Rhythmic Mid-Temporal Discharges Research Articles

WS1.3. Normal EEG: Drowsiness and Sleep, and Normal Variants

The EEG in the normal awake child and adult is well known and needs to be known for proper reading and reporting and identifying an abnormal transient or pattern. The following are points of emphasis: Alpha rhythm seen after age of 5 years, Significant theta activity (4–7 Hz) is present in the EEG of children and adolescents. Delta activity in the awake tracing is rarely seen after the age of 5 years. Beta rhythm is seen anteriorly. All these will be discussed in details with traces. In the evaluation of abnormalities in the EEG, one needs to be constantly aware that there are many EEG transients that morphologically resemble epileptiform discharges and that need to be distinguished from diagnostically crucial epileptiform abnormalities to avoid overdiagnosis or misdiagnosis. These include: Artifacts: for example, electrode pop, muscle potentials, eye movements, electrocardiogram (EKG), chewing, electrical, etc. Normal components of ongoing background activity: for example, vertex sharp transients of sleep, f waves, slow wave sleep, POSTs, mu rhythm, lambda waves, drowsy activity during sleep in children that may often be associated with sharp components, etc. Epileptiform variants of dubious clinical significance: there are a large number of benign epileptiform variants that must be recognized, lest they be misinterpreted. Although morphologically similar, they are nonepileptogenic as they have no established relationship with the process responsible for generating epileptic seizures. Such sharp transients include 14 to 6 per second positive spikes, small sharp spikes or benign epileptiform transients of sleep, 6 Hz spike wave or phantom spike wave, wicket spikes, psychomotor variant pattern or rhythmic midtemporal discharges, breach rhythm, etc. Sleep not only activates diagnostically useful epileptiform EEG patterns, but also unmasks several types of nonepileptogenic sharp transients. It is necessary that anyone dedicating a career in epilepsy be well aware of these. Often reading EEG requires eyeballing and identifying patterns. The more the number of EEGs reviewed the more the possibility of not missing out normal patterns and rhythms. These will be demonstrated in various EEG epochs in the workshop.

Prolonged rhythmic mid-temporal discharges (RMTD) in a 5-year old child

Prolonged rhythmic mid-temporal discharges (RMTD) in a 5-year old child

Electroencephalographic Cerebral Dysrhythmic Abnormalities in the Trinity of Nonepileptic General Population, Neuropsychiatric, and Neurobehavioral Disorders

Electroencephalographic Cerebral Dysrhythmic Abnormalities in the Trinity of Nonepileptic General Population, Neuropsychiatric, and Neurobehavioral Disorders

Electroencephalographic Cerebral Dysrhythmic Abnormalities in the Trinity of Nonepileptic General Population, Neuropsychiatric, and Neurobehavioral Disorders

Subclinical electroencephalographic epileptiform discharges in neurobehavioral disorders are not uncommon. The clinical significance and behavioral, diagnostic, and therapeutic implications of this EEG cerebral dysrhythmia have not been fully examined. Currently the only connotation for distinctive epileptiform electroencephalographic patterns is epileptic seizures. Given the prevailing dogma of not treating EEGs, these potential aberrations are either disregarded as irrelevant or are misattributed to indicate epilepsy. This article reappraises the literature on paroxysmal EEG dysrhythmia in normative studies of the "healthy" nonepileptic general populations, neuropsychiatry, and in neurobehavioral disorders. These EEG aberrations may be reflective of underlying morpho-functional brain abnormalities that underpin various neurobehavioral disturbances.

The Continuous Rhythmic Mid-Temporal Discharge

This case report is of a 15-year-old male who was sent for an EEG because of possible staring spells and a learning disability. At times written examinations in school were successfully completed and at other times the patient would write only his name. In two EEGs 1 month apart during hyperventilation, Rhythmic Mid-Temporal Discharges (RMTD) were activated and appeared continuously for 84 minutes and in the second instance for 140 minutes. No maneuvers could modify the pattern and no clinical changes were reported by the patient. Discussion includes another similar case recently published and the need to test such patients in some way to see the subtle clinical changes that likely do occur. One compromise for the name of this pattern might be Rhythmic Mid-Temporal Epileptiform Activity (RMTEA), avoiding the term discharge, which implies a seizure state that has not yet been established.

