WO2001032087A1

WO2001032087A1 - Neurosurgical endoscopic contact ultrasonic probe

Info

Publication number: WO2001032087A1
Application number: PCT/HR1999/000028
Authority: WO
Inventors: Josip Paladino; Tihomir ŠTIMAC
Original assignee: Josip Paladino; Stimac Tihomir
Priority date: 1999-11-02
Filing date: 1999-11-18
Publication date: 2001-05-10
Also published as: HRP990264A2; AU1401500A

Abstract

Neurosurgical endoscopic ultrasonic contact probe is a variation of ultrasonic knife the manufacturing of which is based on producing longitudinal vibrations of elastic titanium wire. This specific surgical instrument is in fact a dissection device that may be used for the destruction and fragmentation of tissue by beamed vibrations. It may be classified into the group of new micro-surgical instruments that satisfy the criteria of minimal invasive surgery belonging to endoscopically aided procedures. The use of this type of surgical instrument is grounded on creation of strong mechanical vibrations produced by wedged in complex piezoelectrical transducer of minimal dimensions, and that are the result of careful selection of anterior metal titanium piece in the form of mechanical transformer. The titanium wire is meant for single use in resection of tissue. The screw type connection enables its easy and rapid fastening to the probe. The instrument may be used in any rigid endoscope, not only in neurosurgical procedures (endoscopic ventriculostomy in the base of the third brain ventricle, tumour removal in inaccessible and functionally important areas, removal of intervertebral discs), but also in other surgical specialities (heart, abdominal, thoracic, ophthalmological, gynecological, etc.), at a negligible risk of damaging the surrounding neural and vascular structures, and at strictly defined size of the lesion.

Description

NEUROSURGICAL ENDOSCOPIC CONTACT ULTRASONIC PROBE

TECHNICAL FIELD OF APPLICATION

The invention is basically the ultrasonic probe-knife that in combination with cerebral endoscope may be used in performing a number of surgical procedures on the brain According to international classification of patents the instrument is classified as A61B 17/32 - surgical knives or instruments for cutting, endoscopic cutting instruments

The development of neuroendoscopic equipment has significantly contributed to the advancement in the treatment of hydrocephalus when compared with extra-cranial drainage of cerebrospinal fluid or shunt surgery Two types of drainage procedures have widely been used the ventπculo-atrial and the ventπculo-peπtoneal, conveying the CSF to the heart or to the peπtoneal cavity respectively The results of these procedures are not entirely satisfactory for reasons of many and frequently occurring post-operative complications, either of mechanical or biological etiology

The generally accepted procedure in the treatment of hydrocephalus disorders today is the endoscopic ventπculocisternostomy of the third brain ventπcle The endoscope, approximately 6 mm in diameter, is introduced first into the region of the frontal bone, and proceeded to the parietal bone and the third ventncle, the opening is then made in the bottom of the third ventricle by a monopolar electrical coagulator supervised by a 2 mm diameter video-camera Through the same endoscopic opening a special double-balloon catheter is used to widen the opening in the bottom of the third ventπcle to the needed 6 mm By opening the bottom of the third ventπcle a communication is created between the external and internal CSF space and almost physiological circulation of the fluid achieved The procedure does not treat the symptoms of the disease, as is the case in drainage operations, but it resolves the cause and results in definitive recovery of the patient

The introduction of contact wire ultrasonic probe-knife instead of monopolar electro- coagulator may be considered as significant innovation and improvement of the endoscopic ventπculocisternostomy procedure Under eye supervision (video-camera) strong longitudinal vibrations and the procedure of cavitation are used to make the opening of desired size in the bottom of the third brain ventricle

In this way the technical problem of creating an opening in the third ventπcle duπng endoscopic ventnculocisternostomy of the third brain ventπcle is solved by a specifically designed ultrasonic contact probe-knife that enables making a high precision passage by using mechanical ultrasonic power and without damaging the surrounding brain tissue

Beside in neurosurgery, as the already widely used procedure m surgical treatment of hydrocephalus conditions, the ultrasonic endoscopic contact probe-knife may successfully be used to remove tumours and cystic formations in many other surgical specialities (urology, liver surgery, heart surgery, thoracic surgery, otorhynolaπgology, orthopaedics, ophthalmology, etc )

