EFFECT OF MENTAL RETARDATION AND MOTOR DISABILITY ON TESTING WITH VISUAL ACUITY CARDS

The visual acuity of 77 children (aged between 1 1/2 and eight years) with cerebral palsy and mental retardation was tested using acuity cards. Results varied by no more than one octave in 79 per cent of the cases. The median acuity of children with severe motor disabilities was lower and the variability from test to test was greater than for those with mild motor disabilities. Grouping the children roughly according to degree of mental retardation, the more retarded group tended to be more visually disabled and vary more from test to test. In general, day-to-day variability was greater than within-day inter-observer variability. The use of acuity cards to evaluate visual acuity in severely disabled and mentally retarded children, whose acuity is difficult to evaluate with conventional acuity tests, is a useful alternative method.     

Effects of neonatal hypoxic-ischemic brain injury on skilled motor tasks and brainstem function in adult rats

In an attempt to establish more sensitive long-term neurofunctional measurements for neonatal hypoxic-ischemic brain injury, we examined skilled motor task and brainstem functions in adult rats after neonatal cerebral hypoxia-ischemia (H-I), using a staircase test and auditory brainstem response (ABR), respectively. Seven-day-old rats underwent a combination of left common carotid artery ligation and exposure to 8% O(2) for 1 h (n=16). The control animals only received sham operation (n=16). At 3 months of age, the staircase test and ABR were performed. In the staircase test, H-I animals showed marked impairment of skilled forelimb use in the side contralateral to the occluded artery, and the degree of brain damage correlated significantly to skilled forelimb use. In the ABR, H-I animals showed brainstem dysfunction assessed by measuring interpeak latencies for waves III-V and I-V. We also examined the brainstem with antibodies specific for activated caspase-3, a protein involved in initiation of apoptosis, and observed that caspase-3 was activated in the ipsilateral inferior colliculus at 24 h after H-I. The present study shows that both the staircase test and ABR are sensitive and objective long-term neurofunctional measurements that can be used in future studies to assess therapeutic intervention in this neonatal cerebral H-I model.     

Severely retarded children in a defined area of Japan--prevalence rate, associated disabilities and causes

We studied all severely retarded children in a defined area of Japan. The area is a small and rural prefecture with the total population of 880,000. The population of children aged 6-14 years was 102,000. The number of severely retarded children (those who neither walk nor have IQs over 35) was 50. The prevalence rate was 0.49/1,000 and its 95% confidence interval was 0.36-0.65. The rate was significantly lower than that has been reported 20 years ago from another prefecture in Japan. Among the cases, children with very severe retardation (those who are bedridden with their IQs less than 20) accounted for 66% and children who were institutionalized for permanent care accounted for 46%. Association of several disabilities was as follows: cerebral palsy 62%, epilepsy 82%, decreased visual acuity 42%, respiratory distress 16%, and feeding difficulty 32%. The causes of prenatal origin accounted for about two-thirds of the total causes. We concluded that the prevalence rate of severely retarded children is becoming lower in Japan and that the prenatal factors play an important role in the pathogenesis of severe retardation.     

Auditory brainstem response and extratympanic recorded electrocochleography in patients with multiple and severe handicaps

Nine patients ranged between 5 months and 35 years (means 14 years) of age with multiple and severe disabilities were comparatively studied, on extra-tympanic recorded compound action potential (AP) of electrocochleography and auditory brainstem response (ABR). Both ABR and AP were obvious in 3 patients with clear auditory behavioral responses. The ABR was not recorded to high intensity click stimuli in six patients without visible auditory behavioral responses. Four of the 6 cases showed undetectable AP and the 2 rest of the 6 cases showed abnormal but discernible AP. In two cases with history of the anoxic encephalopathy, AP was recorded but ABR was not detected in one case, and in the other, neither AP nor ABR was recorded. At least two different levels of lesions could be differentiated in cases without detectable ABR by using extra-tympanic recorded electrocochleography in these kinds of severely handicapped patients.     

