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Biomedical subjects

R J Porter

Publications and source records attributed to R J Porter.

At least 73 records · Page 4Linked to original sources
PubMed1986

Recognizing and classifying epileptic seizures and epileptic syndromes.

The appropriate diagnosis of the patient with epilepsy is first dependent on a determination of the type of seizure. When the type of seizure has been determined, consideration must be given to the nature of the epileptic syndrome, including concerns regarding the etiology of the attacks. The gradual evolution of the various classification schemes of epileptic seizures and epileptic syndromes complicates the task of the physician but also affords evidence of the dynamism extant in clinical epilepsy research. Intensive monitoring will assist not only in the diagnosis of the individual patient but also in the long-term re-evaluation and revision of the empirical classifications.

Electroencephalography↗
PubMed1985

The clinical value of free phenytoin levels.

The relationship between total and free phenytoin levels and drug toxicity was studied in 80 patients. Twenty-four were taking phenytoin alone. Drug toxicity was assessed by a "blind" rater using an eight-point standardized scoring system. The mean free phenytoin fraction was 0.076 in patients taking phenytoin alone or phenytoin and carbamazepine and 0.11 in patients taking valproic acid (p less than 0.001). The free fraction did not change with the total level over the range tested (6.7 to 39.9 micrograms/ml total phenytoin). There was a strong correlation between free and total levels (r = 0.84). Both free (r = 0.59) and total (r = 0.49) phenytoin levels were positively correlated with the toxicity score. Only total phenytoin levels showed a weak positive correlation with decreasing seizure frequency. Our results suggest that routine free phenytoin level monitoring is not necessary in most clinical situations.

Adolescent↗
PubMed1985

Positron emission tomography in generalized seizures.

We used 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) to study nine patients with clinical absence or generalized seizures. One patient had only absence seizures, two had only generalized tonic-clonic seizures, and six had both seizure types. Interictal scans in eight failed to reveal focal or lateralized hypometabolism. No apparent abnormalities were noted. Two patients had PET scans after isotope injection during hyperventilation-induced generalized spike-wave discharges. Diffusely increased metabolic rates were found in one compared with an interictal scan, and in another compared with control values. Another patient had FDG injected during absence status: EEG showed generalized spike-wave discharges (during which she was unresponsive) intermixed with slow activity accompanied by confusion. Metabolic rates were decreased, compared with the interictal scan, throughout both cortical and subcortical structures. Interictal PET did not detect specific anatomic regions responsible for absence seizure onset in any patient, but the results of the ictal scans did suggest that pathophysiologic differences exist between absence status and single absence attacks.

Adult↗
PubMed1985

Monitoring at the National Institute of Neurological and Communicative Disorders and Stroke.

Intensive monitoring (prolonged, telemetered EEG recording, video tape recording, and plasma drug level monitoring) has an integral role in the correct diagnosis and treatment of patients with intractable epilepsy or suspected epilepsy. The intensive monitoring unit at the Clinical Epilepsy Section, NINCDS, exemplifies a well-integrated system for clinical epilepsy research. The resulting library of video taped seizures is a valuable resource for teaching and the production of films on epilepsy.

Electroencephalography↗
PubMed1985

Advances in the clinical development of antiepileptic drugs.

In this paper we describe advances in the clinical development of antiepileptic drugs as a function of the Antiepileptic Drug Development Program of the National Institute of Neurological and Communicative Disorders and Stroke. This program encompasses both the preclinical and clinical elements of drug development through the Anticonvulsant Screening Project, the Toxicology Project, and the support of controlled clinical trials of potential new drugs that emerge from these projects and promise to be more effective and less toxic than those currently available for the treatment of epilepsy.

Animals↗
PubMed1985

Video recording.

Two video techniques are commonly used for biomedical monitoring. The simplest technique uses 2 or 3 video cameras with a special-effects generator. The more advanced method uses one video camera with a reformatter, a special-effects generator and a time-code generator. The main components of a video recording system are the camera, tape recorder, monitor, special-effects generator, reformatter, audio system and time-code generator. Video recordings can be edited electronically, but the quality of the copies is dependent on the type of editing equipment and the technical expertise available. Video recording has helped to improve the diagnosis and treatment of seizures and has been widely used in clinical epilepsy research. Video monitoring is now generally available in large medical centers for the diagnosis of difficult patients.

