DE29508277U1 - Device for fixing the human head during examinations and interventions - Google Patents

Description

Device for fixation of the human head during examinations and procedures

Description

In many areas of human medicine or medical research and technology, a secure fixation of the head of a patient or a person being examined is necessary; this is of utmost importance in the field of head surgery or ear, nose and throat surgery.

Due to the inclusion of computer technology in diagnosis and therapy, the requirements for accuracy and reproducibility have increased dramatically both in determining a spatially defined point in or on the human head and in fixing the head itself.

The most common methods for fixing the human head are briefly described below:

a) Fixation of the head with tape

The patient's head lies on his back on a foam ring. Adhesive tape stretched across the forehead, upper and lower jaw fixes the head to its support; the following points are disadvantageous: <

- Strong tension on the adhesive tapes can lead to impressions, displacement and/or swelling of the skin;

- after removing the holding elements (adhesive tapes), repositioning in exactly the same position is extremely unlikely and practically no longer possible, which is almost unacceptable in stereotactic operations and in radiotherapy;

- the head cannot be fixed sufficiently, especially laterally, the head mobility cannot be restricted enough.

b) Fixation of the head with face mask

The head lies on the back in a preformed shell, the face is covered by a previously individually made mask, which is anchored laterally. Due to the limited movement between the face and the mask, the head is fixed, whereby the following points have a negative impact:

- the surgical area is not accessible, the skin is covered;

- Swelling of the skin under the tight-fitting mask;

- completely covering the face is stressful for the patient;

- high cost and time expenditure.

c) Fixation of the head by clamping

The patient’s head is clamped into a metal ring from several sides using adjusting screws.

Disadvantages:

- Surgical areas face and back of the head are covered;

- high costs;

- different positions for different interventions are only possible to a very limited extent

- frequent skin shifts.

d) Fixation of the head by screwing the skull

The patient's head is screwed to a metal ring in several places; the disadvantage is the following:

- Screwing the skull bone is an invasive method and is therefore only possible and justified in certain indications;

- the psychological stress on the patient is considerable;

- the method is only applicable to a limited extent to certain storage conditions.

e) Fixation of the head via the teeth (previous methods e.g. Gill-Thomas-Cosman holder)

The upper jaw teeth are glued (cemented) into a non-variable, rigid holding device, which means that the position of the patient's head must be adapted to predetermined conditions.
Further disadvantages are the following points:

- various surgical areas are not accessible due to the complex holding frame (e.g. in ENT the endoscope cannot be inserted through the nose);

- positioning the patient's head is cumbersome and difficult, thus stressful for the patient;

- loosening the glued or cemented connection in the mouth is stressful for the patient;

- the holder is quite complex;

- high costs and a lot of time, the latter being stressful for the patient;

- positioning of the patient's head is only possible to a limited extent.

The problem underlying the invention is to create, based on the last-mentioned approach, a device for fixation of the human head which avoids the disadvantages mentioned, is simple in construction and use and is extremely gentle on the patient; the device should also enable the precise attachment of calibration points (also called markers).

This problem is solved with a device having the features of claim 1.

In contrast to the devices and procedures described at the beginning, the device according to the invention fixes the human head using pressure and adhesive forces that act between the head to be fixed and an impression of the upper jaw and hard palate taken individually from the respective person. Hardening plaster or special plastic materials, such as those used in dental technology, can be used as the impression material.

The connection between the upper jaw impression tray and the upper jaw cross plate can be made before or after the impression is taken.

The impression can be removed from the patient's upper jaw teeth and hard palate after the examination or treatment has been completed by slightly tilting it with relatively little force and thus in a way that is gentle on the patient.

The measures of claim 2 provide a simple way of connecting the upper jaw impression tray and the upper jaw cross plate. The design according to claim 3 improves the device with regard to easy adjustability and the positioning of all relevant elements.

The measures of protection claim 4 extend the application possibilities of the device.

The inclusion of the measures according to protection claim 5 enables the use of the device in examination and treatment methods that require metal-free zones for radiation (CT, radiotherapy, etc.)

The measures of claims 6, 7 and 8 improve the individual and reproducible adjustability of the device.

The design according to claim 9 means an aid for the surgeon. The counter-support according to claim 10 represents additional protection for the patient's head, especially in the upper and back of the head regions, and ensures the fixation of the head, especially in restless/awake patients or in the event of greater force on the patient's head.

The measures according to claim 11 enable an even distribution of pressure and thus relieve the patient.