Prevalence rate of severely retarded children in Tokyo

Prevalence rate of severely retarded children aged 6-14 years was studied in Tokyo. The definition of severely retarded children was those who neither walk nor have their IQs over 35. We visited total of 60 institutions and schools for retarded children in and around Tokyo. Because of the school system in Tokyo that enrolls all children regardless of their disabilities, case finding was exhaustive. The number of severely retarded identified was 830. The prevalence rate was 0.68/1,000 on April 1, 1988. We conclude that the prevalence rate of severe retardation is modestly lower than the rates previously reported from other areas of Japan.     

Prevalence rate of severely mentally and physically handicapped children in school age in Yokohama]

Prevalence rate and pattern of disabilities were studied in severely mentally and physically handicapped children in school age in Yokohama. We visited institutions and schools for retarded children in Yokohama and its neighborhood or made contact with them by telephone. The study disclosed a total of 192 children on May 1, 1988. Prevalence rate was 0.51 per 1,000. Patterns of disabilities were: 1) most of the children (94.8%) lived with their families. 2) eighty-eight percent of the children attended school for retarded children. 3) about twenty percent of the children who attended school needed tube feeding.     

Mortality patterns of non-institutionalized severely retarded children in Tokyo--the third report 1999-2001

We investigated mortality patterns of severely retarded children who were cared at their homes in Tokyo ten years after our first report. During the past two and a half years (from April 1999 to September 2001), we identified 41 fatal cases. The annual case fatality rate (the mortality rate among the investigated children) was 8.2@1000 in all the school-attending children and was 10.1@1000 in children with severe motor and intellectual disabilities. The rate was less than half of that in our past report and seemed to the lowest among those in several studies. Aggravation of basal disorders, severe respiratory infections and/or sepsis, and unexplained sudden death accounted for most of the death. We conclude that advance of medical service and the propagated medical education of teachers working for special schools play an important role to reduce the mortality in severely retarded children.     

Auditory brain-stem responses in hydrocephalic patients

Auditory brain-stem response (ABR) was measured in 40 patients (80 ears) with confirmed hydrocephalus. Eighty-eight percent of these patients showed some form of ABR abnormality. Responses indicative of brain-stem dysfunction consisted of prolonged I-V interwave latency (38%), reduced V/I amplitude ratio (33%), and abnormalities in wave-shape of components III (27%) and V (53%). In addition, 70% of the patients had elevated ABR thresholds; 45% had responses in excess of 20 dB HL and the remaining 25% had no ABR activity. The etiology of the hydrocephalus, head circumference and brain-stem symptoms were not associated with particular ABR abnormalities. Communicating hydrocephalus correlated significantly with both prolonged I-V conduction time and absence of ABR activity, compared with non-communicating hydrocephalus. Four of the 9 patients retested showed ABR improvement on follow-up; one patient showed deterioration. The results were compared to our prior studies of ABR in 60 post-meningitic patients and in 100 severely neurologically impaired institutionalized children in whom the incidence of intrinsic brainstem abnormalities was one-third and two-thirds that of the hydrocephalic group, respectively. The results of this study suggest that ABR can be used to document clinically unsuspected brain-stem pathology that may accompany hydrocephalus. Auditory brain-stem dysfunction is likely to complicate the assessment of hearing sensitivity in hydrocephalic patients.     

A comparison of the three-dimensional auditory brainstem response and the conventional auditory brainstem response in children

For measurement of neural activity in the brainstem auditory pathway, the conventional two-dimensional (2D) auditory brainstem response (ABR) does not provide a true response, because the equivalent dipoles originate from the stereoregularity pathway. It is thus necessary to use three-dimensional (3D) ABR to estimate the true response of the brainstem. We recorded 3D ABR in a group of children and adults, and compared the results with those of the conventional 2D ABR.

The subjects were 22 children (age range 3–10 years) and 10 adults with no neurological disorders, and three patients: a boy and a girl who had experienced sudden brainstem dysfunction, and a girl who had sudden deafness. 3D ABR was recorded for all subjects, and the results were displayed on a computer screen for off-line analysis using an original 3D ABR analysis program.