Electroencephalography↗
PubMed1984

The role of positron emission tomography in the evaluation of seizure disorders.

We studied patients with partial and primary generalized seizures using fluorine-18-labeled 2-fluorodeoxyglucose and positron emission tomography. Interictal studies of patients with partial seizures showed regions of focal or lateralized hypometabolism in 15 of 17 patients with unilateral electroencephalographic foci. Several patients had more than one hypometabolic region. In 1 patient PET hypometabolism was contralateral to the electroencephalographic epileptic focus. Six of 10 patients without definite electroencephalographic foci also showed unilateral PET hypometabolic regions. PET during complex partial seizures in 3 patients showed hypermetabolism at the site of the hypometabolic focus. A postictal scan in 1 patient showed extension of interictal temporal hypometabolism to the frontal lobe as well. Interictal scans in 8 patients with primary generalized seizures did not reveal any hypometabolic regions. One patient scanned during an attack of absence status epilepticus showed a slight decrease in metabolic rate compared to the interictal scan. Temporal lobectomy has been performed in 6 patients with focal PET hypometabolism. PET may obviate the need for depth electrode study in some patients with intractable partial seizures.

Electroencephalography↗
PubMed1984

Phenytoin: the pseudosteady-state phenomenon.

After reaching an apparent steady state, plasma phenytoin (PHT) levels may then undergo inexplicable changes, a phenomenon called " pseudosteady state". We evaluated 13 pseudosteady -state periods in 10 inpatients with complex partial seizures. Eleven of the periods occurred after a change in PHT dosage and two after drug withdrawal. The pseudosteady -state period began 2 to 12 days (means = 5.7 days) after dosage change and lasted 5 to 10 days (means = 6.3 days), during which plasma PHT levels were stable (+/- 5%). Plasma PHT levels thereafter fluctuated spontaneously by greater than 25% for 5 to 22 days (means = 10.8 days). A final steady-state level was reached 13 to 31 days (means = 21.4 days) after the first dosage change. Falling plasma PHT levels increased seizure frequency in two patients, and a level of 52 micrograms/ml led to medication toxicity in another.

Adult↗
PubMed1984

Serial EEG in intractable epilepsy.

We compared serial EEGs performed at admission, discharge, and follow-up (mean, 25 months) to clinical outcome in 70 patients with intractable epilepsy. The diagnosis in each case was confirmed by intensive monitoring. EEG features evaluated were background slowing, focal slowing, and focal, bilateral, or generalized epileptiform discharges. Clinical measures were seizure frequency and medication toxicity. No statistically significant correlations were found between improvement in any EEG feature and any clinical measure. EEG did not predict which patients would benefit from intensive monitoring. Serial EEGs may be of little value in assessing the results of treatment in patients with severe epilepsy.

Adolescent↗
PubMed1984

Disposition of mephenytoin and its metabolite, nirvanol, in epileptic patients.

We investigated the conversion of mephenytoin to nirvanol in five patients with uncontrolled complex partial seizures. After a 50-mg single oral dose, mean peak mephenytoin level was 0.48 microgram/ml and nirvanol 0.37 microgram/ml. After 400 mg, peak mephenytoin level was 3.9 micrograms/ml and nirvanol 2.5 micrograms/ml. On 400 mg daily, mephenytoin reached a mean steady-state level of 1.5 micrograms/ml. Nirvanol mean steady-state level was 18 micrograms/ml. Mean plasma half-life was 17 hours for mephenytoin and 114 hours for nirvanol. Two patients had reduced seizures during mephenytoin therapy and one a transient increase during drug withdrawal. No toxicity was seen, but mephenytoin was not more effective than phenytoin.

Adolescent↗
PubMed1983

Clinical and EEG estimates of absence seizure frequency.

Absence seizure frequency was estimated in 20 patients (5 to 15 years old) before and after treatment with ethosuximide. Estimates were obtained from mothers' histories, observations by nurses, intensive observation by trained observers, physical and neurological examinations, routine EEG, and 12-hour telemetered EEG. Both before treatment (high seizure frequency) and after treatment (low frequency), telemetered EEG was the most reliable method of estimation, and intensive observation was the next best method. After treatment, the mothers' and nurses' estimates of seizure frequency were significantly less than the telemetered EEG estimates. The neurological examination and routine EEG were sufficient to diagnose absence attacks in all 20 patients and to determine if the attacks were completely controlled by therapy in all but two patients.

