Methods and Systems for Measuring a Subject's Susceptibility to a Seizure

Abstract

Systems and methods for monitoring physiological signals from a subject to determine the subject's susceptibility for having a seizure. Also includes are systems and methods for activating an alert when there is a communication error between an implanted device and the external assembly. Additionally included are systems and method for long-term substantially continuous physiological signal data collection. At least a portion of the systems of the present invention may be implanted within the subject. In some embodiments, brain activity signals are sampled from the subject with implanted electrodes and are communicated to an external assembly where the brain activity signals are analyzed to determine the subject's susceptibility for having a seizure.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application claims benefit of U.S. Provisional Patent Application No. 60 / 897,551, filed Jan. 25, 2007, to Leyde et al., entitled “Methods and Systems for Measuring a Patient's Susceptibility to a Seizure,” the disclosure of which is incorporated by reference herein in its entirety.BACKGROUND OF THE INVENTION[0002]The present invention relates generally to systems and methods for sampling and processing one or more physiological signals from a subject. More specifically, the present invention relates to monitoring of one or more neurological signals from a subject to determine a subject's susceptibility to a neurological event, communicating the subject's susceptibility to the subject, reducing a severity of seizures and / or preventing seizures. The invention also relates to continuously storing neurological signals from a subject to train algorithms to determine a subject's susceptibility for having a seizure.[0003]Epilepsy is ...

AI Technical Summary

Benefits of technology

[0025]The algorithms may analyze the sampled EEG signals in the implanted assembly, in the external assembly, or a portion of the advisory algorithm may be in both the implanted assembly and the external assembly. If the seizure advisory algorithm determines that the subject has entered a pro-ictal condition, the external assembly may be used to provide a warning, instruction, or other output to the subject that informs them of their transitioning from an inter-ictal or normal condition to the pro-ictal condition. The output from the external assembly may be visual, audio, tactile (e.g., vibratory), or some combination thereof. Such outputs from the external assembly may allow the user to make themselves safe (e.g., stop cooking, pull to the side of the road when driving, lie down, etc.) prior to the onset of the actual seizure or allow the subject to take an acute dosage of an AED to prevent or mitigate the seizure. Most importantly, the subject's will no longer be surprised by the seizures and will have more control over their life.

[0043]Advantageously, the systems and methods of the present invention may be used to reduce subject anxiety and restore a sense of control in the subject's life, stop or reduce the duration or severity of the seizures, reduce or eliminate physical injuries to the subject, potentially increase vocational opportunities by allowing epileptic subjects to hold down jobs they wouldn't otherwise be able to have, resume their driving privileges, increase comfort with social interaction, and enable certain key activities of daily living.

Problems solved by technology

A seizure typically manifests itself as sudden, involuntary, disruptive, and often destructive sensory, motor, and cognitive phenomena.

Seizures are frequently associated with physical harm to the body (e.g., tongue biting, limb breakage, and burns), a complete loss of consciousness, and incontinence.

A single seizure most often does not cause significant morbidity or mortality, but severe or recurring seizures (epilepsy) results in major medical, social, and economic consequences.

Epilepsy is most often diagnosed in children and young adults, making the long-term medical and societal burden severe for this population of subjects.

People with uncontrolled epilepsy are often significantly limited in their ability to work in many industries and usually cannot legally drive an automobile.

This continuous seizure activity may lead to permanent brain damage, and can be lethal if untreated.

The anticonvulsant and antiepileptic medications do not actually correct the underlying conditions that cause seizures.

These desired therapeutic effects are often accompanied by the undesired side effect of sedation, nausea, dizziness, etc.

Furthermore, some AED are inappropriate for women of child bearing age due to the potential for causing severe birth defects.

However, for the remaining 30% of the subjects, their first AED will fail to fully control their seizures and they will be prescribed a second AED—often in addition to the first—even if the first AED does not stop or change a pattern or frequency of the subject's seizures.

A major challenge for physicians treating epileptic subjects is gaining a clear view of the effect of a medication or incremental medications.

However, it is well recognized that such self-reporting is often of poor quality because subjects often do not realize when they have had a seizure, or fail to accurately record seizures.

If no focus is identifiable, or there are multiple foci, or the foci are in surgically inaccessible regions or involve eloquent cortex, then surgery is less likely to be successful or may not be indicated.

Surgery is effective in more than half of the cases, in which it is indicated, but it is not without risk, and it is irreversible.

Because of the inherent surgical risks and the potentially significant neurological sequelae from resective procedures, many subjects or their parents decline this therapeutic modality.

These functional disconnection procedures can also be quite invasive and may be less effective than resection.

While not highly effective, it has been estimated that VNS reduces seizures by an average of approximately 30-50% in about 30-50% of subjects who are implanted with the device.

Unfortunately, a vast majority of the subjects who are outfitted with the Cyberonics® VNS device still suffer from un-forewarned seizures and many subjects obtain no benefit whatsoever.

The results have shown some potential to reduce seizure frequency, but the efficacy leaves much room for improvement.

However, to date, none of the proposed seizure prediction systems have shown statistically significant results.

While most seizures are short-lasting events that last only a few minutes, the seemingly random nature of the occurrence of seizures is what overshadows and destroys a subject's quality of life.

Images