Four leaf-like vector segments of 3D ABR existed during the first 8 ms after stimulation. Each vector segment corresponded to a peak of the conventional ABR, and showed the original directivity. The amplitudes of waves II and IV of the 3D ABR were significantly larger than those of the conventional ABR. 3D ABR was shown to be superior to the conventional ABR in obtaining absolute amplitude. We were able to clarify the development of brainstem function using 3D ABR. In one patient in whom only one wave was obtained, 3D ABR was able to identify the wave as wave V. These results indicate that ABR is useful both for identifying the kind of wave produced and for suggesting the wave origin.     

Neurological and pathophysiological analyses of patients with absent auditory brainstem evoked response

Seventeen patients with no auditory brainstem evoked response (ABR) who suffered from various neurological disorders were reported. We evaluated the possibilities of co-existent brainstem lesions in addition to the peripheral impairment in the auditory pathway, by assessing neurological findings and other laboratory examinations, including cranial CT and electrically elicited blink reflex. Patients who showed cranial nerve symptoms other than that of the acoustic nerve or abnormal postural reflexes were suspected to have brainstem dysfunction. It was difficult, however, to exclude the influence from the dysfunction in the more central level CNS. Definite brainstem atrophy was revealed radiologically only in one case who was at the end stage of the degenerative disease. Blink reflex was studied in eleven cases, four of whom revealed abnormal responses, also suggesting brainstem dysfunction. All the five cases, consistent with these abnormal laboratory findings, had shown severe delay in motor development. Other five patients who showed rather good auditory behavior were considered to have 'desynchronization' response to ABR in the auditory pathway at the peripheral level. Many pathophysiological conditions may be involved in the phenomenon of absent ABR, which should be carefully evaluated from the viewpoints of clinical neurology.     

Quantitative evaluation of ventricular dilatation using computed tomography in infants with congenital cytomegalovirus infection

Background

Infants with congenital cytomegalovirus infection (CCMVI) may develop brain abnormalities such as ventricular dilatation, which may potentially associate with sensorineural hearing loss. There is currently no recognized method for quantitative evaluation of ventricle size in infants with CCMVI. Our objectives were to establish a method for quantitative evaluation of ventricle size using computed tomography (CT) in infants with CCMVI, and determine a cut-off value associated with abnormal auditory brainstem response (ABR) early in life.

Design/Subjects

This study enrolled 19 infants with CCMVI and 21 non-infected newborn infants as a control group. Infants with CCMVI were divided into two subgroups according to ABR at the time of initial examination: normal ABR (11 infants) or abnormal ABR (8 infants). Ventricle size was assessed by calculating Evans’ index (EI) and lateral ventricle width/hemispheric width (LVW/HW) ratio on brain CT images, and was compared among groups. A cut-off ventricle size associated with abnormal ABR was determined.

Results

EI and LVW/HW ratio were significantly higher in the CCMVI with abnormal ABR group than the control and CCMVI with normal ABR groups. Cut-off values of 0.26 for EI and 0.28 for LVW/HW ratio had a sensitivity of 100% and 100%, respectively, and a specificity of 73% and 91%, respectively, for association with abnormal ABR.

Conclusions

We established a method for quantitative evaluation of ventricle size using EI and LVW/HW ratio on brain CT images in infants with CCMVI. LVW/HW ratio had a more association with abnormal ABR in the early postnatal period than EI.     

Occurrence of anomalies of the central nervous system in handicapped children]

We surveyed anomalies of the central nervous system using cranial CT scan in handicapped children who were institutionalized or staying at their homes. At the institutions for severely retarded children, fourteen cases were found and the rate was 6.1%. All of them were very severely retarded. At the institution for physically handicapped children, 12 cases including 10 cases of hydrocephalus were found and the rate was 9.3%. Most of them could take care of themselves. Nineteen cases were found among children staying at their homes and the rate was 9.4%. Most of them were very severely retarded. We conclude that the anomalies of the central nervous system play an important role in the pathogenesis of handicapped children, especially severely retarded children, and that the burden derives from them is a big problem in our daily clinic and special education.     

