Seizure Types

by Tracy Connell, RN, MSN, CPNP

Ms. Connell is a Pediatric Epilepsy Nurse Practitioner at the Pediatric Epilepsy Center of St. Louis Children’s Hospital and provides care for patients in the New Onset Seizure Clinic.

Introduction

When most people think of a seizure, they think of a person falling to the ground and jerking all over. While this is one type of seizure, there are many other types. In this article, I hope to give you a good understanding of the different types of seizures and how they manifest themselves.

A seizure can be broadly defined as an involuntary symptom or behavior that is due to abnormal electrical activity in the brain. Seizures may be manifested in a wide variety of ways, including dramatic movements, unusual sensations, and alterations of consciousness. Despite the impressive range of possible seizure symptoms, there are a few common, stereotypical seizure types that have characteristic features and have been given specific classifications.

Seizures are first categorized as either generalized or partial.

Generalized Seizures

Generalized seizures are caused by abnormal electrical activity that occurs over the entire brain simultaneously. This group of seizures affect the level of awareness and muscle movement of all extremities. Following are the main types of generalized seizures.

Absence Seizures: This type of seizure is also known as “petit mal”. They are described as staring spells. At times they are difficult to distinguish from normal daydreaming spells. These seizures typically start in childhood and are often outgrown by adolescence, although adults can occasionally also have absence seizures. They can happen dozens of times a day but are very brief, usually lasting just a few seconds, so they are not always noticed. The child may get a dazed look on their face, have some eye blinking or head bobbing and not respond to any type of stimulus. After the seizure is over, the child usually continues his previous activity as if nothing happened. An EEG is very helpful with diagnosing this type of seizure. Patients usually respond very well to medication.

Myoclonic Seizures: These are characterized by sudden brief jerks of a single muscle or muscle group. You may see a sudden jerk of the hand or arm that will cause them to drop or knock things over. It may appear as if they have been startled. You may see the head or body suddenly bend forward or backward. At times the jerk can be so strong that the child can be thrown to the ground. These seizures are not the same thing as the periodic muscle spasms one often experiences when falling asleep.

Atonic Seizures: These are also very sudden brief seizures, but they involve loss of all muscle tone. The child will suddenly go limp and fall to the ground. There is significant risk of head injury during the fall. So, many children with this seizure type wear helmets for protection.

Tonic Seizures: These seizures involve stiffening of parts of the body or the entire body, sometimes causing the child to fall down. Unlike tonic-clonic seizures, there is no progression to a clonic phase (see below).

Tonic-Clonic Seizures: Also known as “grand mal”, these are very intense and can often be very frightening to witness. They generally start with a tonic phase with stiffening of the entire body. The eyes may roll back in the head, the back arches, and arms and legs stiffen. The muscles in the chest can also stiffen so it may appear that the person is not breathing and you may see blue around the lips. There may be an increase in saliva or “foaming at the mouth”. The clonic part is described as rhythmic jerking of the entire body. Once the seizure is over, they may feel worn out and may even sleep for a period of time. They may also experience some confusion.

Partial Seizures

Partial seizures, also called focal, are those seizures that begin in one part of the brain instead of all over. Depending on which lobe of the brain the seizure comes from will determine the way the seizure looks. Partial seizures can be classified based on either the symptoms of the seizure or the part of the brain where they start.

Based on the symptoms of the seizures, partial seizures can be divided into simple partial seizures and complex partial seizures.

Simple partial seizures: Simple partial seizures are noted for staying in just one area of the brain and not interfering with the level of consciousness. Depending on the area of the brain affected, these seizures could be expressed as shaking of a small part of the body, an unusual tingling or numbness of a localized body part, or even an unusual smell, visual hallucination, or ill-defined feeling. Simple partial seizures are often also called “auras”. Regardless of the specific symptom, in all simple partial seizures, the person remains completely aware and alert during the seizure.

Complex partial seizures: A complex partial seizure happens when the abnormal electrical activity involves parts of the brain that affect level of consciousness. Thus, the critical feature of the complex partial seizure is that the person has altered consciousness, so that he may be confused or staring unresponsively. There may also be subtle, repetitive and stereotypical movements of the face or extremities (automatisms). Although complex partial seizures can look similar to absence seizures, they usually last longer, typically 1-2 minutes. In addition, unlike absence seizures, complex partial seizures often are preceded by an aura and are followed by a state of sleepiness. Sometimes a complex partial seizure can start in just one area and spread throughout the entire brain, resulting in a generalized tonic-clonic seizure. This type is known as complex partial with secondary generalization.

Following are descriptions of the different types of seizures and how they typically appear depending on where in the brain they take place. However, sometimes only detailed testing by a neurologist can determine with certainty where seizures are originating.

Frontal lobe: These seizures are usually very short and often occur during sleep. They may be described as twitching or a funny feeling in the face, a finger or leg. The person may be aware all of this is happening (simple partial seizure). Sometimes the head will turn to one side, and the arm on that same side will stiffen. In other cases, very bizarre or complicated movements of the entire body can occur. The seizure may spread causing awareness to be affected and jerking of extremities may happen.

Temporal Lobe: This type usually involves complex partial seizures with staring and repetitive movements that seem to happen without purpose. These movements are called automatisms. There may also be a complaint of a funny feeling around the mouth, be unable to speak, and have increased saliva and twitching of the mouth. You may also see twitching, jerking, or stiffening on one side of the body. At the beginning of the seizure, they may experience a funny smell, a sensation of fear or a funny feeling in the stomach or chest.

Parietal Lobe: There may be a feeling of electricity or tingling sensation that may start in a certain area, or may spread. They may complain that one part of the body feels like it is moving. Sometimes there is a feeling of sinking, choking or nausea, or pain.

Occipital Lobe: These classically begin with visual problems, such as seeing flashes of light or hallucinations. Often the child will complain that they can’t see and have rapid eye blinking. The loss of vision is temporary and will return after the seizure is over.