Adolescent↗
PubMed1983

Removal of sedative-hypnotic antiepileptic drugs from the regimens of patients with intractable epilepsy.

Sedative-hypnotic antiepileptic drugs have potentially toxic effects, but their removal is often thought to be difficult and dangerous. We completely withdrew all barbiturates and benzodiazepines from 78 patients with intractable epilepsy (48 inpatients and 30 outpatients). Initially, 19 patients had plasma levels of sedative drugs above the therapeutic range; 28 were taking more than one of these drugs. Dosages of nonsedative antiepileptic drugs were adjusted to provide optimal seizure control. After 6 months of outpatient follow-up, 69 patients remained on a nonsedative regimen: 35 (51%) showed improvement in both drug toxicity and seizure control, 13 (19%) in toxicity alone, 8 (12%) in seizure control alone; 12 (16%) were unchanged, and 1 was worse. Of 9 patients restarted on sedative antiepileptic drugs by their private physicians, 4 had more toxic symptoms than at discharge, 1 had more frequent seizures, 3 were unchanged, and 1, who had had a temporal lobectomy after drug withdrawal, had less frequent seizures. Sedative drugs are not necessary for optimal seizure control, even in intractable epilepsy, and they may be safely withdrawn.

Adolescent↗
PubMed1983

Intractable seizures: long-term follow-up after prolonged inpatient treatment in an epilepsy unit.

Seventy-four patients with intractable seizures were followed up 6 to 57 months (mean 25 months) after intensive monitoring. At discharge from the hospital, 59% of the patients had at least a 50% reduction in seizure frequency and 63% had decreased antiepileptic drug toxicity. The findings at follow-up compared with those at admission showed reduced seizure frequency in 55% of the patients, diminished medication toxicity in 54%, and improved social adjustment in 38%. A change in the seizure diagnosis was the best predictor of a favorable outcome. Patients with impaired mental status were not less likely to improve. The relationship between seizure type and outcome was not significant, although patients with complex partial seizures tended to be less likely to improve. Intensive monitoring can lead to significant long-lasting improvement of patients with severe epilepsy.

Adolescent↗
PubMed1983

Complex partial seizures: clinical characteristics and differential diagnosis.

Videotape analysis of 163 complex partial seizures in 40 patients showed that the mean duration of the attack was 128 seconds. Automatisms occurred in 159 seizures (97%) and involved more than the face and arms in 132 (80%). Most automatisms were simple, stereotypic, or aimless movements. Postural tone increased in 24 seizures and decreased in 62. Clonic movements of the eyelids occurred in 19 attacks, and clonic movements of the extremities in 4. Only nine patients reported auras. Distinct ictal and postictal phases could be distinguished in 132 seizures (80%); in these, the mean ictal duration was 54 seconds and the mean postictal duration 89 seconds. Videotape analysis provides objective criteria by which complex partial seizures may be differentiated from other seizure types.

Adolescent↗
PubMed1983

A combination of subcuticular suture and sterile Micropore tape compared with conventional interrupted sutures for skin closure. A controlled trial.

We have conducted a controlled trial to compare skin closure using conventional interrupted sutures with a combination of subcuticular suture and sterile Micropore tape in 169 patients undergoing appendicectomy, inguinal herniorrhaphy, or saphenofemoral ligation. We have found that the combination technique consistently gives a better cosmetic result and that the tape acts well as a dressing, is convenient, and is well tolerated by patients.

Adolescent↗
PubMed1983

Antiepileptic drug development program.

The Epilepsy Branch of the National Institute of Neurological and Communicative Disorders and Stroke has responded to the need for new, more effective, and less toxic antiepileptic drugs by cooperating with pharmaceutical companies in key areas of development. The ADD Program screens large numbers of compounds for anticonvulsant activity in appropriate animal models and sponsors clinical trials of promising new drugs for the treatment of epilepsy. The use of investigative techniques developed since the late 1960s allows documentation of seizure type and seizure frequency for maximal objectivity of clinical trial data.

Anticonvulsants↗