Disabilities in 830 severely retarded children

Patterns of disabilities in 830 severely retarded children aged 6-14 years identified through the prevalence study in Tokyo were analyzed. Severely retarded children were defined as those who neither capable to walk nor have their IQs over 35. Sixty-four percent of the total children belonged to class 1 of Ooshima's classification (bedridden and IQs less than 20) and most of the others belonged to class 2 of Ooshima's classification (those who able to sit alone and IQs less than 20). The percentages of the complications were as follows; epilepsy 84%, visual disturbance 40%, respiratory distress 30%, and feeding difficulty 46%. Sixteen percent of the total children were institutionalized. We conclude that the proportion of the most severe retardation has become larger than before and that the day care service for such children at their homes will be more important.     

Epidemiology of spastic tetraplegic cerebral palsy in Sweden. I. Impairments and disabilities

Ninety-six children and adolescents, born in 1959-78, with spastic tetraplegic cerebral palsy (TPL) were studied in terms of impairments and disabilities. The series was population-based and derived from 15 Swedish counties, and the city of Gothenburg, a population of 4.5 million people in all. All the patients had a pronounced motor disability with severe spastic pareses of all four limbs, and all of them were severely mentally retarded. None of them could speak. Ninety-four percent had epilepsy, 47% were severely impaired visually. Additional impairments were hip luxation(s) in 75%, severe contractures in 73% and scoliosis in 72%. Sixty-eight percent of cases had secondary microcephaly; 13% were born microcephalic. - The general uniformity of the severity and multiplicity of the impairment and disability pattern is emphasized - making the TPL group suitable for scientific care load studies on the basic requirements for the care of the profoundly retarded with maximum multi-handicaps.     

Clinicophysiological study of multimodality evoked potentials and computed tomographic findings in persistent vegetative state

The auditory brainstem response (ABR), short latency somatosensory evoked potential (SSEP) and visual evoked potential (VEP) of patients in the persistent vegetative state (PVS) are reported, and the correlations between the electrophysiological findings and the CT scan findings with the three clinical grades of the PVS (transitional, incomplete and complete vegetative syndromes) are discussed. Twenty two patients in a vegetative state caused by subarachnoid hemorrhage (3), hypertensive intracerebral hemorrhage (5), cerebral infarction (6), head injury (3), cerebral anoxia (4) and brain tumor (1). Each evoked response was evaluated for the presence or absence of abnormalities and assigned a grade ranked I to III. Briefly an evoked response was assigned a grade I, II, III if it satisfied the respective criteria of normal, moderately abnormal and severely abnormal or absent electrical activity. On the other hand CT scan findings in the PVS were evaluated for abnormal low density areas, ventricular dilatation and enlargement of the sulci and cisterns indicative of atrophy of the brain parenchyma. SSEP and VEP were better correlated with the clinical grade than ABR, and upper brainstem atrophy and abnormal low density area in CT scan findings were more valuable as an index to expresses the clinical features than ventricular dilatation. On the basis of these results, it is concluded that studies of ABR, SSEP and VEP associated with CT scan findings in the PVS could be a useful diagnostic aid to evaluate the lesions of these patients.     

Multi-modality evoked potentials in hypoxaemia

The auditory nerve-brain-stem evoked response (ABR) has been shown to be insensitive to hypoxic inspiratory gas mixtures which severely depress the EEG. In order to determine the relative sensitivities of additional brain regions and pathways to hypoxaemia, anaesthetized paralysed cats were ventilated with various gas mixtures while recording the evoked responses of the auditory, somatosensory (including peripheral nerve, brain-stem and primary cortical components), visual and vestibular systems. Arterial blood pressure was maintained by dopamine infusion and pH was corrected with bicarbonate. Hypoxic gas mixtures (6-7% O2) presented for 60 min, causing severe hypoxaemia (paO2 20-30 mm Hg; O2 saturation 25-50%), were without effect on the somatosensory, vestibular and visual EPs while the auditory evoked potentials (ABR and cortical components) were depressed. However, if arterial blood pressure was allowed to fall, all of the evoked potentials became severely depressed and isoelectric. These results and others indicate that the cortical components are qualitatively similar to the more peripheral evoked potentials. The resistance of these evoked potentials to controlled hypoxaemia is probably due to their generation by oligosynaptic pathways and to a compensatory switch to anaerobic metabolism and to an elevation of cerebral blood flow.     

