Seizure

Article Author:
J. Stephen Huff
Article Editor:
Najib Murr
Updated:
2/28/2019 10:48:32 PM
PubMed Link:
Seizure

Introduction

Paroxysmal spells might represent events stemming from the central nervous system, cardiac activity, psychiatric causes, and others. Convulsive concussion, convulsive syncope, rigors, movement disorders, sleep-related events, and non-non-epileptic spells or pseudoseizures are all in the differential diagnosis of an event. Epileptic seizures constitute one type of paroxysmal event.[1]  

An epileptic seizure is a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. There are many different types of seizures, and they can be partial or generalized. Partial seizures are the most common seizure type in adults. In a partial seizure, one area of cortex is thought to activate initially and may manifest through simple symptoms such as a motor or sensory phenomena. These partial seizures may rapidly secondarily generalize. Generalized seizures result from diffuse cortical activation at seizure onset. The most common seizure type in adults is partial onset seizures with rapid secondary generalization.[2] 

Complex partial seizures or seizures with dyscognitive features are associated with altered awareness or consciousness. These may have minimal motor manifestations such as lip-smacking or small extremity movements but may present as only a confusional state.

Etiology

Seizures may be either provoked or unprovoked. Provoked seizures may result from electrolyte disorders, toxins, head injury, infectious processes, vascular anomalies, tumors or other mass lesions, and many other causes. Unprovoked seizures by definition occur in the absence of provocative causes or more than seven days after an acute injury or insult such as stroke or brain hemorrhage.

Epilepsy by definition is a condition of recurrent unprovoked seizures. Determining whether a first seizure or recurrent seizures are provoked or unprovoked is fundamentally important for diagnosis and treatment.

Epidemiology

Age-adjusted incidence of epilepsy in North America ranges between 16/100,000 and 51/100,000 person-years. The age-adjusted prevalence ranges from 2.2/1000 to 41/1000 depending on the country. Partial epilepsy may constitute up to two-thirds of incident epilepsies. Incidence increases in the lower socioeconomic populations.[3] 

About 25% to 30% of new-onset seizures are thought to be provoked or secondary to another cause. 

Of patients in United States general hospitals presenting with generalized convulsive status epilepticus, roughly one-fourth are patients with epilepsy with breakthrough seizures, medication irregularity, or new-onset epilepsy, one-fourth are patients with ethanol-related seizures, and one-half are patients with seizures that are provoked by a variety of medical conditions.

Pathophysiology

Focal or generalized epileptiform discharges (ED) constitute the EEG hallmark of seizure activity. At a cellular level, paroxysmal depolarization shift (PDS) seems to trigger ED. Increased activation or decreased inhibition of such discharges could result in seizure activity.[4]                  

There are as many types of status epileptics as there are types of seizures. Status epilepticus is the condition of prolonged or recurrent seizures. The current definition of generalized convulsive status epilepticus includes a single seizure lasting greater than 5 minutes or several seizures without return to full consciousness between the seizures. There is an evolution of generalized convulsive status epilepticus from continuous or discrete seizures to a condition of minimal or no motor activity. The electrical activity reflected by EEG evolves as well. The result may be a type of nonconvulsive status epilepticus representing a medical emergency since the ongoing excessive electrical activity in itself is injurious to the brain.

History and Physical

The first question posed to the physician is whether the event is a seizure from abnormal cortical activity or an event that resembles a seizure. A sudden alteration in consciousness with associated motor movements is the common description of the event. Incontinence may or may not be present. Frequently, following a seizure,  patients present with transient alteration consciousness referred to as the postictal state. Tongue biting, if present, is most frequently lateral.

Status epilepticus is the condition of prolonged or recurrent seizures. Generalized convulsive status epilepticus, by definition, is present when a seizure lasts longer than 5 minutes or if generalized seizures recur without return to full consciousness. If the patient's level of consciousness does not improve after approximately 20 to 30 minutes, the possibility of nonconvulsive status epilepticus should be considered. Sometimes termed subtle status epilepticus, the motor movements of this type of nonconvulsive status epilepticus may only be nystagmoid eye movements, facial twitching, extremity twitches, or in some cases, no motor movement at all.[5]

Evaluation

If the event is thought to be a seizure, the next question is whether it is provoked or unprovoked. Clinical evaluations are guided by the history and physical examination of the patient. Typically laboratory work including electrolytes is obtained. Imaging is often obtained and is of higher yield based on historical factors or focal findings on the neurologic examination. Persistent alteration of consciousness will dictate additional testing such as neuroimaging and other serologic tests. If nonconvulsive status epilepticus is a consideration, arrangements for neurologic consultation and EEG should be made.[1]

Treatment / Management

Benzodiazepines such as diazepam, midazolam, or lorazepam are accepted as the first line medications for continuing seizures.

