WO2006134359A1

WO2006134359A1 - Seizure detection apparatus

Info

Publication number: WO2006134359A1
Application number: PCT/GB2006/002181
Authority: WO
Inventors: Martin Chew Izod; Aline Russell
Original assignee: Greater Glasgow Nhs Board
Priority date: 2005-06-15
Filing date: 2006-06-14
Publication date: 2006-12-21
Also published as: GB0512192D0

Abstract

A seizure detection apparatus suitable for detecting seizures including epileptic seizures. The seizure detection apparatus is particularly useful in the early detection of tonic, clonic, and tonic-clonic epileptic seizures. The apparatus is suitable for detecting any type of motor seizure, including myoclonic seizures. On detection of a seizure, the seizure detection apparatus raises an alarm locally and/or remotely such that, for example, a carer can come to the aid of the individual having the seizure.

Description

Seizure detection apparatus

The present invention relates to the field of seizure detectors and, in particular, to an improved method and apparatus for detecting epileptic seizures.

Epilepsy is a neurological condition which affects approximately 1 in 133 people, and which is characterised by recurrent seizures over a period of time, caused by temporary dysfunction in the brain.

An epileptic seizure can take many forms, all of which are caused by a temporary disturbance to the normal operation of the brain. This temporary disturbance is caused when a shift in the chemical balance of the brain takes place, producing an interruption of electrical signals, which in turn results in neurons in the brain firing faster than normal, and firing in bursts. This electrical "storm" in the brain causes a seizure to take place. As such, all epileptic seizures originate in the brain. The exact location in the brain of the abnormal electrical activity determines how a seizure manifests itself. In particular, there are two broad categories of seizure, generalised and partial. A generalised seizure involves abnormal electrical activity over the whole of the brain, and results in the person losing consciousness. In a partial seizure, the abnormal electrical activity is only in part of the brain, and the person remains totally or partially conscious.

General and partial seizures differ in nature, and general seizures tend to be, on the whole, more physically dramatic, whilst partial seizures can be quite subtle. General and partial seizures can be further categorised and may take many different forms, which are detailed below.

In a "tonic" seizure, the person loses consciousness and their muscles stiffen. The person can fall if standing and can experience breathing difficulties.

A "clonic" seizure is the stereotypical seizure in which the person jerks and convulses rhythmically due to rapid tightening and relaxing of muscles.

A "tonic-clonic" seizure is the most common form of generalised seizure and is a two-phase combination of the previously explained tonic and clonic seizures, involving first the tonic, and secondly the clonic phase.

In the event of an "absence" seizure, the person experiences a momentary spell of unconsciousness, such that it can appear that the person is daydreaming. When a person experiences an "atonic" seizure, the muscles suddenly lose all strength, which can result in the person collapsing dramatically - often leading to injury. An atonic seizure can be considered the opposite of a tonic seizure.

In a "myoclonic" seizure, the person experiences a brief and sudden jerk of part or all of the body. This is dissimilar to the rhythmic type convulsions experienced during a clonic seizure.

Partial seizures can be categorised further still into simple partial and complex partial seizures. In a simple partial seizure, the person remains conscious and may experience twitching, dizziness, nausea, disturbances to hearing, vision, smell or taste, and a strong sense of deja vu. These symptoms are often not obvious to onlookers, as the person is fully conscious and may be functioning normally. However, simple partial seizures sometimes forewarn the onset of more serious "secondary" (tonic-clonic or partial) seizures. In this case, the simple partial seizure may be termed an "aura".

In a complex partial seizure, the person's consciousness is impaired, although this may not be obvious. The person may behave in a strange manner, perhaps plucking at clothes, mumbling or wandering aimlessly. Complex partial seizures may be mistaken for the actions of a drunken or mentally ill person by an onlooker unfamiliar with such seizures. Of these types of seizure, the most common is the tonic-clonic seizure. To obtain a better understanding of tonic-clonic seizures, a step-by-step analysis is described below. In particular, there is detailed the stage of the seizure, the physical consequences and the procedure that a knowledgeable carer should take. For clarification, for the purposes of this explanation "patient" refers to a person with epilepsy, and "carer" refers to a knowledgeable person who is aware of how they should react when they witness an epileptic seizure.

Often, a tonic-clonic seizure begins suddenly and with no warning. Alternatively, a patient may have an aura or a prodrone whilst still conscious. As explained above, an aura is a simple partial seizure which may quickly lead to a tonic-clonic seizure. A prodrone is when a patient feels depressed some hours before a seizure. If a patient knows they might have a seizure, a carer should guide them away from danger and should support and watch them attentively.

