Learning Objectives
- There are a variety of epilepsies, some are benign
- The EEG is helpful for diagnosing epilepsy syndromes
- Some epilepsy syndromes are difficult to treat, and they may require surgery or specialized care
History
A 24 year old law student visits you because of some symptoms her fiancé noticed late one night after studying. She says she does not know what happened, but she stayed up late making notes for her class, and fell asleep at her desk. Her fiancé was visiting her then, and saw that after she had fallen asleep, she seemed to make a groaning noise, then her eyes opened, she looked to the right, and the right arm and leg began trembling. Then she started shaking in the arms and legs on both sides, so he helped her to the floor. She bit her tongue, and she lost control of her urine. After about 60 seconds, she stopped moving, and several minutes later, he was able to wake her up. She felt tired, and she had a headache, but she did not remember what happened, and she could not explain that there was any warning symptom (or aura).
She takes no medications, except acetaminophen as needed. She has no allergies to medications.
Her medical history is largely unremarkable. She had no head injuries or febrile seizures as a child, and she denies headaches. She had minor knee surgery on the left side at age 17.
Her father has hypertension. Her mother had cervical cancer. Her brother and sister have no illnesses. A ten system review of systems is unremarkable.
Examination
Pulse 76. Blood pressure 105/71. Temperature 98.9 F. She is a healthy alert young lady. Her heart sounds and carotid auscultation are normal. Pupillary and funduscopic exam are normal. Language, attention, memory and orientation are normal. Cranial nerve function is normal. Motor function is normal. The reflexes are normal and the toes go downwards. Sensation is normal. Cerebellar and gait function are normal.
Localization and Neuroanatomy
The patient had a symptom suggestive of a seizure. In particular, this sounds like a partial seizure, with left frontal onset, then secondary generalization. What makes this a partial seizure onset is the initial eye deviation to the right side (driven by the frontal eye fields) followed by involuntary movements of the right arm and leg, then followed by movement and loss of awareness throughout. A witness’s account often helps determine the semiology of the seizure.
Diagnosis
There are different types of seizures. A partial seizure has focal positive activity without loss of awareness. This positive activity could be forced eye deviation, involuntary movement or tremor on one side, a sensation of tingling, a visual symptom of bright lights, an abnormal sensation of smell, or the sensation of a memory (déjà vu). A generalized seizure involves loss of awareness. This may occur with or without motor activity of the face or the body. Tonic seizures are characterized by sustained muscle contraction, tonic-clonic seizures are characterized by a mixture of rhythmic, involuntary movement and sustained contraction. The duration of a partial seizure may be very brief, on the order of a few seconds. A generalized seizure may last 30-90 seconds, and sometimes longer. Status epilepticus is a dangerous condition of prolonged generalized seizure. It has a significant risk of sudden death due to asphyxiation and cardiac disorders.
Seizures have many different causes. Adverse effects of medications, disorders of the metabolism affecting the blood chemistry, injuries to the brain, and clinical tendency to have a seizure are some examples. Sometimes a cause of seizures is not found.
In the process of learning the cause of a seizure, certain testing is standard. For a first time seizure laboratory testing is helpful. This should especially evaluate the electrolyte levels. Conditions such as hyponatremia and hypercalcemia may cause a seizure outright. The EEG is generally accepted as valuable in the diagnosis of epilepsy. It may be normal in many cases. If it is not normal, and it suggests an epilepsy syndrome, it may help guide us in treatment and prognosis. The MRI is not necessary in all cases of epilepsy, but it is a routine test in cases of localization-related epilepsy or for first time seizures in adults.
When testing is completed, certain clinical patterns may also suggest the cause of seizures. Some epilepsy syndromes affect children primarily.
Benign rolandic epilepsy is a history of seizures characterized by numbness or twitching around the mouth that interferes with speech but not consciousness. Tonic-clonic seizures may occur during sleep. The EEG shows centro-temporal spikes. Most patients are not treated for this disorder. Seizures tend to cease by the teenage years.
Febrile seizures are tonic clonic spells that occur in young children with a high fever. They occur normally in children between 3 months and 4 years old. They may last several minutes. Normally, no treatment or significant testing is indicated. They tend to occur only once during a lifetime.
