Surgery – Diagnostic testing – Structure of body-contacting electrode or electrode inserted...
Reexamination Certificate
1999-07-02
2001-03-13
Jastrzab, Jeffrey R. (Department: 3737)
Surgery
Diagnostic testing
Structure of body-contacting electrode or electrode inserted...
C600S383000
Reexamination Certificate
active
06201982
ABSTRACT:
TECHNICAL FIELD
This invention relates to electroencephalogram (EEG) electrodes. More particularly, the invention relates to EEG electrodes that can be quickly applied and removed from a patient's scalp. The invention also relates to methods for quickly and easily applying and removing the EEG electrode from the patient's scalp.
BACKGROUND ART
Attachment devices exist for fixing EEG electrodes to a patient's scalp. These devices may use colloidal glue, adhesive tape or bandages. EEG electrodes may also be attached by incorporating them into web matrix helmets. Placing and removing these EEG electrodes from a patient's scalp is time consuming. The EEG electrodes are uncomfortable to wear and may loose signal contact during extended ambulatory monitoring.
Web matrix helmets are headpieces made of a webbing material. Web matrix helmets are fastened to the patient's head by means of a chin strap and/or a neck strap with scalp-pattern electrodes attached along the under-surface of the web material. Web matrix helmets cannot be used unobtrusively in ambulatory settings. Furthermore, each contact area on the patient's head must be thickly coated with an electrolytic gel to obtain good signal quality. Even with this preparation, since the electrodes themselves trap large quantities of hair between the electrode body and the scalp, there is a possibility for signal loss from any one electrode. Also, during the course of long-term monitoring, re-application of electrolytic gel is often necessary to maintain signal quality. Lastly, web matrix helmets do not fit all head shapes and sizes, making electrode placements problematic with some patients.
Scalp placement electrodes may also be attached to the patient by means of an adhesive paste. The electrode is pressed into a large amount of electrolytic adhesive paste or gel applied at the desired placement site, and then the electrode is taped in place to allow the adhesive to set. The electrodes are obtrusive, and a large amount of electrolytic gel is needed to maintain proper contact because the electrode-scalp interface tends to dry out through evaporation. In addition, adhesive-attached scalp electrodes cannot be used in most ambulatory settings because they tend to become dislodged during normal movement or activity. Finally, this type of placement entails a messy and time consuming clean-up.
Colloidal glues achieve stronger bonding between the electrode and the scalp, but their use is both time and labor intensive. In a typical application, electrolytic gel is applied to the patient's scalp, the electrode is seated and taped in place, and the colloidal glue is applied and allowed to dry. This process can take 7-15 minutes per electrode. Removing the electrode requires applying a solvent, and the patient is inconvenienced because the collodion remains in the hair. In addition, the collodion and solvents emit strong fumes, limiting their use to specially ventilated rooms. Also, because the collodion can bond to unintended surfaces, special care must be used not to touch any other material while gluing the electrodes in place. Lastly, many patients may experience scalp irritation due to sensitivity or allergic reactions to the collodion.
SUMMARY OF THE INVENTION
This invention is directed to a quick-placement electroencephalogram (EEG) electrode that may be used for monitoring brain wave activity, for example. The quick-placement EEG electrode includes a first element or fixed section which is coupled to a second element or movable section. The movable section may be constructed of two pieces, such as a plunger and a grabbing element, for example. When the quick-placement EEG electrode is assembled, the plunger contacts the grabbing element. Alternately, the movable section may be molded as a single piece capable of functioning as both a plunger and a grabbing element. In both arrangements, the plunger penetrates a center opening of the fixed section, or cap. Downward pressure applied to the plunger causes the grabbing element to activate. In another arrangement, the fixed and movable sections include a cap and a coil spring.
The quick-placement EEG electrode is designed to clamp to a patient's hair by trapping hair between the first element and the second element. Alternatively, the patient's hair is trapped in the grabbing element alone. In another arrangement, the patient's hair is trapped with downward pressure on the movable section or plunger. A sponge carried in the movable section and containing electrolytic gel is compressed by the downward pressure on the plunger, causing release of the gel at the scalp contact point. The compressed sponge counters the downward force exerted on the trapped hair, acts as a shock absorber, and maintains constant contact between the scalp and the electrode. Finally, the quick-placement EEG electrode is easily removed by pushing down on the plunger or otherwise releasing the grabbing element.
The quick-placement EEG electrode maximizes the accuracy of EEG readings and exploits specific characteristics of electrolytic gel-type electrodes for long term monitoring. Dissipation of the gel from movement (friction) is minimized because the EEG electrode is held securely in place by gripping the base of the patient's hair. In addition, the EEG electrode design provides a covering for the cavity mounted sponge saturated with electrolytic gel. This covering traps the electrolytic gel between the EEG electrode and the scalp, thus minimizing evaporation and allowing the gel to remain stable over a longer time. Because it is attached to the hair, the quick-placement EEG electrode may be quickly applied and removed. Moreover, low visibility of the EEG electrode makes it more practical for long-term ambulatory monitoring.
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Menkes Alex
Sakers John R.
Baltimore Biomedical, Inc.
Dorsey & Whitney LLP
Jastrzab Jeffrey R.
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