The next stage in the seizure is the tonic phase. During the tonic phase the muscles throughout the body tighten and the patient loses consciousness for typically approximately one minute. As a result of this, the patient may fall if they are in a standing position. Also, the tightening of the diaphragm causes breathing difficulties, which in turn can cause cyanosing (turning blue) due to oxygen in the blood being used up. The patient may also cry out due to air being forced from the lungs. This stage of the seizure can also cause incontinence, and may force the patient to bite their tongue due to locked jaw. At this stage of the seizure, a carer should ensure that the patient's surroundings are made safe, and that they are not exposed to any edges, heat sources or other hazards.

After the tonic phase, the seizure then enters the clonic phase. In the clonic phase, the muscles go into convulsion for a time of up to approximately 4 minutes - a clonic phase longer than 4 minutes is considered prolonged. The clonic phase leads to the body (especially the limbs) jerking as the muscles contract and relax in a quick rhythmic sequence. As a consequence, the tongue often gets bitten, the patient salivates and the heart rate increases or decreases. At this stage of the seizure a carer should ensure that the patient's head is cushioned, but not restrained in any way. The patient should be placed on their side, if possible, to help fluids drain from the mouth. If the seizure has lasted for more than 5 minutes, medical attention should be sought, or the seizure should be aborted by the use of drugs.

In the minutes following the seizure, the muscles begin to relax, although the patient is still deeply unconscious. The patient will then begin to slowly regain consciousness and will likely be groggy and possibly confused or disorientated. The patient may also have a sore head and aching limbs.

In the hours and days following the seizure, the patient's behaviour will gradually return to normal, although they may not remember the seizure and they may need to sleep. In the minutes and hours following a seizure, a carer should reassure the person and give them time to recover before allowing them to stand when ready, and gently guiding them, if necessary. The carer should stay with the individual until they have fully recovered.

It is apparent from the detailed description of a tonic- clonic seizure that the presence of an educated carer can be very important in ensuring that the patient having the attack comes to no harm. As such, it can be difficult for individuals who experience seizures of this type to have any degree of independence from their carers. This can be frustrating and inconvenient for people with epilepsy. Moreover, people with epilepsy who have a seizure when not in the vicinity of an educated carer, are at high risk of inflicting head and/or corporal injuries (for example, due to falling) . At worst, unsupervised seizures can result in choking, brain damage and even death.

Over 270,000 people experience tonic-clonic seizures in the UK alone. Many of the problems associated with tonic-clonic seizures can be prevented or lessened by the presence of a knowledgeable carer. There are other complications associated with epileptic seizures, including sudden unexplained death in epilepsy (SUDEP) which involves the sudden death of a person with epilepsy with or without evidence for a seizure, where no other cause of death is found. Deaths occurring from prolonged or multiple seizures (status epilepticus) do not qualify as SUDEP. In fact, the exact mechanisms of SUDEP are only partly established. In brief, the core underlying features relating to SUDEP are thought to be a general tonic-clonic seizure, respiratory difficulties, and cardiac irregularities. Approximately 500 SUDEP deaths per year occur in the UK, making SUDEP the most common form of epilepsy related death. As such, many people with epilepsy are unable to live independently, and must be watched constantly. This is an unwanted and undesirable part of life for people with epilepsy.

Most SUDEP deaths occur unwitnessed, which suggests that should a witness be on hand to monitor the seizure and recovery time, and to provide respiratory stimulation if necessary, then fatalities may be avoided.

Existing apparatus for detecting epileptic seizures is very limited in its usability and applications. Many existing detectors are bed-based and are intended for use overnight or when the person is sleeping. The bed-based detectors have a central unit which is attached, by cables, to a sensor. The sensor is placed between the base of the bed and the mattress.

One such bed-based alarm, the Easylink (Trade Mark) , uses a pad which is placed beneath a mattress. The pad is designed to pick up vibrations which are associated with a seizure. When such vibrations are detected, the alarm is triggered. However, it has been found that the pad is particularly sensitive and can be triggered by external vibrations not associated with a seizure. For example, a bed-based alarm with a sensor pad can be triggered by the vibrations caused by a motor vehicle passing a house or institution where the apparatus is installed.

A further bed-based alarm of slightly different design is the Sensorium (Trade Mark) Sense Alert 102. Again, the Sensorium detector has a central unit which is attached, by cables, to a sensor pad which is placed between the mattress and the bed. In this case, the sensor pad operates like a push button, the button is depressed when the person lying on the top of the mattress convulses. Unfortunately, alarms such as these produce a lot of "false positives". That is to say, push button detectors will often indicate that a seizure has occurred, when in fact some other vibration or movement has set off the detector.

