Magnetoencephalography and magnetic source imaging in epilepsy.

Magnetoencephalograpy (MEG) and Electroencephalography (EEG) provide physicians with complementary data and should not be regarded as mutually exclusive evaluative methods of cerebral activity. Relevant to this edition, MEG applications related to the surgical treatment of epilepsy will be discussed exclusively. Combined MEG/EEG data collection and analysis should be a routine diagnostic practice for patients who are still suffering seizures due to the failure of drug therapy. Clinicians in the field of epilepsy agree that a greater number of patients would benefit from surgery than are currently referred for pre-surgical evaluation. Regardless of age or presumed epilepsy syndrome, all patients deserve the possibility of living seizure-free through surgery. Technological advances in superconducting elements as well as the digital revolution were necessary for the development of MEG into a clinically valuable diagnostic tool. Compared to the examination of electrical activity of the brain, investigation into its magnetic concomitant is a more recent development. In MEG, cerebral magnetic activity is recorded using magnetometer or gradiometer whole-head systems. MEG spikes usually have a shorter duration and a steeper ascending slope than EEG spikes, and variable phase relationships to EEG. When co-registered spikes are compared, it is apparent that EEG and MEG spikes differ. There is agreement among investigators that more interictal epileptiform spikes are seen in MEG than EEG. When MEG is co-registered with invasive intracranial EEG data, the detection rate of interictal epileptiform discharges depends on the number of electrocorticographic channels that record a spike. When patients have a non-localizing video-EEG recording, MEG pinpoints the resected area in 58-72% of the cases.

EEG infraslow activity in absence and partial seizures.

It is currently assumed that for recording of infraslow activity (ISA) DC-coupled amplifiers are required. This report will demonstrate that this may not be the case and presents some data about its potential clinical usefulness. Archived EEGs of 29 seizures from 6 children with absence attacks, accompanied by 3 Hz classical spike-wave discharges (SW), were compared with 20 partial seizures from 10 adult patients. The data from the children were acquired on a Bio-logic system, those from the adults on a Grass-Telefactor instrument. In the children the original 30-minute routine EEG was used while in the adults stored videomonitored data were excerpted to provide 20-minute segments which included the preictal, ictal and postictal state. All data were analyzed with the BESA software package. The seizures were evaluated separately on conventional filter settings, full band of 0.01-to the upper limit of the instrument, and 0.01-0.1 Hz (infraslow activity, ISA). Filter settings of 0.01-0.1 Hz provided a better assessment of ISA than when the full band was evaluated. Absence seizures showed bilateral essentially synchronous ISA with a negative positive sequence in the frontal areas and opposite polarity in the posterior head regions. In partial seizures when seizure onset was clearly lateralizeable from conventional frequency settings ISA corresponded to that hemisphere, but the electrode position could be displaced to a neighboring one from the one which was maximally involved on conventional settings. Topographic analysis showed two types of ISA: one with focal spread only and the other where there was in addition an element of synchrony especially in the frontal areas. It is concluded that ISA can be recovered from conventional EEG recordings and may be helpful not only in determining the area(s) of seizure onset but can also differentiate truly focal seizures from those where an additional generalized seizure tendency is present. This is likely to be important when epilepsy surgery is performed in absence of a demonstrable structural lesion.

Optimal evaluation of digital electroencephalograms.

Currently available digital EEG equipment provides considerably greater opportunities for clinical data analysis than is generally appreciated especially when appropriate software is used. Data from 7 different laboratories that had been obtained for routine diagnostic evaluations on 7 different EEG instruments and stored on compact disks were investigated. Since the instruments do not filter the data at input, ultra slow activity down to 0.01 Hz is currently being recorded but the attenuation factor is instrument dependent. Nevertheless, relevant clinical information is potentially available in these data and needs to be explored. Several examples in regard to epilepsy are presented. Determination of seizure onset may depend on the frequencies that are examined. The use of appropriate filter settings and viewing windows for the clinical question to be answered is stressed. Differentiation between simple and complex spike wave discharges, as well as spread of spikes, can readily be achieved by expanding the time base to 1 or 2 seconds and placing a cursor on the peak of the negative spike. Latencies in the millisecond range can then become apparent. EEGs co-registered with MEG should be evaluated with the same software in order to allow an adequate assessment of the similarities and differences between electrical and magnetic activity. An example of a comparison of EEG, planar gradiometers and magnetometers for an averaged spike is shown.

Double-blind placebo-controlled trial of adjunctive levetiracetam in pediatric partial seizures.

