Biomedical subjects
Publications and source records attributed to E Niedermeyer.
Respiration-linked spindles are frequently recorded from nasopharyngeal electrodes and these have been reported to represent neuronally generated limbic activity. Evidence is presented from sphenoidal and nasopharyngeal recordings suggesting that these spindles are artifactual, due to unstable electrode contacts that record palatal vibration during partial airway obstruction.
This EEG study is based upon pediatric material (0--5 years) of an institution for handicapped children (983 records, 798 children) and a teaching hospital (956 records, 643 children). In records read as abnormal, stress was laid on the degree of abnormality. A grading system of abnormality was consistently employed and facilitated the quantification of EEG abnormalities. The following grades were used: minimally abnormal, slightly abnormal, moderately abnormal, abnormal and very abnormal. The age of the children was broken down as follows: 0--3 months, 4--6, 7--9, 10--12, 13--15, 16--18, 19--21, 22--24, 25--30, 31--36, 37--42, 43--48, 49--54 and 55--60 months. It was found that minor EEG abnormalities (minimally to moderately abnormal) were scarce in the age range from 0--21 months. The rariety of such minor abnormalities proved to be statistically highly significant. A breakdown into epileptic and non-epileptic conditions did not yield much additional information. This could be due to a limited number of EEG responses (with lack of fine intermediate nuances of abnormality) to cerebral impairment below the age of 21 months. It is also possible, however, that further progress in the field of clinical-electrical correlations can demonstrate the mildly abnormal character of certain patterns (hitherto regarded as normal).
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We report a 69-year-old patient, a chronic diabetic, who had a cardiac arrest after myocardial infarction. In the state of acute anoxic coma, massive myoclonic jerks occurred, and it was found that myoclonus could be elicited by light touch of the right trigeminal area (but of no other body region). The myoclonus was associated with complex EEG discharges against an almost flat background of activity. Findings of the autopsy showed cerebral edema with bilateral uncal herniation and prominence of the right cerebellar tonsil. Stimulus-sensitive myoclonus based on proprioceptive stimuli has been reported in chronic postanoxic states. This type of somatosensory elicitation seems to be extremely rare. We discuss the neurophysiological substratum; it is presumed that the cortex was still reached by the somatosensory stimuli.
Computerized axial tomography (CAT) in 38 patients with Lennox-Gastaut syndrome showed normal findings in 20 patients and abnormalities in 18; diffuse cerebral atrophy (8) was the most common abnormality. These findings are not basically different from those recently reported by Gastaut and Gastaut (1976). Emphasis is laid upon age and possible increase of diffuse abnormalities with advancing age. The observation of 2 cases with cerebellar atrophy is also discussed.
In 53 chronic epileptics with severe EEG abnormalities and under treatment with barbituric anticonvulsants, little or no fast activity was found in 44 patients. The serum concentration level (mostly phenobarbital) was in the therapeutic range in 11 and in the excessive range in 14 patients while no levels were obtained in the remaining 19 patients. Despite the lack of drug-induced fast activity, fast repetitive spike discharges and seizures with prolonged fast spike activity were demonstrated. The absence of the fast drug response is regarded as a sign of serious cerebral impairment due to the severity of the epileptic condition. The latter could be further enhanced by toxic drug levels.
Petit mal absences in childhood are often followed by grand mal seizures in adolescence and a coexistence of both types of seizures is not uncommon at all. It is noteworthy, however, that such a coexistence does not imply immediate transition from one type of seizure into the other one. Hence, a grand mal attack may be prepared by all sorts of focal seizures, psychomotor automatisms or bilateral-synchronous myoclonus but immediately preceding petit mal (with generalized spike-wave discharges) is probably extremely rare. The presented case is characterized by unusually late onset of petit mal and grand mal seizures at age 32 and, following a mild head injury, a few episodes of petit mal status (ictal stupor) at age 52. At that time, a series of petit mal absences and eventually a smooth transition from petit mal to grand mal could be recorded. Uncommon frequency characteristics (especially some interspersed spiking at a rate of 9-15/sec) were found at the onset of the ictal spike-wave activity during the petit mal absences. This is regarded as the expression of failing inhibitory mechanisms which generally prevent the immediate development of a grand mal out of a petit mal absence.
Childhood epilepsies (not including the first 2 years of life) are outlined and discussed; particular emphasis is laid upon the variety of certain forms of epileptic conditions and their clinical course. These forms are divided as follows: a) The Lennox-Gastaut syndrome: a poly-etiological condition with distinct clinical-ictal and electroencephalographic characteristics, mostly associated with mental defects and prognostically unfavorable. b) "Common generalized epilepsy" (also called "centrencephalic" epilepsy), characterized by petit mal absences or a combination of petit mal and grand mal and with a predominantly favorable prognosis. c)Childhood epilepsies with focal spikes in the EEG, in most cases a very benign form with an excellent prognosis. These 3 forms of seizure disorders may be divided in subgroups. The distinction of fine diagnostic nuances is quite helpful but requires well integrated epileptological and EEG experience. The special role of temporal lobe epilepsy is briefly discussed. Furthermore, several etiologies of childhood etiologies are singled out such as inborn errors of metabolism (lipidoses, amino-acidurias), essential hereditary myoclonus epilepsy, tuberous sclerosis, Sturg-Weber's disease, encephalitis, brain tumor and brain abscess. The fringe of the seizure ("borderland of epilepsy") is briefly delineated.
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Five patients with acute anoxic episodes requiring resuscitation, with coma and development of epileptic manifestations are reported. Myoclonic types of seizures were predominantly seen in these cases. Rhythmical or burst-like generalized-synchronous spike discharges represented the most common EEG correlate of the epileptic activity. In one patient, a suppression-burst-like pattern was temporarily seen. The two youngest of the patients survived and there was remarkable recovery in spite of the persistence of myoclonic jerking. Stress is laid upon the distinction between tonic brain-stem release phenomena (with concomitant flat or featureless EEG tracings) and authentic epileptic activity in association with spike discharges in cerebral anoxia.
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