Biomedical subjects
Publications and source records attributed to A J Rowan.
We evaluated daytime (6- to 8-hour) intensive monitoring in a consecutive series of 166 studies. Overall success rate in answering clinical questions posed by referring physicians was 67%, and attacks were recorded in 55%. Daytime intensive monitoring provides a useful, cost-effective alternative to prolonged inpatient monitoring and ambulatory monitoring.
We studied a man with repeated seizures characterized by deviation of the head and eyes to the left. A right occipital focus was demonstrated in the EEG. Adversion is usually associated with frontal or temporal lobe seizures; the direction of adversion is equally likely to be ipsilateral as contralateral to the ictal focus. In all reports of occipital epilepsy, the ictal focus has been contralateral to the direction of head turning.
We document a case of isolated epileptic aphasia with clear correlation between episodic clinical and electrographic events. This disorder is rarely recognized, perhaps because it is obscured by ictal motor activity or speech arrest, or by the lack of clinical manifestations if the seizure occurs when the patient is not attempting to speak.
Five patients had absence seizures refractory to treatment with either ethosuximide or valproate sodium. To determine their response to combination therapy with the two drugs, four of the five had serial 24-hour intensive monitoring studies that included cable telemetric EEG recording, closed-circuit television observation, and frequent antiepileptic drug (AED) serum level determinations. The resultant data confirmed the clinical and EEG effects of serial alterations in AED programs. All five became seizure free with combination therapy. Combination therapy with ethosuximide and valproate should be considered in patients whose absence seizures do not respond to standard therapeutic measures.
Epilepsy, one of the oldest identified neurological disorders, is now recognized as a major public health problem affecting about 1 percent of the population. The author differentiates between two major types of the disorder, the generalized and partial epilepsies, and describes different kinds of seizures in epileptic patients. The improved ability of the clinician to diagnose the disorder through use of electroencephalography, intensive monitoring, and CT scan is highlighted. The author concludes with a discussion of the major drugs used to control seizures, their biological half-lives, side effects, and how they interact with other antiepileptic drugs.
The comparative value of sedated sleep and sleep deprivation EEGs was investigated in a consecutive series of 43 patients who had received both types of activation study for diagnostic purposes. Patients were referred because of persisting doubt concerning either the diagnosis of epilepsy, or the type of epilepsy present in those with definite seizures. Forty-one had had routine waking EEGs, all of which were normal or only mildly abnormal. EEGs were rated without access to previous reports or clinical data, and epileptiform discharges (ED) were semiquantified during wakefulness and sleep. De novo precipitation of ED, increase in abundance of ED and discovery of a new independent focus or a new type of ED were taken as the yield of useful information. 44% of sleep deprivation records provided useful information compared to 14% of sedated sleep recordings (P less than 0.005). In addition, sleep deprivation was significantly superior to sedated sleep in differentiating those with a final clinical diagnosis of epilepsy from those with doubtful or no epilepsy (P less than 0.001). It is suggested that the usefulness of the interictal EEG in patients with uncertain epilepsy or epilepsy of unknown type is increased by performance of a diagnostic series to include routine waking, sedated sleep and sleep deprivation recordings.
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We report a clinical evaluation of EEG and video monitoring. In 181 consecutive records, the most common clinical indications were differentiation of epileptic and nonepileptic events (99), seizure recordings for locating a possible focus (23), seizure frequency determination (32), and investigation of possible trigger factors (19). Overall, useful information was obtained in 72% and the clinical question was answered in 67% of records. Prolonged EEG and video monitoring is therefore an important diagnostic aid in patients with proven or suspected epilepsy.
Two groups of long-stay mentally subnormal epileptic patients, those with a chronically high seizure frequency and those who had become seizure-free, were studied for clinical and EEG factors relating to the prognosis of seizures. The mean period of observation was 20 and 22 years, respectively. All patients had a detailed clinical examination including psychometric testing, and for each, two EEG records were selected for blind semi-quantitative interrater analysis: an admission EEG and an EEG obtained within 6 months of the start of the study. Early onset of seizures, a high initial seizure frequency, multiple seizure types, upper motor neuron signs, and severe mental retardation characterized the seizure group. Significant admission EEG findings in this group included an absence of posterior dominant rhythmic activity, generalized delta activity, and frequent generalized paroxysmal discharges. Results of a linear discriminant analysis confirm that the admission EEG and clinical findings provide a basis for predicting outcome with a reliability on the order of 80%.
The acute effect of a single oral dose of sodium valproate on the photoconvulsive response has been studied. In 7 of 9 patients naive to this drug photosensitivity was abolished or reduced. A similar effect was seen in only 2 of 7 already receiving chronic sodium valproate therapy. The effect appeared 1 to 5 hr (mean, 3 hr) after attainment of peak sodium valproate concentration and lasted up to 5 days.
