GB2335046A

GB2335046A - Portable epileptic attack warning and recording device

Info

Publication number: GB2335046A
Application number: GB9904948A
Authority: GB
Inventors: Terry Thomas Jones
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-03-06
Filing date: 1999-03-05
Publication date: 1999-09-08
Also published as: GB9804647D0; GB9904948D0

Abstract

This invention is a user friendly non-intrusive portable miniaturised battery operated electronic biofeedback device to be worn permanently by persons with a history of seizures associated with epilepsy. 1. It recognises, monitors, memorises and warns the wearer of abnormal brain electrical activity associated with epileptic seizures ignoring abnormal brainwave activity present in some patients between seizures. 2. The onset and termination of the abnormal brainwave activity associated with seizures is signalled to the patient and others by appropriate auditory/vibratory/visual signals according to the disability of the patient. 3. Louder auditory and alerting visual signal is triggered by seizures lasting longer than 20 minutes (status epilepticus) which requires urgent medical intervention. 4. The frequency, duration, and intensity of the abnormal brainwave activity associated with seizures is monitored by an electronic memory system compatible to any host PC in a Doctors office. Appropriate medication changes can then be made based on accurate and not anecdotal information. 5. An inflatable head protection device designed to be linked to the seizure signals to reduce risk of head and facial injury.

Description

2335046 ENWARN (Electro-encephalo Feedback Sienal and Memory Device for

Epileptic Attacks

Field of Invention

This invention relates to a n-dniaturised, portable, biofeedback device to be work permanently by patients with a history of major epileptic abnormal brainwave activity associated with seizures. This is not a conventional ambulatory diagnostic EEG recording device, but a user ffiendly warning bio feedback system whereby the specific abnormal brain activities associated with epileptic seizures, e.g. spike and wave activity is recognised and an appropriate signal given to the patient and to attendants of:- 1. Potential seizure brainwave activity.

2. Actual seizure brainwave activity.

3. Termination of seizure activity.

4. Onset of status epilepticus (a seizure lasting longer than 20 minutes requiring medical intervention).

5. A memory system compatible to a host PC.

6. Optional head protection cap or band inflated by actual seizure activity to prevent head and facial injuries.

Background on Epilepsy Diagnostic Devices

Apart from the conventional one-off 16 - 18 channel EEG recordings, 24 hour portable EEG recording devices have been technically developed since 1975 (Marson, Cashwan and McKinnon). Initially this was a discrete four channel analogue recording on a C120 cassette. In 1976 digital technology with 8 channels were introduced (Weaver, Sato).

However, this established technology is a diagnostic procedure for physician and technician analysis only and does not give any information directly to the patient of his seizure activity. The 24 hour recording has to be analysed in EEG Departments. The 8 electrodes are easily displaced by movement. they are expensive. the equipment is bulky, heavy and non-cosmetic.

Attempts to predict seizure activity and measure and monitor the seizures are documented in the Patent Office. However, they rely on:- 1. Brain activity signals.

.I 1? fjo, csX er,AC AIM j ke4 C-4. Z,0 CA.1 0013.

2. Chaotic time series analysis.

d"q44 - 1-1fve-"e-v r tI.JAerw-r) 3. Timing of cerebral pulses. - 1 '9 11; - (D t4 C 0 M 4 L, PJ. 5-) - I., - jC mid d..+ PO -r d5L-CC rA0.0js - 1 et 9 6 -(v I 'i C LFVr.' p I cc Unfortunately, the presence of an abnormal brain rhythm does not in itself predict or indicate seizure activity, indeed approximately 20% of the population have abnormal brain rhythms without necessarily experiencing seizure activity. Also a large percentage of people suffering from epilepsy have abnormal brain activity at an times (interictal dysrhythmia) without actual seizure attacks.

Reason for Invention The inventor, the neuropsychiatrists servicing a large epilepsy population realized that an instant feedback system over and above the conventional diagnostic devices was necessary to warn and monitor actual epileptic seizures as measured by specific spike and wave dysrhythmia over and above the abnormal brain dysrhythmia present at all times in most of the epileptic population. The device was also designed to be:

-3 1. Inexpensive.

2. Light and compact.

3. Cosmetically hidden.

4. Compatible to office PC post systems, (e.g. G.P. surgery) and able to 5. Give waming of impending and actual seizures (ictal activity) by vibratorylauditory/visual signals according to patient needs.

6. Measure and monitor onset duration, frequency and intensity and termination of seizure activity to both wam the patient and also to give accurate information to the attending physician/nurse.

7. Indicate end of seizure for recovery process and resumption of normal activities.

8. Warn of prolonged and serious seizures (status epilepticus, i.e. seizures or repetitive seizures lasting longer than 20 minutes, to allow emergency medical intervention by carers or good Samaritans, (medication plus 999 calls).