TECHNICAL CONDITIONS

For more than 20 years the energy of ultrasound has been used in medical surgical instruments in dentistry, neurosurgery, liver surgery, ophthalmologic surgery (ultrasonic phacoemulsification of eye cataract) These instruments, commonly referred to as cavitrons, ultrasonic aspirators, ultrasonic surgical knives (dystectors), are used to operate on many types of tissues, from the soft to the calcified ones The operation of these instruments is based on the phenomenon of ultrasonic cavitation caused by strong mechanical energy occurring on top of the instrument The ultrasonic transducer-motor operating on the pπnciple of magnetostπctive or piezoelectric effects, is used as the source of concentrated mechanical energy Longitudinal vibrations occurπng on the operating surface of the transducer are transmitted by means of a mechanical transducer-sonotrode, specifically designed for each single application All these instruments are operative in the 20 to 60 kHz frequency area, which means that the tip of the sonotrode produces 20000- 60000 bites per second at acoustic intensity of several hundreds of W/cπT and dynamic pressure up to several tens of MPa When in contact with body tissues such a strong mechanical energy produces cavitation and causes fragmentation, disintegration, teaπng and cutting of the tissue, depending on the applied amount of finely tuned electπcal energy The injection of physiological irrigation solution causes the crushed tissue to emulgate and, if necessary, enables its removal by aspiration The operation of each ultrasonic surgical aspirator may be described by four groups of independent parameters:

1. Parameters describing electrical characteristics maximum applied electrical power in ultrasonic transducer input electrical impedance and admittance of ultrasonic transducer electromechanical transformation coefficient operating frequency wave forms of voltage and current regulation of output power, keeping constant power with regard to load characteristics of phase synchronised feedback generator loop and ultrasonic transducer, for the purpose of keeping the optimal operating frequency

2. Parameters describing the acoustic properties selection of ultrasonic transducer design of titan sonotrode and final shape of the probe-knife tip operating radiation surface of the probe-knife tip dynamics and maximum shift of the operating surface of the probe-knife tip emitted acoustic power, intensity, dynamic pressure, vibration speed the probe-knife tip cavitation zone

3. Parameters describing the acoustic characteristics of the medium (tissue) for which the ultrasonic aspirator is used characteristic acoustic impedance, the speed of sound spread, absorption coefficient, cavitation threshold (liver, brain, eye, teeth, coronary arteries and other blood vessels, muscle tissue, tumours, cysts, nerves, bones, bile and kidney stones, urinary stones, etc.)

4. Parameters defining utilisation characteristics conditions of dynamic adjustment (selection of static pressure, the operator¹ s applied dynamic pressure) operating life-time, hours of operation, number of surgeries, working method the problem of sonotrode overheating periodic replacement of used up segments (sonotrode, and tip of the probe-knife) dynamic stability of operation in real conditions conditions of irrigation, tissue fragmentation, suction, i.e. transport of the fragmented tissue in suspension medium (irrigation fluid) sterilisation conditions. When taking into consideration all of these parameters that define the operation mode and quality of an ultrasonic aspirator-knife of any design, and on the other hand the possibility of its use in different types of surgery (neurology, urology, gynaecology, heart and thoracic surgery, ophthalmology, orthopaedics, etc.), it becomes obvious that there are also as many different specific technical solutions.

Additional problems arise when these surgical instruments are used in traditional fashion The introduction of laparoscopic and endoscopic surgery, performed in the visual field of a miniature video-camera, has pointed the need for new solutions concerning micro-surgical instruments. Hence at the Department of Neurosurgery of Zagreb Clinical Hospital Centre the need has come up to introduce a miniature ultrasonic probe-knife into the rigid cerebral endoscope for the purpose of performing certain operative procedures which this invention is concerned with.

The relevant reference literature provides a number of documents on the basis of which it may be concluded that the current technical conditions and level of technical solutions vary greatly in this specific field of ultrasonic surgical devices. A detailed presentation of previous studies on 240 laboratory rats verifying certain initial assumptions and procedures may be found in the following paper:

Stimac D, "The effect of ultrasonic aspirator on neural tissue ", Zagreb University School of Medicine, Doctoral Degree Thesis, Zagreb, May 1999.

The paper contains most of the world reference literature (528 references!) dealing with the above stated topic published from 1920 to 1999. Furthermore, in June and July 1999 seven successful operations on human subjects have been performed by the use of the new surgical instrument at Zagreb Clinical Hospital Centre and University School of Medicine Department of Neurosurgery

The analysis of 4 groups of key words shows the list of the total of 58 innovations and technical solutions in the field of ultrasonic surgical instruments that in one or the other way are closely connected with the herewith proposed invention, and also characterise technical conditions concerning this specific field. Key words: ULTRASONIC & ASPIRATOR (1976-1999)

