In the treatment of infantile spasms, ACTH or adrenal corticosteroids had been used, but vigabatrin is now found to be as effective, including in patients with underlying tuberous sclerosis (see Elterman et al).
Recurrent generalized convulsions at a frequency that precludes regaining of consciousness in the interval between seizures (convulsive status) constitutes the most serious problem in epilepsy, with an overall mortality of 20 to 30 percent, according to Towne and colleagues, but probably lower in recent years. It is perhaps the most common neurologic emergency. Some patients who die of epilepsy do so because of uncontrolled seizures of this type, complicated by the effects of the underlying illness or an injury sustained as a result of a convulsion. Rising temperature, acidosis, hypotension, and renal failure from myoglobinuria is a sequence of life-threatening events that may be encountered in cases of convulsive status epilepticus. Prolonged convulsive status (for longer than 30 min) also carries a risk of serious neurologic sequelae (epileptic encephalopathy). The MRI during and for days after a bout of status epilepticus may show signal abnormalities in the region of a focal seizure or in the hippocampi, most often reversible, but we have had several such patients who awakened and were left in a permanent amnesic state. The MRI changes are most evident on FLAIR and diffusion-weighted sequences and may also appear in the pulvinar of the thalamus. With regard to acute medical complications, from time to time a case of neurogenic pulmonary edema is encountered during or just after the convulsions, and some patients may become extremely hypertensive, making it difficult to distinguish the syndrome from hypertensive encephalopathy.
The etiologies of status epilepticus vary among age groups but all the fundamental causes of seizures are able to produce the syndrome. The most recalcitrant cases we have encountered in adults have been associated with viral or paraneoplastic encephalitis, old traumatic injury, and epilepsy with severe mental retardation. Stroke and brain tumor have, in contrast, been infrequent causes. More recently, several groups, for example, Gaspard and coworkers have emphasized autoimmune forms of encephalitis including the paraneoplastic variety as the most common explanations for new-onset refractory status epilepticus but add that over half of cases remain cryptogenic.
Treatment of Convulsive Status Epilepticus (Table 15-8)
The many regimens that have been proposed for the treatment of status epilepticus attest to the fact that no one of them is altogether satisfactory and none is clearly superior (Treiman et al).
We have had the success with the following program, which reflects several published approaches. When the patient is first seen, an initial assessment of cardiorespiratory function is made and an oral airway established. As summarized by Bleck, a large-bore intravenous line is inserted; blood is drawn for glucose, BUN, electrolytes, and a metabolic and drug screen. A normal saline infusion is begun and a bolus of glucose is given (with thiamine if malnutrition and alcoholism are potential factors). To rapidly suppress the seizures, we generally use diazepam intravenously at a rate of about 2 mg/min until the seizures stop or a total of 20 mg has been given; alternatively, lorazepam, 0.1 mg/kg given by intravenous push at a rate not to exceed 2 mg/min, is now favored, being marginally more effective than diazepam because of its clinically longer duration of action (see Table 15-8).