neurologic disorders
Seizure Disorders
Symptoms and Signs of Seizure Disorders
Anauramay precede seizures. Aura describes how patients feel as a seizure starts. Auras may consist of motor activity or sensory, autonomic, or psychic sensations (eg, paresthesias, a rising epigastric sensation, abnormal smells, a sensation of fear, a déjà vu or jamais vu sensation). In jamais vu, a familiar place or experience feels very unfamiliar—the opposite of déjà vu. In most cases, the aura that patients describe is part of a focal aware seizure. Most seizures end spontaneously in 1 to 2 minutes. Apostictal stateoften follows generalized-onset seizures; it is characterized by deep sleep, headache, confusion, and muscle soreness; this state lasts from minutes to hours. Sometimes the postictal state includes Todd paralysis (a transient neurologic deficit, usually weakness, of the limb contralateral to the seizure focus). Most patients appear neurologically normal between seizures, although high doses of the medications used to treat seizure disorders, particularly sedating antiseizure medications, can reduce alertness. Any progressive mental deterioration is usually related to the neurologic disorder that caused the seizures rather than to the seizures themselves. Occasionally, seizures are unremitting, as in status epilepticus. Focal-onset seizures may be Focal aware seizures (formerly, simple partial seizures) Focal impaired-awareness seizures (formerly, complex partial seizures) During a focal aware seizure, awareness is intact. If awareness is impaired during any part of the seizure, the seizure is classified as a focal seizure with impaired awareness; awareness may be impaired but not completely lost. Focal aware seizurescause motor, sensory, or psychomotor symptoms. Specific symptoms reflect the affected area of the brain (see table). In jacksonian seizures, focal motor symptoms begin in one hand, then march up the arm (jacksonian march). Other focal-onset seizures affect the face first, then spread to an arm and sometimes a leg. Some focal-onset motor seizures begin with an arm raising and the head turning toward the raised arm (called fencing posture). Epilepsia partialis continua, a rare disorder, is a continuous focal aware motor seizure. It usually involves the arm, hand, or one side of the face; seizures recur every few seconds or minutes for days to years at a time. The cause is usually as follows: In adults: A structural lesion (eg, stroke) In children: A focal cerebral cortical inflammatory process (eg, Rasmussen encephalitis), possibly caused by a chronic viral infection or by autoimmune processes Consider focal-onset seizures in patients with transient, unexplained, recurrent abnormalities that appear psychiatric (eg, hallucinations, complex behavioral automatisms, speech arrest, reduced responsiveness while staring). Focal impaired-awareness seizuresare often preceded by auras. During the seizure, patients may stare. Awareness is impaired, but patients have some awareness of the environment (eg, they purposefully withdraw from noxious stimuli). The following may also occur: Oral automatisms (involuntary chewing or lip smacking) Limb automatisms (eg, automatic purposeless movements of the hands) Utterance of unintelligible sounds without understanding what they say Resistance to assistance Tonic or dystonic posturing of the extremity contralateral to the seizure focus Head and eye deviation, usually in a direction contralateral to the seizure focus Bicycling or pedaling movements of the legs if the seizure emanates from the medial frontal or orbitofrontal head regions Motor symptoms subside after 1 to 2 minutes, but confusion and disorientation may continue for another 1 or 2 minutes. Postictal amnesia is common. Patients may lash out if restrained during the seizure or while recovering consciousness if the seizure generalizes. However, unprovoked aggressive behavior is unusual. Left temporal lobe seizures may cause verbal memory abnormalities; right temporal lobe seizures may cause visual spatial memory abnormalities. Awareness is usually impaired or lost, and motor function is abnormal from the onset. Generalized-onset seizures are classified as motor or nonmotor (absence) seizures. Typical absence seizures(formerly called petit mal seizures) consist of 10- to 30-second loss of consciousness with eyelid fluttering; axial muscle tone may or may not be lost. Patients do not fall or convulse; they abruptly stop activity, then just as abruptly resume it, with no postictal symptoms or knowledge that a seizure has occurred. Absence seizures are genetic and occur predominantly in children. Usually, they begin between ages 5 and 15 years and do not continue into adulthood. Without treatment, such seizures are likely to occur many times a day. Seizures often occur when patients are sitting quietly, can be precipitated by hyperventilation, and rarely occur during exercise. Neurologic and cognitive examination results are usually normal. Atypical absence seizuresusually occur as part of the Lennox-Gastaut syndrome, a severe form of epilepsy. They differ from typical absence seizures as follows: They last longer. Jerking or automatic movements are more pronounced. Loss of awareness is less complete. Many patients have a history of damage to the nervous system, developmental delay, abnormal neurologic examination results, and other types of seizures. Atypical absence seizures usually continue into adulthood. Lennox-Gastaut syndromeis a severe form of epilepsy that causes several types of seizures; the disorder usually begins before the age of 4 years and can continue into adulthood. Periods of frequent seizures may alternate with relatively seizure-free periods. Intellectual function and/or information processing is impaired in most patients with Lennox-Gastaut syndrome; development may be delayed, and behavioral problems may occur. Causes of Lennox-Gastaut syndrome include brain malformations, tuberous sclerosis, perinatal asphyxia, severe head injury, central nervous system infection, and hereditary genetic and degenerative or metabolic disorders. Sometimes no cause is identified. Inmyoclonic absence