status Epilepticus

Status epilepticus (SE) refers to a single or recurrent seizures lasting for gt;30 minutes during which the patient does not regain consciousness. However, a seizure that last for gt;5 minutes is unlikely to stop spontaneously and needs intervention.

ILAE defines SE quot;as a condition due to either failure of the mechanisms to terminate the seizures or initiation of mechanisms which lead to abnormal prolonged seizures (after time-point t1), which can have long-term consequences (after time-point t2) including neuronal death, neuronal injury or alteration of the neuronal networks depending on the type and duration of seizuresquot;.

Most common with generalized tonic-clonic seizures, status epilepticus may develop with any seizure type, e.g. absence seizures, partial seizures (Epilepsia partialis continua), myoclonic seizures, and even febrile seizures (Statusfebrilis). However, time-point tl and t2 differ with type of seizures, being 5 and 30 minutes respectively for generalized seizures, 10 and 60 minutes for focal seizures and 15 and 60 minutes (or unknown) for absence seizures.

Pathophysiology: SE indicates either persistence of neuroexcitatory influences (principally mediated by acetylcholine, glutamate or aspartate) or failure of neuroinhibitory mechanisms, (principally mediated by gamma-aminobutyric acid or GABA).

Studies have shown that continued seizure activity beyond 30 minutes (transitional period) leads to significant changes in cerebral blood flow, lactic acidosis, altered blood-brain barrier, elevation of intracranial pressure, hypoglycemia and autonomic dysfunction- ultimately leading to irreversible neurological damage.

Clinically, while SE usually develops in a known case of seizure disorder following sudden withdrawal of anticonvulsants, sleep deprivation or intercurrent infections, it may be first manifestation of underlying structural or metabolic abnormality in gt; 30% cases.

Management of SE, though more intensive, is principally similar to that of acute seizures, (Table 18.17). Broadly, it involves initial therapy usually with Benzodiazepines, followed by urgent therapy with Fosphenytoin/ Phenytoin, Valproate, Phenobarbitone or Levetiracetam.

Refractory SE, which fails to respond to two drugs, needs to be treated in intensive care with continuous infusion of midazolam, Propofol or Ketamine. Some cases need general anesthesia with ventilator support. SE, which does not respond despite 24 hours of anaesthesia is termed as super-refractory.

Outcome: SE, specially of convulsive type, is associated with high mortality (~10%) or irreversible neurological damage (~10%) due to prolonged cerebral hypoxia and other factors. Risk of recurrence is as high as 25-75%.

18.6.3