Focal seizures and systemic metabolic disorders

Metabolic Alterations Predispose to Seizure Development in High-Fat Diet-Treated Mice: the Role of Metformin

The link between epilepsy and type 2 diabetes (T2DM) and/or metabolic syndrome (MetS) has been poorly investigated. Therefore, we tested whether a high-fat diet (HFD), inducing insulin-resistant diabetes and obesity in mice, would increase susceptibility to develop generalized seizures induced by pentylentetrazole (PTZ) kindling. Furthermore, molecular mechanisms linked to glucose brain transport and the effects of the T2DM antidiabetic drug metformin were also studied along with neuropsychiatric comorbidities. To this aim, two sets of experiments were performed in CD1 mice, in which we firstly evaluated the HFD effects on some metabolic and behavioral parameters in order to have a baseline reference for kindling experiments assessed in the second section of our protocol. We detected that HFD predisposes towards seizure development in the PTZ-kindling model and this was linked to a reduction in glucose transporter-1 (GLUT-1) expression as observed in GLUT-1 deficiency syndrome in humans but accompanied by a compensatory increase in expression of GLUT-3. While we confirmed that HFD induced neuropsychiatric alterations in the treated mice, it did not change the development of kindling comorbidities. Furthermore, we propose that the beneficial effects of metformin we observed towards seizure development are related to a normalization of both GLUT-1 and GLUT-3 expression levels. Overall, our results support the hypothesis that an altered glycometabolic profile could play a pro-epileptic role in human patients. We therefore recommend that MetS or T2DM should be constantly monitored and possibly avoided in patients with epilepsy, since they could further aggravate this latter condition.

Branched-Chain Amino Acids and Seizures: A Systematic Review of the Literature

BACKGROUND

Up to 40% of patients with epilepsy experience seizures despite treatment with antiepileptic drugs; however, branched-chain amino acid (BCAA) supplementation has shown promise in treating refractory epilepsy.

OBJECTIVES

The purpose of this systematic review was to evaluate all published studies that investigated the effects of BCAAs on seizures, emphasizing therapeutic efficacy and possible underlying mechanisms.

METHODS

On 31 January, 2017, the following databases were searched for relevant studies: MEDLINE (OvidSP), EMBASE (OvidSP), Scopus (Elsevier), the Cochrane Library, and the unindexed material in PubMed (National Library of Medicine/National Institutes of Health). The searches were repeated in all databases on 18 February, 2019. We only included full-length preclinical and clinical studies that were published in the English language that examined the effects of BCAA administration on seizures.

RESULTS

Eleven of 2045 studies met our inclusion criteria: ten studies were conducted in animal models and one study in human subjects. Seven seizure models were investigated: the strychnine (one study), pentylenetetrazole (two studies), flurothyl (one study), picrotoxin (two studies), genetic absence epilepsy in rats (one study), kainic acid (two studies), and methionine sulfoximine (one study) paradigms. Three studies investigated the effect of a BCAA mixture whereas the other studies explored the effects of individual BCAAs on seizures. In most animal models and in humans, BCAAs had potent anti-seizure effects. However, in the methionine sulfoximine model, long-term BCAA supplementation worsened seizure propagation and caused neuron loss, and in the genetic absence epilepsy in rats model, BCAAs exhibited pro-seizure effects.

CONCLUSIONS

The contradictory effects of BCAAs on seizure activity likely reflect differences in the complex mechanisms that underlie seizure disorders. Some of these mechanisms are likely mediated by BCAA's effects on glucose, glutamate, glutamine, and ammonia metabolism, activation of the mechanistic target of rapamycin signaling pathway, and their effects on aromatic amino acid transport and neurotransmitter synthesis. We propose that a better understanding of mechanisms by which BCAAs affect seizures and neuronal viability is needed to advance the field of BCAA supplementation in epilepsy.

Correlation between extracellular glucose and seizure susceptibility in adult rats

In adult diabetic patients, periods of hyperglycemia may be associated with exacerbation of focal seizures. Our objective was to determine in the adult rats the correlation between seizure susceptibility and extracellular glucose concentration in two models of seizures. Male rats were injected with two doses of streptozocin (40 mg/kg IP) on 2 consecutive days to induce diabetic hyperglycemia. Controls either received vehicle or were not injected. After 2 weeks, blood glucose concentration was measured, and the rats were subjected to flurothyl seizure test. Another group of rats received glucose solution (20%, 5 ml IP) 30 minutes before testing to induce nondiabetic hyperglycemia. Thresholds for flurothyl-induced clonic and tonic-clonic seizures were determined. Finally, in vitro epileptiform activity was induced in the entorhinal cortex-hippocampal slices from naive rats by perfusing with magnesium-free medium with various glucose concentrations. In additional slices, paired-pulse paradigm was determined in the perforant path. Susceptibility to clonic and tonic-clonic flurothyl-induced seizures positively correlated with blood glucose concentrations as the increased glucose concentration was associated with proconvulsant effects. Similarly, in the in vitro experiments, epileptiform activity was promoted by increased and suppressed by decreased glucose concentrations. Data indicate that, in the adult rats, high glucose concentrations are associated with proconvulsant effects.

Grand mal seizures temporally related to cocaine use: clinical and diagnostic features

STUDY OBJECTIVES

To determine the appropriate diagnostic workup of the emergency department patient with an uncomplicated cocaine-related grand mal seizure.