No Patent no Patent description

1 5.387,190 Probe break detector for an ultrasonic aspirator

2 5,221,282 Tapered tip ultrasonic aspirator

3 5.176,677 Endoscopic ultrasonic rotary electro-cauteπsing aspirator

4 D 16.448 Ultrasonic aspirator for microscopic neurosurgery

5 D313,074 Ultrasonic aspirator for microscope & neurosurgery

6 4,750,488 Vibration apparatus preferably for endoscopic ultrasonic aspirator

7 4,223.676 Ultrasonic aspirator

8 4,063,557 Ultrasonic aspirator

Key words ULTRASONIC & KNIFE (1976-1999)

No Patent no Patent descπption

1 5.702.360 Ultrasonic surgical knife

2 5,695,510 Ultrasonic knife

3 5.342,380 Ultrasonic knife

4 5,261,920 Improved ultrasonic knife

5 5.062,827 Device in ultrasonic aspirator

6 4.974.581 Ultrasonic knife

7 4.188,952 Surgical instrument for ultrasonic separation of biological tissue

8 EP 0305627 B Ultrasonic knife

9 FR 9,308,419 Ultrasonic surgical knife

Key words ULTRASONIC & NEEDLE (1976- 1999)

^•Jo Patent no Patent dcscπption Surgical instrument for crushing crystalline eye lenses by means of

1 5.879,356 ultrasound an of removing lens

2 5,743.871 Phacoemulsification handpiece sleeve and tip

3 5,741,226 Phacoemulsification handpiece sleeve and tip

4 5,725,49- Phacoemulsification handpiece sleeve and tip

5 5.653,724 Angled phacoemulsifier tip

6 5.562,610 Needle for ultrasonic surgical probe

7 5.562.609 Ultrasonic surgical probe

8 5,437,283 Endosurgical ultrasonic probe with integrated biopsy actuator

9 5,413,573 Device for surgical procedure

10 5.383.465 Ultrasonic instrument

1 1 5.209,721 Laparoscopic surgical device and related method 12 5,131,394 Ultrasonic guided needle

Key words ULTRASONIC & SURGICAL (1976-1999)

No Patent no Patent descπption

1 5,308,355 Ophthalmic surgical instruments and method

2 5,776,092 Multifunctional surgical instrument

Ultrasound and impedance feedback system for use with electrosurgical

5,773,281 instruments

Laparoscopic ultrasonic surgical instrument and methods for

5,346,502 manufacturing the instruments

5 5,897,523 Articulating ultrasonic surgical instrument

6 5,437,283 Endosurgical ultrasonic probe with integrated biopsy actuator

7 5, 180,363 Operation device

8 5,484,398 Methods of making and using ultrasonic hand-piece

9 5.421,829 Ultrasonic surgical hand-piece and an energy initiator

10 EP 456,470 Bl Surgical ultrasonic horn

1 1 EP 384,672 B l Ultrasonic surgical scalpel

12 EP 238.667 Ultrasonic instrument for surgical operations

13 5.879,363 Disposable surgical ultrasonic transducer

14 5.800,448 Ultrasonic surgical instrument

15 5.702,360 Ultrasonic surgical knife

16 5,674,235 Ultrasonic surgical cutting instrument

17 5,630,420 Ultrasonic instrument for surgical applications

18 5 562 609 Ultrasonic surgical probe

19 5 507,738 Ultrasonic vascular surgical system

20 5 254.082 Ultrasonic surgical scalpel

21 5 199,943 Ultrasonic surgical hand-piece

22 5 190.517 Electrosurgical and ultrasonic surgical system

23 5.188, 102 Surgical ultrasonic horn

24 5.058.570 Ultrasonic surgical apparatus

25 5.042 461 Horn used in an ultrasonic surgical operating instrument Method and apparatus for ultrasonic surgical fragmentation and

26 4.827,911 removal of tissue

27 4.741,731 Vented ultrasonic transducer for surgical hand-piece

28 4 587,958 Ultrasonic surgical device

29 4.188,952 Surgical instrument for ultrasonic separation of biological tissue

30 EP 591619 Al Hand-piece for surgical operation DISCLOSURE OF THE INVENTION

Primary objective of the invention is to simplify, and improve surgical procedures in the treatment of hydrocephalus and certain types of cystic and tumour diseases in hardly accessible and functionally important regions of the neural tissue

In the procedures when neuroendoscopic equipment is used instead of monopolar electrical coagulator a contact ultrasonic probe-knife that by mechanical force produces fragmentation and cutting of tissue has been applied The procedure was previously tested on 240 laboratory animals and then confirmed "in vivo" in 7 successful surgeries The authors of the invention are not yet fully acquainted with the possibility of purchasing commercial technical supplies that would enable the above described procedures to be performed routinely