In many cases, push button detectors do not pick up subtle movements, although this appears to be dependent on the exact location of the sensor. Often, it takes large convulsive movements before the push button detectors register anything at all.

There are further drawbacks associated with bed-based seizure detectors. For example, as the sensors must be placed underneath a mattress, the person placing the sensors must lift the mattress and attempt to correctly locate the sensors. This can be particularly challenging in a bed with a slatted base, as it is difficult to place the sensors correctly, and the sensors can fall in- between the slats, therefore losing contact with the mattress. Also, the existing bed-base sensors are conspicuous and can cause embarrassment and stigma for the person with epilepsy.

Therefore, it is an object of the present invention to obviate, or at least mitigate, at least some of the drawbacks associated with the prior art. Further aims and objects of the invention will become apparent from a reading of the following description.

According to a first aspect of the present invention, there is provided an apparatus for detecting seizures in an individual comprising at least one motion detection means configured to be sensitive to a seizure and suitable for placing on or about at least part of the individual's body, and an alerting means, where the motion detection means is adapted to activate the alerting means on sensing of a seizure.

The type of seizure detected would typically be characterised by convulsions of the body, and especially the limbs. The type of seizure can also involve the individual collapsing, if they are initially in a standing position.

More specifically, the type of seizure detected would typically be an epileptic seizure, particularly a tonic, clonic or tonic-clonic seizure. However, the apparatus of the present invention is suitable for detecting any type of motor seizure, including myoclonic seizures.

Preferably the motion detection means and the alerting means are spatially remote from each other.

More preferably the motion detection means and the alerting means are adapted to communicate with each other wirelessly.

Optionally the motion detection means and the alerting means are physically connected to each other. Alternatively at least one motion detection means and the alerting means are contained in a single unit.

Preferably the alerting means is adapted to produce at least one alarm signal.

The alarm signal can be an audible alarm.

The apparatus may also comprise an alert receiving means.

The alerting means can adapted to communicate with the alert receiving means.

Preferably the alerting means is adapted to communicate with the alert receiving means wirelessly.

More preferably the alerting means communicates with the alert receiving means using radio frequency (RF) signals.

Optionally the alerting means communicates with the alert receiving means using a GSM network.

Alternatively the alerting means communicates with the alert receiving means using GPS.

The alerting means can further comprise a means for effecting vibration.

Preferably the means for effecting vibration is an eccentric mass micro-motor. Optionally the alerting means further comprises a memory module.

Optionally the alerting means further comprises a data transfer port.

Optionally the alerting means further comprises a motion detection means.

Preferably the apparatus for detecting seizures further comprises at least one electronic filter adapted to distinguish between benign electronic signals and electronic signals associated with a seizure.

Preferably the electronic filter is programmable.

The electronic filter can be located in the motion detection means.

Alternatively the electronic filter is located in the alerting means.

The filter distinguishes between benign signals, or noise, and signals associated with a seizure.

Preferably the motion detection means further comprises a means for translating physical movement into an electrical signal.

Preferably the means for translating physical movement into an electrical signal is at least one accelerometer . The at least one accelerometer can be a triaxial accelerometer.

The at least one accelerometer can comprise a first biaxial accelerometer and a second biaxial accelerometer configured such that they detect movement in three dimensions.

The at least one accelerometer can comprise a first uniaxial accelerometer, a second uniaxial accelerometer and a third uniaxial accelerometer configured such that they can detect movement in three dimensions.

Preferably the at least one accelerometer is a micro- electrical mechanical system (MEMS) accelerometer.

Preferably the apparatus is configured to detect an electrical signal associated with a convulsion.

The apparatus can be configured to count sequential electrical signals.

Also, the alerting means can be adapted to produce at least one alarm signal on detection of a pre-determined number of sequential counts.

Preferably the motion detection means further comprises a radio frequency (RF) transmitter chip.

According to a second aspect of the present invention there is provided a method for detecting seizures in an individual comprising the steps of: detecting motion of at least part of the individual' s body using at least one motion detection means/ assessing if said motion is associated with a seizure; and activating an alerting means on detection of a seizure, wherein the motion detection means is adapted to activate the alerting means on detection of a seizure.

Preferably the method comprises the further step of activating at least one alarm signal on detection of a seizure.

Preferably the method comprises the further step of a time delay between the activation of the alerting means and the activation of the alarm signal.

During the time delay the alerting means may vibrate. During the time delay the alerting means may produce a local audio warning.

The alerting means can be prevented from generating an alarm signal during the time delay step.

The individual can prevent the alerting means from generating an alarm signal during the time delay step.