The measures according to claim 12 can ensure that, in particular after repeated use of an impression, a firm connection is made possible by negative pressure; suitable vacuum pumps with adjustable suction pressure, hose connections and shut-off valves are to be understood as means of generating negative pressure; to support the effect, flat cavities can be created by removing impression material from the finished impression and a shut-off valve can be placed in the front upper jaw area of the impression and the upper jaw impression tray. The further development according to claim 13 is particularly valuable. In modern medicine, calibration points are used to establish fixed points and reference planes in the practical application of imaging procedures such as CT (computer tomography) or MRI (magnetic resonance imaging).

The addition of the claimed fixation device with the measures of claim 13 allows, after an impression has been taken and a holder has been attached to the upper jaw impression tray or to the upper jaw cross plate, calibration points to be set which can be used as reference points for further measures in an imaging procedure with or without fixation of the patient's head.

In the following, an exemplary embodiment is explained using Figures 1 to 14.

Show it:

Figure 1 The entire device in plan view.

Figure 2 The entire device in side view

with a schematic representation of the patient's head.
Figure 3 The entire device in front view

View from the body to the head of a patient not shown. Figure 4 Holder for calibration points in top view.
Figure 5 Bracket for calibration points in side view.
Figure 6 The base plate, brackets, upper jaw cross plate and counter fixation in

Side view, left maxillary transverse plate, right counterfixation. Figure 7 The counterfixation in

View from the head to the body of the patient. Figure 8 The holding rods with the upper jaw cross plate in

Floor plan, front view in the body's longitudinal axis and side view across it. Figure 9 Base holder with base rod and holding rod joint with joint screw in

Floor plan, front view and side view.
Figure 10 The counter fixation with angle plate locking screws and counter pressure discs in smaller scale, floor plan, front view and side view.

Figure 11 The hydraulic design of a tripod

with base holder, holding tubes, ball joints, central locking device and connecting fork.

Figure 12 Bracket for calibration points >

with upper jaw impression tray, screw thread, transverse spacer rod and the right lateral spacer rod (seen from the patient).

Figure 13 The head support ring in

Floor plan, front and side view

Figure 14 The base plate in

Floor plan, front and side views.

The base plate 1, 2, 3 [Figure 13], made of stainless, magnetizable steel, has underfloor support arms [not shown] on its underside and is thus connected to the operating table. The underfloor support arms consist of two solid metal claws, which are screwed to the operating table on the one hand and to the base plate 1, 2, 3 on the other. The base plate 1, 2, 3 can be adjusted horizontally and vertically relative to the operating table and can be rotated to a certain extent around any axis, whereby a high degree of stability is guaranteed in every position.

The head support ring 43 [Figure 13] or the head rest 44 is located on the base plate 1, 2, 3, and is adapted to the shape of the head and can be moved freely depending on the patient's position. When the head is laid back, the head support ring 43 consists of a slightly compressible hard rubber ring on which the back of the head is placed. Head support rings 43 of different diameters and thicknesses are therefore available for different head sizes. The head support ring 43 or the shaped head rest 44 are essential for the even distribution of pressure and the transmission of force from the head to the base plate 1, 2, 3; they also increase the contact surface, which results in a reduction in the surface pressure. The shaped head rest is mainly used when the patient or the person being examined is lying on their side.

The force-transmitting parts of the device [e.g. Figures 9 and 11] each consist of a base holder 5, 13, 19 [Figures 1 - 3, 9 and 11] and a firmly connected (screwed-in) base rod 7, 15 [Figures 2 and 3] and a holding rod 8, 16 [Figures 1, 2 and 3] which is articulated to this and which has a point at the end for attachment to the upper jaw cross plate wing [Figure 3]. The base holder 5, 13, 19 has an on-off switch [Figure 3], with which it can be anchored magnetically or pneumatically at any point on the base plate 1, 2, 3. The articulated connection between the base rod 7, 15 and the holding rod 8, 16 [Figure 3] is ensured by means of screw locks 10, 11 [Figure 2]. In contrast to this, in the hydraulic version of a stand [Figure 11], with the same base holder 19, the force transmission is carried out by holding tubes 22 and ball joints 23. An incision at the end of the holding rod 8, 16 forms the connecting fork 12, 18 [Figure 8], and serves to attach the holding rod 8, 16 or the holding tube 22 to the upper jaw cross plate 27 [Figure 8 and H]. The upper jaw cross plate 27 is connected to the upper jaw impression tray 30 [Figure 12] filled with an impression material 31 [Figure 12] using an adhesive. The upper jaw cross plate wings 28 [Figure 3] leave the patient's mouth in the area of the corners of the mouth. The upper jaw cross plate
27 is made of V4A steel and has a minimum thickness of 2 mm. Its size and shape are variable and can therefore be easily adapted to the respective requirements [Figure 3]. In

A U-shaped space is cut out in the area of the upper jaw cross plate arch 29 in order to gain space and an overview of the oral cavity. The upper jaw cross plate wings 28, like the entire upper jaw cross plate 27, are variably adapted to the needs of the respective procedure in terms of size and shape, especially in terms of their projection. ■'

The structure of the holding device for calibration points [Figures 4, 5 and 12] consists of a transverse spacer rod 33, which is screwed to the upper jaw impression tray 30 in a rotationally and displacement-proof manner. The lateral spacer rod 34 can be adjusted and fixed to the transverse spacer rod 33 by means of a screw/clamp connection.

