EPILEPSYESSENTIALS By Steven Karceski, MD

How to Identify the Signs and Symptoms of Partial Seizures The clinical presentation can at first seem to indicate a number of diagnoses. Here’s how to narrow the choices.

ocalization related epilepsy seizures are refractory to medical manage- dles sensation indicates that the seizure (LRE) is also called partial ment, epilepsy surgery may be considered. involves the somatosensory region (i.e., the epilepsy. A person who has a sin- In order for surgery to be successful, accu- postcentral gyrus). However, this is not the gle kind of LRE may experience rate identification of the region of seizure only area from which sensory symptoms L any combination of partial onset is needed. This localization begins may arise. Contralateral mesial frontal seizures: simple partial, complex partial and with a description of the seizure semiology. structures can also produce sensory symp- secondarily generalized. There are many In combination with medical testing, this toms. In some instances, the superior tem- causes of partial seizures, including head information is a critical step in the presurgi- poral gyrus has been shown to cause bilat- injuries, tumors, infection, and stroke cal evaluation of persons with focal seizures. eral sensory symptoms. (Table 1). Many people with partial Galen first used the term “aura” to refer Pain is an uncommon aura. When it seizures recall having a “warning” or “aura” to the “breath of air” that occurred just occurs, it often means the seizure involves just prior to losing consciousness. The aura before the seizure started. The use of this the contralateral parietal lobe. However, is the simple partial portion of the seizure. term has continued to modern times. The the mechanism that produces the pain is As the seizure propagates, and involves a aura is the portion of the seizure that the not well understood, and there are cases of larger volume of cerebral cortex, conscious- person can recall, and is the simple partial pain that is ipsilateral to the region of ness can no longer be preserved (i.e., the portion of the seizure. If the seizure seizure onset. In these cases, involvement of person loses awareness). It is at this point spreads, consciousness is lost (or altered), the thalamus may be responsible for the that it becomes a complex partial seizure. and the person will not remember any- ipsilateral nature of the symptoms. In some cases, simple partial and complex thing but the aura. At this point, the partial seizures will spread to both hemi- accounts of witnesses may provide clues to Motor Symptoms spheres. When this occurs, the resulting the location of the seizure onset. Unilateral clonic movements are one of the tonic-clonic seizure is referred to as a sec- most frequently encountered lateralizing ondarily generalized.1 Sensory Symptoms signs. Just as with sensory symptoms, the A detailed history and physical exam Up to 60 percent of auras include some face, arm, and hand are most often may provide clues to the origin of the type of sensory component. Most sensory involved. The mechanism in most cases is seizures. The description of the seizure, symptoms are described as “pins and nee- through direct involvement of the primary called the seizure semiology, is critical in this dles”. The symptoms are usually unilateral, motor strip (i.e., the prefrontal gyrus). Less process. To get the clearest description of and most commonly involving the face, often clonic movements can be produced the event, the physician must combine the arm, and hand. In most people, the symp- by the contralateral frontal lobe. patient’s recollection with the observations toms indicate that the seizure started in the Unilateral tonic or dystonic movements of friends, family or other witnesses. Of contralateral cerebral hemisphere. However, may help with seizure localization. Seizures course, some brain regions are “silent.” as with all “rules”, there are always excep- that cause these movements are either That is, a seizure may start in one area but tions, and there have been instances where frontal or temporal lobe in origin. Up to 89 produce no obvious outward signs or the sensory symptoms were ipsilateral to the percent of patients with frontal lobe epilep- symptomatic complaints. When the seizure region of seizure onset. sy had contralateral limb dystonic postur- spreads to “symptomatic” cortex, localizing When carefully examined, sensory ing. In persons with temporal lobe epilep- information becomes available.2 symptoms that “march” from one body sy, dystonic posturing predicts onset in the Localization of seizure onsets is impor- region to an adjacent region have the most contralateral hemisphere nearly 100 per- tant for several reasons. First, identification specific localizing value, indicating that the cent of the time. of partial seizures may direct specific treat- seizure involves the contralateral parietal Asymmetric dystonic posturing can also ments. For instance, if a person’s partial lobe. More specifically, the pins-and-nee- be helpful. Usually, one arm is rigidly

