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Biomedical subjects

E Niedermeyer

Publications and source records attributed to E Niedermeyer.

At least 55 records · Page 3Linked to original sources
PubMed1991

Crossover phenomena in epileptic syndromes of childhood.

Benign Rolandic epilepsy (BRE) and primary generalized epilepsy (PGE) are found at about the same period of childhood. Crossover from PGE to BRE and vice versa may occur; two short case reports provide further evidence for this development. Hence, transitions from a primarily generalized to a focal (partial) epileptic seizure disorder and vice versa is a possibility. Both PGE and BRE are based upon states of hyperexcitability, i.e. dysfunctional rather than structural abnormalities that are capable of changing their spatial distribution.

Child↗
PubMed1991

The "third rhythm": further observations.

Earlier personal observations have indicated the existence of an alpha-like rhythm in the temporal lobe. This rhythm shows no relationship to the posterior alpha and the central mu rhythm; for this reason, it may be called the "third rhythm." This activity is undetectable in scalp leads but may turn into a "breach rhythm" under bone defects. The assessment of a young adult as a possible candidate for temporal lobectomy with the use of epidural electrodes yielded an unusually good demonstration of the "third rhythm." As a matter of fact, there were two types of rhythmical alphoid activity. One of them was more anteriorly located over the temporal lobe and more prominent over the left (epileptologically chiefly involved) hemisphere. This rhythm was often visualized in the temporal scalp electrodes and was felt to be an abnormal phenomenon. The other type of rhythmical activity was maximal in the midsection of the temporal lobe, better developed on the right (epileptologically less affected) side and essentially undetectable in scalp leads. This rhythm appears to be the true physiological "third rhythm". The responsiveness of this rhythm remains unclear. Attenuation on the right side occurred while the patient was singing.

Adult↗
PubMed1991

Considerations of secondary temporalization.

In generalized forms of epileptic seizure disorder, secondary focal involvement of the temporal lobe may gradually develop. Such signs of "secondary temporalization" may manifest themselves in the seizures type (occurrence of complex partial seizures) and in the EEG. Fourteen observations of secondary temporalization are reported: 3 of them in cases of primary generalized epilepsy and 11 in patients with Lennox-Gastaut syndrome. In 9 patients, additional depth implants were carried out in order to detect a primary focal epileptogenic lesion. Secondary temporalization is likely to be caused by independent paroxysmal activity evolving in the limbic structures (amygdala, hippocampus) due to their role of "low threshold areas." Postconvulsive hypoxic damage of the hippocampus is possible but a much less likely cause of secondary temporal lobe manifestations.

Adolescent↗
PubMed1991

Awakening epilepsy ('Aufwach-Epilepsie') revisited.

The concept of 'awakening epilepsy' (introduced by Janz, 1953) occupies a crucial position for the comprehension of primary generalized epilepsy. The associated electroencephalographic manifestations are discussed and the role of abnormal (paroxysmal) arousal responses ('dyshormia') is stressed. The origin of these bilateral-synchronous discharges appears to be located below the frontal midline scalp region in mesial portions of the supplementary motor region. 'Awakening epilepsy' is also interesting from the viewpoint of sleep research. There is also an important age factor; these seizures (mostly grand mal and classical petit mal absences) are most common in older children, adolescents and young adults. The general management of these patients has to take into account the patient's special vulnerability after a night of poor sleep.

Arousal↗
PubMed1990

Further EEG observations in children with the Rett syndrome.

In four cases of the Rett syndrome (RS) (age 3 1/2, 6, 11 and 12 years), paroxysmal activity and especially spike discharges over the central region could be blocked or attenuated by passive finger movements. This response, however, is not demonstrable in the majority of children with RS. The blocking or attenuating effect of passive movements is compared with earlier observations of central spike discharges occurring in children with benign Rolandic epilepsy. In some of these children, central spikes could be blocked by active hand movements. It was assumed that such a positive blocking response underscores the "functional" ("dysfunctional") character of the Rolandic spikes and the lack of local structural damage. In children with cerebral palsy, seizures and central spike (and evidence of structural brain damage), such a blocking response was not obtainable. Taking into consideration these earlier observations, there is reason to presume that the central spike activity found in RS is based on dysfunction rather than on structural impairment.

