Serum prolactin evaluation after "minor" generalised seizures monitored by EEG

Intercorrelation of physiological seizure parameters and hormonal changes in electroconvulsive therapy

OBJECTIVE

Physiological parameters that predict electroconvulsive therapy (ECT) effectiveness may reflect propagation of the induced epileptic seizure. As an indication of seizure propagation to the diencephalon, we here examined the correlation between prolactin increase after ECT and clinical seizure evaluation parameters, focusing on peak heart rate. As a proxy for peripheral endocrine stress response, we examined the correlation to postictal cortisol increase.

METHODS

Participants were consecutively recruited from clinical ECT patients (n = 131, age 18-85 years). The first ECT session in a series was examined. For each participant, blood serum concentrations of prolactin and cortisol were measured immediately before and within 30 min after the seizure. Physiological parameters were extracted from clinical records: peak heart rate (HR) during seizure, electroencephalography (EEG) seizure duration, and motor seizure duration. Correlations were calculated using non-parametric tests.

RESULTS

Serum prolactin increased after ECT and correlated with peak HR, EEG seizure duration, and motor seizure duration. Peak HR during seizure also correlated positively with both EEG seizure duration and motor seizure duration. Correlations were unaffected by age, sex, baseline prolactin levels, antipsychotics, or beta-blocking agents. Serum cortisol increased after ECT but did not correlate with the seizure evaluation parameters, nor with prolactin concentrations.

CONCLUSIONS

Our findings of a positive correlation between peak HR and prolactin that was independent from the peripheral endocrine stress response might be in line with the idea that tachycardia during ECT seizures reflects seizure propagation to the diencephalon. This supports the practice of monitoring cardiovascular response for ECT seizure evaluation.

Interactions between hormones and epilepsy in female patients

Epilepsy and epileptic seizures may influence the release of hormones from the hypothalamus and the pituitary. After complex-partial seizures or generalized tonic-clonic seizures, serum prolactin increases in about two thirds of cases. Apart from this transient effect, interictal epileptic discharges from the temporal lobe may exert a prolonged influence on hormone release. Changes in luteinizing hormone (LH) pulse frequency and increased prolactin levels have been reported. As a consequence, menstrual cycles may be disturbed. The cyclic change of sex serum hormones during the ovulatory menstrual cycle may have an impact on seizure occurrence during the days of ovulation and/or menstruation (e.g., catamenial seizures). By a supplementation of progesterone during the second half of anovulatory cycles, a decrease of seizure frequency can be achieved.

Seizures, hormones and sexuality

Sexual disorders (both hyposexuality and sexual dysfunction) are common in people with epilepsy, occurring in up to two-thirds of patients. However, characteristically, patients do not spontaneously report these problems. Nocturnal penile tumescence testing suggests that the erectile dysfunction has a neurophysiological component. The aetiology remains uncertain but is likely to be multifactorial, involving neurological, endocrine, iatrogenic, cognitive, psychiatric and psychosocial factors. Epilepsy-related factors include the age of onset/duration of epilepsy along with the seizure type and focus. In addition, seizure frequency might be relevant as successful epilepsy surgery can result in an improvement in sexual functioning despite remaining on anticonvulsant medication. Endocrine changes (raised sex hormone binding globulin and reduced free testosterone) have been reported in men with epilepsy, especially when treated with hepatic-enzyme inducing antiepileptic drugs. Studies have not been performed evaluating anticonvulsants that do not induce hepatic enzymes such as lamotrigine. The association between these endocrine changes and hyposexuality is not known. The relationship between seizures, hormones and anticonvulsant medication in women is explored, focusing on issues such as catamenial epilepsy, the menopause, hormone replacement therapy and the polycystic ovarian syndrome. Suggestions for future research and treatment issues are discussed.

Epilepsy and prolactin in adults: a clinical review

Serum levels of prolactin may increase as a consequence of epileptic seizures. The hormone release is caused by the propagation of epileptic activity, usually from the temporal lobe to the hypothalamic-pituitary axis. Due to the intensity of the epileptic afterdischarge, a rise is seen in approximately 60% of complex partial seizures. Prolactin usually fails to rise after psychogenic seizures, therefore, postictal prolactin levels can be used to differentiate between epileptic and psychogenic seizures. However, a subclassification of epileptic seizures by means of prolactin measurement is not possible. In repetitive seizures, prolactin may show a decrease in its postictal release. This is more common in status epilepticus, probably as a result of a diminished propagation of ictal activity during the course of status epilepticus. The influence of chronic epileptic discharges and anticonvulsant medication on prolactin release is moderate.

Serum prolactin in neonates with seizures

We studied serum prolactin (PRL) in 28 newborn infants with acute encephalopathy. Six patients had electrographically confirmed seizures. Twenty-two patients comprised the nonictal group. In the seizure group, PRL was determined at the first onset of the seizure (baseline) and at 15 and 30 min postictal. In the nonseizure group, PRL was determined at the end of the EEG and 15 min later. EEGs were visually analyzed for the presence of seizures and background abnormality (normal or mildly, moderately, or markedly abnormal). Etiologic diagnoses included congenital heart disease (12), hypoxic-ischemic encephalopathy (4), sepsis (4), respiratory distress syndrome (5) meconium aspiration (1), and metabolic disease (2). Serum PRL was significantly higher (p < 0.05) at baseline and 15 min postictally in the patients with seizures than in the nonictal group. However, PRL levels 15 and 30 min postictally were not statistically different from baseline values. Baseline PRL correlated significantly (p < 0.001) with EEG background abnormality in both groups; therefore, patients with the most abnormal EEG backgrounds had higher levels of PRL than those with a relatively normal EEG background. We conclude that newborns with EEG-confirmed seizures, particularly if seizures are not associated with clinical signs, have high baseline serum PRL levels that do not increase significantly in the immediate postictal period. Serum PRL levels correlate with the severity of the brain insult as evaluated by EEG background. Further studies are needed to enhance our understanding of the dynamics of PRL secretion in newborns with seizures and acute encephalopathy.

