RU2452392C1 - Method of dynamic multi-spiral computed tomographic diagnostics of otosclerosis after treatment in patients after stapedoplasty - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medicine, namely to radiodiagnostics and otolaryngology, and can be used for post-operative diagnostics of patients with otosclerosis. Performed is multi-spiral computed tomography with three-dimensional dynamic scanning with section thickness 0.5 mm and interval 0.25 mm in axial projection. Simultaneously performed is impact with probing audio signal, exceeding perception threshold by 15-20 dB, and with test frequency 1000 Hz on middle ear structures with 1 second interval for 4-5 seconds. Multiplanar and three-dimensional reconstructions are built. If it is determined that volume of movements of stirrup prosthesis is reduced in comparison with norm or volume of movements of stirrup prosthesis is absent, otoscxlerosis is diagnosed.

EFFECT: method makes it possible to increase accuracy of diagnostics of otosclerosis in patients after stapedoplasty and determine indications for reoperation.

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Description

The invention relates to medicine, in particular to otorhinolaryngology and radiation diagnostics, and can be used for postoperative diagnosis of patients with otosclerosis, namely, to determine the cause of insufficient functional result of the operation.

Otosclerosis is a disease that affects the bone capsule of the labyrinth. Progressive conductive hearing loss, characteristic of otosclerosis, develops as a result of the formation of an otosclerotic lesion in the oval window, which gradually reduces the mobility of the foot plate of the stapes and eventually immobilizes it (Plester D., Hildmann H., Steinbach E. Atlas der ohrchirurgie - Stuttgart: Kohlhammer, 1989 . - 174 s.).

At the present stage of development of otosurgery, stapedoplasty is an effective method for hearing correction with persistent stapes fixation caused by otosclerosis and adhesive nonperforative otitis media (Gadyan A.T. Application of Er: YAG laser in stapedoplasty in patients with otosclerosis and adhesive average otitis media: Abstract. Medical Sciences. - St. Petersburg, 2009. - 18 p.). Stapedoplasty has been performed for over 50 years, and during this time the basics of the operation have not changed. The main result satisfies more than two-thirds of patients. Gradual deterioration in sound conduction was detected in 5-10% of patients (Plester D., Hildmann H., Steinbach E. Atlas der ohrchirurgie - Stuttgart: Kohlhammer, 1989. - 174 s.).

The following symptoms indicate the inefficiency of the operation:

1. A sharp or gradual conductive or sensorineural hearing loss.

2. Permanent or temporary dizziness.

3. A sharp loud noise in the ear.

The presence of one or more of the above symptoms indicates that newly acquired sound conduction is no longer sufficient. However, symptoms do not determine the cause of the disorder.

Currently, most otosurgeons use audiometry data to evaluate the results of surgery on the stapes. Audiometry is a study necessary to determine the degree of hearing loss. The result of auditory tests is a graph (audiogram) that reflects the nature and degree of hearing impairment in humans. With audiometry, the values of the bone-air interval (CVI) remaining after the operation are determined. This assessment method makes it possible to obtain certain ideas about the successful implementation of the “cochlear reserve” or vice versa (Kosyakov S.Ya., Pakhilina E.V., Fedoseev V.I. Stapedoplasty: one technology, two types of prosthesis // Bulletin of Otorhinolaryngology. - 2008 . - No. 1. - S.42-46). However, it is not possible to visualize the sound-conducting structures of the middle ear during audiometry.

Classical computed tomography (Zonneveld F.W. Computed tomography of the temporal bone and orbit. - Munich - Wiev - Baltimor: Urban and Schwarzenberg, 1987. - P.183) is widely used to visualize the structures of the temporal bone. This diagnostic method allows you to obtain information about the condition of the ligamentous apparatus of the tympanic cavity, allows you to evaluate the density characteristics of the auditory ossicles. However, this diagnostic method has significant drawbacks: due to the thickness of the slice, additional thin strands (less than 1 mm) are not visible, the base of the stapes, the prosthesis, are not always clearly defined.

The prototype of the present invention can be considered classical computed tomography of the temporal bone (Joel D. Swartz, Laurie A. Loevner Imaging of the temporal bone. - Stuttgart: Thieme, 2002. - 1-25 p.). Studies are carried out according to the program of bone reconstruction in a spiral mode with a slice thickness of 0.6 mm, a voltage of 120 kV, a current strength of 300 mA.