A nationwide survey of bilirubin encephalopathy in preterm infants in Japan

ObjectivesTo examine the clinical characteristics of bilirubin encephalopathy in preterm infants (pBE) in Japan.MethodsWe performed a two-step nationwide questionnaire survey. The initial survey determined the number of children with pBE. Using a structured questionnaire, the second survey clarified the clinical manifestations and characteristics of children with pBE, including the perinatal history, neonatal complications, neurological features, verbal communication, diet, and magnetic resonance imaging (MRI) and auditory brainstem response (ABR) findings.ResultsThe initial survey included 190 pBE infants, indicating an incidence of approximately 10 per year. Clinical information was available for 142 of them. The median gestational age was 26 weeks and the median birthweight was 883 g. As to neonatal complications, 20% had none, 25% had one complication, 54% had two or more. Head control was observed in 45% and functional gait in 8%. Purposeful hand use was seen in 41% of patients and verbal communication in 40%. MRI showed T2 hyperintensities in the globi pallidi in 111 of 136 patients, especially between 7 and 18 months of corrected age. ABR abnormalities were present in 88 of 117 patients.ConclusionspBE was infrequent but constantly observed during the study period, especially in very preterm infants, even in those with no severe neonatal complications. Severely impaired gross motor function and relatively preserved manual function and verbal communication were characteristic. MRI and ABR abnormalities will facilitate diagnosis.     

No auditory conduction abnormality in children with attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is a neurobehavioral developmental disorder characterized by lack of sustained attention and hyperactivity. It has been suggested that asymmetrical conduction of the auditory stimulus in the brainstem plays a role in the pathophysiological process of ADHD. In the present study, the functional integrity of the central auditory pathway was assessed using the auditory brainstem response (ABR), mid-latency response (MLR) and slow vertex response (SVR). Twenty ADHD children and twenty controls were recruited for the study and recordings were done on a computerized evoked potential recorder using the 10-20 system of electrode placement. There emerged no significant difference in absolute peak latencies, interpeak latencies and amplitude of ABR or latency of MLR in the ADHD children as compared with the controls. Prolongation of the SVR latency was found in the children with ADHD versus the controls, but the difference was statistically insignificant. The present study does not suggest any auditory conduction abnormality as a contributory factor in ADHD.     

Spectral analysis of heart rate variability in the dysfunction of the brainstem

The heart rate variability, modulated by autonomic nervous system, has been reported to decrease in depression of the central nervous system, especially of the brainstem. To assess the brainstem dysfunction, we analyzed R-R interval values (the intervals between R waves of ECG) in 9 children (7 in comatose children and 2 in central apnea) by spectral analysis using an autoregressive model. The findings of spectral analysis were compared with those of auditory brainstem response (ABR). In comatose children with the brainstem dysfunction, the reduction of the total power was apparent before the appearance of ABR abnormality. In central apnea due to the dysfunction of respiratory center in brainstem, only the respiratory component decreased without the reduction of the total power or ABR abnormality. Spectral analysis of the heart rate variability is a useful means for assessment of the brainstem function.     

Longitudinal study of auditory brainstem response in leigh syndrome

To assess the utility of auditory brainstem response (ABR) in diagnosing brainstem changes in patients with Leigh syndrome (LS), we performed a longitudinal study of five patients with LS using both ABR and neuroimaging techniques (CT and MRI). The brainstem components of the initial ABRs we performed on the patients were abnormal in all five patients. In four of the patients, these abnormal findings preceded any clinical signs of brainstem impairment. Improvements in clinical findings were reflected in improvements in ABR findings in three patients. In one of these three patients, improvements in clinical findings were also reflected in improvements in MRI findings. In the other two patients, MRI findings showed no improvements, despite the improvements in clinical findings. In two of our patients, ABR clearly revealed functional improvements in the brainstem which were not revealed by MRI. Therefore, we conclude that ABR is an essential diagnostic technique for patients with LS.