DESIGN SETTING

Retrospective analysis. A city and county ED with 45,000 selected visits per year.

TYPE OF PARTICIPANTS

Thirty-seven patients with acute grand mal seizure after cocaine exposure were studied. All had historical or laboratory evidence of cocaine use and no history of prior seizure disorder.

INTERVENTIONS

The diagnostic workup varied among patients. Most received computed head tomography (35), whereas fewer received-ECG (18), EEG (16), and lumbar puncture (six).

MEASUREMENTS AND MAIN RESULTS

Thirty-three patients with an uncomplicated cocaine-related seizure had an unremarkable series of diagnostic tests. The four patients with remarkable neurologic manifestations were compared with the remainder of patients who were without neurologic abnormalities. Comparison of groups by route of cocaine intake revealed no significant difference in the time interval to seizure (P = .761).

CONCLUSION

Diagnostic workup probably is not indicated for the patient experiencing a cocaine-related generalized seizure who will recover promptly and have a normal postictal examination.

Hyperglycemia presenting with occipital seizures

Seizures are common in hyperglycemia and are often the first manifestation, particularly in nonketotic hyperglycemia (NKH). Published reports emphasize partial motor seizures almost exclusively. In a 3-year period, we observed three patients in whom occipital seizures, documented by ictal EEG recording, were the initial symptom of hyperglycemia. One patient was mildly ketotic at first. Seizures were visual in two patients and visual and adversive in the third. Seizures regressed with correction of abnormal glucose levels and did not recur during follow-up of less than or equal to 1 year despite discontinuation of antiepileptic drugs (AEDs) in two. Computed tomography (CT) scans did not show correlative abnormalities. Although published reports suggest that frontal lobe structures are particularly susceptible to the epileptogenic effects of NKH, our experience indicates that in NKH epileptic foci may originate in other cortical areas, such as occipital.

Movement disorders as a manifestation of nonketotic hyperglycemia

Movement disorders are well-known presenting signs of metabolic disorders. Focal motor abnormalities may be the chief initial presentation of diabetes mellitus in the nonketotic hyperglycemic state in 6% of patients. Nonketotic hyperglycemia (NKH), in particular, may manifest any of a wide variety of movement disorders. These have been described as focal seizures, epilepsia partialis continua, myoclonus, and opsoclonia. There are descriptions of movement disorders in hyperglycemia that are similar to the coarse flapping tremor of asterixis, the posturing of paroxysmal kinetogenic choreoathetosis, and of "fencing (stance) seizures." Disorders of facial motor function including aphasia, facial muscle twitching and jerking, and disorders of muscular tone have been described. These may include hemiparesis and hemiplegias as well as increased tone, in some cases mimicking the nuchal rigidity of meningitis. The movement disorders in NKH may mimic cerebral vascular accidents, meningitis, or psychiatric disorders, as well as various types of seizures. Clinicians may be able to avoid expensive and time-consuming diagnostic evaluations to rule out NKH in patients with movement disorders. We present two patients with focal motor abnormalities associated with nonketonic hyperglycemia and review the pertinent literature.

Efficacy of a "standard" seizure workup in the emergency department

In many institutions it is the "standard of care" to obtain serum chemistries and anticonvulsant levels as part of the emergency department evaluation of seizure patients. To determine the efficacy of such a workup in the ED, 163 seizure patients presenting to an inner-city teaching hospital were studied in a standardized, prospective manner. After the clinical examination all patients had CBC, serum electrolyte, BUN, creatinine, glucose, calcium, magnesium, and if indicated, anticonvulsant drug level determinations performed. Any patient presenting with a first-time seizure (in patients greater than 6 years old), recent head trauma, focal neurologic deficit, or focal seizure activity had cranial computerized tomography (CCT). After obtaining historical and physical examination and before receiving laboratory results, as many as five likely etiologies were listed and assigned probability ratings. After review of the laboratory data (and CCT scan, if obtained), final etiologies again were listed and assigned percentages of likelihood. Significant abnormalities (ie, those that changed diagnosis, management, or disposition) were found in 104 patients; 96 had subtherapeutic anticonvulsant levels, five had abnormal CCT scans, two had hypoglycemia, and one had hyperglycemia as the cause of seizure. The clinical examination successfully predicted those abnormalities in all but two cases (one each of hyperglycemia and subdural hematoma). We contend tha routine serum chemistries in patients presenting to the ED are of extremely low yield, and that the clinical examination can predict accurately the need to obtain these studies. CCT scanning is useful in selected patients, and was found to be abnormal in five of 19 (25%) patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic disorders presenting as stroke

In a series of 1460 consecutive patients admitted to an "acute" stroke unit, 10 patients (0.7%) were found to have a metabolic encephalopathy which mimicked stroke. Of these, three had hypoglycaemia, four had hyperglycaemia, three had hyponatraemia, and one had suffered from hypoxia. Metabolic disorders should be excluded in all patients with a diagnosis of suspected stroke, especially if the presentation is associated with a confusional state or focal seizures. The conventional symptoms and signs of the metabolic disorders may be minimal or absent. The relative rarity of these disorders among patients with suspected stroke is overshadowed by the importance of early recognition and treatment, in order to minimize morbidity and mortality.