Assessing if the motion is associated with a seizure consists of counting sequential electrical signals associated with convulsions. Preferably at least one alarm signal is produced on detection of a pre-determined number of sequential counts.

It will now be described, by way of example only, various embodiments of the invention with reference to the following Figures, of which:

Figure IA shows an alarm unit;

Figure IB shows an exploded view and some of the internal components of the alarm unit;

Figure 1C shows the rear of the alarm unit with the cover removed;

Figure 2 shows how the alarm unit can be located on a user;

Figure 3 shows a wrist mountable device which contains a motion detector;

Figure 4 is a simplified flow diagram that illustrates the most important steps in raising an alarm on detection of a seizure;

Figure 5 illustrates the seizure detection apparatus installed in a room.

Referring to Figure IA, an alarm unit is depicted at 1 and has a front cover 2 and a rear cover 3 which contain the internal components of the alarm unit 1. Visible on the front cover 2 of the alarm unit 1, is one side of a double-sided alarm button 4, the opposite side of which can be activated from the rear cover 3 of the alarm unit 1. Also visible in Figure IA is an audible alarm 5 and a series of light emitting diodes (LEDs) 6 which present feedback to a user (not shown) . Such feedback includes information relating to battery power, sensor testing and GSM reception/radio frequency check. Also protruding from the front cover 2 of the alarm unit 1 are a series of function buttons 7 that can be activated, such that the LEDs 6 will indicate to the user information concerning the battery, the sensors, and the GSM reception/radio frequency check.

Whilst in this example the alarm unit has a front and back section that are joined together, it will be appreciated that the alarm unit can be any suitable shape, and can be constructed from a single moulding, or from several individual modules. In addition, it will understood that the alarm button, audible alarm, LEDs and function buttons as described are intended to be exemplary, and that the alarm unit will not be restricted to these specific features. For example, the alarm button may only be accessible from one side of the alarm unit, and the audible alarm could be replaced by a visual alarm.

Furthermore, the alarm unit could contain an LCD or LED screen in addition to, or instead of, the LEDs and function buttons. The screen can incorporate touch- screen technology for operating the alarm unit. The alarm unit can further comprise addition functions. For example, the alarm unit can also function as a mobile phone, a PDA, a music player and/or games console.

Referring once more to Figure IA, on the side of the alarm unit 1 is located a cancel button 8 which can be operated by the user (not shown) to cancel the alarm either before, or after, it activates. Also visible is a cord attachment point 9 which allows the alarm unit 1 to be attached to a cord and worn, for example, as a pendant. There is a charge and data port 10 which allows the alarm unit 1 to be charged, and which allows the transfer of data to and from a PC or any other suitable device.

The cancel button 8 is a "pinch" button which is located on either side of the alarm unit 1, such that it is difficult to operate mistakenly. In order to activate the cancel button, the user must perform a "pinch" action, which is unlikely to occur inadvertently. Around the double-sided alarm button 4 is a lip 11 which prevents the double-sided alarm button 4 from being operated accidentally. The double-sided alarm button 4 is recessed inside an inverted dome-shape 12, which again makes it less likely for the double-sided alarm button 4 to be activated accidentally. There can also be seen a mute switch 13 which can be operated so that the audible alarm 5 does not sound.

Both the double-sided alarm button and the cancel button are easily locatable, and can be operated through clothing meaning that they can be operated quickly and easily. This is particularly important as the length of time between a user experiencing an aura and losing consciousness is often less than one second. Therefore, the user has a limited amount of time in which to manually activate the panic button. Also, as the functions can be accessed through clothing, it is possible for a user to discreetly cancel false alarms without revealing the alarm unit, thus minimising embarrassment and removing some of the stigma associated with epilepsy.

Referring now to Figure IB, there is shown some of the internal components of the alarm unit 1 attached to a printed circuit board (PCB) 17. In particular, reference is made to GSM chips 14 which allow the alarm unit 1 to send signals via the mobile phone network (GSM network) . Also shown is a radio frequency transceiver 16 which allows the alarm unit 1 to send and receive wireless signals. Also illustrated in this diagram is a flash memory chip 15 which can record seizure data, and store data received through the data port 10, or via any other suitable data source, including data transferred wirelessly.

Referring now to Figure 1C, the alarm unit 1 is presented from the rear with the rear cover (not shown) removed. As can be seen, the battery 18 and the micro controller 19 are located on the rear of the printed circuit board 17, as is an eccentric mass motor 23.

It will be appreciated that the internal components described are far from exhaustive and do not limit the number or type of components that can be used. For example, in this embodiment, the printed circuit board is a two-sided printed circuit board, but it will be appreciated that any suitable circuit board can be used. Also, the alarm unit can contain further components such as an eccentric mass micro motor which produces a vibration. However, any suitable device for producing vibration can be used. In use, the eccentric mass micro motor produces a vibrate alert which will activate prior to the alarm triggering, such that the user has the opportunity to cancel the alarm.

