Minimally Invasive Monitoring Systems

Abstract

The present invention provides systems and methods for ambulatory, long term monitoring of a physiological signal from a patient. At least a portion of the systems of the present invention may be implanted within the patient in a minimally invasive manner. In preferred embodiments, brain activity signals are sampled from the patient with an externally powered leadless implanted device and are transmitted to a handheld patient communication device for further processing.

Description

CROSS-REFERENCED TO RELATED APPLICATIONS [0001] The present application claims benefit of U.S. Provisional Patent Application Ser. No. 60 / 805,710, filed Jun. 23, 2006, to Harris et al., entitled “Implantable Ambulatory Brain Monitoring System,” the complete disclosure of which is incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] The present invention relates generally to systems and methods for sampling one or more physiological signals from a patient. More specifically, the present invention relates to long term, ambulatory monitoring of one or more neurological signals from a patient using a minimally invasive system. [0003] Epilepsy is a disorder of the brain characterized by chronic, recurring seizures. Seizures are a result of uncontrolled discharges of electrical activity in the brain. A seizure typically manifests itself as sudden, involuntary, disruptive, and often destructive sensory, motor, and cognitive phenomena. Seizures are frequently associated with ...

AI Technical Summary

Benefits of technology

[0014] Instead of requiring the patient to stay in an EMU, where the patient's are in an unnatural stressed situation, the systems and methods of the present invention allow for out of hospital monitoring and will allow the patient to go about their lives substantially unimpeded. The ambulatory systems of the present invention provide for substantially continuous sampling of brain wave electrical signals (e.g., electroencephalography or “EEG” and electrocorticogram “ECoG”, which are hereinafter referred to collectively as “EEG”). The ambulatory systems of the present invention are more likely to record the occurrence of a seizure—particularly for patients who have infrequent seizures.

[0025] In one embodiment, the implantable device is leadless, passive and externally powered. In such embodiments, the external device may comprise a signal generator that generates an output that powers the components of the implantable device. The output that powers the components of the implantable device is typically a radiofrequency signal, but could be any number of types of signals. The output from the signal generator is typically generated at a frequency between about 200 Hz and about 1000 Hz to facilitate substantially continuous sampling of the brain activity signals. The passive, leadless device may comprise an antenna that is adapted to receive the output from the external device and transmit the data signal back to the external device. The passive, leadless device may also include a microprocessor that is powered and interrogated by the output from the signal generator and is adapted to sample the brain activity signal and encode the brain activity signal in the data signal that is transmitted by the antenna back to the external device.

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 patients.

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.

However, for the remaining 30% of the patients, 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 patient's seizures.

For those patients with infrequent seizures, the problem is further compounded by the fact that they must remain on the drug for many months before they can discern whether there is any benefit.

As a result, physicians are left to prescribe AEDs to these patients without clear and timely data on the efficacy of the medication.

A major challenge for physicians treating epileptic patients 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 patients often do not realize when they have had a seizure, or fail to accurately record seizures.

In addition, patients often have “sub-clinical” seizures where the brain experiences a seizure, but the seizure does not manifest itself clinically, and the patient has no way of making note of such seizures.

For example, the patients are often sleep deprived, and if the patients are on medication, the medications may be decreased or stopped.

However, for patients who have infrequent seizures, even in such a stressed state, many of such patients do not have a seizure during their stay in the EMU, and such costly and time consuming in-hospital monitoring provides little or no insight into the patient's condition.

For example, one drawback that has not been addressed by video-EEG monitoring is the fact that the sleep deprivation and / or a decrease or complete stoppage of the AEDs may cause cluster seizures and / or induce status epilepticus—which may not be reflective of the patient's typical seizures or seizure frequency.

Thus, the EEG data that is collected in the EMU may not accurately reflect the patient's condition—which can complicate attempts to diagnose and properly treat the patient.

Images