Biomedical subjects
Publications and source records attributed to S R Benbadis.
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Idiopathic generalized epilepsies (IGEs) are a well defined group of epilepsies, with onset predominantly in childhood. Recent evidence suggests that IGEs may also be prevalent but under-diagnosed in adults. IGEs respond well to appropriate treatment and 80-90% of cases become fully controlled. However, correct identification of IGE and selection of a broad-spectrum antiepileptic drug (AED) is crucial if cases of 'pseudo-intractability' are to be avoided. Preliminary evidence suggests that some of the newer AEDs are broad spectrum and may offer advantages in the treatment of IGEs. There is strong evidence that childhood-, adolescent- and adult-onset IGEs share biologic determinants and are best viewed as a spectrum or continuum of conditions. The diagnosis of IGE, even as a group, is very important for proper management.
To analyze the yield of short-term outpatient EEG video monitoring, the authors reviewed data on all patients who underwent this procedure at their center. All patients were suspected of having psychogenic nonepileptic seizures (PNES) on clinical grounds. The total number of cases of short-term outpatient EEG video monitoring was 74. In 49 (66%) cases, the suspected diagnosis of PNES could be confirmed, thereby obviating the need for prolonged inpatient EEG video monitoring.
PURPOSE: Limited capability exists to predict when vagus nerve stimulation (VNS) battery deterioration becomes significant. Initial models last 2-5 years. We evaluated the first 18 patients with pharmacoresistent epilepsy after reimplantation to examine the clinical course observed during VNS end of service (EOS). METHODS: Of 72 patients with VNS, 18 patients had generator replacement. EOS was estimated based on duration of use and stimulus parameters in accordance with manufacturer guidelines. Eight males and ten females had pharmacoresistent epilepsy for a mean of 17.9 years. Thirteen with localization-related epilepsy (LRE) and 5 nonverbal patients with symptomatic generalized epilepsy (SGE) failed a mean of 11.1 antiepileptic drugs (AEDs) over 21.5 years. Seven had intracranial evaluations and five failed epilepsy surgery. Reimplantation was performed after a mean of 34.4 months. Symptoms at end of service (EOS) were addressed by postoperative survey submitted at initial reprogramming within 2 weeks of reimplantation. Stimulus parameters were compared before and after surgery. RESULTS: Nine of thirteen (69.2%) verbal patients and 11 of 18 (61.1%) total patients had signs or symptoms prior to replacement, suggesting clinical EOS, and 4 of 18 (22.2%) failed interrogation denoting battery failure without symptoms; however, this did not reach significance (chi2=0.359,p=0.54). Increased seizures were the most frequent sign in 8 of 18 (44.4%), with intensification in 7 of 18 (38.9%). Irregular stimulation was detected in 5 of 18 (27.7%), with less intense stimulation in 4 of 18 (22.2%). Painful stimulation and behavioral worsening each occurred in 2 of 18 (11.1%). A subjective improvement in function after reimplantation was noted in 12 of 13 (92.3%) verbal patients, with greater intensity and consistency. Maximally tolerated reimplant current averaged -0.56 mA less. All but one (94.4%) felt surgery should be performed before clinical EOS occurred. CONCLUSIONS: We conclude that clinical signs and symptoms may arise during VNS EOS and following replacement. Seizure increase or a change in seizure pattern was most frequently observed. The tolerated reimplant current was less than the preoperative output current in most cases. Battery replacement before EOS appears desirable from a patient perspective.
The proportion of patients with psychogenic nonepileptic seizures (PNES) who also have epilepsy has been reported to vary from 10% to over 50%. The authors reviewed all 32 patients diagnosed with PNES in our EEG-video monitoring unit over a period of 1 year, and only 3 (9.4%) had interictal epileptiform discharges to support a coexisting diagnosis of epilepsy. Thus, the authors believe that only a small proportion of patients with PNES have coexisting epilepsy.
Significant advances have been made in the diagnosis and treatment of epilepsy over the past decade. With the advent of electroencephalographic video monitoring, physicians are now able to reliably differentiate epilepsy from other conditions that can mimic it, such as pseudoseizures. In addition, neuroimaging has changed the way treatment for difficult epilepsy is approached. As a result, the classification systems that have been in use since the early 1980s are currently being revised. A broader range of treatment options for epilepsy is now available. Many new antiepileptic drugs have become available in recent years, including felbamate, gabapentin, lamotrigine, topiramate, tiagabine, levetiracetam, oxcarbazepine and zonisamide. These medications offer options for patients with epilepsy whose seizures cannot be controlled using the classic agents. Several classic antiepileptic drugs have been modified and reformulated. The ketogenic diet has resurfaced as a treatment option in certain types of epilepsy. The vagus nerve stimulator, approved in 1997, represents a completely new treatment modality for patients with seizures not controlled by medications. Epilepsy surgery is now a well-documented and effective treatment for some patients with intractable epilepsy.
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Status epilepticus (SE) is a common, serious, potentially life-threatening, neurologic emergency characterized by prolonged seizure activity. Generalized convulsive status epilepticus (GCSE) is the most widely recognized form of SE. Direct consequences of convulsive movements from SE can result in injury to the body and brain. Nonconvulsive status epilepticus (NCSE) is underrecognized, with controversy surrounding the consequences and treatment. High mortality rates with GCSE have been noted in the past. New treatments for SE are emerging with new parenteral drug formulations as well as new agents for refractory SE, offering an opportunity to improve outcome. Special drug delivery systems, drug combinations, and neuroprotective agents that prevent the subsequent development of epilepsy may soon emerge as future options for treating SE.
