Method for electrically stimulating the human brain

Abstract

A method and apparatus for electrically stimulating the human brain which includes applying electrodes directly to the cerebellum and feeding electrical impulses to such electrodes with a view to aiding individuals suffering from intractable hypertonia, epilepsy and other ailments, said electrical impulses having a duration of from 0.5 to 2.5 milliseconds, an ampliude of from 0.5 to 14.0 volts, and a frequency of from 1 to 300 pulses per second.

Description

This invention pertains to a technique for electrically stimulating the human brain to alleviate certain disorders, and more particularly applying electrical impulses to the cerebellum of the brain.

There are substantial numbers of people who suffer from disorders such as intractable hypertonia, epilepsy and related ailments. Although drugs have been used to alleviate the symptoms of such ailments, there are unfortunately cases where the drugs are ineffective or must be used in such massive doses as to cause depression and drowsiness in the patient.

It is also possible to alleviate such symptoms in some cases by means of surgery. However, surgery involves the risk of an adverse outcome and is irreversible.

Accordingly, it is a general object of this invention to provide a technique to alleviate the symptoms of ailments such as hypertonia, epilepsy, stroke and the like.

Another object of this invention is to provide an improved technique for treating the symptoms of such ailments without recourse to massive doses of drugs or to irreversible surgery.

Briefly, the invention contemplates a method of treating particular human ailments by applying to the cerebellum electrical pulses having a specified range of frequencies, amplitudes and duration.

Other objects of this invention will be apparent from the following detailed description when read with the accompanying drawing, where:

FIG. 1 shows a schematic representation of apparatus for practicing the invention;

FIG. 2 is a block diagram of a transmitter; and

FIG. 3 is a block diagram of a receiver utilized in the invention.

The apparatus of the instant invention comprises two sets of electrodes 10 implanted in the head of the patient; with each set being in direct contact with the neocerebellum and the paleocerebellum respectively. The electrodes 10 are connected via signal leads 12 to a pair of receivers 14 embedded in the chest of the patient, the signal leads being internal to the patient.

Opposite the implanted receivers 14 is an antenna 16 connected via an external signal lead 18 to an external transmitter 20. In operation, the transmitter 20 emits signals which are fed via signal lead 18 to antenna 16 which radiates the signals to the implanted receivers 14, which in turn transmit voltage pulses via implanted signal leads 12 to implanted electrodes 10. More specifically, the signals received by electrodes 10 are voltage pulses which stimulate the indicated portions of the cerebellum.

It has been found that voltage pulses which are rectangular in waveform and have durations of from 0.5 milliseconds to 2.5 milliseconds; and preferably, 1.0 milliseconds lead to good results when their amplitudes are between 0.5 and 14 volts.

The pulse repetition rate is a function of the ailment being treated. In the case of epilepsy, the pulse repetion rate should be of the order of 10.0 pulses per second with pulse amplitudes of 5.0 to 10.0 volts.

When treating hypertonia, the pulse repetition rate should be in the order of from 100 to 200 pulses per second with pulse amplitudes of 10.0 to 14.0 volts. Furthermore, it has been found in some cases of epilepsy, it is desirable to feed alternate bursts of pulses to the electrodes so that the paleocerebellum and neocerebellum are continuously, but alternately stimulated. It has been found that such bursts should have a duration of from about 1 minute to about 30 minutes, and preferably about 8 minutes.

In other cases, continuous stimulation may be indicated; while in other instances when the patient senses the onset of aura, stimulation is initiated.

Although the individual components of the system are well known in the electronic art; they will be discussed for the sake of completeness.

The transmitter 20 shown in FIG. 2 can be a two-channel transmitting device wherein each channel comprises a keyed oscillator, i.e. a sine wave oscillator of which when turned or keyed on, emits a packet of carrier signals. The oscillator each channel has a different carrier frequency. Each of the keyed oscillators can be driven by a voltage controlled one shot multivibrator, i.e. a multivibrator, which, as long as it receives a control voltage, emits, say 1.0 millisecond pulses having the desired repetition rate.

The voltage controlled one shot multivibrator can be controlled by a further symmetrical free running multivibrator or similarly functioning circuit with a pair of out of phase outputs, each being connected to one of the voltage controlled one shot multivibrators.

The symmetrical multivibrator is dimensioned to change state and consequently energize alternate outputs at the desired frequency, e.g. once every 8.0 minutes. Thus, it can be seen that the transmitter 20 feeds to antenna 16 1.0 millisecond packets of carrier signal wherein the carrier signal has a first frequency for all packets occuring during one 8.0 minute interval, and a second frequency for all packets occuring during the next 8.0 minute interval. Astable multivibrators with a period of 8.0 minutes, may also be used.

Antenna 16 can be fixed to the exterior of the patient's chest by means of adhesive tape or the like; or, can be implanted subcutaneously, in which case, the transmitter 20 should be easily detachable from lead 18.

The receivers 14 shown in FIG. 3 can be identical except for operating frequency. Each receiver can comprise: a tuned amplifier tuned to either the first or second frequency; an envelope (conventional AM) detector connected to the output of the amplifier; and a Schmitt trigger circuit coupled to the output of the envelope detector for amplifying and squaring the output of the envelope detector.

Thus, each receiver alternately omits pulses which are fed via subcutaneous leads tunnelled from the anterior chest wall to the posterior fossa and then to their respective sets of electrodes 10 directly contacting the cerebellum.

The electrodes 10 are essentially 4 pairs of platinum disc electrodes on a silicon coated mesh of Dacron fiber or the like, applied to the neocerebellum and the paleocerebellum.

The details of the operation for positioning the electrodes with respect to the cerebellum, can be found in the article entitled Physiologic Neurosurgery at New York's St. Barnabas Hospital, pages 32- 53 of Contemporary Surgery, Vol. 2, No. 6, June 1973, published by McGraw Hill.

Although a specific configuration of the transmitter, receiver and electrodes has been disclosed; it should be apparent that other devices which can generate the required waveforms for application directly to the cerebellum, can be used to treat a number of ailments.

Further, while the apparatus has been disclosed for alternate stimulation of the neocerebellum and paleocerebellum, it is possible to stimulate either region alone, or both regions simultaneously. In each case there is need for only a single channel transmitter and a single channel receiver.

Claims

I claim:

1. A method of stimulating the human brain comprising the steps of: affixing at least one set of electrodes directly to a region of the cerebellum; generating electrical pulses having a duration of from 0.5 to 2.5 milliseconds, an amplitude of from 0.5 to 14.0 volts and a frequency of from 1 to 300 pulses per second; and applying the generated electrical pulses to said electrode.

2. A method as in claim 1 wherein a first set of electrodes are affixed to the paleocerebellum region of the cerebellum and a second set of electrodes are affixed to the neocerebellum region of the cerebellum.

3. A method as in claim 2 wherein said electrical pulses are alternately applied in bursts to said first and second sets of electrodes.

4. A method as in claim 3 wherein each burst of pulses has a duration of from 1.0 minute to 30.0 minutes.

5. A method as in claim 1, wherein the duration of the pulses is 1.0 millisecond and the pulses have a rectangular waveform.

6. A method as in claim 5, wherein the amplitude of the pules is 10.0 volts and the frequency of the pulses is 200 pulses per second.

7. A method as in claim 5, wherein the amplitude of the pulses is from 5.0 to 10.0 volts and the frequency of the pulses is 10.0 pulses per second.