New anticonvulsant drugs. Focus on flunarizine, fosphenytoin, midazolam and stiripentol

In the past decade, several new antiepileptic drugs have been tested. Most recently, 5 new antiepileptic drugs have been launched onto European and US markets. These include vigabatrin, oxcarbazepine and lamotrigine in Europe, and felbamate and gabapentin in the US. In addition to these, 3 additional drugs are in the clinical investigational stage: flunarizine, fosphenytoin and stiripentol. A fourth agent is midazolam, which was originally introduced in 1986, but recently has shown effectiveness in the treatment of status epilepticus. Flunarizine is a selective calcium channel blocker that has shown anticonvulsant properties in both animal and human studies. It is a long-acting anticonvulsant that clinical studies have shown to have effects similar to those of phenytoin and carbamazepine in the treatment of partial, complex partial and generalised seizures. Fosphenytoin was developed to eliminate the poor aqueous solubility and irritant properties of intravenous phenytoin. It is rapidly converted to phenytoin after intravenous or intramuscular administration. In clinical studies, this prodrug showed minimal evidence of adverse events and no serious cardiovascular or respiratory adverse reactions. It may have a clear advantage over the present parenteral formulation of phenytoin. Midazolam is a benzodiazepine that is more potent than diazepam as a sedative, muscle relaxant and in its influence on electroencephalographic measures. It has been shown to be an effective treatment for refractory seizures in status epilepticus. Stiripentol has anticonvulsant properties as well as the ability to inhibit the cytochrome P450 system. There are significant metabolic drug interactions between stiripentol and phenytoin, carbamazepine and phenobarbital (phenobarbitone). Stiripentol has been studied in patients with partial seizures, refractory epilepsy and refractory absence seizures with some efficacious results.

Recurrent intracranial epithelioid hemangioendothelioma associated with multicentric disease of liver and heart: case report

Epithelioid hemangioendothelioma is an unusual vascular neoplasm with prominent cytoplasmic vacuolization representing primitive lumen formation. A case is presented of this unique vascular neoplasm in a woman with a seizure disorder who had cardiac, hepatic, and recurrent nervous system lesions. To our knowledge, this is the third known case of intracranial epithelioid hemangioendothelioma. Emphasis is placed on the indolent course of this rare neoplasm, with a recommendation for aggressive surgical treatment and diligent follow-up.

Neurologic complications of critical medical illnesses

OBJECTIVES

To identify the neurologic complications of critical medical illnesses, and to assess their effect on mortality rates and on medical ICU and hospital lengths of stay.

DESIGN

Prospective clinical evaluation of all medical ICU admissions for 2 yrs.

SETTING

A 14-bed, general medical intensive and coronary care unit in a large university hospital.

PATIENTS

Patients (n = 1,850) admitted to the hospital, of whom 92 were admitted for primarily neurologic problems. Of the remaining 1,758 patients, 217 (12.3%) experienced a neurologic complication.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients developing a neurologic complication while in the medical ICU demonstrated an increased risk of inhospital mortality when compared with patients who did not suffer such problems (45.7% vs. 26.6%; p < .00001). Patients with neurologic complications experienced 2.5-fold longer medical ICU stay times (p < .001) and almost two-fold longer hospital stay times (p < .001). Metabolic encephalopathy, seizures, hypoxic-ischemic encephalopathy, and stroke were the most common complications. Sepsis was the most frequent cause of encephalopathy, and cerebrovascular lesions were the most common cause of seizures. Formal neurologic consultations were requested in only 36% of these patients.

CONCLUSIONS

Neurologic complications are associated with increased mortality rates and longer medical ICU and hospital lengths of stay. These conditions are probably underrecognized at present. ICUs have the potential to serve as environments for neurologic teaching and research.

Intravenous midazolam for the treatment of refractory status epilepticus

OBJECTIVE

To determine the usefulness of midazolam as a therapeutic agent for status epilepticus refractory to conventional treatment.

DESIGN

Retrospective study.

SETTING

ICUs of two university hospitals.

PATIENTS

Seven patients with refractory status epilepticus who failed treatment with diazepam, lorazepam, and phenytoin, with or without phenobarbital. All patients received mechanical ventilation before receiving midazolam.

INTERVENTIONS

Intravenous midazolam by bolus administration followed by infusion.

MEASUREMENTS AND MAIN RESULTS

Midazolam terminated status epilepticus in all patients in less than 100 secs, as determined by clinical observation (three patients) or electroencephalographic monitoring (four patients). One patient developed mild hypotension.

CONCLUSIONS

In this small study, midazolam appears to be an effective and safe alternative to high-dose barbiturate coma for the termination of status epilepticus when conventional agents have failed.

Prolonged survival following the inadvertent intrathecal administration of vincristine: clinical and electrophysiologic analyses

A 23-year-old man with a lymphoblastic lymphoma accidentally received 2.0 mg of vincristine intrathecally instead of intravenously. Although he underwent immediate CSF drainage, symptoms of an ascending myeloencephalopathy developed at 48 h. This progressed to coma, initially with a diffusely slow EEG, which evolved into alpha coma. He also developed a left frontal focus of epileptiform activity. He was transferred to our institution 1 month later. His court-appointed guardian refused to allow discontinuation of supportive treatment; therefore, the evolution of the disorder can be followed for 12 months. Although alpha coma remained the predominant pattern, some EEG evolution did occur, with a progressive decrease in amplitude being most prominent. An increase in amplitude in the 10th month was accompanied by the return of some nystagmoid eye movements. The patient's lymphoma then recurred, and further treatment was not attempted. This tragic case, in which transient exposure to a microtubular poison produced severe CNS toxicity, allows some insights into the mechanisms of alpha coma.

Tetanus: pathophysiology, management, and prophylaxis

As tetanus has become a rare disease in the developed world, physicians have become less comfortable with its diagnosis and management. The extent of adequate antitetanus immunity in the adult population, especially the elderly, is waning, in great measure because primary care physicians have not made prophylaxis a priority in their routine encounters with patients. Furthermore, as the population of immunocompromised hosts grows, an increasing percentage of our patients may not respond to standard active immunization routines. Unless these trends are reversed, we face a substantial increase in the incidence of this dread disorder. Tetanus is also of interest as a relatively simple model of disordered motor control that can instruct us in the management of the many more common causes of neurogenic muscular rigidity. The toxin produced by Clostridium tetani finds increasing use in laboratories investigating brain function as well. Clinical tetanus is divided into four symptomatic types: generalized tetanus, local tetanus, cephalic tetanus, and neonatal tetanus. This monograph discusses the diagnostic aspects of each type of tetanus, its pathophysiology, diagnosis, differential diagnosis, and treatment. Preventing tetanus should be a high priority for all primary care physicians. Active immunization with tetanus toxoid is remarkably effective and safe. Passive immunization with human tetanus immune globulin is indicated in certain circumstances, which are discussed below.

Convulsive disorders: status epilepticus

Status epilepticus (SE) remains one of the most serious disorders affecting the central nervous system. Recent progress in understanding the mechanisms of the brain damage produced by SE make even more apparent the need to quickly terminate this condition, prevent its recurrence, and treat its complications. Intracellular calcium concentrations rise, prompting a cascade of excitotoxic consequences. Therapy for SE currently consists of agents which stop seizures (benzodiazepines, phenytoin, barbiturates). This review discusses their use in SE.