Children with non-verbal learning disabilities (NLD): coherence values in the resting state may reflect hypofunctional long distance connections in the right hemisphere.

EEG intrahemispheric coherences (HCohs) in the resting state in twenty-four 4 Hz frequency windows between 1 and 51 Hz were studied in 18 children with "non-verbal learning disorder" (NLD) and compared to a group of 18 children with "verbal learning disorder" (VLD). New facts were found in the NLD group. These concern hemispheric balance, expressed as left minus right (L-R) homologous HCohs: 1a). In the high frequencies (25-51 HZ) the number of long-distance HCohs, higher in the right hemisphere (RH), is lower than HCohs, which are higher in the left hemisphere (LH). A reversed interhemispheric asymmetry is seen for short distance HCohs in that band. These asymmetries are not found in the VLD group, and the tendency is even reversed. 1b). In the low frequencies (1-27 Hz) all higher HCohs are more numerous in the RH, irrespective of interelectrode distance (IED). In these bands there are no NLD-VLD group differences; 2). In NLD there is a significant inverse relationship between IED and (L-R)HCoh values (designated as LRDif) in the high frequencies: the larger the IED, the higher the LRDif. In the lower frequencies there is no such tendency. In the VLD group these relationships were absent. These preliminary results suggest long distance gamma band hypoconnectivity in the RH of NLD children, in line with the hypothesis of an RH long distance connectivity problem in NLD. This may explain difficulties with mtermodal perception (gestalt function). Finally in the NLD group some gamma band interhemispheric (ICohs) over F7/F8 and T3/T4 were lower than in VLD children and some gamma band ICohs were higher in NLD compared to VLD over O1/O2. This is possibly connected with the cognitive differences subserved by these areas, i.e., language, respectively visuospatial function.

Diagnosing Alzheimer's disease in community-dwelling elderly: a comparison of EEG and MRI.

In a study on the course of cognitive impairment in people over 65 years of age, 58 randomly selected community dwelling elderly underwent EEG and MRI studies. The EEG was visually and quantitatively (qEEG) assessed. Nine out of 58 subjects appeared to have Alzheimer dementia (AD) according to CAMDEX criteria. In this group medial temporal lobe atrophy on MRI, as an objective criterium for AD, showed a total accuracy of 72%, visually assessed EEG 81% and qEEG 81-84%. There was an incomplete overlap in subjects regarding MRI and EEG abnormalities, implying that both methods may be complementary.

H reflex latency as an adequate predictor of the spinal evoked potential latency.

By stimulation of the posterior tibial nerve, somatosensory responses can be recorded at the level of the popliteal fossa, thoraco-lumbar spinal region and scalp. The thoraco-lumbar spinal potential is frequently difficult to record. Therefore several methods to estimate its latency were used and the results were compared with the real latency of the N24 recorded at spinal level in a group of healthy volunteers. A formula using the Hoffmann reflex latency (H-M interval) proved to be the most adequate for this purpose. By knowing the spinal potential latency, either through direct recording or through estimation by the formula, determination of a central conduction time, the N24-P40 interval, is possible. Normative values for this parameter are given.

Anterior temporal focal abnormalities in EEG in normal aged subjects; correlations with psychopathological and CT brain scan findings.

Normal aged subjects (65-83 years) were examined by EEG and CT brain scan; also a Geriatric Mental Scale (GMS) and Neuropsychologic Assessment Battery were administered. Based on the EEG findings 2 subgroups could be distinguished: one with focal abnormalities in the left fronto-temporal region and one without these focal abnormalities. The focal delta subgroup proved to perform poorly on the Fluency Test, a simple quick bedside, but very sensitive, test for word association productivity. Also this subgroup showed more ventricular dilatation than the non-focal group. Therefore slight left-sided antero-temporal abnormalities in normal aged subjects are not irrelevant but an early (subclinical) sign of temporal lobe pathology as expressed in deterioration of language function.

The influence of attention on visual evoked potentials in normal adults and dementias.

In normal subjects (n = 58, 22-71 y) the influence of the attention level on the VEP latency is studied, as is done in an additional small group of dementias (n = 14). The motor reaction time test (MRT) was selected to measure the attention level. The MRT was administered simultaneously with the VEP (checkerboard pattern reversal). By comparing VEP in test and non-test situations it proved that administration of MRT during VEP examination does not influence the VEP latencies. In dementias the motor reaction time is delayed but the degree of MRT delay did not correlate with the VEP latencies. This holds true for healthy volunteers as well as for demented patients. It is thus concluded that the latency increase of the late peaks of the VEP in dementias cannot be attributed to attentional deficits.