The marker pins 37 can either serve as calibration points themselves or as carriers for markers (e.g. in the form of lead pellets); the markers can also be attached to any other place on the holder.

The practical application of the device according to the invention will be described below using CAS (computer assisted surgery):

The CAS is an interoperative navigation aid. Before the operation, the patient is scanned in the CT or MRI. The individual sections are then reconstructed into a 3D object with the corresponding stereotactic spatial coordinates on the Allegro (processing computer) and transferred to a workstation (viewing wall) in the operating room. This virtual image is calibrated to the patient in the operating room using a passive mechanical arm coupled to the viewing wall, at the end of which there is a probe. Sensors on each of the arm's six rotation axes tell the computer the relative angles of the arm parts to each other, which enables the computer to calculate the stereotactic coordinates of the probe tip.

By moving to several points [e.g. anatomical points or points marked by radiopaque calibration points (markers)] on the patient or on the calibration device and correspondingly correlating them with the reconstructed 3D object on the screen, the computer is able to fit this 3D object into this virtual space. The better the moved to points match the points correlated on the screen, the more precisely the virtual image and the patient's head match, which leads to a high level of system accuracy. The surgeon can orient himself during the operation using the reconstructed 3D object and several two-dimensional images, which always show the probe tip.

The successful use of the viewing wall is only guaranteed if the patient's head is completely fixed. The system is currently not yet able to register movements of the patient and thus correct the position. Therefore, before each use of the probe (when fixated with tape), it is currently necessary to check the position of the head by moving to the corresponding calibration points (landmarks). Recalibration is therefore required for each head movement. The consequences include, among other things, a considerable extension of the operation time.

In addition, a change in position between the calibration check and the use of the probe for planning, orientation and navigation can have serious consequences for the patient, because this error is not detected by the system and can therefore result in misinterpretation.

This limits the reliability of the entire system.

Calibration requires a sufficiently large and easily accessible skin area. This is necessary for the marker calibration, in which markers are placed on the skin. Surface calibration is used to improve the marker calibration, in which the skin areas used for recalibration must not be moved by attaching the holder. By moving the skin and/or the markers attached to it in relation to the head, a correlation of the real patient head to the 3D object reconstructed from the CT data with the desired and required precision is not possible. This applies to both marker and surface calibration.

In all these cases, the situation is therefore unsatisfactory, if not alarming.

When using the device according to the invention, the following procedure is followed:

First, an upper jaw impression is taken of the patient using an upper jaw impression tray and impression material. If this is done shortly before the CT scan, the patient can be scanned in the CT after the calibration device has been set up without removing the impression tray and without using the head holder. The calibration device is set up so that the markers on the holders (small beads made of radiopaque material are usually used) are in the scanned area.

If the upper jaw impression is taken a long time before the CT appointment, the precise fixation of the calibration device can no longer be guaranteed because removing it once or several times reduces the adhesive force of the impression tray on the upper jaw. It is therefore advisable to scan the patient (and thus the calibration device) while it is fixed in the head holder.

The procedure is as follows:

After the spoon has been inserted into the oral cavity, it is firmly connected to the cross plate, which is still in movable contact with the elements of the head holder described above. The spoon is then carefully pressed onto the teeth or the hard palate. Then, after the operator has ensured that the spoon and thus also the calibration device are in the correct position, the head holder is fixed by locking all of the joints and by anchoring the base stand to the base plate. A positive side effect of this precise head fixation during the CT scan is the avoidance of movement artifacts that often occur.

After the CT examination, the holder is released and the impression tray
together with the calibration device.

During the subsequent surgical procedure, which can take place after a shorter or longer period of time, the impression tray is fitted in combination with the calibration device onto the upper jaw of the patient's head and fixed to it by the holder, following the procedure already described for the CT scan.
The calibration points required for CAS interventions can now be approached on the calibration device, thus allowing a correlation between the real patient's head and the virtual 3D image. It is particularly worth emphasizing the fact that the calibration points are immovably positioned in relation to the patient's head. By using the head mount in combination with the calibration device, maximum accuracy can be achieved in such stereotactic interventions.

Finally, the advantages of the device according to the invention are summarized:

- Exact fixation of the head. ■

-'· Maximum visibility and freedom of movement for the surgeon in the operating field.