Serum prolactin response to thyrotropin-releasing hormone during status epilepticus

Determination of serum prolactin can help distinguish between epileptic and pseudo-epileptic attacks since generalized tonic-clonic and complex partial seizures frequently are accompanied by a transient rise in prolactin. In status epilepticus, however, serum prolactin levels are well within the normal range: cellular depletion due to the prolonged seizure activity has been suggested as a mechanism for this finding. The control of prolactin secretion is complex. Among several possible regulators, inhibitory dopamine and stimulatory thyrotropin-releasing hormone (TRH) may take part in the regulation of prolactin levels in connection with epileptic activity. There may be subpopulations of prolactin-producing cells that react differently in response to various regulators. A dopamine receptor blocker given during status epilepticus brings forth a distinct increase in prolactin levels. In order to add to the understanding of prolactin changes in connection with status epilepticus, we injected TRH i.v. during status epilepticus in seven consecutive patients. All patients had prolactin levels within the normal range (< 25 micrograms/l) before injection of TRH which resulted in at least a two-fold increase in prolactin levels. Our results contradict the hypothesis of cellular depletion of prolactin in connection with status epilepticus. The mechanism behind prolactin values within the normal range after prolonged seizure activity remains unknown.

Serum prolactin response to metoclopramide during status epilepticus

Transient elevation of serum prolactin frequently follows generalised tonic-clonic and complex partial seizures. However, the levels of prolactin during status epilepticus are not increased above the normal range. Exhaustion of central prolactin supplies has been proposed as a possible mechanism for the absence of prolactin increase during status epilepticus. To test this hypothesis we injected intravenous metoclopramide (10 mg) in eight consecutive patients with status epilepticus. One patient had generalised tonic-clonic status epilepticus. Seven patients had EEG-verified non-convulsive status epilepticus, consisting of one typical absence status, one atypical absence status and five complex partial status epilepticus. Metoclopramide raised the mean (SD) prolactin levels at least five-fold in all patients, from 5.8 (8.0) micrograms/l to 87.0 (39.0) micrograms/l, within 60 minutes after the injection. Thus the mechanism for low prolactin values in status epilepticus is not cellular depletion of stored prolactin, but more likely an altered regulation, presumably induced by prolonged seizure activity.

Serum prolactin concentrations and epilepsy. A study which compares healthy subjects with a group of patients in presurgical evaluation and circadian variations with those related to seizures

In 20 healthy subjects (10 female and 10 male) and 17 patients undergoing presurgical epilepsy evaluation with intracranial EEG electrodes, circadian variations of serum prolactin (PRL) were measured. A comparison between the peak values found in normals with the postictal rises in patients, led us to consider 700 microU/ml to be the threshold of diagnostic value and the observed rises above this level to be all induced by seizures. In order to assess the clinical value of this threshold, PRL was measured postictally in a further 30 patients with epilepsy and in 11 patients with psychogenic seizures. In none of the latter group did PRL rises exceed 700 microU/ml, while they did so in 39% of the complex partial seizures and in 80% of the tonic-clonic seizures. There was no significant difference with respect to sex (a rise over 700 microU/ml in 42% in male and in 55% in female patients). Based on the findings in 17 patients investigated by means of intracranial electrodes, we were not able to establish different criteria for different focus localisations: in 66% of both temporal as well as frontal lobe seizures the 700 microU/ml level was exceeded. As a trend, in the period preceding an epileptic seizure we found a slightly decreasing PRL level, whereas in healthy persons the PRL concentrations gradually increased in the 40 minutes before the maximum spontaneous peak was reached.

Serum prolactin during status epilepticus

The serum concentration of prolactin is frequently increased after single epileptic seizures and has therefore been used as a method to differentiate between hysterical attacks and epileptic seizures. We determined plasma prolactin concentrations in fifteen patients with status epilepticus. Seven patients had absence status, five complex partial and three generalised tonic-clonic status epilepticus. Prolactin levels were normal in all patients which indicates that, in contrast to single seizures, status epilepticus is not associated with an increase in serum prolactin.

Reproductive endocrine disorders in women with primary generalized epilepsy

It is known that women suffering from temporal lobe epilepsy may frequently present reproductive endocrine disorders (REDs). We hypothesized that a high occurrence of REDs could be found also in primary generalized epilepsy (PGE), and therefore investigated the hormonal and ovarian echographic profiles in 20 PGE female patients of reproductive age. Fourteen reported normal menstrual cycles, while 6 complained of longstanding menstrual irregularities. All but three patients were receiving antiepileptic drug (AED) therapy. In all subjects, the basal levels of gonadotropins, prolactin, and gonadal steroids were assayed. The response of luteinizing hormone (LH) to gonadotropin-releasing hormone was also investigated and ovarian ultrasonographic findings were evaluated. In five of six patients with menstrual problems (25% of the group), a well-defined RED was diagnosed (polycystic ovarian disease in three cases and hypothalamic ovarian failure in two). The 14 patients with normal menstrual cycles showed an elevation of mean basal follicle-stimulating hormone and prolactin, and a blunting of mean LH response. Our results suggest that a high occurrence of REDs may be found also in PGE. We hypothesize that a neurotransmitter dysfunction might be the common pathogenetic mechanism resulting in both REDs and PGE. The hormonal alterations observed in the patients with normal menstrual cycles seem to support our hypothesis. Previous data seem to rule out a possible AED effect accounting for the hormonal findings observed in our series. However, further studies are needed to confirm our preliminary results.