Essentially the invention is based on the transformation of electrical energy by complex ultrasonic transducer-motor (Fig 1) into very strong longitudinal vibrations of elastic titanium wire 1 4 to 2 mm in diameter and 35 to 90 cm long

A complex ultrasonic transducer is composed of four piezoceramic rings (1), selected from the barium zirconate titanate base with increased Curie's temperature, that by variable electrical field over the electrodes (2) vibrate in longitudinal resonant frequency of complex transducer, together with anteπor (3) and posteπor (4) metal piece The anteπor metal piece (3) is made of titanium alloy with lower acoustic impedance characteristics than the acoustic impedance of piezoceramic rings, the posterior metal piece (4) is made of stainless steel alloy with increased specific density of the material and hence its greater acoustic impedance Two insulating ceramic rings (5) are inserted into the complex "sandwich" design of ultrasonic transducer for the purpose of separating the basic metal construction of the transducer from the electrical voltage By applying the screws (6) of increased strength the whole construction of the complex transducer piezoceramic πngs (1), electrodes (2), anterior metal piece (3), posterior metal piece (4), and insulating ceramic rings (5), is brought into the state of static mechanical pre-pressure, selected in the manner which allows for the coefficient of electromechanical transformation of the device to be optimal, I e maximal The increased and optimal electroacoustic activity of this complex construction of ultrasonic transducer - motor (Fig 1 ), has been achieved by selecting appropriate dimensions, shape, elastic properties and density of materials (1),

(3,), (4) and (5). These elements are also essential to the selection of mechanical resonant frequency of the complex piezoelectrical transducer. For its intrinsic resonant mechanical frequency the approximately 25000 Hz frequency has been selected. The intrinsic resonant mechanical frequency is also influenced by the screw (7) to which a 1.4 to 2 mm diameter titanium alloy wire is fastened. The alloy is characterised by great toughness and resistance to wearing of the material, since it may sustain great mechanical strains, it has small internal losses resulting from mechanical vibrations, and it does not produce negative effects to the surrounding tissue. In terms of impedance the ultrasonic transducer sustains the length of elastic titanium wire up to 90 cm. The selection of wire length, for maximal electroacoustic activity and transmission of mechanical energy is usually = n lamda/2, where lamda/2 represents basic half-wave length of the complex ultrasonic transducer at operating resonance frequency. The screw (7) together with the elastic titanium wire may exert influence up to 20% the resonance frequency of the complex ultrasonic transducer.

The complex ultrasonic transducer (Fig. 1), the subject of the invention, has been selected on the basis of specific simulation program, the so-called Taylor's approach that, taking into consideration about twenty of the above-described parameters and the parameters of electromechanical construction of ultrasonic transducer, enables to optimise the value of the use of this instrument in practice. The piezoceramic rings (1) are made of materials that have reduced dielectrical and mechanical losses in operating state, so that the heating of the transducer satisfying the essentially needed ergometric requirements is significantly decreased. Elastic suspension is achieved through specifically designed rubber ring (8) and two "O" rings (Fig. 2). The complex ultrasonic transducer is mounted in a special housing (10). Suspension of the transducer is carried out strictly in the zone of vibration knot, decreasing in this way heating of the transducer, minimising the transfer of ultrasonic vibrations to the operator's hands, and achieving silent and inaudible operation The complex ultrasonic transducer is tightened to its housing on the anterior side by two nuts (1 1 and 12). On the posterior side of the housing the lid (14) and the "O" ring (13) ensure complete impermeability to the ultrasonic transducer. The active part of ultrasonic transducer is connected by output switch (16) to the connector (15) on the posterior side of the transducer. Free space between the ultrasonic transducer and the body (17) is filled with sound-absorbing material. In this way transmission of vibrations to the housing is additionally reduced. The material also ensures firm positioning of silicone outputs (16) so that their shifting is prevented and insulating resistance decreased. The design of ultrasonic probe-knife provides for complete impermeability, which makes it impossible for decrease of electrical resistance or the breakthrough of high voltage to occur during operation. The selection of appropriate materials enables sterilisation procedure at T=135°C. The ultrasonic probe-knife is designed in the manner that it can be opened only by force, the result of which is its complete and irreparable destruction. By precise asymmetric positioning of piezoceramic part of the ultrasonic transducer a high degree of electromechanical utilisation is achieved (=0 7), parasitic oscillations eliminated and useful longitudinal vibrations on tip of the titanium wire significantly increased, where for reasons or ultrasonic vibrations cavitation and the resulting fragmentation of tissue occur

FIGURES

Basic characteristic of the invention are presented in the following figures

Figure 1 Technical solution of the complex ultrasonic transducer

Figure 2 Elastic suspension of the complex ultrasonic transducer into the probe housing

