Generalized Tonic-Clonic Seizures
Generalized tonic-clonic seizures typically have no preceding aura but may have a prodrome of apathy or irritability. During the tonic phase, the jaw snaps shut followed by 10 to 15 seconds or longer of tonic spasms, apnea, and cyanosis. The clonic phase usually consists of 1 to 2 minutes of rhythmic generalized muscle contractions and increased blood pressure. The postictal phase lasts for minutes to hours, with confusion, somnolence, and possibly agitation.
The ictal EEG usually consists of generalized spike and wave or polyspike activity. The interictal EEG is highly variable with a normal background in some patients and slowing present in others.
Generalized seizures are rare in newborns. Generalized seizures occur most frequently in children secondary to fevers and metabolic derangements.
Absence seizures typically have no preceding aura or prodrome. An absence seizure usually lasts for only several seconds to minutes. There is a sudden interruption of consciousness, staring, 3-Hz blinking, and less frequently automatisms. There is no postictal confusion.11
The ictal EEG usually consists of 3-Hz generalized spike and wave activity with some slowing of the discharge frequency during the seizure. The interictal EEG usually has a normal background. Atypical absence seizures have generalized spike and wave activity but usually have a frequency less than 3 Hz.12
Absence seizures typically start between ages 4 and 10 years and resolve by age 20 years. Atypical absence epilepsy usually occurs in children who are neurologically or developmentally abnormal.13
Febrile seizures occur with a prodromal fever. A simple febrile seizure occurs as a brief generalized tonic clonic seizure occurring after the onset of fever. A complicated febrile seizure has prolonged seizure activity or focal seizure activity. Febrile seizures are covered in detail in Chapter 4.
Juvenile Myoclonic Epilepsy
The seizures associated with juvenile myoclonic epilepsy typically have no preceding aura but may have a prodrome of morning myoclonus. The seizures may consist of generalized tonic-clonic activity; however, absence seizures may also occur. The postictal phase is variable depending on the seizure type.11
The ictal EEG usually consists of generalized polyspike and slow wave activity. The interictal EEG is typically unremarkable.12
The age of onset of juvenile myoclonic epilepsy is typically 10 to 20 years. Patients are usually developmentally and neurologically normal.13
Progressive Myoclonic Epilepsy
The family of disorders known as the progressive myoclonic epilepsies (Table 3-3) consists of a number of loosely related disorders. These epilepsy subtypes are quite rare and have complex presentations and diagnostic findings. Most of these disorders have a genetic basis, though sporadic cases have occurred in some cases (Table 3-4). The EEG associated with these disorders is variable. The background is often slow. The seizures are typically generalized.11
Table 3–3.Progressive Myoclonic Epilepsies ||Download (.pdf)
Table 3–3.Progressive Myoclonic Epilepsies
|Juvenile neuroaxonal atrophy|
|Late infantile and juvenile GM2 gangliosidosis|
|Myoclonic epilepsy and ragged red fibers (MERRF)|
|Neuronal ceroid lipofuscinosis (NCL) (also known as Batten disease)|
|Noninfantile Gaucher disease|
|Unverricht–Lundborg disease (Baltic myoclonus)|
Table 3–4. Distinguishing Characteristics of the Progressive Myoclonic Epilepsies ||Download (.pdf)
Table 3–4. Distinguishing Characteristics of the Progressive Myoclonic Epilepsies
|Juvenile neuroaxonal dystrophy|
|Juvenile Gaucher disease|
|Sialidosis type II|
|Focal Occipital Spikes|
|Little or No Dementia|
|Noninfantile Gaucher disease|
|Sialidosis type I|
|Juvenile neuroaxonal dystrophy|
|Late infantile NCL|
|Dentatorubral pallidoluysian atrophy|
|Sialidosis type II|
West syndrome typically begins between 3 months and 3 years of age.14-16 The seizures associated with West syndrome consist of a jack-knifing movement and myoclonus. The EEG consists of a hypsarrhythmia pattern with bursts of asynchronous slow waves; spikes and sharp waves alternate with a suppressed EEG.17 The clinical features of West syndrome include infantile spasms and mental retardation, which varies according to the etiology of the spasms.
Aicardi syndrome is an X-linked disorder present from birth that is associated with infantile spasms. The seizures are described as infantile spasms, but alternating hemiconvulsions may also be seen. The clinical features of Aicardi syndrome include coloboma, chorioretinal lacunae, agenesis of the corpus callosum, vertebral anomalies, and seizures.18
Lennox–Gastaut syndrome typically begins between 1 and 10 years of age. There are multiple seizure types, associated with variable degrees of mental retardation.
