses (ABRs)

Auditory cortical evoked responses (ACRs) were recorded in 65 preterm infants, at least on 3 occasions in 48 of them. The infants were divided into 5 groups according to their gestational age (GA). The recording sessions were performed at 8 conceptional age (CA) levels, defined as the gestational age added to the chronological age. The last recordings were obtained at 50-52 weeks CA. The ACRs were analyzed for the primary complex containing middle latency components (MLR) and the secondary complex, containing the slow late components. The ACR records first appear at about 25 weeks CA, initiating the premature stage followed by a transitional stage around term date and the gradual development into the mature stage, achieved at 50-52 weeks CA. The detectability rate of the various components generally increased with increasing conceptional age, for some of the components, especially N2p and N2, this rate achieved a value of about 80%. The degree of prematurity did not influence appreciably the development of the ACR. The waveforms, and to a lesser extent the latency and amplitude values, are strongly age dependent. Remarkable topographic differences between the ACR parameter latency and more importantly amplitude values are found between the derivations from the vertex and the central temporal areas, supporting the theory of different generation sites for the ACR components. The premature and mature ACR appeared relatively insensitive to changes in the states of vigilance. The ACR in premature infants are useful in developmental studies with respect to the central audition in premature infants and might contribute in the clinical assessment on the quality of the premature central auditory system.

The Discriminating Role of EEG Power Spectra in Dyslexic Children

SummaryThe aim of this investigation is to compare EEG power-density spectra between dyslexic and normal children. The children have been selected on the basis of specific reading and writing tasks; those with severe organic diseases and mental disorders were excluded.Groups aged 8, 9 and 10 years have been compared. In the 8-year-old group the power in the alpha band is higher in normals, in the 9-year-old group there was a higher power of the mu rhythm in normals and in the 10-year-old group the power in the temporal theta band is lower in normals. A possible relation between these findings and psychomotor development is discussed.ZusammenfassungDas Ziel der vorliegenden Untersuchung ist ein Vergleich der EEG-Breitbandfrequenzanalyse beim dyslexischen und beim normalen Kind. Die dyslexischen Kinder wurden aufgrund spezifischer Lese- und Schreibstörungen ausgesucht, wobei solche mit schweren organischen Hirnfunktionsstörungen oder anderen psychischen Anomalien ausgeschlossen wurden. Der Vergleich geschah zwischen zwei Gruppen von Kindern im Alter von 8, 9 und 10 Jahren.Bei den 8jährigen war die Spannung im Alphaband bei den Normalen höher, bei den 9jährigen erschien bei den Normalen die Spannung des mu-Rhythmus höher, und bei den 10jährigen war die Spannung im temporalen Thetaband bei den Normalen niedriger. Es wurde auf die möglichen Beziehungen zwischen diesen Feststellungen und der psychomotorischen Entwicklung in der Diskussion eingegangen.

The maturation of the central auditory conduction in preterm infants until three months post term. IV. Composite group averages of the cortical auditory evoked responses (ACRs).

Composite group averages were constructed from cortical auditory evoked responses (ACRs), which are recorded sequentially at maximally 8 conceptional age levels in 5 groups of 49 preterm infants, with additional inclusion of the records of 16 prematures obtained at different conceptional age levels. The group averages for the 5 gestational age groups showed replicable waveforms at all conceptional age (CA) levels reflecting the intragroup stability of the ACR complex. From the earliest age levels, from 25 weeks CA on, ACR group averages can be obtained, containing relative low voltage fast waves and high voltage slow waves. The most outstanding developmental changes in the ACR complex are the waveform changes. Until about 36 weeks CA a premature waveform is found, followed by a transitional phase with low voltage noisy records. Finally the adult waveform is found in the measurements at three months after term date. The latency values of the group averages are determined by the waveform changes. Persistent amplitude differences are found for the slow late waves between the vertex and the central temporal derivations.

Autosomal dominant idiopathic hypoparathyroidism and nervous system dysfunction: report of three cases and review of the literature.

