Neonatal seizure | |
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Other names | Seizures in neonates |
A neonatal seizure is a seizure in a baby younger than age 4-weeks that is identifiable by an electrical recording of the brain. [1] It is an occurrence of abnormal, paroxysmal, and persistent ictal rhythm with an amplitude of 2 microvolts in the electroencephalogram,. [2] These may be manifested in form of stiffening or jerking of limbs or trunk. Sometimes random eye movements, cycling movements of legs, tonic eyeball movements, and lip-smacking movements may be observed. Alteration in heart rate, blood pressure, respiration, salivation, pupillary dilation, and other associated paroxysmal changes in the autonomic nervous system of infants may be caused due to these seizures. Often these changes are observed along with the observance of other clinical symptoms. [3] A neonatal seizure may or may not be epileptic (due to a primary seizure disorder). Some of them may be provoked (i.e. due to a secondary cause). Most neonatal seizures are due to secondary causes. [4] With hypoxic ischemic encephalopathy being the most common cause in full term infants and intraventricular hemorrhage as the most common cause in preterm infants. [4]
According to the International League against Epilepsy (ILAE), seizures are defined as excessive or synchronous neuronal activity in the brain that is manifested as signs or symptoms. As per the classification system by the American Clinical Neurophysiology Society, seizures can be classified into electroclinical (clinical signs of a seizure and electrical brain monitoring signs of a seizure), clinical only, and electrographic-only seizures (signs of a seizure on electrical brain monitoring without clinical-visual signs of a seizure). Some infants, especially critically ill ones, may experience electrographic-only seizures. [5] [6]
Neonatal seizures have been classified into various types. Neonates were found to experience either tonic or clonic seizures. If seizures were found to be focal, they were further classified into unifocal or multifocal. [7] Seizures in the neonatal population can be mainly categorized into acute symptomatic seizures and neonatal epilepsy that is related to genetic or structural factors. [8] Brain injury due to hypo-ischemic encephalopathy, ischemic stroke, intracranial hemorrhage or infection, inborn errors of metabolism, transient metabolic and brain malformations, lead to acute symptomatic seizures. [9] Neonatal epilepsy may be credited to genetic syndromes, developmental structural brain abnormalities, or metabolic diseases. [10]
The incidence of seizures is more common in the neonatal stage than in other stages of life. [11] Neonatal seizures are comparatively rare and affect 1 or 3.5 in 1000 infants born. [12] They are the most frequent neurological problem in the nursery that is associated with greater risks of morbidity and mortality, [13] [14] often requiring evaluation and treatment in a neonatal intensive care unit. Better care delivered in neonatal care units, with improved healthcare facilities, has decreased the mortality rate associated with these seizures. However, the long-term morbidity rate remains approximately the same. [15]
Neonatal seizures are generally subclinical and their diagnosis based on the clinical observations is generally difficult. [16] [17] Diagnosis relies on identification of the cause of the seizure, and verification of actual seizure activity by measuring electrical activity with electroencephalography (EEG). The set of guidelines developed by the American Clinical Neurophysiology Society helps the healthcare providers know when the EEG is appropriate and corresponds to the seizures. [18] Treatment depends generally on the underlying cause of the seizure if it is provoked. anti-epileptic drugs are also administered.
