Differential diagnosisdiagnostic approach

This case involves a child with a history of recent generalized tonic-clonic seizures, and now, continuous lethargy and frequent staring spells Because the duration of this episode is longer than 5 minutes, could this represent a case of SE? Using a semiological classification system, status epilepticus (SE) is divided into convulsive SE (CSE) and nonconvulsive SE (NCSE) NCSE is defined as altered awareness associated with electrographic seizure activity, and may occur in either a generalized or focal epilepsy. Although clear tonic or clonic activity is not seen, there may be subtle movements associated with electrographic seizure In children, there are several types of NCSE: NCSE after CSE, with generalized epilepsies (absence SE), with focal epilepsies (complex partial SE), and with the entity referred to as autonomic epilepsy CSE itself is easily recognized, and typically does not require EEG confirmation for diagnosis . However, in patients with CSE in whom convulsive movements are successfully treated with benzodiazepines, persistence of altered awareness raises the question of NCSE This occurs infrequently after the treatment of SE and requires EEG confirmation NCSE occurred in 14% of adults in whom CSE was controlled, whereas the percentage was higher in a small pediatric series (26%) .

In this case without overt CSE but with frequent seizures without a return to baseline mental status, NCSE must still be considered The entity of nonconvul-sive seizures (NCS) has also been recently described These represent a continuum, with NCSE as electrographic SE, and NCS as intermittent electrographic seizures, usually in the setting of an acute encephalopathy More than likely, the continuum evolves from isolated NCS that develop an increased duration and increasing frequency, ultimately merging as continuous NCSE With NCSE, the continuous elec-trographic seizures are thought to be the cause of the altered awareness However, with NCS, it is unclear if the NCS are the cause of the altered awareness, result from the underlying cause of epilepsy, or both

If any form of NCSE is seen after the treatment of CSE, NCSE occurs in the presence of an acute encephalopathy, or if NCS are possibly responsible for persistent altered awareness, then additional antiepileptic therapy is needed If the elec-trographic SE or NCS resolve, and mental status improves, then the epileptiform activity was likely causative of the altered awareness . Unfortunately, we may not be able to predict this in advance

An EEG is necessary for the identification of NCSE or NCS Indications for emergent EEG have been proposed and include (1) unexplained altered awareness (with or without motor activity, (2) no return to baseline mental status within 30 minutes after control of CSE, (3) the use of neuromuscular paralysis in an acute encephalopathy or patient with a seizure disorder, and (4) refractory SE that requires pentobarbital, or other high-dose, suppressive medications However, it is relatively uncommon for there to be a full return to baseline mental status after the control of CSE . We usually use clinical assessment, such as an improvement in mental status with some responsiveness or at least a response to noxious stimuli, as indicators excluding NCSE, which typically also has some accompanying subtle motor movements

In persistent altered awareness without preceding CSE, an absence, complex partial, or autonomic SE must be considered . In children, absence SE almost exclusively occurs in those with known absence epilepsy, and therefore would typically have a history of increasing absence seizures with ongoing altered awareness Absence SE has been referred to as spike-wave stupor Although EEG is needed to absolutely confirm absence SE, presumptive treatment could be administered in a child with known absence epilepsy and altered awareness

Nonconvulsive complex partial SE occurs when there is altered awareness associated with focal electrographic seizure activity on EEG It is differentiated from complex partial SE by the overt motor or convulsive manifestations typically associated with focal seizures, and has been rarely reported in children The clinical manifestations include altered awareness, staring, eye deviation, automatisms, crying, lip smacking, amaurosis, and decreased visual tracking and recognition

The entity of autonomic epilepsy has recently been delineated The majority of childhood cases occur with the Panayiotoupolos syndrome, although autonomic symptoms may occur in other childhood and adult epilepsy syndromes SE is estimated to occur in over 40% of these children This is a subtype of complex partial SE because EEG shows focal rather than generalized epileptiform activity The typical case develops out of sleep, feeling sick, followed by the retching and vomiting, and frequently accompanied by pallor, tachycardia, bradycardia, and mydriasis This is then followed by fluctuating altered awareness and may progress to overt convulsive activity

In a small clinical series, NCSE occurred in 10% of pediatric ICU patients who underwent continuous EEG monitoring Associated diagnoses included hypoxic-ischemic encephalopathy, acute infection, intracranial hemorrhage, and epilepsy This suggests that NCSE and NCS should be strongly considered in patients with unexplained altered awareness, particularly in the presences of acute intracranial pathology or previous seizures

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