DETAILS OF MATERIALISATION OF THE INVENTION

On the basis of figs. 1 and 2 it may be seen what type of problems occurred during technical manufacturing of the invention. Basically, the problems are of two kinds. It is indispensable to produce high quality technical device from the material point of view, and to possess highly sophisticated knowledge in neurosurgery in order for the surgical procedure to be successfully performed

When selecting piezoceramic rings (1) account must be taken of a well-balanced selection of electrical ε^^τ , tgδ), piezoelectrical ψn. ^^ _p) and elastic (N,, N_it, p, Q_M) dimensions. To satisfy the quality needs with regard to manufacturing of complex piezoelectrical transducer and to achieve satisfactory coefficient of electromechanical activity, the uneven areas in flat surfaces of piezoceramic rings must be better than ± 2 μm. For this reason the piezoceramic rings have to be used that are polarised without putting the electrodes on. The fitting between the metal pieces surfaces (3 and 4) and the electrodes should be plane-parallel also not less than ± 2 μm. In order for sterilisation to be performed at T"=135°C, it is desirable that the Curie temperature (Tc) of piezoceramic rings be as high as possible.

The mechanical resonance frequency of the complex piezoelectrical transducer (about 25000 Hz) is determined on the basis of elastic properties of the materials in positions (1), (2), (3), (4), (5), (6), (7). By a moment key the pre-straining of the screw (6) is made and in this way the most appropriate factor of electromechanical scheme of the complex ultrasonic transducer achieved. This is also the way in which the best coefficient of electroacoustic utilisation of the complex ultrasonic transducer is obtained.

The construction and selection of operating characteristics of complex ultrasonic transducer are grounds upon which the operation of neurosurgical endoscopic ultrasonic contact probe is based. Just prior to the operation, the previously prepared sterilised titanium needle-knife is mounted by the screw (7) upon the above-described complex structure; the titanium needle-knife is of varying diameters (1.4 - 2 mm) and lengths (35 - 90 cm); it is introduced into the canal of a rigid endoscope and by the help of a video camera the needed surgical procedure is carried out. Technical achievement of this invention was materialised through the prototype of the instrument used in experimental testing on laboratory animals (the total of 240 animals) and later on in 7 "in vivo" successfully performed surgeries on human subjects. It is clear that professional approach and competent skill of a surgeon are essential to successful application of the invention.

MODE OF APPLICATION

The above described invention is a new useful technical solution that may be used in neurosurgery and other allied surgical specialities. The technology of its design is relatively simple and does not require any substantial resources, but rather a high degree of professional competence and knowledge. The authors of the invention possess complete manufacturing and technical documentation, specification of material and manufacturing procedure and technical conditions, final testing and quality verification. The complete device can economically be manufactured in the Republic of Croatia.

Claims

1. Neurosurgical endoscopic ultrasonic contact probe is a specific micro-surgical instrument - knife, that by the use of ultrasonic longitudinal vibrations enables vibration of titanium wire ensuring in this way cutting of tissue; it is characterised by being composed of complex ultrasonic transducer, operating instrument - an elastic titanium wire of a given diameter and length, and specifically designed housing of the probe.

2 Neurosurgical endoscopic ultrasonic contact probe according to Claim 1 is characterised by the fact that ultrasonic mechanical energy is beamed on the top of the anterior mechanical piece (3) into the complex transducer across the posterior metal piece (4) by transforming electrical energy into the mechanical one through piezoceramic rings (1), electrodes (2) and insulating ceramic rings (5) wedged in by a screw (6)

3 Neurosurgical endoscopic ultrasonic contact probe according to Claims 1 and 2 is characterised by the fact that the complex piezoelectrical transducer is centred and mechanically isolated by a rubber ring (8) and by "O" rings (9) in the metal housing ( 10) by nuts (1 1) and (12).

4 Neurosurgical endoscopic ultrasonic contact probe according to Claim 3 is characterised by the fact that the charging of piezoelectrical rings is ensured through electrical output switch (16) and coupled to electrical source by connector (15)

5 Neurosurgical endoscopic ultrasonic contact probe according to Claim 4 is characterised by the fact that the space (17) is suspended in sound-absorbing mass, that by "O" rings (13) ensures impermeability of the entire construction through the posterior lid (14)

6 Neurosurgical endoscopic ultrasonic contact probe according to Claims 1, 2, 3, 4, and 5 is characterised by the fact that the operating part of the probe-knife ends in the elastic titanium wire of a given diameter and length that together with a specifically designed nut (7) function as a whole