Staring spells in a child not associated with any movement is typical of childhood absence epilepsy (CAE). The EEG may show 2-4 Hz spike and wave changes, and patients respond to treatment with zarontin, valproate, or lamotrigine. Many patients stop having the events during adolescence.
Some patients develop staring spells at older ages, 10-18. They may also have tonic-clonic seizures. This combination fits the pattern of juvenile absence epilepsy. In this case, the EEG is abnormal, similar to that of CAE, and medications may be helpful for controlling the seizures. The seizures do not abate during adulthood, however.
A common epilepsy syndrome which affects teenagers and adults is juvenile myoclonic epilepsy (JME). This condition may include myoclonic jerks with apparent retained awareness, absence seizures, and generalized tonic-clonic seizures. The EEG in this condition is abnormal, showing spike and wave complexes, sometimes in response to photic stimulation. This condition may be treated with valproate, levetiracetam or lamotrigine. The tendency to have seizures may be increased with sleep deprivation.
Some types of epilepsy syndromes affect adults, primarily.
Perhaps the most common variety of epilepsy, at least in adults, is temporal lobe epilepsy. This condition is associated with a warning symptom (aura) of an abnormal smell, sense of fear or memory recall. These aura symptoms are associated with discharges from the mesiotemporal cortex. Patients may have episodes of staring, twitching or fumbling of the fingers. These are complex-partial seizures. A tonic-clonic seizure may occur. This condition may be associated with a normal EEG. Hippocampal sclerosis may be found on MRI of the brain. This condition may respond to a variety of medications, or it may be medically refractory. Sometimes patients respond to epilepsy surgery for this condition.
Frontal lobe epilepsy is a condition that may be associated with staring spells, generalized tonic-clonic seizures, or partial onset or simple partial seizures. A variety of different causes of this condition should be considered, and EEG and MRI test results are variable. Both are important to determining the prognosis and ideal treatment of this condition. Many patients respond to treatment with medication, and some cases require epilepsy surgery.
There are other epilepsy syndromes, which are relatively rare, which may be important to clinical neurology. These include Lennox Gastaut syndrome, Landau Kleffner syndrome, Rasmussen syndrome, and myoclonic epilepsy.
Pseudoseizures are a kind of episodic disorder that is considered within the broad range of seizures and epilepsy syndromes. These are characterized by variable symptoms, variable durations, symptoms related to stressful conditions, and failure of anticonvulsant treatment. Examples of symptoms include bilateral, nonrhythmic movement of the arms and legs without loss of consciousness. These are associated with psychological or behavioral disorders and conversion disorder. Sometimes pseudoseizures are a misdiagnosis of temporal lobe or frontal lobe epilepsy.
Treatment
There are numerous anticonvulsant medications. Many of these were mentioned above. Each of them may have unique efficacy, side effects, and management issues. For adults, levetiracetam is a favorite medicine of clinicians, due to its benign side effect profile, low cost, and efficacy for a variety of seizures.
Certain epilepsy syndromes require the care of an epilepsy surgery center. These tend to be refractory seizures of frontal or temporal lobe onset, difficult seizure syndromes, such as LGS, or unexplained refractory symptoms, such as pseudoseizures.
Review Questions
- The definition of epilepsy is
a. The tendency to have seizures
b. A clinical case of two or more unprovoked seizures
c. a variety of conditions that predispose a person to have seizures
d. a dangerous condition that requires medical treatment and safety precautions
e. All of the above - The management of epilepsy differs from that of a first time seizure in that
a. MRI of the brain is repeated for epilepsy cases
b. blood tests are repeated for epilepsy cases
c. Patients with epilepsy often use medications to prevent seizures, while patients with a first time seizure rarely use these medications
d. Patients with epilepsy are asked not to drive, while patients with a first time seizure are safe to drive
e. Patients with epilepsy usually have a family history of seizures
3. There are many medications that may be used to prevent seizures. Which of these is most often used to prevent seizures in adults?
a. felbamate
b. vigabatrin
c. levetiracetam
d. lacosamide
e. phenobarbital