SummaryThe neurological manifestations of idiopathic hypoparathyroidism in a father, his son, and his daughter are reported. In all three epilepsy was the first manifestation of the disease. Father and son also showed mental deterioration and striocerebellar symptoms; their CT scans revealed symmetrical calcification in the basal ganglia and dentate nuclei. The extent of this calcification increased during normocalcemia, which was produced by dihydrotachysterol therapy. This indicates that other factors than merely hypocalcemia influence the intracerebral calcifying process.Somatosensory evoked potentials (SSEP) showed an abnormal nonspecific complex, indicating dysfunction of the cortical gray matter.It is suggested that in the evaluation of idiopathic hypoparathyroidism one also must be beware of the possibility of epilepsy, mental deterioration, striocerebellar symptoms, intracerebral calcification and SSEP disturbances.ZusammenfassungEs wird über eine Familie mit neurologischen Symptomen bei idiopathischem Hypoparathyroidismus berichtet; Vater, Tochter und Sohn waren erkrankt. In allen drei Fällen bildeten cerebrale Anfälle das erste Symptom der Krankheit. Vater und Sohn hatten auch psychische Veränderungen und strio-cerebelläre Symptome. Die Computer-Tomographie zeigte Verkalkungen in Stammganglien und den Nuclei dentati. Im Verlauf einer Dihydrotachysterol-Therapie, durch die Normocalzämie erreicht wurde, nahm die Ausdehnung der Verkalkungen noch zu. Dies weist darauf, daß neben den Faktoren, die zur Hypocalzämie führen, noch andere Faktoren den kalzifizierenden Prozeß im Bereich des Hirnparenchyms beeinflussen.Somatosensorische evozierte Potentiale (SSEP) zeigten Veränderungen der unspezifischen Antwort, woraus auf eine kortikale Störung geschlossen wird.Wir machen darauf aufmerksam, daß bei cerebralen Anfällen, psychischen Störungen, strio-cerebellären Symptomen, zerebralen Verkalkungen und SSEP-Störungen man auch an den Hypoparathyroidismus denken muß.

The maturation of the central auditory conduction in preteram infants until three months post term. III. The middle latency auditory evoked response (MLR)

Middle latency auditory evoked responses (MLRs) were recorded in 64 premature infants; serially in 54 of them. The last recording sessions occurred at 50-52 weeks conceptional age (CA), defined as the gestational age (GA) added to the chronological age. The MLRs were analyzed for the components PO, Na and Pa, and the interpeak latency difference (IPLD) Na-PO. The detectability rate of PO and Na reached 80-90% at about 30 weeks CA. Pa reached the highest rate of about 60% at 52 weeks CA. The degree of prematurity did not result in clear differences with respect to the parameter values. Also, the side of stimulation did not influence the MLR parameter values. The latency values of the MLR components are strongly age dependent. Topographic differences were found between the sides ipsi- and contralateral to stimulation. They are, however, different for PO, Na and Pa. The influence of the state of vigilance on the parameter values could generally only be established at CA levels of about 32 and 52 weeks CA. The amplitude values at 52 weeks CA are especially sensitive for sleep or awake state. The particular pattern of age dependency of the different components and their topographic differences are consistent with a differential generation of bilateral nature. The early appearance of the response supports the generation of an early functioning subcortical structure in the auditory pathway.

The maturation of the central auditory conduction in preterm infants until three months post term. I. Composite group averages of brainstem (ABR) and middle latency (MLR) auditory evoked responses

Brainstem (ABR) and middle latency (MLR) auditory evoked responses were obtained sequentially in 49 preterm infants until three months post term date. In addition, the records of 16 preterm infants, obtained at different conceptional age levels, were included. The recording of these responses was performed successively in one procedure, together with auditory cortical evoked responses. The infants were divided into 5 groups according to their gestational age, i.e. the term at birth. Composite group averages were determined, showing the group stable components of the 5 gestational age groups at 8 different conceptional age levels, i.e. term at the time of the recording. The intra group stable components could thus be determined for further study of developmental trends in the responses. The group averages also serve as a reference in the visual analysis of the individual records. The averaged ABRs showed that with increasing conceptional age increasingly better identifiable waveforms were obtained. These were particularly outstanding for peaks I and V ipsilateral to stimulation, and peaks IIc and Vc contralateral to stimulation. This enabled the measurement of the central conduction times. The MLRs were especially remarkable for their latency changes which occurred in peak PO and the troughs Na and Nb. The results indicated that the conduction of the subcortical auditory afferent signals can be measured successfully in groups of very premature infants with ABRs and MLRs.