Neonatal seizures that are provoked (due to a secondary cause) usually resolve in the neonatal period when the secondary cause is treated. Neonates with epilepsy syndromes often have seizures later in life. [4] It has been estimated that approximately 15% of neonatal seizures represent epilepsy syndrome. [19] The incidence of seizures is higher in the neonatal period than at any other time of life, [20] and most often occurs in the first week of life. [21]
Seizures in the neonatal population often present differently than in other age groups due to brain immaturity. [22] Electroclinical seizures are defined by evidence of seizure activity on electroencephalogram as well as clinical signs or symptoms. [23]
Classification systems have been developed based on neonatal seizure motor manifestations, summarized below. [24]
Clonic seizures are defined by repetitive contractions of groups of muscles, typically of the limbs, face, or trunk. [25] These may involve one group of muscles (focal) or multiple groups of muscles (multifocal). An isolated focal seizure can move or spread, and can even alternate from one side of the body to the other. If they occur on both sides of the body, they may occur simultaneously in an asynchronous manner. [26] If a multifocal seizure, is limited to muscles of one side of the body, it may occur synchronously or asynchronously. [26] Focal clonic seizures cannot be suppressed by repositioning of limbs or by physical suppression. [27] Due to the neonatal brain's immaturity, the typical Jacksonian march may not occur. Focal seizures typically have very close correlates on EEG, with measurable EEG abnormalities with each seizure movement. The rhythm of the clonic movements and EEG abnormalities is usually slow, at 1-3 movements per second.
Focal tonic seizures are characterized by sustained muscle contraction of facial, limb, axial, and other muscle groups. It often involves asymmetric positioning of the neck and trunk and appears as abnormal posturing of a single limb. Horizontal eye deviation may or may not be involved. [27] They may be symmetric, asymmetric, focal, or multifocal. Such seizures cannot be provoked by stimulation or suppressed by restraint.
A focal tonic seizure can generalize, or the first seizure can occur as a generalized seizure, or seizures that impair the neonate's level of consciousness. Generalized tonic seizures typically appear as symmetric and sustained posturing of limbs in either an extensor or flexor distribution. Generalized tonic seizures often manifest with the tonic extension of the upper and lower limbs and also may involve the axial musculature in an opisthotonic fashion. Generalized tonic seizures mimic decorticate posturing; the majority are not associated with electrographic seizures.Such seizures can be initiated by stimulation and can be suppressed by restraint.
Myoclonic movements can either be caused by seizures or be benign neonatal sleep myoclonus, a common mimicker of seizures in neonates. Myoclonic seizures are characterized by isolated and fast contractions of muscle groups that are non-repetitive. It generally involves flexor muscle groups of upper extremities- trunk, diaphragm, face. [28] These movements typically occur in the limbs or face. Stimulation can provoke myoclonic seizures.
Spasms include either flexor or extensor or both flexor and extensor. These occur in clusters and cannot be provoked by stimulation or suppressed by restraint. [3]
Some clinicians use the term subtle seizures to describe seizures that appear to be more normal and there is an absence of distinct tonic or clonic movements but the presence of abnormal eye movements, stereotyped lip-smacking, or apneic events. [29] They may be difficult to diagnose clinically due to the subtleness of symptoms. [29] Sometimes in subtle seizures complex limbic hyperactivity that is purposeless along with crying could be observed. [29]
Benign neonatal seizures are not classified as epilepsy and the seizures usually resolve after 1–4 months. [30] A benign familial neonatal seizure onsets as early as 3 days of birth and may involve one or both sides of the brain. Recurrent seizure episodes are observed to occur in neonates. Electroencephalogram of infants with BFNS often have normal readings. Sometimes, they may show theta pointy, a specific abnormality. They usually begin with tonic stiffening accompanied by apnea. Later clonic jerks are witnessed. It occurs in 1 in every 1,00,000 newborns. [31]
This condition is usually inherited and is passed on in autosomal dominant manner. This condition is also caused due to mutation in KCNQ2 or KCNQ3 gene that may be carried by people bearing no family history of benign familial neonatal seizure. Mutation in these genes lead to excessive excitability of neurons. [31]
Most of the infants with BFNS develop normally but some neonates with it may later develop intellectual disability which becomes evident in early childhood. [31] In some patients approximately 15%, epilepsy recurs later in life. Myokymia is also witnessed in a few cases. [31]
Seizures in the developing brain are more common than in a mature brain for several reasons. First, the developing brain is hyperexcitable due to excess in excitatory glutaminergic neurons and immaturity of inhibitory gamma-amino butyric acid (GABA) neurons. Preterm infants are at especially high risk for seizures for this reason. [32] During the neonatal developmental stages, numerous pathophysiological mechanisms, lead to excessive excitation and reduced inhibition, which lowers their seizure threshold when compared with that of adults. This has been proved in animal (rodent) models wherein the adult and infant models are administered with the chemoconvulsant agent and their threshold seizure potential is compared. [33] This lowered seizure threshold potential makes the neonatal brain susceptible to acute symptomatic seizures.
