Scalp topography of somatosensory evoked potentials following median and posterior tibial nerve stimulation in Down's syndrome

A quantitative somatosensory testing of pain threshold in individuals with mental retardation

The commonly held view, mainly based on behavioral observations, is that individuals with mental retardation (MR) have a decreased sensitivity to pain. However, the sensitivity to noxious stimuli was not systematically measured in these individuals. For this purpose we developed an experimental protocol with which we trained individuals with mild MR (unspecified MR and Down's syndrome) in heat-pain threshold (HPT) measurement on the hand, and then performed the measurement using both the method of limits (MLI) which relies on reaction time (RT) and the method of levels (MLE) which is RT-free. This allowed for an indirect assessment of the RT and conduction velocity (CV) of these individuals. We found that HPT in individuals with unspecified MR (41.23+/-1.86 degrees C) and Down's syndrome (40.96+/-2.93 degrees C) was significantly lower than that of controls (42.86+/-2.42 degrees C) when measured with the MLE (P < 0.05). With the MLI no significant differences in HPT were found between the groups. However, the RT and CV values of individuals with unspecified MR and Down's syndrome were significantly lower compared to controls (e.g. mean RT of 1.86 and 2.55 compared to 1.2 s, respectively, P < 0.01). From this work it would appear that individuals with MR are not only pain-sensitive, but also more sensitive to heat-pain than normal. It is suggested that computerized quantitative testing of pain threshold is feasible in individuals with MR preferably by using RT-free methods (e.g. the MLE) due to the low RT and CV values exhibited by them.

[Guidelines for recording/analyzing quantitative EEG and evoked potentials. Part II: Clinical aspects]

Digital EEG (DEEG) and quantitative EEG (QEEG) are recently developed tools present in many clinical situations. Besides showing didactic and research utility, they may also have a clinical role. Although a considerable amount of scientific literature has been published related to QEEG, many controversies still subsist regarding its clinical utilization. Clinical applications are: 1. DEEG is already an established substitute for conventional EEG, representing a clear technical advance. 2. Certain QEEG techniques are an established addition to DEEG for: 2a) screening for epileptic spikes or seizures in long-term recordings; 2b) Operation room and intensive care unit EEG monitoring. 3. Certain QEEG techniques are considered possible useful additions to DEEG: 3a) topographic voltage and dipole analysis in epilepsy evaluations; 3b) frequency analysis in cerebrovascular disease and dementia, mostly when other tests have been inconclusive. 4. QEEG remains investigational for clinical use in postconcussion syndrome, learning disability, attention disorders, schizophrenia, depression, alcoholism and drug abuse. EEG brain mapping and other QEEG techniques should be clinically used only by physicians highly skilled in clinical EEG interpretation and as an adjunct to traditional EEG work.

Age-and height-dependent changes of amplitude and latency of somatosensory evoked potentials in children and young adults with Down's syndrome

Middle-latency somatosensory evoked potentials (MLSEPs) were recorded from 19 scalp electrodes in 34 patients with Down's syndrome (DS) aged 7.4 to 35.7 years and in 16 normal control subjects aged 6.4 to 34.4 years. DS patients showed an increase in amplitude of P22, P45, and N60. P100 latency was significantly shortened. After normalization for height of subjects, N20 and N60 latencies were significantly longer in the patient group than in control subjects. On the other hand, it was possible to observe in both groups a significant trend for MLSEP amplitudes to decrease with age during the age period considered in this work. This study further confirms that the pattern of increase in amplitude of MLSEP components observed in DS is a finding peculiar of this syndrome and is not correlated with early aging processes.