seizures,the arms and shoulders jerk rhythmically (3 times/second), causing progressive lifting of the arms. Typically, these seizures last 10 to 60 seconds. Impairment of awareness may not be obvious. Myoclonic absence seizures are caused by various genetic disorders; sometimes the cause is unknown. Eyelid myocloniaconsists of myoclonic jerks of the eyelids and upward deviation of the eyes, often precipitated by closing the eyes or by light. Eyelid myoclonia can occur in motor as well as nonmotor seizures. Atonic seizuresoccur most often in children, usually as part of the Lennox-Gastaut syndrome. Atonic seizures are characterized by brief, complete loss of muscle tone and consciousness. Children fall or pitch to the ground, risking trauma, particularly head injury. Tonic seizuresoccur most often during sleep, usually in children. The cause is usually the Lennox-Gastaut syndrome. Tonic (sustained) contraction of axial muscles may begin abruptly or gradually, then spread to the proximal muscles of the limbs. The neck is often stiff. Tonic seizures usually last 10 to 15 seconds. In longer tonic seizures, a few, rapid clonic jerks may occur as the tonic phase ends. Inclonic seizures,sustained rhythmic jerking occurs in the limbs on both sides of the body and often in head, neck, face, and trunk. Clonic seizures usually occur in infants and should be distinguished from jitteriness or shuddering attacks. Clonic seizures are much less common than tonic-clonic seizures. Tonic-clonic seizuresmay be Generalized-onset (formerly primarily generalized) Focal-to-bilateral tonic-clonic (formerly, secondarily generalized) Generalized-onset tonic-clonic seizures typically begin with an outcry; they continue with loss of consciousness and falling, followed by tonic contraction, then clonic (rapidly alternating contraction and relaxation) motion of muscles of the extremities, trunk, and head. Urinary and fecal incontinence, tongue biting, and frothing at the mouth sometimes occur. Seizures usually last 1 to 2 minutes. There is no aura. Focal-to-bilateral tonic-clonic seizures begin with a focal aware or focal impaired-awareness seizure, then progress to resemble other generalized-onset tonic-clonic seizures. Myoclonic seizuresare brief, lightning-like jerks of a limb, several limbs, or the trunk. They may be repetitive, leading to a tonic-clonic seizure. The jerks may be bilateral or unilateral. Unlike other seizures with bilateral motor movements, consciousness is not lost unless the myoclonic seizure progresses into a generalized tonic-clonic seizure. Inmyoclonic-atonic seizures,the extremities or trunk jerks briefly, then goes limp (drop attack). Seizures usually begin at age 6 months to 6 years. In two thirds of children, febrile seizures and generalized-onset convulsive seizures precede the myoclonic-atonic seizure. These seizures are more common among males (2:1). Development and cognition are typically normal but may become impaired when or after seizures begin. has replaced the term infantile spasms, although Infantile Spasms may be used for epileptic spasms that occur during infancy. Onset of epileptic spasms may be focal, generalized or unknown. They are characterized by sudden flexion and adduction of the arms and forward flexion of the trunk. Seizures last a few seconds and recur many times a day. They occur only in the first 5 years of life, then are replaced by other types of seizures. Developmental defects are usually present. Juvenile myoclonic epilepsyis a type of generalized myoclonic-tonic-clonic seizure; it is characterized by myoclonic, tonic-clonic, and absence seizures. It typically appears during adolescence. Seizures begin with a few bilateral, synchronous myoclonic jerks, followed in 90% of cases by generalized tonic-clonic seizures. They often occur when patients awaken in the morning, especially after sleep deprivation or alcohol use. Absence seizures occur in about one third of patients. Febrile Seizures None Complicated febrile seizures Preexisting neurologic abnormalities Onset before age 1 year A family history of seizure disorders ) occur in > 80% of patients with Dravet syndrome ( Symptoms and signs references ). Status epilepticus is continuous seizure activity; onset can be generalized or focal. Status epilepticus has 2 forms: Convulsive (with prominent motor symptoms) Nonconvulsive (without prominent motor symptoms) Generalized convulsive status epilepticusinvolves at least one of the following: 5 minutes ( Symptoms and signs references ) ≥2 seizures between which patients do not fully regain consciousness The previous definition of>30-minute duration was revised to encourage more prompt identification and treatment. Untreated generalized seizures lasting>60 minutes may result in permanent brain damage; longer-lasting seizures may be fatal. Heart rate and temperature increase. Generalized convulsive status epilepticus has many causes, including head trauma and rapid withdrawal of antiseizure medications. Nonconvulsive status epilepticusincludes focal-onset status epilepticus and absence status epilepticus. These seizures often manifest as prolonged episodes of mental status changes. EEG may be required for diagnosis. Sudden unexplained death in epilepsy (SUDEP) is a rare complication of seizures; cause is unknown. SUDEP usually occurs at night or during sleep. Risk of SUDEP is highest for patients who have frequent seizures, especially generalized tonic-clonic seizures. No measures have been shown to decrease risk of SUDEP, but the best possible control of seizures is recommended. 1.Nelson KB, Ellenberg JH: Prognosis in children with febrile seizures.Pediatrics61 (5):720–727, 1928. https://doi.org/10.1542/peds.61.5.720 2.He Z, Li Y, Zhao X, Li B: Dravet syndrome: Advances in etiology, clinical presentation, and treatment.Epilepsy Res188:10704, 20221. doi: 10.1016/j.eplepsyres.2022.107041. Epub 2022 Oct 29. 3.Trinka E, Cock H, Hesdorffer D, et al: A definition and classification of status epilepticus: Report of the ILAE (International League Against Epilepsy) Task Force on Classification of Status Epilepticus.Epilepsia56 (10):1515–1523, 2015. doi: 10.1111/epi.13121 Epub 2015 Sep 4. 