Neonatal seizures have a number of causes. Determining the cause of a confirmed seizure is important because treatment and prognosis vary based on underlying etiology of the seizure. In contrast to seizures that occur in other age groups, seizures that occur during the neonatal period are most often caused by the following processes:
Seizure activity in a neonate is difficult to diagnose, as many seizures have subtle clinical symptoms. Diagnosis relies on a combination of brain monitoring (electroencephalography)(EEG) and observing clinical signs or symptoms of a seizure. [4] EEG may be continuous or intermittent, and it may also be combined with video recording of the infant to correlate any seizure movements with EEG recordings. [4]
There are several modes of EEG that are commonly used to diagnose neonatal seizures. Conventional continuous multichannel conventional EEG is the gold standard for diagnosis of epileptiform activity, but requires expert interpretation. Newer amplitude integrated EEG (aEEG) (also termed cerebral function monitoring, or CFM) allows easier monitoring of brain activity, but may not allow identification of short duration, low amplitude, or very high frequency seizure activity. [41] Often, both modes are displayed concurrently.
Evaluation for infection (often with blood counts, blood cultures, or lumbar puncture) may be done to determine if there is a secondary cause of seizures. [4] Blood glucose and electrolyte testing can identify metabolic problems that can be corrected. Further testing includes evaluation for genetic causes and other more rare metabolic causes. [42] Genetic testing may be done with an epilepsy gene panel to determine presence of neonatal primary genetic epilepsy syndromes. [4] Brain injury such as cerebral infarction or hemorrhage can be evaluated with imaging techniques such as magnetic resonance imaging (MRI) and brain ultrasound. [4]
Infants can exhibit stereotyped movements that may be hard to distinguish from seizure activity. Since many of these non-seizure movements are not dangerous and require no treatment, differentiation from actual seizure activity is useful.[ citation needed ] Jitteriness is common in the neonatal period and is seen in upwards of 2/3 of neonates. It is characterized by a tremor that is especially prominent during sleep or periods of agitation. [ citation needed ] Gaze deviation or eye movements do not occur. Benign neonatal sleep myoclonus (BNSM) is another common movement that can be mistaken for a seizure. It is characterized by jerking limb movements only during sleep, and stop with waking of the infant. [4]
Once diagnosis is made, the goals of management are to identify the cause of the seizure, stop the seizure activity, and maintain physiologic parameters such as oxygenation, ventilation, blood glucose, and temperature. [4]
Treatment greatly depends on the cause of the seizure. For example, infectious causes of seizures (meningitis, meningoencephalitis), are often treated with antimicrobials. Similarly, electrolyte or glucose abnormalities are treated by correcting the underlying abnormality.
If the cause of the seizures are unlikely to be easily or quickly corrected, once diagnosis of a seizure is made, the mainstay of treatment is pharmacotherapy with anti-epileptic drugs. Phenobarbital is the first line anti-seizure medication in neonatal seizures, regardless of the cause of the seizure. [4] Phenytoin, levetiracetam, midazolam and lidocaine are used as second line agents. [4] Almost 66% of patients with acute symptomatic seizures, don't have a complete response to the initial dose administered regardless of the medication. [43]
Term or near term infants with moderate to severe hypoxic ischemic encepphalopathy causing neonatal seizures may be treated with therapeutic hypothermia. [4]
With prompt diagnosis, mortality after diagnosis of neonatal seizures has decreased dramatically from an estimated 33% in the 1990s to around 10% in the 2010s. [32] Underlying cause of the seizure remains the greatest predictor of ongoing seizures and neurologic problems later in life. Controversy remains with the extent of damage the seizures themselves cause. Clinician consensus is that frequent or intractable seizures (status epilepticus) leads to neuronal damage and are associated with later neurodevelopment problems. [44]
Infants that are premature, have hypoxemic ischemic encephalopathy, CNS infection, severe intraventricular hemorrhage, structural central nervous system defect, or severely abnormal EEG tracings have a worse prognosis. [32]
Low Apgar scores, need for resuscitation at birth, and perinatal distress place the neonate at greater risk for seizures [45] ".