OBJECTIVE: To evaluate the efficacy and tolerability of levetiracetam (LEV) as adjunctive therapy in children (4 to 16 years) with treatment-resistant partial-onset seizures. METHODS: This multicenter, randomized, placebo-controlled trial consisted of an 8-week baseline period followed by a 14-week double-blind treatment period. During the treatment period, patients received either placebo or LEV add-on therapy and were up-titrated to a target dose of 60 mg/kg/day. RESULTS: One hundred ninety-eight patients (intent-to-treat population) provided evaluable data. The reduction in partial-onset seizure frequency per week for LEV adjunctive therapy over placebo adjunctive therapy was significant (26.8%; p = 0.0002; 95% CI 14.0% to 37.6%). A 50% or greater reduction of partial seizure frequency per week was attained in 44.6% of the LEV group (45/101 patients), compared with 19.6% (19/97 patients) receiving placebo (p = 0.0002). Seven (6.9%) LEV-treated patients were seizure-free during the entire double-blind treatment period, compared with one (1.0%) placebo-treated patient. One or more adverse events were reported by 88.1% of LEV-treated patients and 91.8% of placebo patients. The most common treatment-emergent adverse events were somnolence, accidental injury, vomiting, anorexia, hostility, nervousness, rhinitis, cough, and pharyngitis. A similar number of patients in each group required a dose reduction or withdrew from the study as a result of an adverse event. CONCLUSION: Levetiracetam adjunctive therapy administered at 60 mg/kg/day is efficacious and well tolerated in children with treatment-resistant partial seizures.

Infant botulism in the age of botulism immune globulin.

Infant botulism causes acute bulbar dysfunction, weakness, and respiratory failure in infants living in endemic regions of the United States. Until Food and Drug Administration approval of botulism immune globulin (BIG) in October 2003, management of infant botulism had changed little since the 1970s. Currently, IV therapy with BIG is advised to shorten the duration and diminish the potential complications of the disorder. This review describes two decades of experience with infant botulism and provides a contemporary perspective on the role and benefit of BIG.

Neurologic variant of epidermal nevus syndrome with a facial lipoma.

A 1-year-old girl presented for evaluation of a linear plaque on her forehead. She was born at 36 weeks' gestation following an uncomplicated pregnancy and delivery. At birth, she was noted to have an enlarged right cheek. She had no seizure history, but developed grand mal seizures 1 year later. On examination, she had a yellow plaque on her forehead which extended onto her nose. Under her right jaw, extending onto her anterior neck, there was a café-au-lait macule within which there was a yellow plaque which followed the lines of Blaschko. Her right cheek was enlarged and was erythematous (Fig. 1). Magnetic resonance imaging (MRI) of her face showed a mass in the right cheek deep to the subcutaneous fat tissue layer. The signal from the mass was identical to that from the fat, indicating that the mass represented a lipoma. This was later excised surgically and was histologically a lipoma. MRI of the brain demonstrated enlargement of the right lateral ventricle in addition to enlargement of the right cerebral hemisphere. There was also evidence of abnormal gyral architecture. Computerized tomography (CT) three-dimensional reconstruction of the skull demonstrated overgrowth of the right maxilla, right mandible, and right orbit (Fig. 2).

Harrington rod instrumentation: a cause of Brown-Sequard syndrome.

We describe a child with Brown-Sequard syndrome beginning at C8-T1, immediately following Harrington rod instrumentation for idiopathic scoliosis. We believe this is most likely related to either a common variation of the branches of the anterior spinal artery to one side or due to rupture of the ipsilateral spinal vein. This possible complication should be considered in patients undergoing Harrington rod instrumentation.

Tentative assignment of piebald trait gene to chromosome band 4q12.

A case of de novo del(4)(q12q21.1) is presented. Three of four patients with comparable deletion show abnormal integumentary pigmentation, which is compatible with the known autosomal dominantly inherited piebald trait. Further analysis of breakpoints of five cases with proximal interstitial 4q deletion suggests the possible localization of the piebald trait gene within the band 4q12.

Efficacy of phenobarbital in neonatal seizures.

A retrospective study of neonatal seizures in a tertiary care neonatal intensive care unit determined a 3.2% incidence, and confirmed the relatively poor efficacy of the traditional anticonvulsants phenobarbital and phenytoin. Only 33% responded to an initial adequate loading dose of phenobarbital, while 56% responded to either or both anticonvulsants. Although multifocal clonic seizures were most common (42%), tonic seizures were next in frequency (30%). Tonic seizures which did not respond to phenobarbital responded quite poorly to the addition of phenytoin compared to other seizures types. Tonic seizures may be the result of brainstem release phenomena and require a different strategy for management. Among nonresponders in this study, there was a 56% mortality rate but only 33% of responders died. There is a critical need for studies to find more efficacious agents than phenobarbital and phenytoin to treat seizures in the newborn.