- Positioning of the head in variable positions for use in various procedures.

- No invasive procedure required to fix the head.

- No skin displacement caused by the supports.

- Possibility of attaching various types of instruments, e.g. endoscope.

- Definition of exact calibration points by means of a calibration device attached above the teeth, which can be used as part of the holder.

- The holder and the conditions of fixation are adapted to the individual circumstances of the patient’s head and not the other way round (this is only possible to a limited extent or not at all with the devices described above!).

- General: Simple and time-saving handling, therefore gentle on the patient, hygienic, optimal.

* * * * * * . &diams;.
* · « * * * « «*· · &bull; * « · * · · Reference symbol 1 Base plate 2 Base plate made of metal (steel) without perforations 3 Base plate made of metal (steel) with transparent and/or radiolucent openings 4 Power transmission devices 5 Base holder designed as a magnetic holder 6 On-off switch electrical/magnetic 7 Basic staff 8th Holding rod 9 Support rod joint (swivel joint) 10 Joint screw 11 Screw lock / toggle 12 Connecting fork 13 Base holder designed as a pneumatic holder 14 On-off switch pneumatic (suction generator) 15 Basic staff 16 Holding rod 17 Support rod joint 18 Connection fork slot 19 Base holder hydraulic 20 Hydraulic locking device 21 tripod 22 Holding tube(s) 23 Ball joint 24 Swivel joint 25 Connecting fork for hydraulics 26 Swivel joint lock 27 Upper jaw transverse plate 28 Upper jaw transverse plate wing 29 Upper jaw transverse plate arch 30 Upper jaw impression tray 31 Upper jaw impression material 32 Holding device for calibration points 33 Cross spacer bar 34 Lateral distance rod 35 Spacer roller(s) 36 Screw fixation 37 Marker pens 38 marker 39 Counterfixation 40 Angle plate 41 Locking screw (toggle screw) 42 Counter pressure disc Accesories 43 Headrest ring 44 Headrest shaped

Claims (1)

Main claim Protection claim 1 Device for fixation of the human head - with a base plate (1, 2, 3) <? - with a detachable on the base plate (1, 2, 3)
attachable and freely positionable base holders (5, 13, 19) - with base rods (7, 15) fixed in the base holders (5, 13, 19) - with retaining rods (8, 16) that can be connected in an articulated manner to the base rods (7, 15) characterized in that that a detachably attached upper jaw cross plate (27) is provided at the end of the holding rods (8, 16), that a known upper jaw impression tray (29) can be attached to the upper jaw cross plate (27), which tray bears an individually taken impression of the upper jaw teeth and the hard palate. Protection claim 2 Device according to claim 1, characterized in that the upper jaw impression tray (29) can be connected to the upper jaw cross plate (27) by means of an adhesive. Protection claim 3 Device according to one of the preceding claims, characterized in that freely pivotable stands ((21) with a central locking device are provided which are connected to the base holders (5, 13, 19). Protection claim 4 Device according to one of the preceding claims, characterized in that the base plate (1, 2, 3) can be adjustably attached to an operating table. Protection claim 5 Device according to one of the preceding claims, characterized in that the base plate (1, 2, 3) is perforated in sections and/or in strips by X-ray-permeable material. Protection claim 6 Device according to one of the preceding claims, characterized in that the base plate (1, 2, 3) has markings which enable a secure repositioning of the detached base holder (5, 13, 19). Protection claim 7 Device according to one of the preceding claims, characterized in that the base holders (5, 13, 19) are designed as magnetic holders or as pneumatic holders. Protection claim 8 Device according to one of the preceding claims, characterized in that the stands (21) can be fixed and locked by means of fluid pressure. ⁷ Protection claim 9 Device according to one of the preceding claims, characterized in that base rods (7, 15) and/or holding rods (6, 16) or stands (21) are designed as carrying and receiving devices for medical devices such as endoscopic apparatus, wound hooks, hand rest surfaces. Protection claim 10 Device according to one of the preceding claims, characterized in that a counter-fixation (39) is provided, by means of which a counter-pressure can be exerted on the human head-adjustable surfaces. Protection claim 11 Device according to one of the preceding claims, characterized in that a head support ring (43) or an anatomically shaped head support (44) is provided. Protection claim 12 Device according to one of the preceding claims, characterized in that means for applying a negative pressure to the upper jaw impression tray (29) in the front region of the upper jaw are provided. Protection claim 13 Device according to one of the preceding claims, characterized in that one or more adjustable holders (33, 34, 35, 36) are provided for the positioning of calibration points, which can be attached to the upper jaw impression tray (30) and/or to the upper jaw cross plate (27).