For all infants with neonatal seizures regardless of cause, the rate of subsequent seizures during childhood is estimated between 10 and 20%. [46] Infants who survive severe global HIE have the highest rate of epilepsy later in life. [32]
Untreated or repeated neonatal seizures, especially prolonged seizures or status epilepticus, are associated with hippocampal sclerosis later in life. [4]
It is difficult to determine the incidence of seizures in the neonatal period. Estimations range between 1-5 per 1,000 live births, with other estimates being 1.1 cases per 1,000 live births in full term infants and 14 cases per 1,000 live births in preterm infants. [42] [4] The actual rate of seizures during the neonatal period may be higher due to a lack of accurate diagnosis of sub-clinical seizure activity without continuous EEG monitoring. The epidemiology moreover varies in high-income countries (HIC) from that in low-income ones (LIC). The incidence is estimated to be 1-3 per 1000 live births in HIC whereas it ranges from 36 to 90 per live birth in LIC.[ citation needed ] Acute causes of seizures (hypoxemic ischemic encephalopathy, infection, intracranial hemorrhage, stroke, etc.) are more common than the first episode of neonatal epilepsy syndromes.[ citation needed ]
Since interpretation of continuous EEG monitoring requires a trained neurologist, automated interpretation software has been proposed. Algorithms and machine learning have been studied, however logistical and mathematic challenges remain.[ citation needed ]
Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. An epileptic seizure is the clinical manifestation of an abnormal, excessive, and synchronized electrical discharge in the neurons. The occurrence of two or more unprovoked seizures defines epilepsy. The occurrence of just one seizure may warrant the definition in a more clinical usage where recurrence may be able to be prejudged. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrical activity in the brain. These episodes can result in physical injuries, either directly, such as broken bones, or through causing accidents. In epilepsy, seizures tend to recur and may have no detectable underlying cause. Isolated seizures that are provoked by a specific cause such as poisoning are not deemed to represent epilepsy. People with epilepsy may be treated differently in various areas of the world and experience varying degrees of social stigma due to the alarming nature of their symptoms.
A seizure is a sudden change in behavior, movement, and/or consciousness due to abnormal electrical activity in the brain. Seizures can look different in different people. It can be uncontrolled shaking of the whole body or a person spacing out for a few seconds. Most seizures last less than two minutes. They are then followed by confusion/drowsiness before the person returns to normal. If a seizure lasts longer than 5 minutes, it is a medical emergency and needs immediate treatment.
A headache is often present in patients with epilepsy. If the headache occurs in the vicinity of a seizure, it is defined as peri-ictal headache, which can occur either before (pre-ictal) or after (post-ictal) the seizure, to which the term ictal refers. An ictal headache itself may or may not be an epileptic manifestation. In the first case, it is defined as ictal epileptic headache or simply epileptic headache. It is a type of pain seizure that can remain isolated or be followed by other manifestations of the seizure. On the other hand, a ictal non-epileptic headache is a headache that occurs during a seizure but it is not due to an epileptic mechanism. When the headache does not occur in the vicinity of a seizure, it is defined as inter-ictal headache. In the case it's a disorder separate from epilepsy, it's a comorbidity.
Lennox–Gastaut syndrome (LGS) is a complex, rare, and severe childhood-onset epilepsy syndrome. It is characterized by multiple and concurrent seizure types including tonic seizure, cognitive dysfunction, and slow spike waves on electroencephalogram (EEG), which are very abnormal. Typically, it presents in children aged 3–5 years and most of the time persists into adulthood with slight changes in the electroclinical phenotype. It has been associated with perinatal injuries, congenital infections, brain malformations, brain tumors, genetic disorders such as tuberous sclerosis and numerous gene mutations. Sometimes LGS is observed after infantile epileptic spasm syndrome. The prognosis for LGS is marked by a 5% mortality in childhood and persistent seizures into adulthood.