Brain↗
PubMed1990

Spindle coma: observations and thoughts.

The occurrence of physiological patterns of NREM sleep ("spindle coma") is well known since the first major study of Chatrian et al who--like most of the authors of subsequent studies--placed particular emphasis on the etiological role of CNS trauma. Further work showed that nontraumatic causes may also result in spindle coma. This study is based upon 11 observations of spindle coma extracted from 861 patients with acute severe CNS conditions. The age of the patients ranged from 6 months to 46 years. Metabolic, infectious and hypoxic problems were the most common etiologies; there was no case of CNS trauma. It is assumed that spindle coma represents a combination (i.e. coexistence) of true sleep and coma, the latter accounting for the failure of arousal that is attributed to impairment of the activating ascending reticular formation (midbrain level). The presence of spindles (and also vertex waves and K complexes) indicates relative integrity of the cerebral hemispheres. Such a constellation is more likely to occur in CNS trauma but--as our nontraumatic patient population shows--may also materialize in other types of CNS pathology.

Adult↗
PubMed1990

Alpha-like rhythmical activity of the temporal lobe.

In addition to the classical posterior alpha rhythm and Rolandic mu rhythm, a third type of rhythmical activity in alpha- (or sub-alpha-) frequency can be recorded over the temporal lobe and especially over the midtemporal region. This rhythm usually escapes detection in the scalp EEG but is commonly seen over bone defects ("breach rhythm"). With the use of epidural electrodes, however, this rhythm becomes quite prominent and dominates the activity of the temporal lobe unless there is excessive local EEG abnormality and/or pathology. This temporal rhythm lies in the range of 6-11/sec and thus often extends into the theta frequency range. There is no proven blocking effect; this mere fact sets it apart from posterior alpha and Rolandic mu rhythm. It is essentially a rhythm of the waking state but may linger into drowsiness and even into light NREM sleep. It is also separable from the highly controversial frontotemporal "kappa rhythm" of bygone times. EEG recordings from the depth of the temporal lobe (limbic structures) do not demonstrate such a rhythm that is likely to originate from the neocortical portion. Its neurophysiological and psychophysiological significance is enigmatic.

Adult↗
PubMed1989

The electroencephalogram and mental activation.

The mental activation (MA) is a simple test consisting of two questions and two commands given during the waking record. The responses are documented by + or - sign notations made by the technologist. In this manner, data were rapidly obtained from 1280 patients; there were 598 patients with EEG records within normal limits and 682 with various degrees of EEG abnormality. The MA serves the following purposes: a. to study the repercussions of the test on the EEG activity, b. to ascertain the optimal level of vigilance, c. to attempt a correlation of MA responses and the degree of EEG abnormality and d. to obtain brief information on the patient's mental state. The test is administered during conventional EEG recordings. It was found that alpha blocking or attenuation was the exception rather than the rule during the test. Diffuse and focal slowing also remained unchanged in the vast majority of the cases, whereas focal intermittent rhythmical delta activity (FIRDA) was blocked or reduced in most patients exhibiting this pattern. Epileptic conditions were also studied and it was found that, in a single observation, even the most difficult part of the test (item D: mental arithmetic) could be carried out during ictal-subclinical regional EEG activity.

Adult↗
PubMed1988

Post-hypoxic action (intention) myoclonus: a clinico-electroencephalographic study.

