9
CHAPTER
Clinical Evaluation
Aatif M. Husain and Abeer J. Hani
The clinical evaluation of epilepsy patients, like any other patient, involves a careful review of the history, thorough examination, and directed laboratory and neuroimaging studies. However, there are certain unique characteristics of an epilepsy evaluation that set it apart from not only other medical conditions, but also other neurologic conditions. Whereas history from the patient is very important, arguably even more important is observer history from a family member or friend of the epilepsy patient. The observer can provide details of the seizures that the patient cannot provide. The examination provides further clues about whether a brain disorder or lesion is present. Neurologic examination is important, as well as general physical and skin examinations. EEG and neuroimaging evaluation are also very important, and depending on the clinical situation, magnetic resonance imaging (MRI) or computed tomography (CT) may be more appropriate. Laboratory testing helps exclude possible provoking factors for seizures, and occasionally, particularly in pediatrics, may lead to a neurologic or metabolic disorder causing seizures. The unique features of the clinical evaluation of an epilepsy patient will be discussed in further detail.
One of the main goals of the clinical evaluation is to classify the seizure type. Recently, the International League Against Epilepsy (ILAE) updated seizure classification (1). A summary of this classification is presented in Table 9.1. Once the seizure types are identified, the clinical evaluation can help determine the epilepsy syndrome. The classification of epilepsy syndromes is presented in Table 9.2. Details of these classifications are presented in Chapters 3 and 4.
In this chapter the patient’s episodes are referred to as seizures. It is recognized that when initially evaluating a patient, it may not be clear if the episodes are indeed epileptic or nonepileptic seizures. Moreover, there is disagreement as to whether nonepileptic episodes should be called seizures, attacks, or spells (2). There are advantages and disadvantages for each of these terms, but in this chapter the term “seizure” will be used without implication of whether it is epileptic or not, unless otherwise specified.
HISTORY
The history is the most important feature of the clinical evaluation of an epilepsy patient. Whereas the patient can describe many aspects of the history, she/he is necessarily a poor witness of the actual seizure. Since obtaining a description of the actual seizure is important, talking with a family member or friend who has seen the seizures is important. In addition to obtaining the basic demographic information, determining handedness is very important. This helps establish cerebral dominance, which, in turn, may help with localization of seizure onset.
Description of Seizure(s)
The examiner must first determine how many different types of seizures the patient has experienced. The nature of each seizure type must be described. In addition, the age of onset, frequency, and evolution over time should be determined.
A detailed description of what happens to the patient during a seizure is very important to obtain. The various features of a seizure that should be noted are presented in Table 9.3. The presence of an aura should be determined. Mentation during an aura is not altered, and the patient is aware of their surroundings. An aura can be of various types, including various sensory hallucinations, light-headedness, déjà vu sensation, abnormal taste or sensation, or an indescribable sensation. The duration of the aura and the consistency with which the aura precedes the seizure should be noted. Most often the aura is followed quickly by the seizure, but sometimes auras occur in isolation and are only rarely followed by a seizure. By definition, an aura is a restricted, focal epileptic discharge. If the presence of an aura can be confirmed, it becomes very likely that the seizure is focal. The manifestation of the aura represents the site of onset of the ictal discharge.
An aura must be distinguished from a prodrome. The latter is a sense of being unwell or other vague sensation that can precede a seizure by minutes to days. The prodrome may be followed by an aura, which quickly leads to a seizure, or the prodrome may eventually lead to a seizure directly. Whereas an aura is an epileptic phenomenon, a prodrome is not. A prodrome can occur with focal or generalized seizures, and does not help establish a site of onset of the ictal discharge.
TABLE 9.1 Classification of Seizures (Prior Classification Presented in Italics)
Focal seizures (partial seizures) Without impairment of consciousness or awareness (simple partial seizures) With observable motor or autonomic components Involving subjective sensory or psychic phenomenon only (aura) With impairment of consciousness or awareness (dyscognitive) (complex partial seizures) Evolving to bilateral, convulsive seizure (secondarily generalized seizure) |
Generalized seizures Tonic–clonic (in any combination) Absence Typical Atypical Absence with special features Myoclonic absence Eyelid myoclonia Myoclonic Myoclonic Myoclonic atonic Myoclonic tonic Clonic Tonic Atonic |
Unknown Epileptic spasms |
Source: Adapted from Ref. (1). Berg AT, Berkovic SF, Brodie MJ, et al. Revised terminology and concepts for organization of seizures and epilepsies: report of the ILAE Commission on Classification and Terminology, 2005–2009. Epilepsia. 2010;51:676–685.
