Brief bursts of pulse stimulation terminate afterdischarges caused by cortical stimulation.

OBJECTIVE: To determine whether cortical electrical stimulation can terminate bursts of epileptiform activity in humans, we used afterdischarges (ADs) as a model of epileptiform activity. METHODS: Cortical stimulation was performed for clinical localization purposes using subdural electrodes implanted in patients undergoing preresection evaluations for treatment of medically intractable seizures. We used 0.3-millisecond pulses of alternating polarity, repeated at 50 pulses/second. When stimulation produced AD, we often applied short additional brief bursts of pulse stimulation (BPS). We examined the effectiveness of BPS in aborting ADs in 17 patients using survival analysis. RESULTS: With BPS, ADs stopped within 2 seconds in 115 cases, 2 to 5 seconds in 22 cases, and in more than 5 seconds in 89 cases. Without BPS, ADs stopped within 2 seconds in 21 cases, 2 to 5 seconds in 114 cases, and in more than 5 seconds in 340 cases. BPS was an effective method to abort ADs (Cox proportional hazards model: p<0.0001). At any time during the course of ADs, the instantaneous rate of stopping ADs within 2 seconds after BPS was applied was 4.6 times greater than when BPS was not applied (95% CI = 3.7, 5.7). In eight cases, ADs progressed to the occurrence of clinical seizures, always when BPS was not applied. CONCLUSIONS: Afterdischarges significantly decreased in duration after we applied brief bursts of pulse stimulation. Although afterdischarges are not identical to spontaneous epileptiform activity, these results support the idea that electrical stimulation, applied in an appropriate manner at seizure onset, could abort seizures in humans.

An automated injection system (with patient selection) for SPECT imaging in seizure localization.

PURPOSE: Ictal single-photon-emission computed tomography (SPECT) provides lateralization but has technical limitations: (a) a "truly ictal" injection must be shortly after seizure onset; (b) therefore, a seizure of brief duration may be missed; (c) more than one patient may need testing at any given time; (d) a trained health professional must stay next to each patient to inject; and (e) because the radionuclide is placed in the syringe in advance of the injection, decay of the radioactive element could result in less than optimal uptake, if the same volume of material were to be used regardless of the time after ligand preparation. METHODS: We developed an automated method of ligand injection that shortens time and increases efficiency of ictal SPECT ligand injection. By using an experimental setup, we compared manual injection times with times using an automated injection system. We determined relative costs and efficiency in work hours for the manual and automated methods. RESULTS: Injection times were 8-14 s with automated versus 19-26 s with manual injection. Readjusting volume for "ligand" decay was simple and accurate with the automated system. Injection times for clinical SPECT studies in three patients were 13, 13, and 12 s, respectively. The price of one pump equals 120 work hours of a nurse or 24 ictal injection attempts. Much of the nurse's time is "wasted" because no seizure occurs. CONCLUSIONS: The method can be more efficient of staff, shorten injection time, and facilitate obtaining "truly ictal" injections. It allows more cost-effective use of personnel.

A deep vein thrombosis prevention program for patients undergoing long-term invasive epilepsy monitoring.

Some patients may require invasive monitoring techniques, such as implanted depth or subdural grid electrodes, prior to resection of the epileptogenic focus. The additive effect from the lack of anticoagulant therapy, due to the unique nature of invasive monitoring, constraints on mobility associated with continuous EEG recording, along with other risk factors predisposes patients to vessel occlusion. Deep vein thrombosis (DVT) is an unfortunate, potentially life-threatening and often overlooked post-surgical complication. A team approach in developing and implementing a DVT prevention program has been successful in preventing pulmonary embolus in the invasive monitoring patient population. The use of graduated elastic compression stockings, intermittent pneumatic compressive devices and exercises are the major features of the program.

Safety in long-term EEG/video monitoring.

The goal of epilepsy monitoring is to capture several seizures, utilizing continuous electroencephalography (EEG)/video for later analysis. Various provocative techniques, such as withdrawing antiepileptic drugs or sleep deprivation are used to precipitate seizures. Patients run a higher risk of injuries due to having an increase in seizure frequency and/or intensity or a change in seizure type. Evaluating the potential for, and preventing injuries is an important part of risk management. However, very little information has been published regarding safety issues in an epilepsy monitoring unit (EMU). Several types of safety issues have been identified during monitoring: uncontrolled behavior (ictal and post-ictal aggression, self injurious behavior, psychosis); seizure related injuries (falls, status epilepticus); problems related to electrodes (pulling out scalp and surgically implanted electrodes); and specific concerns regarding children in the EMU. Use of restraints and sitters in selected patients, appropriate medication for psychosis, shock absorbing carpet and "child-proofing" rooms for the young are among the preventative actions discussed. Central to risk management is the education of the staff in the assessment of each patient's potential for injury and use the appropriate interventions. Consideration should be given to balancing the need to avert harm, with an unrestricted environment.

Placebo-controlled pilot study of centromedian thalamic stimulation in treatment of intractable seizures.

Stimulation of centromedian (CM) thalamic nuclei has been proposed as a treatment for seizures. We implanted programmable subcutaneous (s.c.) stimulators into CM bilaterally in 7 patients with intractable epilepsy to test feasibility and safety. Stimulation was on or off in 3-month blocks, with a 3-month washout period in a double-blind, cross-over protocol. Stimuli were delivered as 90-microseconds pulses at 65 pulses/s, 1 min of each 5 min for 2 h/day, with voltage set to half the sensory threshold. Stimulation was safe and well-tolerated, with a mean reduction of tonic-clonic seizure frequency of 30% with respect to baseline when stimulator was on versus a decrease of 8% when the stimulator was off. There was no improvement in total number of generalized seizures with stimulation, and treatment differences were not statistically significant. Stimulation at low intensity did not alter the EEG acutely, but high-intensity stimulation induced slow waves or 2-3 Hz spike-waves with ipsilateral frontal maximum. In an open-label follow-up segment with stimulator trains continuing for 24 h/day, 3 of 6 patients reported at least a 50% decrease in seizure frequency. There were no side effects. This pilot project demonstrated the feasibility of controlled study of thalamic stimulation in epilepsy, but further study will be needed to demonstrate efficacy.

Dextromethorphan for treatment of complex partial seizures.

We performed a double-blind, crossover, add-on study of the antitussive agent dextromethorphan (DM 120 mg/d) as therapy for seizures on 9 patients suffering from severe complex partial seizures. DM had no significant influence on key laboratory values, nor on anticonvulsant drug levels. Side effects were negligible. Complex partial seizure frequency increased 25% during the DM arm of the study, although this increase was not clinically significant.

A fatal overdose of carbamazepine: case report and review of literature.

Carbamazepine is a drug of choice for partial epilepsies, certain affective disorders and neuralgic pain syndromes. It has an excellent safety record; however, overdose can be dangerous. This article reports one of the very few fatalities from carbamazepine overdosage, in an individual with a peak carbamazepine level of 54 mg/L. Manifestations of this and other major carbamazepine overdoses reviewed from the literature were similar to those of tricyclic - anticholinergic overdose, with coma, hypotension, respiratory depression, cardiac arrhythmias, abnormal movements and seizures. Fatality from cardiovascular causes occurred despite decline of serum carbamazepine levels to the putatively non-toxic range, emphasizing the potential for delayed consequences of carbamazepine overdosage. Management should consist of vigorous gastric lavage and installation of activated charcoal, full supportive care in a monitored setting and consideration of early charcoal hemoperfusion, before the patient becomes hypotensive.