A patient with post-hypoxic action myoclonus classified as reticular reflex myoclonus was subjected to an electrophysiological investigation. The myoclonic movements involved mainly the legs but could also affect the whole body. Somatosensory evoked responses were not increased and electroencephalography (EEG) was normal when the patient was relaxed. Startle, self-paced movement or movement on command induced repetitive myoclonic jerks preceded and accompanied by repetitive small spikes in the EEG with phase reversal in the midline at the vertex or slightly posterior to it, regardless of the limb moved. The central spiking subsided considerably earlier than the myoclonic jerks as shown by polygraphic recordings. The EEG spikes were also provoked by mere imagination of movement and persisted in spite of a dramatic reduction of myoclonic activity after treatment with clonazepam. The observations suggest that the vertex spiking in post-hypoxic action myoclonus indicates synchronous cortical activation, but is not closely coupled with activation of the Betz cells of layer V where the pyramidal pathway originates.

Aorta, Abdominal↗
PubMed1987

Depth EEG studies in the Lennox-Gastaut syndrome.

Depth EEG recordings were carried out in 16 patients with clinical and EEG evidence of the Lennox-Gastaut syndrome (LGS), in attempts to identify a surgically-resectable focus. Structures explored included the mesial temporal (amygdaloid) areas, the orbito-frontal cortex, the superior parasagittal cortex, and in three cases deep cerebellar nuclei. All patients showed disordered and slow background activity in depth leads. Slow spike-waves were prominent in orbito-frontal and parasagittal frontal areas, but were generally reflected as well in surface frontal leads. Runs of rapid spikes were recorded in 7 patients, again mainly in deep frontal leads. Independent interictal spikes were observed in 9 patients, chiefly from one or both amygdaloid areas. Ictal events were recorded in 9 patients. Frontal lobes were most often involved at the start, and a few cases showed origin of apparently generalized surface activity beginning unilaterally in deep frontal lobe. None of the identified interictal nor ictal foci were sufficiently dominant to justify local surgical resection. Frontal bilateral synchrony, when present, was adequately visualized by noninvasive surface EEG recording. Depth electroencephalography in our hands therefore has a very limited role in evaluation of patients with LGS.

Adolescent↗
PubMed1987

Temporal minor slow and sharp EEG activity and cerebrovascular disorder.

The clinical significance of temporal minor slow and sharp activity (TMSSA) is discussed on the basis of earlier literature and personal observations (209 patients, 227 EEG records). This pattern consists of mixed 2-7/sec and 8-14/sec activity with intermingled minor sharp transients (occasionally even frank spikes) over the anterior temporal-midtemporal region and, in the vast majority (84% in our material) predominantly on the left side. This pattern is most prominent in early drowsiness, and may change to rhythmical spiky discharges in light NREM sleep ("wicket spikes"). The origin of TMSSA is unclear. There is reason to believe that hippocampic ischemia might be the underlying substratum but the evidence remains tenuous. Vertebrobasilar artery insufficiency states may result in TMSSA since the hippocampus largely depends on this vascular system (via posterior cerebral artery). The occurrence of TMSSA usually represents a mild abnormality of potentially considerable clinical significance.

Adult↗
PubMed1986

Rett syndrome and the electroencephalogram.

The EEG is almost always abnormal in patients with Rett syndrome. This is demonstrated in a study based upon 230 EEG records obtained from 44 patients. Rhythmical slowing (mostly 3-5/sec) represents the most common EEG abnormality (30 patients). Diffuse, scattered or bilateral-synchronous spikes or sharp waves were found in 22 patients. Slow spike-wave complexes were present in 9 patients. With advancing age, the EEG abnormalities tend to decline and ill-defined low voltage records may develop. These changes may parallel an intrinsic disease course with an early active phase followed by a phase of residual impairment.

Brain↗
PubMed1986

Acquired epileptic aphasia. Diagnostic aspects of progressive language loss in preschool children.