Reliability of Doppler sonography in extracranial cerebro-vascular stenosis

Of our patients who underwent quantitative Doppler sonography (Haemato-Tacho-Graphy), 382 underwent carotid angiography and 61 vertebral artery angiography. The reliability of the method proved to be between 90 and 95 percent for carotid as well as for vertebral arteries. The HTG proved to be a useful addition to angiography in patients with extracranial cerebro-vascular stenosis.

The Central Auditory Conduction at Term Date and Three Months After Birth III. Middle Latency Responses (MLRs)

Middle latency responses (MLRs) were obtained in 25 healthy newborns with a follow-up recording at 3 months in all but three. A four-channel recording provided topographic information. Linkage of the ear references reduced the myogenic contamination of the recordings. P0 and Na proved to be the most consistent components in the sinusoidal MLR wave sequence. Topographic differences suggest a generation of P0 and Na contralateral to stimulation. A significant latency decrease was found for P0 and na between term and 3 months. The most important latency and amplitude changes may occur before term date and immediately thereafter. The MLRs are the link between the auditory brainstem responses (ABRs) and the auditory cortical responses (ACRs), and it may be possible to use them for recordings in newborn infants. They provide information about the generation of specific components as well as regarding the auditory afference in the stimulus propagation between the brainstem and the cortical auditory areas.

Somatosensory evoked response in controlled A-alpha sensory fiber disease

SummaryIn contrast to the distal sensory response, the somatosensory evoked response (SSER) is detectable in patients with A-alpha sensory fiber diseases such as Friedreichs ataxia.In four patients with this disease a combined histological and electrophysiological investigation of sensory propagation was performed. The sural nerve was analyzed in terms of the various fiber diameters and the distal sensory and somatosensory evoked cortical responses recorded after sural and median nerve (finger) stimulation. A distinct evoked response could be detected with rather low amplitudes and retarded latency times, while in general no distal sensory response was found. The anatomical and physiological consequences are discussed.ZusammenfassungIm Gegensatz zu den sensiblen Nervenaktionspotentialen ist das Somato-sensible Evoked-Potential bei Patienten mit einer Friedreichschen Ataxie (eine A-alpha-sensible Nervenfasernerkrankung) gut zu erregen.Bei vier Patienten mit dieser Erkrankung haben wir eine histologische und elektrophysiologische Untersuchung vorgenommen. Die N.-suralis- und N.-ulnaris-sensiblen Nervenaktionspotentiale und Evoked Response sind analysiert worden. Kombiniert hiermit wurde eine Analyse der Faserdurchschnitte einer N.-suralis-Biopsie durchgeführt. Die anatomischen und physiologischen Konsequenzen sind diskutiert worden.

Changes in carotid flow velocity induced by direct percutaneous carotid angiography in man

SummaryQuantitative percutaneous flow velocity measurements are possible in carotid arteries. The results of the direct percutaneous angiography were measured by means of a Doppler directional flow velocity device and registered on a polygraph. The results indicate an increase in the flow velocity of the injected as well as the non-injected carotid system. This implies that there are no local constrictions of the carotid artery following intervention and, furthermore, it implies a systematic effect of the puncture and injection itself, or of the contrast medium, on the whole cerebral circulation. A diffuse vasodilatation, at least in the cerebral circulation, is postulated. The possible implications are discussed.ZusammenfassungMittels Doppler-Sonographie und polygraphischer Registrierung wurde quantitativ percutan der Blutstrom in den Carotiden vor und nach direkter percutaner Arteriographie gemessen. Es ergibt sich hierbei eine Zunahme der Durchflußgeschwindigkeit sowohl auf der Seite der Kontrastmittelinjektion wie auch auf der Gegenseite. Dies bedeutet, daß keine lokale Einengung der A. carotis nach dem Eingriff vorliegt, und im weiteren, daß die Gefäßpunktion und die Injektion oder aber das Kontrastmedium einen systemischen Effekt auf die Gehirnzirkulation ausüben. Es wird eine diffuse Gefäßerweiterung, zumindest im Bereiche der cerebralen Zirkulation, angenommen. Die möglichen Folgerungen werden diskutiert.