Keywords

Cerebral palsy, hearing impairment, otoacoustic emission, brainstem auditory evoked

Introduction

Cerebral palsy is a complex disease of the central nervous system, affecting not only body movement and muscle coordination, but leading also to complications such as hearing impairment, which in turn affects the delay in speech and mental development [1-7]. In children with cerebral palsy, due to the delay of brain development or its pathology of development, there may be a later formation of speech function, these children understand the speech addressed to them, but their own speech is formed at a later date [3]. At the same time in pathogenesis of speech pathology the leading disorder can be damage of auditory analyzer, and disorder of hearing-motor conditional connections leads to insufficiency of motor component of speech in children with cerebral palsy, which further forms delay and underdevelopment of phonematic hearing [8-10]. According to various sources, cerebral palsy develops in 2-3.6 cases per 1000 live births and is the main cause of childhood neurological disability in the world. The prevalence of cerebral palsy in Uzbekistan is 3.7 cases per 1000 newborns (Mutalova Z.D. The structure of diseases of children with disabilities in Uzbekistan under 16 years old (2012-2014) Institute of Health and Medical Statistics). Among premature babies, the incidence of cerebral palsy is 1%. In newborns with a body weight of less than 1500 g, the prevalence of cerebral palsy increases to 5-15%, and with extremely low body weight - up to 25-30% [11-14]. Thus, the leading and main ones in cerebral palsy are motor disorders, in case of change of muscle tone, coordination disorders, presence of pathological synsikinesis and senergia, involuntary movements, as well as disorders of pose. Motor disorders have an adverse effect on the formation of mental, speech and auditory functions (Alieva Z.S., 2001,2005) [15]. A frequent disorder in children with infantile cerebral palsy is speech disorder, the frequency of which according to some authors is between 65 and 85%. Speech disorders can be associated with both deep mental retardation and the deafness bordering deafness. Often these speech disorders are combined [15-18]. In addition to damage to certain brain systems, secondary underdevelopment or later formation of those parts of the cerebral cortex that are extremely important for speech function and most strongly develop already in postnatal ontogenesis (premotor-frontal, dark-temporal regions of the cerebral cortex) plays an essential role in the genesis of speech disorders in these children (Klossovsky B.N., 1949; Megun G., 1960, Anokhin ILK., 1961) [19]. Since speech is a complex multi-level functional system, correction of speech disorders in children with cerebral palsy is important, along with the study of auditory function. Due to the fact that speech impairment may be due to hearing loss [19-25].

Four main forms of cerebral palsy are distinguished depending on muscle tone disorders

• spastic

• ataxic

• dyskinetic (subdivided into athetoid and dystonic forms)

• Mixed forms of cerebral palsy.

Cerebral palsy is also classified regarding the affected parts of the body

• Hemiplegia (damage to one half of the body - right or left),

• Diplegia (paralysis that affects both halves of the body, but more of the legs),

• Tetraplegia (damage to the arms and legs).

According to (Semenova K.A., Makhmudova N.A.1979) hearing impairment is noted in 10-40% of children with cerebral palsy, more often with a hyperkinetic form. When a diagnosis is correct and made in a timely manner, it gives an opportunity, as early as possible, to begin correction of auditory disorders and integration of the child into the speech environment, thus improving the quality of life of the baby [26-29].

Methods

The subject group consisted of 75 children, 40 (53%) males and 35 (47%) were females, ranging from 3 to 14 years of age. Clinical examination of children began with a thorough history of the child, starting from the moment of birth to the present period. The largest number of children 48, which amounted to 64% (Table 1), was with frequent forms of cerebral palsy (spastic diplegia). A significant part of the children’s history had a combination of several risk factors that inevitably entail the addition of other factors and thereby sharply increase the likelihood of hearing loss. Such a factor, for example, is birth weight less than 1500 g, which entails hypoxia, the need for prolonged mechanical ventilation and the use of ototoxic drugs. Thus, it was found that most of the examined children 53 (70.7%) were born prematurely (from 24 to 36 weeks of gestation), 48 (64%) of children with low body weight. At 64.5% (31 people) had burdened obstetric history: a history of abortion had a 15 (31%) women, the share of abortions and dead born had by 10.4% and 12.5%, respectively. Analysis and statistical processing of 23 (48%) labor histories of pregnant women with various gestoses. The examination of children was carried out by the following methods: clinical examination of patients (general and otorhinolaryngological) and functional research methods of the auditory analyzer. All children underwent acoustic impedancemetry, including tympanometry with determination of the type of tympanogram and acoustic reflex. When registering tympanograms, 48 % of children received type “A”, 31% - type “B” and 21% - type “C”. In order to differential diagnosis of conductive and sensorineural hearing loss, as well as to study the correlation of data obtained during acoustic impedancemetry depending on the condition of the middle ear, children were recorded caused by otoacoustic emission at the frequency of the distortion product. The stimulus intensity was used in the range from 50 to 70 dB, while the level of two tones was the same or varied by 5-10 dB. Based on measurements of the DPOAE amplitude obtained by presenting tones of different frequencies, a DP gram was automatically constructed a graph of the dependence of the DPOAE amplitude on the tone frequency. For each point of the curve, the background noise level was also calculated. The amplitude of DPOAE exceeded the noise level by at least 3 dB. One of the main objectives of this study was the differential diagnosis of auditory analyser disorders. Currently, the use of acoustic auditory evoked potentials is of great importance to clarify the extent and location of lesions of the auditory analyser. For this purpose, children underwent an electrophysiological study of hearing using the method of recording short latency brainstem auditory evoked potentials - an assessment of the state of the stem structures of the auditory analyzer. When registering the BAEP, broadband clicks, tonal pulses with a rise frequency and a duration of 2 ms were used as sound stimuli; with a presentation frequency of 11/sec, 2,000 responses accumulated, analysis time - 20 ms; bandwidth - 30-1500 (12 dB per octave).