Psychopathological changes in a patient with rhythmic midtemporal discharges after antiepileptic medication

In 1937, Gibbs et al. described rhythmic waves in the frequency range of 4-7 cycle/set during ictal “automatisms.” This pattern, also found in patients with psychomotor seizures (Gibbs et al. 1938), was called “psychomotor variant pattern” by the same authors in 1952. No agreement concerning the clinical significance of these electroencephalographic (EEG) findings was reached in the following years (e.g., Garvin 1953; Gastaut 1953; Gibbs et al. 1963; Gibbs and Gibbs 1964; Small et al. 1968). Garvin (1968) found this “psychomotor variant pattern” in 0.28% of 13,442 patients who had been referred to his EEG laboratory. Eleven of these 38 patients had psychiatric diagnoses like panic episodes, difficulties with school, behavior problem, nervousness. In another study involving 16,800 consecutive EEG recordings during a 5 l-month period, obtained in different EEG laboratories attached to general hospitals, Lipman and Hughes (1969) called the psychomotor variant pattern “rhythmic midtemporal discharges” (RMTD). This characteristic was found in 0.3% of all recordings. Of these 55 cases, 47% (26) had psychiatric disorders, with a paucity of frank psychoses (without further description). The term RMTD had been introduced because the use of the clinical term (psychomotor variant) for the interpretation of EEG has been previously discouraged (Storm van Leeuwen et al. 1966). In 1973, Hughes and Cayaffa suggested an ictal pattern for 11 patients with first evidence of RMTD. This assumption was further emphasized in a later study (Hughes and Olson 1981) involving 1000 patients who showed “temporal lobe discharges” (including RMTD) , as compared to 2000 psychiatric and normal control persons. The authors found that 33% of the RMTD group showed psychopathology, as compared to only 15%25% in all other groups; however, clinical seizures were most common (82%) in patients with anterior temporal discharges and were less frequent in those with midtemporal discharges (27%). The correlation of RMTD with psychopathology was partially reconfirmed later by

Episodic dyscontrol disorder and paroxysmal EEG abnormalities: Successful treatment with carbamazepine

Rhythmic midtemporal discharges (RMTD or psychomotor variant) and 6/set spike and wave complexes (6SW) are considered to be controversial electroencephalic (EEG) patterns because of a variable association with clinical seizures and nonspecific psychological features (Gibb et al. 1963; Garvin 1968; Thomas and Klass 1968). Many electroencephalographers consider these uncommon patterns to be normal variants (Maulsby 1979). However, numerous studies have demonstrated a positive correlation between psychiatric symptomatology and these EEG findings (Small et al. 1968; Milstein and Small 1971; Olson et al. 1971; Hughes and Hermann 1984). This article describes a patient with EEG findings of both RMTD and 6SW: psychiatric symptomatology lessened and paroxysmal EEG abnormalities abated with carbamazepine treatment.

Psychiatric correlates of rhythmic midtemporal discharges and 6/sec spike and wave complexes

In order to better characterize the psychopathology in patients with the two specific EEG patterns, rhythmic midtemporal discharges (RMTD) and 6/sec spike and wave complexes (S + W), the newly developed Diagnostic Interview Schedule (DIS) was administered to 40 patients in four groups. One group had RMTD, the other 6/sec S + W complexes; there were two control groups, both with normal electroencephalograms (EEGs), one group with, and the other without, a history of psychiatric illnesses. The RMTD group had significantly less symptomatology than the 6/sec S + W and the psychiatric control groups, but it had a significantly higher percentage of somatization symptoms; patients with 6/sec S + W showed a tfendency toward anxiety-related disorders. The psychiatric control group had no specific trends, but demonstrated more overall psychopathology than the two groups with a specific EEG pattern.

Rhythmic mid-temporal discharges in the EEG of normal children and adolescents.

Rhythmic mid-temporal discharges in the EEG of normal children and adolescents.

Unexplained electrographic temporal discharges (author's transl)

Unilateral or bilateral electrographic temporal discharges at 5 Hz were analyzed in relation to their morphological characteristics, their topography, and their evolution in II subjects. The clinical context, in which there was no evidence of epileptic disorder, was also analyzed. These discharges were compared to other infraclinical critical phenomena reported in the literature, and related to similar manifestations described by the Gibbs "school" as "Psychomotor variant type of discharge", or by Hughes group as "Rhythmic mid Temporal discharges".

Rhythmic mid-temporal discharges. An electro-clinical study

This study is concerned with a rare EEG abnormality, the rhythmic bursts of 6 and 12/sec temporal lobe sharp waves, previously known as “psychomotor variant”. This discharge is seen mainly on the mid-temporal area, and appears most often in adolescents and young adults. Seizures (36%), major motor and psychomotor in type, vegetative complaints (60%), especially headache, and psychiatric disorders (46%) were the most common symptoms seen in these patients. Compared to a group with single temporal lobe sharp waves, these patients showed fewer major motor seizures but an equal incidence of psychomotor attacks. The semiological similarity of this disorder to the 6/sec spike and wave pattern was noted. The term “Rhythmic Mid-Temporal Discharges” (RMTD) is suggested for this EEG abnormality.