What is a seizure?

癫痫发作是脑细胞(也称为神经元或神经细胞)之间不受控制的电活动爆发，导致肌肉张力或运动(僵硬)暂时异常, twitching or limpness), behaviors, sensations or states of awareness.

Seizures are not all alike. A seizure can be a single event due to an acute cause, such as medication. When a person has recurring seizures, this is known as epilepsy.

为了实施最合适的治疗方法，医生得到准确的癫痫诊断是很重要的. 局灶性和全身性癫痫发作通常有不同的原因，准确诊断癫痫发作类型通常有助于确定癫痫发作的原因.

Whether or not the doctor can determine the cause for an individual’s seizures, treatment will likely mean medication. 难以控制的癫痫发作可通过神经刺激或饮食治疗得到改善. 癫痫发作是由于局灶性疤痕或脑部其他病变的患者可能是癫痫手术的好候选人.

Focal, or Partial Seizures

局灶性癫痫也被称为部分性癫痫，因为它们开始于大脑的一个区域. They can be caused by any type of focal injury that leaves scar tangles. Medical history or MRI will identify a cause (such as trauma, stroke or meningitis) in about half of the people who have focal seizures. 发育性疤痕——作为胎儿和早期大脑生长的一部分——是儿童局灶性癫痫发作的常见原因.

Focal Seizures: What Happens

Focal seizures can start in one part of the brain and spread to other areas, causing symptoms that are mild or severe, depending on how much of the brain becomes involved.

At first, the person may notice minor symptoms, which is referred to as an aura. 这个人可能改变了感觉或感觉某事即将发生(预感)。. 一些经历过先兆的人说胃里有一种上升的感觉，就像坐过山车一样.

As the seizure spreads across the brain, more symptoms appear. If the abnormal electrical activity involves a large area of the brain, the person may feel confused or dazed, or experience minor shaking, muscle stiffening, or fumbling or chewing motions. Focal seizures that cause altered awareness are called focal unaware seizures or complex partial seizures.

癫痫发作的电活动可以停留在大脑的一个感觉或运动区域, resulting in a focal aware seizure (also called simple partial seizure). 这个人意识到正在发生什么，可能会注意到不寻常的感觉和动作.

局灶性癫痫可发展为扩散到整个大脑的重大事件，并引起强直阵挛性癫痫发作. 这些癫痫发作对治疗和预防很重要，因为它们会导致呼吸系统问题和伤害.

Generalized-onset Seizures

全面性癫痫发作是大脑皮层异常神经放电的激增或多或少同时发生. 最常见的原因是脑电活动的“刹车”(抑制回路)和“加速器”(兴奋回路)失衡.

Generalized-onset Seizures: Genetic Considerations

Generalized seizures may have a genetic component, 但只有少数全身性癫痫患者的家庭成员也有同样的情况. 患有全身性癫痫发作的患者的儿童或其他家庭成员发生全身性癫痫发作的风险略有增加, but the severity of the seizures can vary from person to person. Genetic testing may reveal a cause for generalized seizures.

睡眠不足或大量饮酒会增加兴奋性反应，增加全身性癫痫发作的风险, especially in people with a genetic tendency to have them.

Types of Generalized-Onset Seizures

Absence Seizures (“Petit Mal Seizures”)

Childhood absence epilepsy 在儿童中表现为短暂的凝视发作，通常在4到6岁之间开始. Children usually outgrow these. Juvenile absence epilepsy starts slightly later and can persist into adulthood; people with these kinds of seizures may develop tonic-clonic seizures in addition to absence of seizures in adulthood.

Myoclonic seizures

肌阵挛发作包括突然的身体或肢体抽搐，可累及手臂、头部和颈部. 痉挛发生在身体两侧，呈丛集状，尤其在早晨. When these seizures develop in adolescence along with tonic-clonic seizures, they are part of a syndrome called juvenile myoclonic epilepsy. 人们也可能有肌阵挛性发作作为其他癫痫相关疾病的一部分.

Tonic and Atonic Seizures (“Drop Attacks”)

Some people, usually those with multiple brain injuries and intellectual disability, have tonic seizures consisting of sudden stiffness in the arms and body, which can cause falls and injuries. Many persons with tonic seizures have a syndrome called Lennox Gastaut syndrome. 这种情况可能涉及智力残疾，多种癫痫发作类型，包括强直性癫痫发作. People with Lennox Gastaut syndrome can have a distinctive EEG pattern called slow spike and wave.

Persons with diffuse brain disorders also may have atonic seizures, characterized by a sudden loss of body tone that results in collapsing, often with injuries. 紧跟着紧张性发作的一系列短暂的强直发作称为紧张性-无强直发作. 强直性和失张力性癫痫通常用特定的药物治疗，有时用神经刺激和饮食疗法.

Tonic, Clonic and Tonic-Clonic (Formerly called Grand Mal) Seizures

强直阵挛发作可由任何局灶性或全身性发作类型演变而来. 例如，局灶性癫痫发作可扩散到大脑两侧并引起强直阵挛发作. 一连串的肌阵挛发作可以持续并演变成强直阵挛发作. 全身性强直阵挛发作可单独发生，也可作为另一综合征的一部分发生，如青少年肌阵挛性癫痫(JME)或成年期青少年缺失性癫痫.