Visual evoked potentials (VEPs) in senile dementia (Alzheimer type) and in non-organic behavioural disorders in the elderly; comparison with EEG parameters.

Forty-two patients with senile dementia of the Alzheimer type were compared with normal subjects (51) and with elderly patients with nonorganic psychiatric disorders (40). All were examined by EEG (routine visual inspection and power spectrum density analysis) and VEP (pattern reversal) testing. In dementia the late components (N130, P165, N220) of the VEP are delayed, but the EEG was abnormal more often than the VEP.

Somatosensory evoked potentials in healthy volunteers and in patients with dementia.

In 56 healthy volunteers short, middle and long latency somatosensory evoked potentials were recorded bilaterally. The median nerve was electrically stimulated at the wrist. The impact of arm length and age on the peak latencies of the identified SEP components was investigated. Arm length relates to shoulder and neck SEP and to the N20, the primary cortical response. Age relates to all components of the SEP. A pilot study was performed in a small number of patients with senile dementia. A significant delay of the middle and long latency potentials compared to healthy volunteers was shown.

Peripheral nerve conduction, visual evoked potentials and vitamin B1 serum level in chronic alcoholics.

70 chronic alcoholics were tested. In all patients VEP (pattern reversal) and MMCV (of the peroneal nerve) was examined. Moreover 47 of the patients underwent Hoffman reflex testing as well. In 16 (23%) of the patients the VEP P100 latency was delayed, in 21 (30%) the MMCV was decreased and in 16 (34%) the H-M interval was increased. A positive correlation was found between VEP latency and peroneal MMCV. VEP P100 delay is possibly caused by a subclinical optic neuropathy.

Normal Hoffmann reflex latencies (H-M interval) in relation to age and body length.

The effects of age and body length on the Hoffmann reflex (H-M interval) was evaluated. 179 normal subjects (15-75 y, 150-200 cm) were tested. The normal upper limit (M + 2SD) of the H-M interval ranges from 22.0 ms (male, 155 cm, 20 y) to 34.3 ms (female, 195 cm, 70 y). The limit of 28 ms, that is often mentioned, holds only for young adults with a body length of less than 175 cm. Moreover it proved that a normal limit of the H-M interval asymmetry of less than 2 ms is too strict. For a mixed population less than 3 ms seems to be a safer upper limit for normal asymmetries.

Neurological condition at birth in relation to the electroencephalogram (EEG) and visual evoked potential (VEP) at the age of 5.

The correlation between the neonatal neurological condition (Prechtl) and VEP and EEG parameters at the age of 5 have been investigated in 87 normal children. It was found that the more optimal the neurological condition at birth, the shorter the VEP peak latencies (especially of the late components) at the age of 5. Only few and weak correlations between the neonatal condition and EEG at the age of 5 were found. The VEP appears to be a more sensitive detector for late sequelae of supposed perinatal neurological problems than EEG. VEP changes can be explained by "inattention' or "distraction'. Another factor may be delayed maturation.

EEG and visual evoked responses in children with learning disorders.

A study was made of 58 children with learning disorders, in all of whom a spontaneous EEG as well as a Visual Evoked Response (VER) was registered. The latencies in the secondary complex of the VER were increased and the amplitudes of waves II and III were increased as compared with normal subjects. Two subgroups--children with a good and children with a poor clinical test score--did not differ in VER parameters. A spontaneous EEG evaluated as abnormal was present in 45% of the children. These children showed more absence of peaks in both VER complexes and more increased latencies in the primary complex than children with a normal EEG. The findings show that the VER is a valuable supplement to EEG in demonstrating organic changes in children with learning disorders.

Visual evoked response in senile and presenile dementia.

The visual cortical evoked response was studied in 19 patients suffering from a condition diagnosed as senile or presenile (type Alzheimer) dementia. When compared with a group of normal subjects used as reference group, the latencies of waves II through VI were increased or markedly increased in these patients, and the amplitudes of waves III and VI (and, less consistently, those of waves II and IV) were increased. This corroborates the sparse data on other types of dementia available in the literature.