Zenzo Miwa

Hereditary sensory and autonomic neuropathy types IV and V in Japan

Hereditary sensory and autonomic neuropathy (HSAN) is a group of genetic disorders involving varying sensory and autonomic dysfunction. HSAN types IV and V are characterized by congenital generalized loss of pain and thermal sensation. HSAN type IV is additionally accompanied by decreased sweating and intellectual disability. From 2010 to 2013, we (members of the Japanese Research Group on Congenital Insensitivity to Pain) carried out research on HSAN types IV and V. Research by this group included epidemiological data, examination of clinical findings, solutions of disease etiology, investigation of complications and development of their management. Complications were categorized into musculoskeletal complications, oral/dental complications, dermal complications, ocular complications, complications resulting from impaired thermal control, anesthetic considerations, other complications possibly related to autonomic dysfunction, and abnormal mental development and behavior. Treatment and care for patients with HSAN types IV and V require a wide range of knowledge and experience, and a multidisciplinary team approach. Therefore, we produced the “Guideline of Total Management and Care for Congenital Insensitivity to Pain (Ver.1)” in 2012, to provide information for medical specialists based on our knowledge and experience. This guideline includes medical issues, as well as descriptions of social participation and welfare. This review outlines the situation of HSAN types IV and V in Japan, and the recommendations of treatment and care for patients, mostly based on research conducted by the Japanese Research Group.

Epidemiology of hereditary sensory and autonomic neuropathy type IV and V in Japan

Hereditary sensory and autonomic neuropathy (HASN) refers to a group of rare congenital disorders characterized by loss of pain sensation and other sensory or autonomic abnormalities. Among them, a relatively large proportion of patients with HSAN type IV, which is accompanied by anhidrosis and intellectual disability, are reported from Israel and Japan. HSAN type V, with normal sweating and mental development, is rarely reported in Japan. In 2009, we founded a research group for congenital insensitivity to pain and performed the first epidemiological survey of HSAN types IV and V in Japan. Questionnaires were sent to a total of 3,488 certified training institutions of five nationwide medical societies comprising pediatricians, neurologists, orthopedic surgeons, and dentists. Answers were obtained from 1,610 institutions, and 192 HSAN patients (152 with type IV and 28 with type V) were reported from 105 institutions. After excluding duplicated patients, we identified a total of 62 current, 36 past, and five deceased patients for HSAN‐IV, and a total of 14 current, 13 past, and 0 deceased patients for HSAN‐V. Using these figures, we estimated that the number of Japanese patients with HSAN types IV and V as 130–210 and 30–60 patients, respectively. We identified no gender differences, and patients with a family history of the disorder were limited to affected siblings in both conditions. Most patients with HSAN‐IV were 5–40 years of age, whereas half of the patients with HSAN‐V were 40 years or older.

Objective assessment of internal stress in children during dental treatment by analysis of autonomic nervous activity

AIMS The aim of this study was to assess the internal stress of children during dental treatment based on autonomic nerve activity and facial muscle activity. METHODS We recorded the electrocardiogram of children during the treatment of composite resin restoration and analysed autonomic nerve activity by means of power spectral analysis of heart rate variability. Simultaneously, electromyography (EMG) activity of the corrugator muscle was recorded in children during dental treatment, and the relationship between sympathetic nerve activity and corrugator EMG activity was analysed. RESULTS In all subjects, the mean sympathetic nerve activity was significantly higher during oral examination and after treatment compared with pre-treatment. Depending on the sympathetic nerve responses to the other treatment procedures, the subjects could be classified into two groups: the stress group and the nonstress group. Sympathetic nerve activity was significantly higher during infiltration anaesthesia and cavity preparation compared with pre-treatment activity in the stress group, whereas it was consistently lower than the pre-treatment levels during most treatment procedures in the nonstress group. The mean amplitudes of the averaged corrugator muscle EMG during dental treatment did not differ between the stress and nonstress groups. CONCLUSION The present results suggest that the measurement of autonomic nervous activity, especially sympathetic nervous activity, is quite useful in assessing the internal stress of children, even when no expressed sign of unease are present during dental treatment.

Optical Measurement of Blood Oxygen Saturation of Dental Pulp

The applicability of arterial pulse oximetry to dental pulp was demonstrated using in vitro and in vivo measurements. First, porcine blood of known oxygen saturation (SO2) was circulated through extracted human upper incisors, while transmitted-light plethysmography was performed using three different visible wavelengths. From the light intensity waveforms measured in vitro, a parameter that is statistically correlated to SO2 was calculated using the pulsatile/nonpulsatile component ratios of two wavelengths for different SO2. Then, values were measured in vivo for living incisors, and the corresponding SO2 values were calculated using the results of in vitro measurements. The estimated SO2 values of the upper central incisors measured in vivo were from 71.0 to 92.7%. This study showed the potential to measure the oxygen saturation changes to identify the sign of pulpal inflammation.

Internal stress in children and parental attitude to dental treatment with passive restraint

Abstract Purpose The purpose of this study was to examine the internal stress in uncooperative children treated under passive restraint and the changes of it in later treatments under cooperative condition with no need of restraint. We also conducted questionnaire among parents to survey their opinion towards the treatment with restraining device. Methods The subjects for electrocardiogram (ECG) recording were the child patients who were referred to the university clinic by the primary care dentists. We recorded ECG of the patients during dental treatment and assessed the autonomic nervous activity as a physiological response to stress. The recordings from uncooperative children were continued at every visit until they became cooperative and no longer restrained. A questionnaire survey was conducted among parents who have experienced the use of the restraining device to their children. Results Though the sympathetic nerve activity, which elevates with internal stress, and the heart rate were relatively high under restraint in uncooperative children, both diminished in the later session when children became cooperative enough to remove restraint. The questionnaire survey demonstrated that most parents whose children underwent treatment with restraining device showed positive attitudes toward the use of it. Conclusions The results of this study suggest that the experience of dental treatment with passive restraint would not necessarily be a traumatic event for children in a short term and parents would accept the necessity through the experience of the treatment in case urgent treatments are required.

Analysis of physiological responses associated with emotional changes induced by viewing video images of dental treatments

Since the understanding of emotional changes induced by dental treatments is important for dentists to provide a safe and comfortable dental treatment, we analyzed physiological responses during watching video images of dental treatments to search for the appropriate objective indices reflecting emotional changes. Fifteen healthy young adult subjects voluntarily participated in the present study. Electrocardiogram (ECG), electroencephalogram (EEG) and corrugator muscle electromyogram (EMG) were recorded and changes of them by viewing videos of dental treatments were analyzed. The subjective discomfort level was acquired by Visual Analog Scale method. Analyses of autonomic nervous activities from ECG and four emotional factors (anger/stress, joy/satisfaction, sadness/depression and relaxation) from EEG demonstrated that increases in sympathetic nervous activity reflecting stress increase and decreases in relaxation level were induced by the videos of infiltration anesthesia and cavity excavation, but not intraoral examination. The corrugator muscle activity was increased by all three images regardless of video contents. The subjective discomfort during watching infiltration anesthesia and cavity excavation was higher than intraoral examination, showing that sympathetic activities and relaxation factor of emotion changed in a manner consistent with subjective emotional changes. These results suggest that measurement of autonomic nervous activities estimated from ECG and emotional factors analyzed from EEG is useful for objective evaluation of subjective emotion.