The first series of sections is carried out in the axial plane, reconstruction - in the coronary projection.

However, this diagnostic method has significant drawbacks: it is not possible to assess the movement of the auditory ossicle chain, the stapes prosthesis in the oval window, which, in turn, does not accurately diagnose the cause of the insufficient functional result of stapedoplasty.

At present, it is possible to identify the cause of the inefficiency of stapedoplasty only by performing an audit operation.

The objective of the invention is to improve the accuracy of diagnosis of otosclerosis after stapedoplasty.

This problem is solved by the method consisting in the fact that they carry out multispiral computed tomography with volume dynamic scanning with a slice thickness of 0.5 mm and an interval of 0.25 mm in axial projection, while simultaneously acting with a sounding sound signal exceeding the perception threshold by 15-20 dB and with a test frequency of 1000 Hz, on the structures of the middle ear, on the previously installed prosthetic stapes with an interval of 1 second for 4-5 seconds, build multi-planar and three-dimensional reconstructions and when determining the reduction in range of motion otosclerosis is diagnosed with a stapes prosthesis compared with the norm or the absence of range of motion of the stapes prosthesis.

In practice, the diagnostic method is as follows:

1. The patient’s head is located in a standard head stand, fixed to prevent a change in position.

2. A system is inserted into the external auditory meatus that delivers sound vibrations of a given frequency and intensity to the structures of the middle ear. The basis of the sound delivery system that we created is an impedance audiometer (Impedance Audiometer AT235h, Interacoustics, Denmark) with an integrated audiometry unit. Two air telephones are connected to the connector of the audiometer of the specified apparatus in a modification of the in-channel sound conduction with silicone tubes attached to them for conducting sound. The tubes, in turn, are connected to disposable earbuds that fit tightly into the ear canal of the test ear. For the purity of the test and the elimination of sound loss, the absolute tightness of the system is required. In cases of the patient having hypertrichosis, excess hair growing in the external auditory meatus must be removed in advance, because they can create an air gap between the earmold and the skin.

3. To mark the study area perform a tomogram. Tomography begins from the lower edge of the mastoid process and ends at the level of the upper edge of the mastoid process.

4. Tomography is carried out according to the protocol:

MSCT protocol of the temporal bone.

Tomography mode surround dynamic Cut thickness 0.5 mm Gantry Tilt 0 Field of study about 4 cm Voltage 80 kV Amperage 300 mA Type of reconstruction bone

1. After performing tomograms, the first series of sections is carried out in axial projection. Scanning progression from the temporal bone to the cranial vault. At the same time, in the manual mode of audiometry for 4-5 seconds, a probing sound signal is intermittently supplied to the test ear with a test frequency of 1000 Hz and an intensity exceeding the perception threshold by 15-20 dB (i.e., sound is transmitted for the first second, to the second second - not served, etc.). The sound intensity is selected on the basis of a previously made audiogram or on the basis of a test audiogram conducted immediately before MSCT examination.

5. Then, the investigated temporal bone is reconstructed with a 0.5 mm enlargement and reconstruction.

6. After obtaining sections in the axial projection, multiplanar reconstruction (MPR) in the coronary projection is performed.

7. Determine the location and fixation of the loop of the prosthetic stapes prosthesis, evaluate the location of the distal end of the prosthesis, measure the distance from the distal end of the prosthesis to the lower surface of the stapes base plate at the moment of maximum amplitude, evaluate the vestibule window.

8. For the second (other side) of the temporal bone, a similar study is carried out, starting from 2 points.

Fifteen patients after stapedoplasty were examined on a Toshiba Aquilion ONE 320-spiral computer tomograph, the proposed method.

