Rainer Boor

Topiramate and metabolic acidosis in infants and toddlers.

Summary: u2002Purpose: Topiramate (TPM) inhibits carbonic anhydrase, with metabolic acidosis as a possible side effect, although this has been reported in only two adult cases. We investigated the acid–base metabolism in infants and toddlers treated with TPM.

Combined spike-related functional MRI and multiple source analysis in the non-invasive spike localization of benign rolandic epilepsy

OBJECTIVEnTo localize the irritative zone in children by combined spike-related fMRI and EEG multiple source analysis (MSA) in children with benign rolandic epilepsy.nnnMETHODSnInterictal spikes were averaged and localized using MSA, and source locations were displayed in the anatomical 3D-MRI in 11 patients (5-12 yrs, median 10). Interictal spikes were additionally recorded during the fMRI acquisition (EEG-fMRI), and the fMRI sequences were correlated off-line with the EEG spikes.nnnRESULTSnMSA revealed an initial central dipole in all patients, including the face or hand area. A second dipolar source was mostly consistent with propagated activity. BOLD activations from EEG-fMRI, consistent with the locations of the initial dipoles, were found in four patients. We found additional large areas of BOLD activations in 3 of these subjects extending into the sylvian fissure and the insula. These were identified as propagated activity by MSA using the short time differences in the source waveforms.nnnCONCLUSIONSnMSA provided reliable localization of the spike onset zone in all children with benign rolandic epilepsy. Using the combination of EEG-fMRI and MSA we were able to discriminate the spike onset zone from propagated epileptiform source activity, using the spatial resolution of the EEG-fMRI technique and the temporal resolution of the MSA. However, the sensitivity of the EEG-fMRI technique was low and further improvements of the technique are warranted.nnnSIGNIFICANCEnThis study shows that a combination of EEG-fMRI and MSA may be a powerful tool to describe the irritative zone of patients with idiopathic focal epilepsies. Clinical studies in patients with non-idiopathic focal epilepsies may clarify whether both techniques can be used as complementary clinical tools to localize the onset of interictal epileptic activity in focal epilepsies.

EEG-related Functional MRI in Benign Childhood Epilepsy with Centrotemporal Spikes

Abstract: The localization of epileptic foci is an important issue in children with extratemporal epilepsies. However, the value of noninvasive methods such as the EEG‐assisted functional magnetic resonance imaging (fMRI) has not been sufficiently investigated in children.

Maturation of near-field and far-field somatosensory evoked potentials after median nerve stimulation in children under 4 years of age

OBJECTIVESnThe maturation of subcortical SEPs in young children.nnnMETHODSnMedian nerve SEPs were recorded during sleep in 42 subjects aged 0-48 months. Active electrodes were at the ipsilateral Erbs point, the lower and upper dorsal neck, and the frontal and contralateral centroparietal scalp; reference electrodes were at the contralateral Erbs point, the ipsilateral earlobe and the frontal scalp; bandpass was 10-3000 Hz. The peaks were labelled by their latencies in adults.nnnRESULTSnThe peak latencies of N9 (brachial plexus potential) decreased exponentially with age during the first year, but increased with height thereafter. The interpeak latencies (IPLs) N9-N11, which measure conduction between brachial plexus and dorsal column, decreased with age (linear regression). The IPLs N11-P13 and N11-N13b, which measure conduction between the dorsal column and approximately the cervico-medullary junction, did not change across this age range. The IPLs N13a-N20, N13b-N20 and P13-N20, which measure central conduction, showed negative exponential regressions with rapidly decreasing latencies during the first year of life and slowly decreasing latencies thereafter.nnnCONCLUSIONSnMaturation of the peripheral segments of the somatosensory pathway progresses more rapidly than that of the central segments. The maturation of central conduction is not completed within the first 4 years of age. Our maturational data may serve as a reference source for subsequent developmental and clinical studies.

Ischemic Stroke and Migraine in Childhood: Coincidence or Causal Relation?

Although migraine is an accepted cause of cerebral infarction in adults, this association is less well recognized in children. We present two children with migraine and cerebral infarction, which we regard as migrainous stroke, though neither patient fulfills all criteria of the International Headache Society for the diagnosis of migrainous infarction. Review of the literature concerning examples of migraine-associated stroke in childhood suggests that these criteria are too restrictive to comprise the majority of migrainous strokes, especially in this age group. (J Child Neurol 1999; 14:451-455).

Subcortical somatosensory evoked potentials after median nerve stimulation in children

We report our normative data of subcortical somatosensory evoked potentials (SEPs) after median nerve stimulation from a group of 55 children 4-15 years of age and 18 young adults 18-29 years of age. We recorded near-field potentials from the brachial plexus, the cervical cord and the somatosensory cortex. The far-field potentials P13, P14 and N18 from the brainstem were recorded from the scalp electrodes, when a non-cephalic reference at the contralateral Erbs point or an ear reference was used. The N9 (brachial plexus), N13a (dorsal horn), P13 (caudal medulla oblongata), N18 (medulla oblongata) and N20 (somatosensory cortex) were present in all subjects. The N13b (dorsal column near the foramen magnum or cuneate nucleus) was observed in all children and in 16 adults, P14 (medial lemniscus) in 52 children and 17 adults. The median nerve SEPs provide reliable information about the function of the somatosensory pathway from the upper limb. The subcortical median nerve SEPs should be particularly useful to detect lesions of the upper cervical cord and the cervicomedullary junction. The subcortical SEPs remain unchanged during sleep and facilitate reliable SEP recordings, when sedation is necessary in infants and children.