Many medications are used in the treatment of epilepsy as first-line or add-on. They can be grouped based on their mechanism of action. Sodium channel blockers (carbamazepine, oxcarbazepine, eslicarbazepine, phenytoin, fosphenytoin, lamotrigine, lacosamide, and zonisamide), potassium channel opener (ezogabine), agonist of GABA receptor (benzodiazepine and barbiturates), GABA reuptake inhibitors (tiagabine), inhibitors of GABA-transaminase (vigabatrin), multiple mechanisms (gabapentin, pregabalin, valproic acid), glutamate antagonists (topiramate, felbamate, perampanel), and binding to synaptic vesicle 2A protein (levetiracetam, brivaracetam).

If the patient has noncompliance with a medical regimen and has returned to normal mental status, medications may be resumed. Testing for medication levels may be appropriate if available for the particular medication.

Pearls and Other Issues

Most seizures terminate in less than five minutes. Generalized convulsive status epilepticus as described above is a medical emergency. Whether from provoked causes or reflecting unprovoked seizures, initial treatment is commonly the same. Benzodiazepines such as diazepam, midazolam, or lorazepam are accepted as first-line medications. Side effects are primarily respiratory depression and largely related to the rate of administration. The best second-line medication is unclear and is the subject of current study. Alternatives include phenytoin, fosphenytoin, valproate, levetiracetam, and others. Should generalized convulsive status epilepticus continue, often advanced airway management is necessary. Blood pressure support may be necessary. The best treatment for refractory status epilepticus is unknown, but options include propofol, barbiturates (pentobarbital) or benzodiazepine continuous infusions in addition to other anesthetic medications. ICU admission will be necessary with continuous EEG monitoring.[6][7][8][9][10]

Outcomes following generalized convulsive status epilepticus depend on any underlying cause of the seizures and the duration of the status epilepticus. 

Investigation for provoked causes of seizures should always be considered. Rapid glucose and electrolyte testing are recommended for all patients. Clinical conditions including failure to return to full consciousness should trigger further testing.

A first unprovoked seizure in an adult who has returned to normal neurological baseline often does not require initiation of medical treatment.[11] Caution regarding engaging in potentially hazardous activities should be discussed with the patient until followup and reassessment occurs.

Enhancing Healthcare Team Outcomes

Communication of observations between health team members is essential. 


References

[1] Clinical policy: critical issues in the evaluation and management of adult patients presenting to the emergency department with seizures., Huff JS,Melnick ER,Tomaszewski CA,Thiessen ME,Jagoda AS,Fesmire FM,, Annals of emergency medicine, 2014 Apr     [PubMed PMID: 24655445]
[2] ILAE official report: a practical clinical definition of epilepsy., Fisher RS,Acevedo C,Arzimanoglou A,Bogacz A,Cross JH,Elger CE,Engel J Jr,Forsgren L,French JA,Glynn M,Hesdorffer DC,Lee BI,Mathern GW,Moshé SL,Perucca E,Scheffer IE,Tomson T,Watanabe M,Wiebe S,, Epilepsia, 2014 Apr     [PubMed PMID: 24730690]
[3] The descriptive epidemiology of epilepsy-a review., Banerjee PN,Filippi D,Allen Hauser W,, Epilepsy research, 2009 Jul     [PubMed PMID: 19369037]
[4] Pathophysiology and definitions of seizures and status epilepticus., Huff JS,Fountain NB,, Emergency medicine clinics of North America, 2011 Feb     [PubMed PMID: 21109098]
[5] A definition and classification of status epilepticus--Report of the ILAE Task Force on Classification of Status Epilepticus., Trinka E,Cock H,Hesdorffer D,Rossetti AO,Scheffer IE,Shinnar S,Shorvon S,Lowenstein DH,, Epilepsia, 2015 Oct     [PubMed PMID: 26336950]
[6] Emergency Neurological Life Support: Status Epilepticus., Claassen J,Riviello JJ Jr,Silbergleit R,, Neurocritical care, 2015 Dec     [PubMed PMID: 26438462]
[7] Epilepsy Emergencies., Hantus S,, Continuum (Minneapolis, Minn.), 2016 Feb     [PubMed PMID: 26844736]
[8] Intramuscular midazolam versus intravenous lorazepam for the prehospital treatment of status epilepticus in the pediatric population., Welch RD,Nicholas K,Durkalski-Mauldin VL,Lowenstein DH,Conwit R,Mahajan PV,Lewandowski C,Silbergleit R,, Epilepsia, 2015 Feb     [PubMed PMID: 25597369]
[9] Intramuscular versus intravenous therapy for prehospital status epilepticus., Silbergleit R,Durkalski V,Lowenstein D,Conwit R,Pancioli A,Palesch Y,Barsan W,, The New England journal of medicine, 2012 Feb 16     [PubMed PMID: 22335736]
[10] Status epilepticus in adults., Betjemann JP,Lowenstein DH,, The Lancet. Neurology, 2015 Jun     [PubMed PMID: 25908090]
[11] Management of a First Seizure., Bergey GK,, Continuum (Minneapolis, Minn.), 2016 Feb     [PubMed PMID: 26844729]