9. Provide optional head band protection inflatible during seizure activity to reduce head and facial injury.

Special Populations Needing this Device 1. Learning Disabled (people relying on carers, family, etc. for visual monitoring of their seizure activity. This is usually anecdotal and inaccurate and does not give the Epileptologist the necessary information for medication changes.

2. Epileptic sufferers in risky work or leisure situations.

3. Controlled stable epileptic population on probationary driving licences.

4. Expectant mothers who have a 10% increase in seizure activity, thereby decreasing infant morbidity.

5. Patients living alone or the aged who need a warning device of potential seizure to themselves and to others.

6. Epileptic sufferers of a track record of repeated head injury when unconscious.

7. Patients non-compliant with medication (objective feedback given to the Physician by the electronic memory system which is compatible and facilitates the transfer of data to the host PC for more accurate analysis.

General Technical Field

1. One or more scalp/skin electrodes cosmetically hidden and located near the focus of the seizure abnormal brainwave activity previously identified by conventional diagnostic EEG readings.

2. A black box containing the main unit, housed in a small container easily carried and hidden on the body with a battery power source interfaced with a remotely housed pre-amplifier, using a fast data transfer technique.

3. The main unit also incorporates vibratory/auditorylvisual feedback signals according to the patient's disability needs activated by the detection of onset and termination of seizure dysrhythmia and/or the warning (aura of a potential seizure brainwave activity).

4. An electronic memory system allowing for a high sampling rate and transfer of data to a host PC. The memory system (cards/chip) can be replaced very simply and at any time to be reset for further recording.

5. Optional inflatible head band triggered by the black box sensors.

-6 TECHNICAL DESCRI1PTION The Prototype uses known technologies to develop the algorithms necessary to monitor and analyse the brain rhythms during epileptic seizures. Many electrical signals (currents) travel around the body at all times, each of these signals is of differing amplitudes and frequencies. The signal measured during an epileptic seizure is unique and thus is identifiable. However, this signal is just one signal amongst many and thus we need software filters and algorithms to remove the other signals. The initial work in the project will involve producing a working prototype that can do just this.

It must be realised that the prototype is a digital-sampfing device, and is not unique in the field of digital sampling and analysis, in fact we will be buying the specific software libraries for exactly this purpose.

The Prototype will be based on a miniature PC host system, namely the Toshiba libretto. This platform will allow us to use National Instruments PCMCIA Digital sampling card. The Toshiba libretto itself is unique as it runs the full version of Windows 95198 (Operating System), this allows us to use Delphi 4 (Programming Environment) and National Instruments Analysis Library (Filters and Algorithms). Together these produce an extremely powerful system which is the size of a handheld PC'slOrganiser.

This system is essentially the prototype with a large amount of flexibility and will be used for the initial patient trials.

The prototype wifi prove the concept and allow the development of a production version. The production version will be based on a single Digital Signal Processor, and be a fairly simple device in itself However, the technical difficulty comes in developing the software algorithms.

The DSP chip will most likely be based on the Texas Instruments very impressive TMS320C4x range. Using the algorithms developed the programme will be written in "C" and optimised using the Texas Instruments Assembly optimisers.

The second device will be a small lightweight device, which will be carried at all times by the user. The device will store and supply the user with vital information about the fit. The device will also have an infra red link for access to a PC.

An analysis programme would look at the data stored by the unit, and could be supplied to the user or the patients Doctor. The device itself works independently and does not require a PC, but the PC option would still be there.

CLAMS

Claims

Claim 1:

A portable miniaturised electro-encephalo feedback device to analyse, record and give warning of the specific (spike and wave) abnormal brainwave activity associated with an epileptic seizure, comprising:- a) Auditory/vibratorylvisual signal systems triggered by the specific abnormal brainwave activity associated with a seizure to warn patient of onset duration and termination of potential seizure brainwave activity (ictal).

b) Louder auditory/visual signals triggered by seizure duration of 20 minutes or more or by repeated seizures without regaining consciousness to warn of a medical emergency (status epilepticus).

c) Memory system compatiblewith host PC to monitor frequency duration and intensity of the abnormal brainwave activity associated with seizures.

Claim 2:

A portable miniaturised electro-encaphalo feedback device as in Claim 1, incorporating a tactile (vibratory signal) optional visual/auditory signal for the deaf and blind, triggered by the aura (warning abnormal brainwave activity occurring seconds, n-dnutes or hours prior to an impending seizure).

Claim 3:

Portable miniaturised electro-encaphalo feedback device as in Claim 1, incorporating a protective skuUcap or head band which can be inflated by the actual abnormal brainwave dysrhythmia associated with seizure activity.