Assessment of brainstem function in Chiari II malformation utilizing brainstem auditory evoked potentials (BAEP), blink reflex and masseter reflex

Brainstem dysfunction was evaluated in 67 patients with myelomeningocele and Chiari II malformation using brainstem auditory evoked potentials (BAEP), blink reflex (BR) and masseter reflex (MR). Signs and symptoms related to Chiari II malformation were observed in 18 patients while 49 patients had normal brainstem findings. BAEP and BR showed a higher sensitivity of brainstem involvement than MR (BAEP=1.0, BR=0.83, MR=0.50). BR, and in particular, MR were of higher accuracy (BR=0.52, MR=0.72) than BAEP (0.39) in separating patients with brainstem signs and symptoms related to Chiari II malformation. We feel that this is due to anatomic and physiologic peculiarities of the brainstem structures mediating BR and MR. Our results suggest that brainstem reflexes can support the decision of further treatment.

Brainstem auditory and visual evoked potentials in infants with myelomeningocele

Brainstem auditory evoked potentials (BAEPs) and visual evoked potentials (VEPs) were recorded in 47 infants with myelomeningocele to determine if the evoked potentials reflected the early neurological status, and if they had prognostic value as to the childrens neurological outcome. The infants were tested between 1 day and 3 months of age (mean 24 days), while still in hospital after the myelomeningocele repair. Outcome was assessed at a mean of 2 years of age. Normal BAEPs were found in 41% and normal VEPs in 62% of the patients. BAEPs were abnormal in all infants studied who had symptomatic Arnold-Chiari (AC) malformation (n = 9); VEPs were abnormal in only 55% of symptomatic infants. Of the infants who did not have symptomatic AC malformation, 53% had normal BAEPs, 69% had normal VEPs. Of the patients with normal BAEPs, 81% had normal cerebral function on follow-up. Of the patients with abnormal BAEPs, 87% had central neurological abnormalities on follow-up. Of the patients with normal VEPs, 63% were normal on follow-up; of the patients with abnormal VEPs, 71% were abnormal on follow-up. Thus, the VEPs studied early in the neonatal course do not appear to be sufficiently sensitive to be valuable prognostically in these infants. However, the BAEPs were consistently abnormal in symptomatic AC malformation and showed a positive predictive value of 88% and an accuracy in predicting central neurological sequelae of 84%.

Somatosensory evoked potentials after posterior tibial nerve stimulation--normative data in children.

We report normative data of somatosensory evoked potentials to posterior tibial nerve stimulation from 47 children 4-15 years of age. We recorded near-field potentials from the peripheral nerve, the cauda equina, the lumbar spinal cord and the somatosensory cortex. Far-field potentials were recorded from the scalp electrodes with a reference at Erbs point and on the earlobe. The near-field potentials N8 (peripheral nerve) and P40 (cortex) were present in all children. N20 (near-field from the cauda equina) was recorded in 38 subjects. N22 (near-field from the lumbar spinal cord), P30 and N37 ( both far-field waveforms probably generated in the brainstem) were recorded in 46 subjects each. The latencies and the peripheral conduction time (N8-N22) increased with age, while the central conduction time (N22-P40) and the intracranial conduction time (P30-P40) both decreased with age (up to about 10 years of age). The spinal conduction time (N22-P30) was relatively independent of age. The interpeak latencies allow the assessment of specific portions of this pathway. The subcortical posterior tibial nerve-somatosensory evoked potentials are of particular interest in children when the cortical peaks are influenced by sedation and sleep, or by anaesthesia.

Somatosensory evoked potentials in Arnold-Chiari malformation.

Nearly all patients with repaired myelomeningoceles have an Arnold-Chiari (AC) malformation and about 20% of these patients develop clinical signs of brainstem dysfunction. The management of symptomatic AC malformation is still controversial and techniques are needed to provide an objective assessment of brainstem function. We recorded somatosensory evoked potentials (SEPs) in 52 patients aged between 8 months and 20 years (median 7.3 years) with AC malformation, to determine whether the SEPs discriminate patients with symptomatic AC malformation from those without symptoms. The subcortical far-field components P13, P14 and N18, which are generated within the brainstem, were recorded with non-cephalic reference electrodes and the cortical N20 with a frontal reference. Fourteen patients (27%) had signs and symptoms of brainstem dysfunction, which were related to the AC malformation. Abnormal SEPs were mainly recorded in symptomatic patients (sensitivity 0.7, specificity 0.9). The SEPs were particularly useful in patients from 4 years of age (sensitivity 0.9, specificity 0.9), but not in the younger age group. Abnormal somatosensory conduction reflects dysfunction of the brainstem or the upper cervical cord and may be clinically useful to assess patients with late onset symptomatic AC malformation.