Psychogenic non-epileptic seizures (PNES), also referred to as pseudoseizures, non-epileptic attack disorder (NEAD), functional seizures, or dissociative seizures, are episodes resembling an epileptic seizure but without the characteristic electrical discharges associated with epilepsy. PNES fall under the category of disorders known as functional neurological disorders (FND) and are typically treated by psychologists or psychiatrists.
In the field of neurology, temporal lobe epilepsy is an enduring brain disorder that causes unprovoked seizures from the temporal lobe. Temporal lobe epilepsy is the most common type of focal onset epilepsy among adults. Seizure symptoms and behavior distinguish seizures arising from the medial temporal lobe from seizures arising from the lateral (neocortical) temporal lobe. Memory and psychiatric comorbidities may occur. Diagnosis relies on electroencephalographic (EEG) and neuroimaging studies. Anticonvulsant medications, epilepsy surgery and dietary treatments may improve seizure control.
Frontal lobe epilepsy (FLE) is a neurological disorder that is characterized by brief, recurring seizures arising in the frontal lobes of the brain, that often occur during sleep. It is the second most common type of epilepsy after temporal lobe epilepsy (TLE), and is related to the temporal form in that both forms are characterized by partial (focal) seizures.
In the field of neurology, seizure types are categories of seizures defined by seizure behavior, symptoms, and diagnostic tests. The International League Against Epilepsy (ILAE) 2017 classification of seizures is the internationally recognized standard for identifying seizure types. The ILAE 2017 classification of seizures is a revision of the prior ILAE 1981 classification of seizures. Distinguishing between seizure types is important since different types of seizures may have different causes, outcomes, and treatments.
Abdominal epilepsy is a rare condition consisting of gastrointestinal disturbances caused by epileptiform seizure activity. It is most frequently found in children, though a few cases of it have been reported in adults. It has been described as a type of temporal lobe epilepsy. Responsiveness to anticonvulsants can aid in the diagnosis. Distinguishing features of abdominal epilepsy include (1) Abnormal laboratory, radiographic, and endoscopic findings revealing paroxysmal GI manifestations of unknown origin (2) CNS symptoms (3) Abnormal EEG. Most published medical literature dealing with abdominal epilepsy is in the form of individual case reports. A 2005 review article found a total of 36 cases described in the medical literature.
Benign familial neonatal seizures (BFNS), also referred to as benign familial neonatal epilepsy (BFNE), is a rare autosomal dominant inherited form of seizures. This condition manifests in newborns as brief and frequent episodes of tonic-clonic seizures with asymptomatic periods in between. Characteristically, seizure activity spontaneously ends during infancy and does not affect childhood development. However, some studies have reported that a minority of children with BFNS consequently develop intellectual disability. Additionally, BFNS increases lifetime susceptibility to seizures as approximately 14% of those afflicted go on to develop epilepsy later in life. There are three known genetic causes of BFNE, two being the voltage-gated potassium channels KCNQ2 (BFNC1) and KCNQ3 (BFNC2) and the third being a chromosomal inversion (BFNC3). There is no obvious correlation between most of the known mutations and clinical variability seen in BFNE.
Todd's paresis is focal weakness in a part or all of the body after a seizure. This weakness typically affects the limbs and is localized to either the left or right side of the body. It usually subsides completely within 48 hours. Todd's paresis may also affect speech, eye position (gaze), or vision.
A generalized tonic–clonic seizure, commonly known as a grand mal seizure or GTCS, is a type of generalized seizure that produces bilateral, convulsive tonic and clonic muscle contractions. Tonic–clonic seizures are the seizure type most commonly associated with epilepsy and seizures in general and the most common seizure associated with metabolic imbalances. It is a misconception that they are the sole type of seizure, as they are the main seizure type in approximately 10% of those with epilepsy.