The degree of mental status impairment during a seizure should be determined. When there is no impairment of consciousness or awareness, the presence of motor, sensory, or autonomic features is noted. These are the same as auras. In the previous ILAE classification, these were referred to as simple partial seizures (3). If the patient is unable to respond to surrounding, consciousness and awareness are altered, and the seizure is referred to as dyscognitive. Previously, these were called complex partial seizures. Various motor, autonomic, and other symptoms, such as tongue biting and incontinence, may also be present in seizures with altered consciousness, and their presence is noted. The motor activity may be in the form of automatisms of the hands or mouth, clonic activity, myoclonic jerks, falls, etc. These features help in localizing the site of onset of the seizure.
Various postictal phenomena are frequently noted, and their presence should be determined. These include fatigue, headaches, confusional state, and psychosis. The duration of the seizure and the postictal phase should be determined, keeping in mind that seizures are terrifying events for family, friends, and onlookers, and that the duration of the event is frequently overestimated. Most seizures, whether focal or generalized, usually do not last longer than 60 to 90 seconds.
TABLE 9.2 Classification of Electroclinical Syndrome and Other Epilepsies Most Likely to be Seen in Veterans (Adult Patients)
Electroclinical syndrome arranged by age of onset Adolescence – Adult Juvenile absence epilepsy Juvenile myoclonic epilepsy Epilepsy with generalized tonic–clonic seizures alone Progressive myoclonus epilepsies Autosomal dominant epilepsy with auditory features Other familial temporal lobe epilepsies Less specific age relationship Familial focal epilepsy with variable foci Reflex epilepsies |
Distinctive constellations Mesial temporal lobe epilepsy with hippocampal sclerosis Rasmussen syndrome Gelastic seizures with hypothalamic hamartoma Hemiconvulsions-hemiplegia-epilepsy Epilepsies that do not fit into any of these diagnostic categories can be distinguished first on the basis of the presence or absence of a known structural or metabolic condition (presumed cause) and then on the basis of the primary mode of seizure onset (generalized vs. focal) |
Epilepsies attributed to and organized by structural-metabolic causes Malformations of cortical development Neurocutaneous syndromes Tumor Infection Trauma |
Angioma Perinatal insults Stroke Etc. |
Source: Adapted from Ref. (1). Berg AT, Berkovic SF, Brodie MJ, et al. Revised terminology and concepts for organization of seizures and epilepsies: report of the ILAE Commission on Classification and Terminology, 2005–2009. Epilepsia. 2010;51:676–685.
In children, the interviewer often has to rely on parental report for a description of the events of concern and to obtain information about seizure types, auras, ictal and postictal phases. Some children may have insight into their seizures and it is often worthwhile to get their version of the events. Postictally, it is not uncommon to have postictal Todd’s paralysis in children with focal seizures and that may be a helpful localizing sign of seizure onset. It is often helpful to utilize this opportunity to teach family members about different seizure manifestations that they may look for during a seizure and to urge them to try to videotape the events of concern whenever feasible.
TABLE 9.3 Features of a Seizure History and Description
Aura Olfactory hallucinations Visual hallucinations Auditory hallucinations Light-headedness Déjà vu Abnormal taste Abdominal sensation Indescribable sensation |
Duration of Aura <30 sec 31–59 sec 1–5 min >5 min |
Mental status Loss of awareness Loss of consciousness Aphasia |
Motor Activity Automatism (facial or manual) Focal motor activity Generalized motor activity Focal to generalized motor activity |
Sensory Symptoms Paresthesia Dysesthesia Numbness |
Autonomic Symptoms Other Symptoms Tongue biting Incontinence |
Postictal phase Fatigue Headache Confusional state Psychosis |
Duration of seizures <30 sec 31–59 sec 1–5 min >5 min |
Duration of postictal state No postictal period <5 min 5–30 min >30 min |
Description of First Seizure
Details of the first recognized seizure should be sought from the patient and family members. All features discussed earlier about individual seizure types should be asked in reference to the first seizure. How this seizure type has evolved and whether it is still occurring should be determined. The examiner should appreciate that the first recognized seizure may not have been the first ever seizure. The first ever seizure may have been subtle, such as a brief staring spell, and not recognized as a seizure. Some patients only recognize that they have epilepsy after a tonic–clonic seizure. This is not uncommon in children with childhood absence seizures whose absence seizures may go unrecognized for several months and are often brought to attention following a generalized tonic–clonic seizure.
General Issues Relevant to Seizures
There are several other details of the patient’s overall seizure history that should be determined. A summary of these is presented in Table 9.4. Sometimes seizures have specific triggers and their identification may have a significant impact on seizure control. Seizures may also have circadian triggers, occurring during a particular phase of the sleep–wake cycle, such as only upon awakening from sleep or only in sleep. These features, if identified, help narrow the epilepsy syndromic diagnosis. Whether seizures result in injuries should be noted, as this will help determine the safety advice that should be given to patients. In addition, fitness for driving and operating other machinery may be influenced by prior injuries. Patients should be questioned about a prior history of status epilepticus (SE). This information may help in localization of seizure onset and may affect medical management of these patients.