12 Practical Neurology April 2008 Vomiting Definitions of Seizure Types Occurring rarely, ictal vomiting (or gag- Simple Partial Seizure: consciousness is unimpaired. The symptoms or signs of a simple partial seizure ging) indicates that the seizure involves are determined by the region of brain in which the seizure occurs. The seizure occupies a limited volume (usually) the nondominant insular cortex. of cerebral cortex. Electrical stimulation testing in animals Complex Partial Seizure: consciousness is impaired.The seizure occupies a larger volume of cerebral cor- and humans causes vomiting. In addition, tex such that normal thinking is impaired. Often, complex partial seizures cause automatisms (complex resection of this region of brain can cause coordinated and involuntary movements). In some people, the automatism will be a perseveration of the decreased gut motility. Although helpful in activity they were performing at the time the seizure started. For others, the automatism may be primarily oral: repetitive chewing, swallowing, lip smacking or pursing of the lips. Other types of motor automatisms localizing seizures, ictal vomiting may be include repetitive picking of the clothes or semi-purposeful manipulation of objects in the environment. misleading. Seizures that start ion the tem- Secondarily Generalized Seizure: The seizure starts as a simple partial or complex partial seizure, but poral lobe often spread to the ipsilateral propagates to both hemispheres, manifesting as a tonic-clonic seizure. A tonic-clonic seizure starts with insular cortex. In addition, temporal lobe a tonic phase (stiffening) followed by low amplitude, high frequency bilateral shaking. As the seizure pro- seizures can quickly spread to the contralat- gresses, the clonic movements increase in amplitude and slow in frequency. eral insular cortex. In other words, although ictal vomiting usually means that Table 1. Common Causes of Seizures the nondominant insular cortex is involved, by itself, it may not indicate the Newborn, Infant, and Child Adolescent and Adult hemisphere in which the seizure arose. • Infection • Infection • Perinatal Injury (hypoxia; ischemia; intracranial • Drugs or drug withdrawal Conclusions hemorrhage; trauma) • Stroke (hemorrhagic; ischemic) Two-thirds of people with seizures will • Structural (congenital malformations of the • Mass lesion (tumor, AVM) stop having them when they take medica- brain) tions.3 The remaining one-third may be • Metabolic (hypoglycemia; hypocalcemia; hypo- • Metabolic (uremia; hepatic failure; hypo- candidates for resective epilepsy surgery. magnesemia; inborn errors of metabolism) glycemia; electrolyte abnormalities) An accurate description of the seizure • Other (familial; vitamin B6 deficiency; febrile • Other (familial; mitochondrial diseases; neu- convulsion) rodegenerative conditions; psychiatric) semiology is the first step in identifying the epileptogenic cortex. The physician extended at the elbow while the other is leg, called Todd’s paresis or Todd’s palsy. combines this with high-resolution MRI, flexed at the elbow, giving a “figure 4” sign. When this occurs, it helps to at least later- EEG, and video-EEG monitoring to nar- The side of the extended elbow indicates alize the seizure onset. Todd’s paresis indi- row the list of possibilities. In some that the seizure started contralaterally in cates a contralateral seizure onset. Though instances, functional studies such as the majority of cases. Seizures that include not entirely clear, the weakness may be SPECT, PET or MEG are needed to the “figure 4” sign as part of their semiolo- due to exhaustion of the affected neurons. identify the epileptogenic zone. The suc- gy either arise from the opposite temporal After a seizure, there may be a regional cess epilepsy surgery depends partly on lobe or the contralateral frontal (usually increase in inhibitory neurotransmitters the region of brain that must be removed; mesial) lobe. to prevent further seizures. It may be that however, up to 85 percent of people with Partial seizures can cause versive head the increased inhibition causes the con- refractory epilepsy can become seizure- and eye deviation. This finding is impor- tralateral weakness of a Todd’s. free following certain kinds of resective tant in two stages of the partial seizure. If epilepsy surgery. PN the head and eye deviation occurs while the Auditory Symptoms 1. Dreifuss, F. Classification of Epileptic Seizures. In: Epilepsy: A person is alert (the simple partial seizure), it Auditory symptoms occur in less than Comprehensive Textbook, edited by J. Engel and TA Pedley. Lippincott- indicates contralateral motor involvement one-fifth of partial seizures.2 Often, the Raven Publishers, Philadelphia. 1997. Pp: 517-524. 2. Loddenkemper T., and P Kotegal. Lateralizing signs during seizures in (as described above). Versive head and eye sounds are heard bilaterally; less often it is focal epilepsy. Epilepsy & Behavior 2005;7:1-17. movements that occur as the seizure is sec- unilateral. Sometimes, instead of hearing 3. Kwan P, Brodie MJ. Early identification of refractory epilepsy. N Engl J ondarily generalizing indicate that the a noise, the person will describe “muf- Med 2000; 342: 314-9 seizure started in the contralateral hemi- fled” hearing. In all cases, the seizure Steven Karceski, MD is Associate Clinical Professor of sphere. However, in this instance, the ver- involved the superior temporal gyrus. Neurology at the College of Physicians & Surgeons of sive head movements do not have localiz- Because this structure receives input from Columbia University and Director of the Columbia Epilepsy Center at the Atlantic Neuroscience Institute. ing, only lateralizing value. both ears, seizures that involve this region After a seizure (the post-ictal period), a more often cause bilateral ringing, chirp- Conflicts of Interest Statement: Steven Karceski, MD: speaker for Cyberonics, Glaxo, UCB and Ortho-McNeil. person may have weakness in one arm or ing, or buzzing noises in both ears.

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