Ohtahara syndrome (OS), also known as Early Infantile Developmental & Epileptic Encephalopathy (EIDEE) is a progressive epileptic encephalopathy. The syndrome is outwardly characterized by tonic spasms and partial seizures within the first few months of life, and receives its more elaborate name from the pattern of burst activity on an electroencephalogram (EEG). It is an extremely debilitating progressive neurological disorder, involving intractable seizures and severe intellectual disabilities. No single cause has been identified, although in many cases structural brain damage is present.
Benign Rolandic epilepsy or self-limited epilepsy with centrotemporal spikes is the most common epilepsy syndrome in childhood. Most children will outgrow the syndrome, hence the label benign. The seizures, sometimes referred to as sylvian seizures, start around the central sulcus of the brain.
Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex and allocortex. It is typically non-invasive, with the EEG electrodes placed along the scalp using the International 10–20 system, or variations of it. Electrocorticography, involving surgical placement of electrodes, is sometimes called "intracranial EEG". Clinical interpretation of EEG recordings is most often performed by visual inspection of the tracing or quantitative EEG analysis.
Sleep-related hypermotor epilepsy (SHE), previously known as nocturnal frontal lobe epilepsy, is a form of focal epilepsy characterized by seizures which arise during sleep. The seizures are most typically characterized by complex motor behaviors. It is a relatively uncommon form of epilepsy that constitutes approximately 9-13% of cases. This disorder is associated with cognitive impairment in at least half of patients as well as excessive daytime sleepiness due to poor sleep quality. This disorder is sometimes misdiagnosed as a non-epileptic sleep disorder. There are many potential causes of SHE including genetic, acquired injuries and structural abnormalities.
Epilepsy is a neurological condition of recurrent episodes of unprovoked epileptic seizures. A seizure is an abnormal neuronal brain activity that can cause intellectual, emotional, and social consequences. Epilepsy affects children and adults of all ages and races, and is one of the most common neurological disorders of the nervous system. Epilepsy is more common among children than adults, affecting about 6 out of 1000 US children that are between the age of 0 to 5 years old. The epileptic seizures can be of different types depending on the part of the brain that was affected, seizures are classified in 2 main types partial seizure or generalized seizure.
An epilepsy syndrome is defined as "a characteristic cluster of clinical and Electroencephalography (EEG) features, often supported by specific etiological findings ."
Drug-resistant epilepsy (DRE), also known as refractory epilepsy, intractable epilepsy, or pharmacoresistant epilepsy refers to a state in which an individual with a diagnosis of epilepsy is unresponsive to multiple first line therapies. Based on the 2010 guidelines from the International League against Epilepsy (ILAE), DRE is officially diagnosed following a lack of therapeutic relief in the form of continued seizure burden after trialing at least two antiepileptic drugs (AEDs) at the appropriate dosage and duration. The probability that the next medication will achieve seizure freedom drops with every failed AED. For example, after two failed AEDs, the probability that the third will achieve seizure freedom is around 4%. Drug-resistant epilepsy is commonly diagnosed after several years of uncontrolled seizures, however, in most cases, it is evident much earlier. Approximately 30% of people with epilepsy have a drug-resistant form. Achieving seizure control in DRE patients is critical as uncontrolled seizures can lead to irreversible damage to the brain, cognitive impairment, and increased risk for sudden unexpected death in epilepsy called SUDEP. Indirect consequences of DRE include seizure related injuries and/or accidents, impairment in daily life, adverse medication effects, increased co-morbidities especially psychological, and increased economic burden, etc.
Renée A. Shellhaas is an American pediatric neurologist and professor. She is the David T. Blasingame Professor of Neurology at Washington University School of Medicine in St. Louis and associate dean for faculty promotions and career development. She was previously an associate chair of career development and a clinician-investigator in pediatric neurology at the University of Michigan.