EXAMPLE 1. Patient K., 58 years old. A directing diagnosis is otosclerosis, a condition after stapedoplasty on the left (2009). The patient underwent dynamic multispiral computed tomography of the right temporal bone. The study was performed on a Toshiba 320-spiral Aquilion ONE computed tomograph with volume dynamic scanning with a slice thickness of 0.5 mm. The patient's head was located in a standard head stand, fixed to prevent a change in position. A one-time earmold is inserted into the external auditory canal, connected to an air telephone (in the modification of in-channel sound conduction), which in turn is connected to the audiometry connector of an impedance audiometer (Impedance Audiometer AT235h, Interacoustics, Denmark). There is no sound yet. To mark the study area, a topogram was performed. Tomography was performed from the lower edge of the mastoid process and finished at the level of the upper edge of the mastoid process, the field of study was about 4 cm, the voltage was 80 kV, the current strength was 300 mA, the type of reconstruction was bone. After completing the topogram, the first series of sections in axial projection was performed. Scanning progression from the temporal bone to the cranial vault. At the same time, for 4-5 seconds, they used a sounding signal of 55dB (35dB + 20dB) and with a test frequency of 1000 Hz using an impedance audiometer on the structures of the middle ear, including the previously installed stapes prosthesis with an interval of 1 second (t. e. for the first second, sound is given, for the second second - is not made, etc.). Then, a reconstruction of the right temporal bone was performed with an increase and reconstruction of a 0.5 mm section. After obtaining sections in the axial projection, a multiplanar reconstruction (MPR) was performed in the coronary projection. On the tomograms, a densification and thickening of the base of the stapes was noted. A functional test noted a decrease in the range of motion of the base of the stapes, the range of motion of the hammer-anvil and anvil-stirrup joints was saved. The location and fixation of the stapes prosthesis loop are correct, the distal end of the prosthesis is located in the foot plate, the distance from the distal end of the prosthesis to the lower surface of the stapes base plate at the moment of maximum amplitude was less than 1 mm, a narrowing of the vestibule window width was noted. Based on the data of dynamic MSCT, otosclerosis was diagnosed, it was determined that the prosthetic stapes on the left is located correctly, is mobile. Subsequently, the patient underwent stapedoplasty on the left, which confirmed the accuracy of the dynamic MSCT data.

EXAMPLE 2. Patient V., 43 years old. A directing diagnosis is otosclerosis, a condition after stapedoplasty on the right (2005). The patient was admitted in connection with a relapse in hearing loss in the operated ear. The patient underwent a similar dynamic multispiral computed tomography of the right temporal bone. On the tomograms received: the prosthesis "K-Piston-Titanum" is installed, the loop of the prosthesis is located correctly, tightened. The distal part of the prosthesis is located in the niche of the oval window on the basis of the stapes, does not go beyond it during functional testing. The remaining structures without visible pathological changes. Based on the data of dynamic MSCT, otosclerosis was diagnosed, it was determined that the prosthetic stapes on the right is located incorrectly due to the insufficient length of the prosthesis. Subsequently, the patient underwent revised stapedoplasty on the right, which confirmed the accuracy of the dynamic MSCT data.

The developed method for diagnosing otosclerosis in patients undergoing stapedoplasty improves the diagnostic accuracy of this disease. The developed method has the following advantages:

1. Allows you to determine the location of the loop of the prosthetic stapes prosthesis on the long process of the anvil, the distal part of the prosthesis relative to the edges of the niche of the oval window, which allows you to determine whether the prosthesis is correctly located.

2. Allows you to determine the amplitude of movement of the distal part of the prosthesis in anticipation and thus makes it possible to evaluate the operation of the sound-conducting system.

Thus, the developed method for diagnosing otosclerosis after ineffective surgical treatment allows us to determine the condition, mobility of the auditory ossicle chain, stapes prosthesis and at the preoperative stage to identify the reasons for the insufficient functional result after stapedoplasty, which will significantly help to determine further therapeutic tactics and determine the indications for surgery.

Claims (1)

A method for the dynamic multispiral computed tomography diagnosis of otosclerosis in patients undergoing stapedoplasty, which consists in performing multispiral computed tomography with volumetric dynamic scanning with a slice thickness of 0.5 mm and an interval of 0.25 mm in axial projection, while simultaneously acting with a sounding sound signal, exceeding the perception threshold by 15-20 dB and with a test frequency of 1000 Hz, on the structures of the middle ear, on the previously installed stapes prosthesis with an interval of 1 s for 4-5 s, build m ltiplanarnye and three-dimensional reconstruction and in determining the volume reduction prosthesis movements stirrup compared with a norm or absence of movements of the prosthesis volume stirrup diagnosed otosclerosis.