Outcome and complications of chronically implanted subdural electrodes for the treatment of medically resistant epilepsy.

BACKGROUND: Surgery for medically resistant epilepsy is safe and effective. However, when noninvasive techniques are insufficient, then consideration is given to invasive electrocorticography (EcoG). OBJECTIVE: The aim of the study was to analyze results and complications of subdural electrodes placement in the treatment of intractable epilepsy. METHODS: Ninety-one consecutive patients who underwent placement of subdural electrodes (1999-2010) were considered for this study. All patients underwent a standardized pre-operative evaluation. Invasive subdural electrode placement was considered when there were inadequate ictal recordings, there was discordance between EEG and neuroimaging or the epileptogenic zone was localized near eloquent cortex. RESULTS: Resective epilepsy surgery was performed in 70/91 patients (76.9%). Twenty-four out of seventy (34.3%) who underwent surgical resection were seizure-free (CL-I) at last follow-up. A statistical evaluation revealed a very strong trend for patients with positive lesional pre-operative MRI to have improved outcomes compared to normal brain MRI population (p=.028). There were 10 surgical related complications (11%), but no mortality or permanent morbidity. Statistical analysis demonstrated that placement of a subdural grid in any combination was statistically significant (p=.01) for surgical complications. CONCLUSIONS: Invasive monitoring is a useful and necessary technique for the surgical treatment of intractable epilepsy. Careful surveillance is required during the monitoring period especially when the patient has undergone large subdural grid placement. A good working hypothesis can minimize complications and achieve better outcomes.

The diagnostic utility of the ictal cry.

Epileptic generalized tonic-clonic (GTC) seizures are differentiated from nonepileptic spells primarily by history. The historical features that can aid in making a diagnosis, such as urinary incontinence and tongue biting, are few. One additional piece of information we propose may be of clinical value is the stereotypical "ictal cry." We reviewed audio from 20 consecutive GTC seizures and 20 consecutive psychogenic convulsive nonepileptic spells recorded in our epilepsy monitoring unit. The audio components of the recordings from each group were compared. The typical laryngeal sound was found to have both high sensitivity (85%) and specificity (100%) for epileptic GTC seizures. In none of the 20 psychogenic cases was the typical epileptic vocalization expressed; these cases were mostly associated with other utterances such as weeping, moaning, and coughing. The ictal cry is strongly associated with epileptic GTC seizures and, thus, warrants inquiry when obtaining the history from witnesses of a patient's seizure.

Interrater reliability of EEG-video monitoring.

OBJECTIVE: The diagnosis of psychogenic nonepileptic seizures (PNES) can be challenging. In the absence of a gold standard to verify the reliability of the diagnosis by EEG-video, we sought to assess the interrater reliability of the diagnosis using EEG-video recordings. METHODS: Patient samples consisted of 22 unselected consecutive patients who underwent EEG-video monitoring and had at least an episode recorded. Other test results and histories were not provided because the goal was to assess the reliability of the EEG-video. Data were sent to 22 reviewers, who were board-certified neurologists and practicing epileptologists at epilepsy centers. Choices were 1) PNES, 2) epilepsy, and 3) nonepileptic but not psychogenic ("physiologic") events. Interrater agreement was measured using a kappa coefficient for each diagnostic category. We used generalized kappa coefficients, which measure the overall level of between-method agreement beyond that which can be ascribed to chance. We also report category-specific kappa values. RESULTS: For the diagnosis of PNES, there was moderate agreement (kappa = 0.57, 95% confidence interval [CI] 0.39-0.76). For the diagnosis of epilepsy, there was substantial agreement (kappa = 0.69, 95% CI 0.51-0.86). For physiologic nonepileptic episodes, the agreement was low (kappa = 0.09, 95% CI 0.02-0.27). The overall kappa statistic across all 3 diagnostic categories was moderate at 0.56 (95% CI 0.41-0.73). CONCLUSIONS: Interrater reliability for the diagnosis of psychogenic nonepileptic seizures by EEG-video monitoring was only moderate. Although this may be related to limitations of the study (diagnosis based on EEG-video alone, artificial nature of the forced choice paradigm, single episode), it highlights the difficulties and subjective components inherent to this diagnosis.

The management of idiopathic generalized epilepsies.

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.

Short-term outpatient EEG video with induction in the diagnosis of psychogenic seizures.

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.

Vagus nerve stimulation for pharmacoresistant epilepsy: clinical symptoms with end of service.

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.

MRI of the brain is safe in patients implanted with the vagus nerve stimulator.

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.

How many patients with psychogenic nonepileptic seizures also have epilepsy?

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.

Advances in the treatment of 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.

A prospective comparison between two seizure classifications.

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.

Epileptic seizures and syndromes.

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 etiology and diagnosis of status epilepticus.

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.

The neurosurgical treatment of epilepsy.

Despite the new advancements in antiepileptic drug development, thousands of people with epilepsy will remain intractable to medication. For a considerable proportion of these people, epilepsy surgery is a consideration for better control of their seizures. Resective surgery is now standard practice for patients with medication-refractory epilepsy. Temporal lobectomy continues to be the most common surgery performed. Once patients fail 2 to 3 optimal trials of antiepileptic medication, further drug therapy offers a minimal number of patients freedom from seizures. In contrast, temporal lobectomy in carefully selected patients may result in seizure-free outcomes in more than 70% to 90% of patients with intractable seizures. As technology and drug availability increases in the new millennium, it is important for the primary care physician to be aware of epilepsy surgery as a means to treat patients with antiepileptic drug-refractory epilepsy. Arch Fam Med. 2000;9:1142-1147

Should patients with psychogenic nonepileptic seizures be allowed to drive?

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.