In Figures IA, IB and 1C, the alarm unit contains a GSM chip, but it will be appreciated that the GSM chip can be any suitable means for communicating with a remote device. For example, suitable means would include any other type of wireless connection, such as GPS or radio frequency (RF) connections, Bluetooth™ connections, Wi- Fi™ (Wireless Fidelity) connections and microwave connections.

Also, it will be apparent that the RF chip referred to in Figures IA, IB and 1C is intended as an example of how the alarm unit can communicate with a remote device. Therefore, it will be understood that any suitable means of communicating with a remote device will suffice. For example, the alarm unit can be physically connected to a remote device by means of cables or wires.

Referring now to Figure 2, there is illustrated a user 20 on whom is situated, at different locations, the alarm unit 1. As can be seen from this illustration, the alarm unit 1 may be located in several different locations, including the user's pocket, on a waistband, strapped to the arm or around the neck as a pendant. Referring now to Figure 3, there is shown a strap 21 for locating around the wrist or ankle (not shown) . The strap 21 contains a motion detection unit 22. The motion detection unit 22 contains a three-axis accelerometer, a battery, and a RF transmitter chip (none shown) . The motion detection means also contains a microcontroller (not shown) .

In use, the three-axis (triaxial) accelerometer can detect motion in three different axes, and can convert this motion into an electrical signal. However, it will be understood that any means that can detect motion and convert the detected motion into an electrical signal can be used. For example, the three axis accelerometer can be replaced by two two-axis (biaxial) accelerometers arranged perpendicularly with respect to each other to effect reading in three axes. Alternatively, three one axis (uniaxial) accelerometers, configured to detect movement in three dimensions, can be used. Furthermore, the RF transmitter chip simply acts as a means of communicating with another device, and it will be appreciated that any other wireless or wired means would be suitable for use.

It will be appreciated that the exact design of the strap as illustrated is merely exemplary, and is not intended to limit how the strap might be embodied. For example, the strap may be a silicone or rubber band designed such that one size fits all, and which has an orifice into which the motion detection unit can fit. Alternatively, the strap could be a flexible thin module constructed from polypropylene and in which the motion detection unit is completely sealed.

A further alternative is that the motion detection unit is attached to a strap which has a buckle, similar to a watch. A yet further alternative is that the motion detection unit has several modules which are linked by smart materials, such as AVS and polyester carbon nylon. An embodiment such as this has the advantage that it disguises the function of the strap and motion detection unit as jewellery, and makes the modules smaller and more aesthetically pleasing. Further alternatives include a snap band and a twist cuff constructed from tensioned steel and bakelite respectively. Straps such as these would incorporate the motion detection unit and are quick and fun to put on.

In the examples given above, the strap is mainly designed to fit around the wrists and ankles. However, it will be appreciated that the motion detection unit can be placed in any suitable area, and in any suitable means. For example, the motion detection unit may be incorporated into an item of clothing (such as a sock or a jumper) or an item of footwear. Also, the motion detection means may be integrated into an insole of the shoe, or may be designed such that it can fit easily between a foot and a shoe.

In the examples described, the motion detection unit has an electronic filter which reads the signals produced by the accelerometer, and which distinguishes between benign signals (or noise) and signals associated with a seizure. This is done by programming the filter to accept or reject input signals based on the amplitudes and frequencies of the input signals. In the examples described the filter will allow through signals that correspond to a user collapsing from a standing position (as in a tonic, or the tonic phase of a tonic-clonic seizure) , and a user convulsing (as in a clonic, or the clonic phase of a tonic-clonic seizure) .

In practice the filter allows through signals that have amplitude greater than 0.25V as these are associated with a person collapsing. The filter also allows through signals that have a frequency between 1 and 5Hz and amplitude between -0.05 and 0.05V as these are associated with convulsions. It will be appreciated that these figures are exemplary and are provided as a means of explanation only.

The apparatus may comprise more than one filter. For example, the apparatus may comprise a filter programmed to detect signals during everyday use, and a filter programmed to detect or distinguish between normal movement and seizures when the user is at least partially immersed in water. The use of a second filter of this type is useful when the user is swimming or bathing.

The filter can be programmable such that it may be customised by the user. Clearly each user will have unique movements; the filter can be programmed to recognise these movements and thus will help minimise false alarms. The filter may also be programmed to fit with the user's lifestyle. For example, the filter can be programmed to recognise activities such as playing a musical instrument, getting on/off or travelling in a train, cardiovascular activities such as running or swimming. Of course, these activities are exemplary only and it will be understood that the filter can be programmed to recognise many other activities.

