Petit Mal Absence Research Articles

Visual and auditory evoked responses during penicillin-induced generalized spike-and-wave activity in cats.

In 13 healthy adult cats chronically implanted with parasagittal electrodes applied to the dural surface, curarization was performed and baseline recordings of the visual evoked response (VER), auditory evoked response (AER), and brainstem auditory evoked response (BAER) were made. Following the procedure of Prince and Farrell (1969), the animals were then given intramuscular doses of 300,000 to 500,000 U/kg of penicillin with the subsequent development of diffuse, bilaterally symmetrical, photosensitive spike-and-wave discharges in the EEG from 1 to 1 1/2 hr later and concomitant facial myoclonus, arrest of movement, and "absence-like" staring in non-curarized animals. The VER, AER, and BAER were monitored at 15-min intervals for several hours during which time the VER consistently decreased in amplitude up to the time at which the first spike-and wave bursts could be elicited by photic stimulation, approximately 1 hr after injection, after which all early components (0-200 msec) of the VER were progressively increased from 150 to 300% until spontaneous spike-and-wave bursts were consistently recorded (1 1/2-2 hr). Coincident with this change, a marked increase in late components (200-500 msec) was also observed. Both th early diminution and later augmentation of the VER were equally observable in visual and nonvisual cortex. Changes in the AER were also recorded with the development of this model, and were similar to those of the VER but of a lesser degree. The amplitudes of waves I through V of the BAER were found to increase from 28 to 88% maximal at 1 1/2 hr following penicillin injection. These data and the similarity of this model to human petit mal epilepsy argue against increased inhibitory impulses to the visual system during the ictal discharge being responsible for the subjective loss of visual information during petit mal absence. If the amplitude of the evoked response is directly related to the functional integrity of a sensory system, this suggests that the impairment of sensory input, or absence, during spike-and-wave paroxysm is due to interference with sensory processing rostral to the brainstem ascending auditory pathway, and probably does not occur in primary sensory cortex but rather in cortical or subcortical association tracts.

Immediate Transition from a Petit Mal Absence into a Grand Mal Seizure

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.

Differential diagnosis of dizziness (author's transl)

The common denominator of the different meanings of dizziness is a disturbance of spatio-postural orientation, which indicates an imminent danger of fall. Höhenschwindel (fear of hights) with grasping and holding in the primate is instinctive behavior caused by a visual cliff or sudden dizziness. Because of the many possible meanings of dizziness, the case history is important for differential diagnosis. Vertiginous and non-vertiginous dizziness, black out and unsteady gait without vertigo should be distinguished. In addition, the duration and time course of the attack, releasing mechanisms and accompanying symptoms of dizziness should be explored. In recurrent dizziness without hearing loss, vestibular, vascular, cardial and epileptic disorders should be considered as well as intoxication, cerebral tumor, cerebellar hemangioblastoma, multiple sclerosis, neurosis and psychosis. Epileptic dizziness occurs not only in the prodromal stage of grand mal attacks and in temporal lobe epilepsy, but also in petit mal absences of short duration (less than 5 s) in which the blurring of consciousness is not apparent; absences of short duration are easily overlooked in childhood. Besides the objective history obtained from the patient's relatives, EEG-recording when falling asleep in the morning after one night of sleep deprivation are the best means for the diagnosis of epilepsia. Spontaneous nystagmus after complete exclusion of visual fixation is a physiological phenomenon. For differential diagnosis between physiological and pathological spontaneous nystagmus, Frenzel's spectacles in the dark room are indispensable. The distinction of spontaneous nystagmus in the narrower sense, gaze nystagmus and fixation nystagmus is discussed. The diagnostic importance of the direction of nystagmus is mentioned. Jerking nystagmus may be congenital. Pendular nystagmus may be acquired. Therefore, additional criteria for the differential diagnosis between congenital and acquired nystagmus are necessary.

Treatment of epileptic seizures with clonazepam. A reappraisal.

The therapeutic efficacy of orally administered clonazepam has been evaluated in 32 epileptic patients, with substantial improvement in 22. The drug is active in all types of seizures, particularly in myoclonus, petit mal absences, and partial complex epilepsy; it seems the drug of choice in generalized infantile organic epilepsy, although the treatment of these patients is still unsatisfactory. In some patients, the drug seemed less effective after months of therapy. Drowsiness is the main side effect.