This article describes the main characteristics of the different types of seizures and their classifications. The main types of epilepsies are reviewed, including their main, clinical, and EEG features and an overview of their treatment.
The International Classification of Epileptic Seizures is the most widely used, but an alternative system based purely on ictal symptoms and signs has been proposed: the semiological classification. Our objective was to compare the two in a sample of patients evaluated at epilepsy centers. We collected 78 consecutive patients evaluated in outpatient epilepsy clinics who subsequently underwent noninvasive video-EEG monitoring at three centers. Patients with pseudoseizures were excluded. Seizures were first classified based on information obtained during clinic visits, and again after video-EEG monitoring. Each time, seizures were classified using both the International Classification and the semiological classification. Eventual epilepsy syndrome diagnosis was based on all the clinical data, video-EEG monitoring, and other independent tests including imaging studies. Sixty-six (87%) patients were classified as having 'complex partial seizures' in the International Classification. Using the semiological classification, these same 66 patients were classified as follows: automotor (34), dialeptic (17), hypermotor (13), hypomotor (2). Seizure classification changed between initial 'clinic-based' data and the 'monitoring-based' classification in 27 cases using the ILAE, vs. six using the semiological classification. Seizure classification tended to change significantly between pre- and post-monitoring using the ILAE but not the semiological classification. The term complex partial seizure included multiple categories of the semiological classification, and was very nonspecific. The semiological classification may be better suited for everyday clinic use, since it is based solely on clinical characteristics.
Metallic devices generally represent a contra-indication for MRI scanning. Based on laboratory testing, the neuro cybernetic prosthesis (NCP) is labelled MRI compatible when used with a send and receive head coil. However, there are no published clinical data to support the safety of brain MRI in patients with the NCP. Our objective was to report clinical experience with such a population. We questioned 40 centres that had implanted the NCP system as of 10/1/99. If MRI had been performed on any vagus nerve stimulator patients, we collected information on these patients, the MRI technique used, any events noted during the scan, including both subjective reports (by the patient ), and observable (objective) changes noted by the staff. Twelve centres (30%) responded. Over a time period of 3 years, there were a total of 27 MRI scans performed in 25 patients. All scanners were 1.5 T. A head coil was used in 26 scans, and a body coil in one. The indications for the scans were diverse. Seven were related to the epilepsy, including aetiology or pre-surgical evaluation. Others were unrelated, including brain tumours, cerebral haematoma, vasculitis, headaches, and head trauma. Three scans were performed with the stimulator on, while 24 were performed with the stimulator off. One patient had a mild objective voice change for several minutes. No other objective changes were noted in any of the patients. One 11-year old reported chest pain while experiencing severe claustrophobia. Twenty-five patients denied any discomfort around the lead or the generator. We conclude that this clinical series supports the safety of routine brain MRI using a send and receive head coil in patients implanted with the NCP System.
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The diagnosis of psychogenic nonepileptic seizures (PNES) can only be made with EEG-video monitoring. The authors describe a provocative technique without placebo. Patients with a clinical suspicion for PNES underwent an activation procedure using suggestion, hyperventilation, and photic stimulation. Of 19 inductions performed, 16 (84%) were successful in inducing the habitual episode. The authors' technique had a sensitivity comparable to those using placebo (e.g., saline injection), but does not have disadvantages.
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The prevalence of psychogenic non-epileptic seizures is difficult to estimate. We propose an estimate based on a calculation. We used the following data, which are known or have been estimated, and are generally accepted. A prevalence of epilepsy of 0.5-1%; a proportion of intractable epilepsy of 20-30%; a percentage of these referred to epilepsy centers of 20-50%; and a percentage of patients referred to epilepsy centers that are psychogenic non-epileptic seizures: 10-20%. Using the low estimates, the prevalence of psychogenic non-epileptic seizures would be 1/50 000. Using the high estimates, the prevalence of psychogenic non-epileptic seizures would be 1/3000. The prevalence of psychogenic non-epileptic seizures is somewhere between 1/50 000 and 1/3000, or 2 to 33 per 100 000, making it a significant neurologic condition.
PURPOSE: To investigate the risk of driving accidents in patients with psychogenic nonepileptic seizures. METHODS: First, a survey was conducted in 82 physician-members of the American Epilepsy Society to determine what they recommend in patients with psychogenic seizures in regard to driving privileges. Second, we studied a population of 20 patients with proven psychogenic nonepileptic seizures diagnosed by prolonged EEG-video monitoring. We obtained the patients' driving records from the Wisconsin Department of Transportation. We used 1991 Wisconsin crash data as the reference year. We compared the expected number of motor vehicle crashes with the observed number of crashes. chi2 with Yates' correction for continuity was used to test for statistical significance. RESULTS: Of the 82 physicians questioned, 37 (45%) responded. Among respondents, the distribution was as follows: 49% applied the same restrictions as for patients with epilepsy; 32% did not place patients under any restrictions; and 19% decided on a case-by-case basis. The total number of reported crashes in the sample was eight, with no fatal crashes. This was not statistically significant (corrected chi2, 0.53) compared with the expected number of motor vehicle crashes for the sample. CONCLUSIONS: This small series does not support the use of driving restrictions for patients with psychogenic nonepileptic seizures.
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