The filter can also be "intelligent" such that it can learn, or be taught, signals that are specific to an individual user. Again, this will minimise false alarms, and increase the sensitivity of the apparatus to an individual's specific type and pattern of seizure.

When a signal associated with a person collapsing is allowed through the filter, the motion detection unit communicates with the alarm unit via the RF transmitter chip in the motion detection unit and the RF transceiver in the alarm unit. The alarm unit then produces an alarm signal in the form of an audible alarm and/or by alerting a carer via the GSM network or via a RF signal that the user is having a seizure. When a signal associated with a convulsion is detected, the motion detection unit counts the signal. Once the number of sequential counts reaches a pre-determined number the motion detection unit will communicate with the alarm unit and trigger an alarm signal in the same manner as described above.

It will be appreciated that the filter can be located in the motion detection unit or the alarm unit.

In the examples given, the motion detection means is a micro electrical mechanical system three-axis accelerometer . However, it will be appreciated that there are many types of accelerometer, such as piezoelectric, piezoresistive, and strain based, which can also be used. Also, although in the examples given the accelerometer is a three-axis accelerometer, it will be appreciated that alternative accelerometers that measure in a different number of axes can also be used. For example, two two-axis accelerometers can be arranged perpendicularly with respect to each other, thereby generating a reading in three axes. In addition, three one-axis accelerometers configured to detect movement in three dimensions can be used. It must be stressed that measuring in fewer than three axes increases the possibility of not detecting a convulsion.

Whilst in this example the motion detection means is an accelerometer, it will be appreciated that other suitable means for translating physical movement into an electrical signal can be used.

In a further embodiment the alarm unit, as illustrated in Figures IA, IB and 1C, also contains a motion detector (not shown) , such that the alarm unit and the motion detector are one single unit. Such a unit could be, for example, worn as a watch around the wrist. In an embodiment such as this, the motion detector would not necessarily be required to communicate wirelessly with the alarm unit, as the motion detector would be incorporated within the alarm unit.

In an alternative embodiment, the alarm unit containing the motion detection unit is also in connection with separate motion detection units that are located around the body. For example, the alarm unit may be worn around the neck or placed in a pocket whilst the separate motion detection units can be placed around the ankles and wrists.

In a yet further embodiment, the motion detection units can be incorporated into a piece of clothing or footwear such as a jumper, trousers, socks, shoes, insoles and sweatbands . In this embodiment the alarm unit can also be incorporated into a piece of clothing, or can be a separate module.

Referring now to Figure 4, there is illustrated a flow diagram which illustrates how the apparatus for seizure detection operates. Starting at the top of the flow diagram, it can be seen that the seizure detection apparatus is ordinarily in low power mode, which helps prolong the battery life of the alarm unit. The seizure detection apparatus remains in low power mode until it detects one or more of the following events: the user falling, the panic alarm button being pressed, a convulsive movement. When one or more of these events is detected, the seizure detection apparatus switches into full power mode. As the detection of a person falling or the panic alarm button being pressed are definitive, when the seizure detection apparatus recognises these events the alarm unit begins to vibrate to warn the user that the alarm signal is going to trigger. This time delay allows the user to cancel the alarm if it is a false alarm. If the alarm is cancelled, then the seizure detection apparatus switches back into low power mode. If the alarm is not cancelled, then the alarm unit confirms that a seizure has occurred and will raise the alarm audibly, via the GSM network, via radio frequency communication, via GPS communication, and/or via some other suitable audible, visible, wireless or wired means.

In the event that the motion detection unit detects a convulsive movement, it must perform a series of steps before communicating with the alarm unit. When a convulsion is detected, the seizure detection apparatus switches into full power mode. The motion detection unit will pass the signal through a filter to determine if the signal received is associated with a potential seizure. If the motion detection unit determines that the input does not relate to a seizure, then the seizure detection apparatus will revert to low power mode. If the motion detection unit detects that the input is a seizure, then it will count the signal. After a set number of signals have been counted, the motion detection unit will transmit a signal via a RF transmitter to the alarm unit. (If the convulsions stop before this set limit is reached, then the motion detection unit establishes that a seizure is not taking place and the seizure detection apparatus will return to low power.) The alarm unit will count the number of signals received from the motion detection unit until a user specified level is reached, at which point the alarm unit will begin to vibrate to warn the user that the alarm signal is about to trigger. After a set time delay, the alarm unit will confirm that a seizure has occurred and will raise the alarm via the routes described previously. Alternatively, if the alarm is cancelled before the seizure is confirmed by the alarm unit, then the apparatus will return to low power mode.