Focal abnormality in petit mal epilepsy Intracranial recordings and pathological findings

SUMMARYThe various sites of origin for the 3-cps symmetrical synchronous spike-wave discharge associated with petit mal epilepsy have been reviewed. Three clinical cases are reported in detail, in one of which chronic intracranial sub-temporal electrodes demonstrated a mesial temporal focus. Pathological findings are reported from 2 children with bilateral spike-wave paroxysms in the EEG, both of whom had clinical attacks of petit mal absence, and 1 of whom, in addition, displayed gelastic seizures and precocious puberty. Compression of brainstem structures by neoplasm was demonstrated in both. The evidence for a restraining influence of ascending brainstem pathways on the development of bilateral synchrony and for central or cortical genesis of the bilateral spike-wave discharge is reviewed. Possible impairment of the anatomical and biochemical integrity of ascending midbrain inhibitory systems by lateral brainstem compression during mesial temporal herniation associated with elevated intracranial pressure is considered as a possible predisposing factor in bilateral spike-wave discharge.

Photomyoclonic response of epileltic and non-epileptic subjects during wakefulness, sleep and arousal

1. 1. The clinical photomyoclonic response (PMR) of eleven photosensitive epileptic patients and two non-epileptic subjects was studied by polygraphic EEG and ultraviolet apparatus recording of single responses and by computer summation. The responses spread after single light flashes over the deltoid, biceps, forearm flexors, quadriceps and gastrocnemius muscles with latencies of about: 61, 64, 65, 83 and 95 msec respectively. Agonists and antagonists contracted almost simultaneously. 2. 2. These latencies are virtually identical to those of the sub-clinical physiological reflex described by Bickford as the “photo-motor response”. The PMR is considered as an enhancement of it. 3. 3. In NREM sleep, following arousal from NREM sleep and during REM sleep, the PMR and the photoconvulsive response were diminished. Following arousal from REM sleep they were less diminished and quickly became those of wakefulness. 4. 4. In patients with petit mal absences and petit mal myoclonus, arousal from NREM sleep, unlike that from REM sleep, provoked prolonged myoclonus associated with EEG poly-spike and wave discharges while the PMR and PCR remained suppressed.

VARIABLE MANIFESTATION OF PETIT MAL ABSENCE A CLINICAL AND ELECTROENCEPHALO-GRAPHICAL STUDY

Summary One thousand epileptics were examined clinically and electroencephalographically. From these, 24 cases of petit mal absence confirmed by the examinations were studied. A certain correlation between age and frequency range of the 3 c/sec complexes was observed. Over half of the subjects showed some variations from typical or pure petit mal absence and asymmetries of the complex patterns and of the motor manifestations were noted. Mechanisms of pathophysiology in these cases with atypical petit mal absence were discussed.

THE SO-CALLED EPILEPTIC EEG AND ITS CLINICAL CORRELATION A GENERAL SURVEY FROM THE 1,200 AUTO-EXPERIENCED CASES*

Summary The results of the findings obtained from EEGs of the 1,200 cases with definite epilepsy were summarized as follows: 1) The synthetic interpretation proved that the approximately normal cases accounted for 4%, the borderline-abnormal for 6% and the definitely abnormal for 90%, thereby seizure discharge was observed in 85% of the total number of cases. 2) Dysrhythmia in respect to the basic activity was observed in half of the cases, which was verified also by the EEG auto-analyser. 3) With regard to the abnormal EEG-findings, the non-focal diffuse findings were perceived in 15% of the cases, the so-called centrencephalic type in 30%; and the focal signs in 55%. Moreover, in 95% of the latter, the existence of either the areal or discrete foci were confirmed in 85%. 4) Concerning seizure discharge, it appeared in 96% of the abnormal EEGs, and the ratio of the focal to the non-focal was 3:2. It also appeared in the following decreasing order: spike-&-wave complexes spikes; the other patterns were very scanty. 5) As for the distributions of the foci, the following numerical order was obtained: the temporal the occipital; only the last two were sparse in number. 6) Abnormal EEG-findings appeared in 50% of the resting record, but were increased to 90% by activations, thus the significance of activating techniques was presumed. 7) In regard to the relations between clinical seizure patterns and EEG-findings, there existed a definitely positive correlation between petit mal absence and/or automatism and rhythmic 3 c/s spike-&-wave complex. And, as for the other patterns, the centrencephalic type was usually observed in cases of both generalized convulsion and the petit mal group, and the focal signs (especially the temporal ones) almost always in both the focal seizure group and the psychomotor seizure group, and the multiple spikes for the most part in cases with both myoclonic seizure and massive myoclonic seizure. However, it seems to be difficult to introduce any definite and uniform relation according to the each seizure type unitarily. 8) In clinical EEG-examination, even in the case of epilepsy, a generalized or multi-dimensional interpretation using systematic procedures, including application of activating techniques, is yet necessary.