In children, seizure precautions, including avoiding contact sports and supervision during swimming and performing social activities should be reviewed. While ensuring a safe supervised environment for children with epilepsy, it is important to make sure that they are socially empowered to participate in nonrisky social activities.
Many epilepsy patients have a variety of sleep complaints and disorders. Daytime sleepiness is a common complaint and may be due to medications, sleep deprivation, or primary sleep disorder such as sleep apnea. Presence of untreated sleep apnea may result in greater difficulty in controlling seizures. Thus, asking patients about sleep complaints, in particular, symptoms of sleep apnea, is very important and may help in better managing these patients.
TABLE 9.4 Other Seizure Details
Triggers Stress Sleep deprivation Infection/illness Fasting Illicit drugs Alcohol use Menstrual cycle Flashing lights |
Seizure occurrence time Diurnal Nocturnal Upon awakening No pattern |
Injuries with seizures Bruise Laceration Burn Fracture |
History of status epilepticus |
Similarly, children with epilepsy often have associated comorbidities, including intellectual disability, cerebral palsy, attention deficit hyperactivity disorder (ADHD), autism, learning difficulties, and depression. These conditions may be handicapping and proper identification and treatment is paramount to improve the quality of life of these children.
Etiology/Risk Factors
When a patient is first diagnosed with epilepsy, one of the foremost questions she/he has is, “Why did I have a seizure?” Every patient must be questioned about risk factors for seizures that may suggest an etiology. The etiology will ultimately be found only in a minority of patients with seizures, but that does not preclude a thorough evaluation. Common historical elements that the patient should be questioned about are presented in Table 9.5.
In adult patients, questions about childhood are often skipped, but these are very important and should be asked. This is of utmost importance in children presenting for evaluation of seizures. Birth-related history is important to determine: Was the delivery premature? Were there any congenital malformations? Were there any maternal illnesses, and was the delivery cesarean, vaginal, or forceps/suction assisted? Did the patient require admission to the neonatal intensive care at birth and why? How was the neonatal and infantile period? Did the patient reach her/his neurodevelopmental milestones (including walking and talking) on time? Did she/he require any special services, including speech therapy, physical therapy, or occupational therapy during childhood? Childhood problems such as febrile seizures and educational difficulties should also be determined. Some conditions that can cause seizures are seen more often in adults, and these include strokes, brain tumors, and dementias. Presence of these should be sought. Infections such as encephalitis and meningitis can occur at any age and may be the cause of seizures. Family history of seizures should also be noted to determine if there is any genetic predisposition to seizures. After assessing these risk factors and completing the clinical evaluation, an etiology may be determined. Possible etiologies for seizures are presented in Table 9.6.
TABLE 9.5 Risk Factors for Seizures
Maternal illness during pregnancy Prematurity Birth-related injury Congenital malformations Febrile seizures Stroke Tumor Dementia Meningitis Encephalitis Family history of seizures Trauma Other |
TABLE 9.6 Etiology of Seizures
Viral, bacterial, and parasitic infections Traumatic brain injury Stroke Intraventricular hemorrhage Hypoxic–ischemic encephalopathy Other metabolic or toxic insults Neurocutaneous syndromes; Inborn errors of metabolism Genetic and chromosomal development encephalopathies Developmental encephalopathy of unknown cause as evidenced by the presence of mental retardation, cerebral palsy, or autism with no evidence of a specific insult of disorder to which cause can be attributed preceding the onset of epilepsy Malformations of cortical or other brain development with or without known genetic determinants Neoplasia Mesial temporal sclerosis Dementia Other degenerative neurologic diseases Genetic or presumed genetic Epilepsy of unknown cause, without relevant abnormalities on examination, cognition, history, or imaging; Other |
Source: Adapted from Ref. (15). NINDS. NINDS common data elements: epilepsy [online]. http://www.commondataelements.ninds.nih.gov/epilepsy.aspx#tab=Data_Standards. Accessed April 1, 2013.
Traumatic brain injury (TBI) is a common cause of seizure in younger patients, keeping in mind that epilepsy can develop years after the trauma (5). Trauma-related questions that the examiner should attempt to get answers to are presented in Table 9.7. Most important questions that the patient may be able to answer are the severity and type of trauma. Establishing the approximate time of trauma is important as well.
Prior Treatment
Questioning the patient about prior treatments is important. Ideally, the drug, dose, plasma concentrations achieved, any side effects, and reasons for discontinuation should be determined for each drug the patient has used in the past. In addition, combination therapies that have been attempted should also be noted. Of course, in many situations, patients will not remember all the details of the medications they have tried previously. At a minimum, the name of each AED and why it was discontinued should be determined. If a medication caused a serious allergic reaction, that should be noted.