The clinical and electroencephalographic (EEG) effects of sodium valproate were studied in four patients by means of serial 24-hour EEG recordings and simultaneous hourly determinations of serum drug concentrations. The patients all had frequent clinical seizures and generalized spike-wave discharges. Valproate appeared to reduce diurnal paroxysmal discharges (PD) and clinical seizures, but the effect on nocturnal PD was less marked. The extent and duration of the depression of PD and seizures varied. Altering the distribution of the total daily dose may change the pattern of clinical seizures and PD. Valproate concentrations fluctuated widely over 24 hours, and the significance of single estimations often cited in the literature appears dubious. Peak serum concentrations above 100 micrograms per milliliter may be necessary in some patients to achieve clinical and EEG improvement.
We studied 10 patients with transient global amnesia (TGA). Routine electroencephalograms (EEGs) were normal in six; two showed mild temporal lobe abnormalities, one had bitemporal delta activity with rare sharp waves, and one showed bioccipital rhythmic theta activity. Nasopharyngeal (NP) recordings were obtained in seven patients; five showed independent mesial temporal spike discharges during drug-induced sleep. The discharges are probably due to transient ischemia in deep temporal structures.
In two pediatric patients with the clinical picture of basilar artery migraine, transient electroencephalographic disturbances were seen. Both children manifested posterior rhythmic delta activity in close temporal proximity to their attacks. Resolution of these abnormalities was documented by serial electroencephalographic tracings. These electroencephalographic findings are consistent with transient dysfunction in the neural structures supplied by the basilar artery and its branches. Pediatric patients in whom there is a clinical picture of basilar artery migraine and who have a family history of migraine and transient electroencephalographic changes of the type herein described need not undergo invasive neurodiagnostic study.
Four (possibly five) boys are described with a profound comprehension deficit for acoustic language, leading to severe or complete abolition of expressive speech. One boy had presumed megalencephaly from birth but was of superior intelligence. He had a severe articulation deficit from early childhood, with delayed acquisition of speech. Another boy is thought to have a small angiomatous anomaly in the depth of the left parietal lobe. No brain lesions are known in the other three. Evidence for bilateral brain dysfunction consists of minor motor abnormalities in three boys, oromotor deficits in two boys, and bilaterally synchronous diffuse or independent focal paroxysmal discharges in the EEG of three, possibly four, of the boys. Seizures have occurred in only three boys, and have been easily controlled with anticonvulsants. One boy with a grossly abnormal EEG has had no clinical seizures to date and has not benefited frome one year of anticonvulsant therapy. Two of the boys are brothers, including the boy in whome the diagnosis is questionable since speech was never normal and since he has had neither seizures for an abnormal EEG. The severity of EEG abnormalities did not correlate closely with the course of the language deficit. The relationship of this syndrome to acquired aphasia in children, to Wernicke's aphasia and pure word deafness in adults, and to developmental lagnuage disability with predominantly receptive deficits, is discussed. One child illustrated the close association between writing and phonologic encoding and decoding operations, and two children the preservation of linguistic skills provided the acoustic channel was by-passed and language presented visually. This latter point has been emphasized because of its implications for the remedial education of children with this syndrome.
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Current methods permit frequent, accurate serum anticonvulsant drug concentration measurements and continuous, 24-hour electroencephalographic recording with minimal environmental restriction. These techniques were used to perform longitudinal, 24-hour recordings of electroencephalographic paroxysmal activity and sleep-wake state concurrently with frequent measurements of serum anticonvulsant drug concentrations in two patients with poorly controlled convulsions. Drug administration was designed with the intent of producing high serum concentrations at times of maximum electroencephalographic paroxysmal activity. The suppression of clinical seizures coincided with decreased numbers of paroxysmal bursts in the electroencephalogram and increased serum anticonvulsant drug concentration.
A retrospective study comparing the EEG findings of two groups of patients with primary systemic malignant disease (mainly bronchial carcinoma) was carried out. One group of 13 patients (20 EEGs) had proven supratentorial cerebral metastases at necropsy, some also subtentorial, and the other group of 10 patients (15 EEGs) had no cerebral involvement at necropsy. The latter group was studied to assess the possible confusing effects in the EEG of metabolic derangements and other factors which would interfere with accurate prediction of the presence of metastases. The EEGs were masked and assessed independently by two raters using a special proforma. They found that recordings from patients with cerebral metastases had persistent focal delta activity, intermittent focal or local delta activity, persistent or intermittent lateralized delta activity, monorhythmic frontal delta activity in the alert patient, as well as a higher frequency of post-central background rhythms. These factors predicted the presence of cerebral metastases (when they were 2 cm in diameter or larger) in 12 out of the 13 patients (four of these without localized neurological disorder), the EEGs being taken on average eight weeks before death. It is concluded that the EEG is valuable in the investigation of these patients.
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