A. Earl Walker: neurosurgeon, neuroscientist, and epileptologist.
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Epilepsy↗
Biomedical subjects
E Niedermeyer
Publications and source records attributed to E Niedermeyer.
[Subacute encephalopathy with seizures in chronic alcoholism].
We report a case of subacute encephalopathy with seizures in chronic alcoholism (age 34 years). This syndrome clearly differs from the known neurological complications of chronic alcoholism. One of the authors has observed (and reported) such cases in the Baltimore area. Subacute encephalopathy is characterized by lethargy, confusion and neurological deficits such as hemiparesis, homonymous hemianopsia and aphasia. Epileptic seizures (generalized tonic-clonic, focal) are obligatory. The EEG shows very prominent slowing and periodic lateralized paroxysmal discharges (PLEDs). The condition is complicated by a variety of internal-medical complications. Structural neuroradiological tests are either normal or irrelevant. The cause and pathogenesis remain obscure. The subacute course ends with gradual resolution.
Adult↗
Dextromethorphan and high-dose benzoate therapy for nonketotic hyperglycinemia in an infant.
To test the hypothesis that nonketotic hyperglycinemia causes overstimulation of the excitatory N-methyl-D-aspartate receptor by allosteric glycine activation, and that reduction of glycine and blocking of the cation channel coupled to the receptor would be beneficial, we administered benzoate and dextromethorphan, a blocker of the N-methyl-D-aspartate channel to an infant with nonketotic hyperglycinemia. Therapy with benzoate, 500 mg/kg per day, was started on day 5, and the dosage was increased to 750 mg/kg per day on day 8, with prompt normalization of the neurologic and electroencephalographic findings. The glycine concentrations in both plasma and cerebrospinal fluid were substantially reduced. Dextromethorphan was added to the regimen on day 12. The electroencephalogram remained normal until the infant was 8 months of age, when diffuse slowing became apparent. Serial brain magnetic resonance imaging showed delayed myelination. At 12 months of age, physical examination findings and growth were normal except for hypotonia. The developmental quotient was approximately 60, and the child was free of seizures. This outcome, although not ideal, is better than that typical for nonketotic hyperglycinemia. Our results suggest that trials with additional patients and other N-methyl-D-aspartate cation channel blockers are warranted.
Benzoates↗
Asymptomatic HIV infection does not cause EEG abnormalities: results from the Multicenter AIDS Cohort Study (MACS)
We conducted EEG testing in 200 asymptomatic homosexual men, half of whom were HIV seropositive. We chose to include half of the subjects because they were rated as impaired on a neuropsychological screening test. We used both traditional visual EEG interpretation and quantitative EEG analysis. Abnormal EEGs and borderline degrees of EEG slowing occurred in 32% of these men. These EEG changes were not related to HIV serostatus. EEG changes did correlate with the impaired neuropsychological test performance. Clinicians faced with abnormal EEG results or borderline EEG slowing in an asymptomatic HIV-seropositive patient should not attribute the EEG change to effects of the serostatus itself but should look for other causes.
Acquired Immunodeficiency Syndrome↗
Electroencephalogram and seizures in chronic alcoholism.
CNS complications of chronic alcoholism are frequently difficult to assess due to the variety of direct and secondary conditions which can result from alcoholic drinking and lifestyles. The influence of alcoholism and alcohol-related factors on the EEG of patients with chronic alcoholism was studied in 213 patients (15.4% of all adults who had EEGs) using visual analysis. The influence of a variety of alcohol-related factors - drinking history, clinical complications, traumatic head injuries, head CT findings and laboratory results - on the EEG and alcohol-related seizures was studied. The effect of EEG results on the decision to treat alcohol-related seizures was also assessed. 152 of the patients had seizures, mostly (90% of those with defined seizure types) generalized tonic-clonic seizures. 53% of all seizures occurred in the early withdrawal period (8 h to 7 days abstinence). A history of partial seizures was significantly associated with findings of focal EEG abnormalities, a history of head injuries and structural lesions on CT. The clinical significance of these findings was unclear, however, as the majority of patients who had focal EEG abnormalities or structural brain lesions still appeared to have generalized withdrawal seizures. The EEG and CT appeared to be complementary tests: for most patients, focal abnormalities were demonstrated on only one of the two tests. The majority of patients (56%) with normal EEGs had predominantly low voltage recordings (less than 25 muV), compared with 13.9% of 1167 patients without a history of alcoholism (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