It will be appreciated that the flow diagram and the description are intended as an example of how the apparatus for detecting seizures operates in practice. It will be understood that alternative flow diagrams with fewer or additional steps, and in a different sequence, can also be used. The apparatus for detecting seizures is not limited to the sequence of events as described and the flow diagram is merely an example of how the seizure detection apparatus can work in practice.

Referring now to Figure 5, there is illustrated the seizure detection apparatus installed in a room. The diagram shows an alarm unit 1, a user 20 wearing straps 21 which contain motion detection units (not shown) . This embodiment is useful for care homes and hospital wards where it may be more desirable to have the alarm unit in a fixed location. In this embodiment, the motion detection unit communicates with the alarm unit wirelessly by radio frequency signals; however it will be appreciated that other means of wireless communication may also be used. Similarly, the alarm unit can contact a carer by radio frequency means, and again it will be understood that other means, including audible means, of alerting a carer can also be used.

In an alternative embodiment the alarm unit is in fact a wall-mounted relay unit which picks up waves transmitted by the motion detection units. In this embodiment the motion detection units contain emitters which emit an electromagnetic pulse at a set frequency, which in this example is 200Hz. These pulses are detected by at least three relay units which transfer the information received to a computer. Using the time difference between each pulse reaching the relay units the computer can calculate the location of the emitter, and thus the location of the user. When this reading is taken frequently (e.g. 200 times per second) movement can be monitored and thus seizures can be detected.

The filter incorporated into the apparatus enables the detection device to avoid false alarms or traces which may be considered similar to those of a convulsion. If, in the unlikely event, that a signal is interpreted as a convulsion, when in fact it is not a convulsion, this can be cancelled by the user before the alarm is triggered due to the vibratory or local audio alert time delay before the alarm signal triggers.

Various modules can be added to, or incorporated with, the seizure detection apparatus, including an electroencephalogram (EEG) which can record the electrical activity of the brain and will further aid the detection of seizures. Also, the Lifeshirt™ which can be used to measure heart rate and breathing activity can also be incorporated into the device, and will further aid the detection of SUDEP. Another potential plug-in is a small microphone wired into a collar which would pick up on gurgling noises which are sometimes made by people during a seizure. This would provide a further input which would help aid the accurate detection of the seizures.

As has been alluded to elsewhere in the description, when a seizure occurs in an individual, it is also possible that they will have an episode of incontinence. Therefore, smart underwear which has conductive wiring sewn into it could be incorporated into the device, such that the device may also detect incontinence. Further plug-ins include an oximeter and an electromyogram (EMG) . An oximeter measures oxygen levels in the blood, which often decrease during seizure due to troubled breathing. An EMG records the electrical activity of the muscles and can further aid the detection of seizures.

The seizure detection apparatus will be useful in the detection of epileptic seizures. In particular, the seizure detection apparatus will be useful in the early detection of tonic, clonic, and tonic-clonic epileptic seizures. It will be appreciated that the apparatus of the present invention is suitable for detecting any type of motor seizure, including myoclonic seizures.

In detecting these seizures, the seizure detection apparatus will raise an alarm locally and/or remotely such that a carer can come to the aid of the individual having the seizure. This affords those with epilepsy more independence as they will not have to be constantly visually monitored by a carer. This also allows a carer more freedom as they will not have to continually closely monitor the individual with epilepsy. This will prove especially useful in hospitals and care wards where a carer may have several patients to look after. Furthermore, by quickly alerting a carer that an individual has had a seizure, it is possible that many cases of SUDEP could be avoided.

The discrete nature of the motion detection unit and the alarm unit makes the seizure detection apparatus usable on a day-to-day basis. In particular, the motion detection units in the form of wrist and/or ankle bands will be unidentifiable as a medical device. Also, the alarm unit can be worn or carried, and operated out of sight. Thus the seizure detection apparatus removes much of the stigma associated with having epilepsy and will be much more appealing to children and teenagers with epilepsy.

Further modifications may be made without departing from the scope of the invention herein intended.

Claims

1. An apparatus for detecting seizures in an individual comprising at least one motion detection means configured to be sensitive to a seizure and suitable for placing on or about at least part of the individual's body, and an alerting means, where the motion detection means is adapted to activate the alerting means on sensing of a seizure.

2. An apparatus as claimed in Claim 1, wherein the motion detection means and the alerting means are spatially remote from each other.

3. An apparatus as claimed in Claims 1 or 2, wherein the motion , detection means and the alerting means are adapted to communicate with each other wirelessly.