The EEG reveals a slow spike wave complex with a frequency of 1 to 2.5 Hz, multifocal spikes, and generalized paroxysmal fast activity (GPFA).19
Partial Seizures: Localization-Related Epilepsy
Jacksonian motor seizures are simple partial seizures with no alteration of consciousness. These seizures begin with tonic contractions of the face, fingers, or feet and transform into clonic movements that march to other muscle groups on the ipsilateral hemibody. There is no alteration in consciousness, but postictal aphasia may occur if the primary epileptogenic zone involves the dominant hemisphere. Simple partial seizures may involve autonomic (Table 3-5), sensory, motor, or psychic functions.
Table 3–5. Possible Autonomic Seizure Clinical Features ||Download (.pdf)
Table 3–5. Possible Autonomic Seizure Clinical Features
Benign Rolandic epilepsy usually begins between ages 5 and 10 years and is transmitted in an autosomal dominant pattern with variable penetrance. It is fairly common, with an incidence of 21/100,000 children.20 The clinical features include a single nocturnal seizure with clonic movement of the mouth and gurgling. Secondary generalization is common. Alteration in consciousness, aura, and postictal confusion are rare. The seizures resolve by age 16 years.21,22
The interictal EEG consists of central and mid-temporal high-amplitude spike and wave with a characteristic dipole. The ictal EEG usually consists of a focal central or mid-temporal ictal onset, with the possibility of secondary generalization.23,24
Temporal lobe epilepsy accounts for approximately 70% of partial seizures. Many patients have a prior history of febrile seizures or head trauma. A prodrome consisting of lethargy is common. Auras are also common but not universal and include an array of findings such as déjà vu. The ictal findings or semiology include oral or motor automatisms, alteration of consciousness, head and eye deviation, contralateral twitching or tonic–clonic movements, and posturing. Right temporal lobe seizures are often hypermobile. Left temporal lobe seizures often result in behavior arrest. Versive head movements are relatively common, and 90% of patients with versive head movements had a primary epileptogenic zone in the contralateral hemisphere. Ipsiversive movements are less common but occur most commonly in patients with temporal foci. The postictal phase consists of minutes to hours of confusion and somnolence.24-30
Frontal lobe epilepsy accounts for approximately 20% of partial seizures. A prodrome is rare. Auras are unusual. The seizures typically consist of combinations of behavior alteration and automatisms of very brief duration. Frontal seizures often have atypical presentations and vary widely depending on the region of the frontal lobe from which the seizures arise (Table 3-6). Postictal confusion is rare.31-36
Table 3–6.Frequency of Aura Types by Location ||Download (.pdf)
Table 3–6.Frequency of Aura Types by Location
|Aura Type||Temporal (%)||Frontal (%)||Occipital (%)|
Occipital lobe epilepsy is rare, accounting for less than 10% of partial seizures. Prodromes are rare with occipital lobe seizures and auras are unusual. As with the frontal lobe seizures, the seizure characteristics are dependent on the area of the occipital lobe involved. When the striate cortex is involved, there are typically elemental visual hallucinations. Involvement of the lateral occipital lobe results in twinkling, pulsing lights. Seizures arising from the temporo-occipital are usually associated with formed visual hallucinations.37-39
Parietal lobe seizures are also relatively uncommon. The may be seen as simple partial seizures but they will often propagate. The initial features can include contralateral paresthesias, contralateral pain, idiomotor apraxia, and limb movement sensations. As the seizure progresses and propagates, asymmetric tonic posturing and automatisms may develop.40-42
Landau–Kleffner syndrome is a rare, invariably progressive, idiopathic acquired aphasia related to a focal epileptic disturbance in the area of the brain responsible for verbal processing.43 The syndrome begins between ages 3 and 10 in a child with normally acquired language abilities. The child then develops a verbal auditory agnosia and infrequent nocturnal partial or secondarily generalized seizures. The syndrome has a pathognomonic EEG pattern consisting of high-voltage multifocal spikes, predominating in the temporal lobes.44 Treatment is usually with valproic acid and benzodiazepines.45 Sometimes corticosteroids and IV Ig or even surgery with subpial transection46 are used in refractory cases. The outcome for overall language and cognitive function depends in part on how early the syndrome is recognized and treated, but over 2/3 of children are left with significant language or behavioral deficits.47
Rasmussen encephalitis is a syndrome of diffuse lymphocytic infiltration of the brain associated with partial seizures and progressive neurological deterioration with hemiparesis. This disorder typically affects children 1 to 14 years old. The syndrome is associated with perivascular cuffing on pathologic sections, and antibodies to the glutamate subunit GluR3 are commonly identified. The disorder is usually unilateral. Rasmussen encephalitis is very difficult to treat and frequently requires surgical management with hemispherectomy.