Table 1: The distribution of the examined children in the form of cerebral palsy

Results and Discussion

The data obtained revealed a bilateral lesion of the peripheral part of the auditory analyzer. Beilateral sensorineural hearing loss was detected in 21 - I - II degree, in 12 - III degree and in 15 - IV degree. Marked changes in the main parameters of BAEP were detected in the study of the stem structures of the auditory analyzer in children with cerebral palsy. Thus, disorganization, configuration disturbances of the component composition (I, III, V) were noted. The smoothness of the components was noted due to a decrease in the amplitude of the response by 2-2.5 times. The analysis of time parameters showed that, with a similar dependence of latency on changes in the intensity of the stimulus in children with cerebral palsy, in contrast to the norm, the time parameters of the main components of the BAEP (I, II, V) are significantly delayed: I - by 0.1±0, 6; III - by 0.2±0.06 and by V - by 0.37±0.07 ms. Peak intervals of the main components I - III; I - V; III - V are increased in comparison with the norm in the whole range of reactivity of BAEP. Studies have shown that the most pronounced peak-to-peak I - V intervals are increased by 0.18 ms compared to normal. In children with cerebral palsy with deep hearing impairment, a narrow dynamic range is observed, on average not exceeding 40-45 ms. An L - shaped dependence of latency on the increase in stimulus intensity was revealed; a significantly higher percentage of impaired volume function is noted. Thus, the study allowed us to identifyimpaired auditory function in the sound-absorbing type in children with cerebral palsy. Assessment of auditory function allowed the results of a comprehensive, objective examination to determine the level of damage to the auditory analyzer and the localization of the process, as well as conduct electro-acoustic rehabilitation of this category of children. As you know, the leading and main in cerebral palsy are motor disorders that have an adverse effect on the formation of mental, speech and auditory functions [26]. A frequent violation in children with cerebral palsy is speech disorder, the frequency of which, according to some authors, ranges from 65 to 85%, while others from 70 to 80% of children. Speech disorder may be delayed speech development (late formation of the motor component of speech, especially its sound-producing side), dysarthria (pseudobulbar, extrapyramidal, cerebellar, cortical). Speech disorders can be associated with both deep mental retardation and hearing loss bordering deafness. Often, these speech disorders are combined. The study of the stem structures of the auditory analyzer in children with cerebral palsy, having normal thresholds of auditory sensitivity, revealed

Pronounced changes in the main parameters of the BAEP: disorganization, disturbances in the configuration of the component composition (I, II, V) were noted; smoothing of components was noted due to a decrease in the amplitude of the response by a factor of 2-2.5. Analysis of time parameters showed that, with a similar dependence of latency on changes in stimulus intensity in children with cerebral palsy, in contrast to the norm, the time parameters of the main components of short avoked breain (I, II, V) significantly tightened: I - by 0.1±0.7; III - by 0.1 8±0.05 and by V - by 0.39±0.08 ms. Peak intervals of the main components I - III; I - V; III - V are increased in comparison with the norm in the whole range of reactivity of SVP. Studies have shown that the most pronounced peak-to-peak I - V intervals are increased by 0.18 ms compared to normal. In children with cerebral palsy with deep hearing impairment, a narrow dynamic range is observed, on average not exceeding 40-45 ms. An L - shaped dependence of latency on the increase in stimulus intensity was revealed, a significantly higher percentage of impaired volume function (FCFN) was noted. In a comparative aspect, the signal response in children with cerebral palsy was less mature. The amplitudes of the waves of auditory evoked potentials, as a rule, were smaller in comparison with normal values. In contrast, the peak-to-peak intervals in most cases corresponded to normal values. Table 2 presents the values of BAEP depending on the etiological factor of cerebral palsy