4. An apparatus as claimed in any preceding Claim, wherein the motion detection means and the alerting means are physically connected to each other.

5. An apparatus as claimed in any preceding Claim, wherein at least one motion detection means and the alerting means are contained in a single unit.

6. An apparatus as claimed in any preceding Claim, wherein the alerting means is adapted to produce at least one alarm signal.

7. An apparatus as claimed in Claim 6, wherein the alarm signal is an audible alarm.

8. An apparatus as claimed in any preceding Claim, wherein the apparatus further comprises an alert receiving means.

9. An apparatus as claimed in Claim 8, wherein the alerting means is adapted to communicate with the alert receiving means.

10. An apparatus as claimed in Claim 9, wherein the alerting means communicates with the alert receiving means wirelessly.

11. An apparatus as claimed in Claim 10, wherein the alerting means communicates with the alert receiving means using radio frequency signals.

12. An apparatus as claimed in Claim 10, wherein the alerting means communicates with the alert receiving means using a GSM network.

13. An apparatus as claimed in Claim 10, wherein the alerting means communicates with the alert receiving means using GPS.

14. An apparatus as claimed in any preceding Claim, wherein the alerting means can further comprise a means for effecting vibration.

15. An apparatus as claimed in Claim 14, wherein the means for effecting vibration is an eccentric mass micro-motor.

16. An apparatus as claimed in any preceding Claim, wherein the alerting means further comprises a memory module.

17. An apparatus as claimed in any preceding Claim, wherein the alerting means further comprises a data transfer port.

18. An apparatus as claimed in any preceding Claim, wherein the alerting means further comprises a motion detection means.

19. An apparatus as claimed in any preceding Claim, wherein the apparatus for detecting seizures further comprises at least one electronic filter adapted to distinguish between benign electronic signals and electronic signals associated with a seizure.

20. An apparatus as claimed in Claim 19 wherein the electronic filter is programmable.

21. An apparatus as claimed in Claims 19 or 20, wherein the electronic filter is located in the motion detection means.

22. An apparatus as claimed in Claims 19 or 20, wherein the electronic filter is located in the alerting means.

23. An apparatus as claimed in any preceding Claim, wherein the motion detection means further comprises means for translating physical movement into an electrical signal.

24. An apparatus as claimed in Claim 23, wherein the means for translating physical movement into an electrical signal is at least one accelerometer .

25. An apparatus as claimed in Claim 24, wherein the at least one accelerometer is a triaxial accelerometer.

26. An apparatus as claimed in Claim 24, wherein the at least one accelerometer comprises a first biaxial accelerometer and a second biaxial accelerometer configured such that they can detect movement in three dimensions.

27. An apparatus as claimed in Claim 24, wherein the at least one accelerometer comprises a first uniaxial accelerometer, a second uniaxial accelerometer and a third uniaxial accelerometer configured such that they can detect movement in three dimensions.

28. An apparatus as claimed in Claims 24 to 27, wherein the at least one accelerometer is a micro-electrical mechanical system (MEMS) accelerometer.

29. An apparatus as claimed in Claims 23 to 28, wherein the apparatus is configured to detect an electrical signal associated with a convulsion.

30. An apparatus as claimed in Claim 29 wherein the apparatus is configured to count sequential electrical signals.

31. An apparatus as claimed in Claim 30 wherein the alerting means is adapted to produce at least one alarm signal on detection of a pre-determined number of sequential counts.

32. An apparatus as claimed in any preceding Claim, wherein the motion detection means further comprises a radio frequency (RF) transmitter chip.

33. A method for detecting seizures in an individual comprising the steps of: detecting motion of at least part of the individual' s body using at least one motion detection means; assessing if said motion is associated with a seizure; and activating an alerting means on detection of a seizure, wherein the motion detection means is adapted to activate the alerting means on detection of a seizure.

34. A method as claimed in Claim 33, wherein the method comprises the further step of activating at least one alarm signal on detection of a seizure.

35. A method as claimed in Claims 33 or 34, wherein the method comprises the further step of a time delay between the activation of the alerting means and the activation of the alarm signal.

36. A method as claimed in Claim 35, wherein during the time delay the alerting means vibrates.

37. A method as claimed in Claims 35 or 36, wherein during the time delay the alerting means produces a local audio warning.

38. A method as claimed in Claims 35 to 37, wherein the alerting means can be prevented from generating an alarm signal during the time delay step.

39. A method as claimed in Claims 33 to 38, wherein assessing if the motion is associated with a seizure consists of counting sequential electrical signals associated with convulsions.

40. A method as claimed in Claim 39 wherein at least one alarm signal is produced on detection of a pre- determined number of sequential counts.