A case of acquired epileptic aphasia presenting as language delay and hyperactivity is presented and clinical aspects reviewed. Acquired epileptic aphasia is a diffuse neurologic process of unknown etiology that presents in preschool children. Although progressive language loss and seizures are the major manifestations, deficits in attention and socialization may be noted. The electroencephalogram is usually diagnostic. While almost all (80%) children develop seizures, approximately half present as language delay without seizures. Recognition of the progressive and global nature of the language dysfunction may permit earlier diagnosis and intervention.

Aphasia↗
PubMed1986

The Lennox-Gastaut syndrome and its frontiers.

After a brief discussion of the historical aspects of the Lennox-Gastaut syndrome, the electroencephalographic, epileptological and other clinical characteristics are presented. This severe and almost intractable seizure disorder must be distinguished from a variety of other epileptic conditions which may electroencephalographically mimic the Lennox-Gastaut syndrome.

Adult↗
PubMed1985

Epileptic seizure disorders. Developments in diagnosis and therapy.

There has been considerable progress in various segments of epileptology over the past two to three decades. The diagnostic sector has benefited from more advanced and sophisticated EEG-related techniques. The advent of computerized tomography has expedited the clinical evaluation of epileptic patients and new high-technology methods have been introduced. A new type of diagnostic subdivision (based on age-determined epileptic conditions and certain epileptic syndromes) is of great practical significance because of its prognostic implications (distinction of basically benign and severe forms of epileptic seizure disorders). The therapeutic sector has been stimulated by the introduction of new antiepileptic medications and particularly by profound insights into metabolic and pharmacokinetic characteristics of anticonvulsants; this has resulted in the introduction of techniques for serum level determinations. There have been new developments in the field of neurosurgical treatment of epileptic seizure disorders.

Anticonvulsants↗
PubMed1985

Sleep spindles.

Sleep spindles are discussed from various viewpoints. The definition of this pattern has been debated and requires clarification. There is evidence of two spindle types around 14 c/s and 12 c/s. The existence of a third spindle type (around 10 c/s) is controversial. The relationship of spindles to vertex waves and K complexes and the role of spindles in sleep staging are other topics that are covered. As "transient nonstationarities," spindles may escape methods of EEG computer analysis; special methods of spindle detection have been designed. Spindle activity may be influenced by various sedative drugs. An exceptional coexistence of spindles and waking patterns may occur in patients with 5-HIAA-hypersomnia. Sleep spindles change with age and show a typical configuration in early childhood; their decline in old age is also discussed. In monkeys and apes, "natural" spindle activity declines after adolescence. The distinction between natural and experimentally induced (barbiturate) spindles in animals must be stressed. After a discussion of spindle anomalies in neurological diseases, depth EEG data are presented. Spindles are found in the frontal cortex, whereas the scalp EEG indicates light drowsiness or even wakefulness. Attempts are made at an integrated view of these findings. A "shock-absorbing" function is attributed to spindles.

Adolescent↗
PubMed1985

Frontal intermittent rhythmical delta activity and anterior bradyrhythmia.

Rhythmical intermittent delta activity was found in 162 patients (out of a total of 5,542 patients; i.e. 2.9%). The typical features of frontal rhythmical intermittent delta activity (FIRDA) were noted in 105 patients while in 43 the pattern of anterior bradyrhythmia (AB) was present. Mental decline with delirium or dementia was the most common clinical correlate in cases of FIRDA, whereas cerebrovascular disorder represented the by far most frequent etiology in cases of AB. The patient group with AB proved to be older than the population with FIRDA. Stress was laid on the distinctive EEG features of FIRDA and AB as well as their relationship to the level of vigilance. FIRDA invariably showed a maximum over the frontopolar region whereas AB was maximally developed either over frontopolar or over superior frontal areas. There is reason to presume that a superior frontal maximum is related to arousal mechanisms (with input into the supplementary motor zone). On the other hand, it is hypothesized that the frontopolar maximum of FIRDA reflects thought processes in a frontal lobe with compromised circulation.

Adolescent↗