Convulsive episodes in patients with group A xeroderma pigmentosum.

OBJECTIVES: To clarify the incidence of convulsive episodes in patients with group A xeroderma pigmentosum (XPA). MATERIALS AND METHODS: By investigating the history of convulsive episodes of our 33 XPA patients through either their medical charts or direct interviews with their caretakers. RESULTS: Five patients had several episodes of afebrile convulsion at ages older than 12. With the exception of one patient who began to show convulsive episodes at 13, no other XPA patients exhibited febrile seizures. As far as our 33 XPA patients were concerned, 15% exhibited epilepsy, and 3% experienced febrile seizures. CONCLUSIONS: Japanese XPA patients showed a lower incidence of febrile seizures, while exhibiting a higher incidence of epilepsy. It is assumed that the brain of young patients with XPA is difficult to develop convulsions.

Nocturnal enuresis and the pontine reticular formation.

OBJECTIVES: To assess the previously proposed hypothesis that enuretic patients have a dysfunction in the pontine reticular formation. METHODS: In 18 patients with intractable nocturnal enuresis, rapid eye movement (REM)-related phasic chin muscle activity loss in REM sleep was examined by means of a single-night polysomnography. RESULTS: In 5 of 18 patients, this physiologically seen phenomenon was found to be disturbed. CONCLUSIONS: Since REM-related phasic chin muscle activity loss is disturbed by the functional impairment in the pontine reticular formation, some enuretic patients could be considered as presenting a dysfunction in this structure.

Rapid eye movement sleep in breath holders.

One-night polysomnography was performed on seven subjects suffering from breath-holding spells, including one whose death was suggested to be a consequence of a breath-holding spell. The fatal case showed no rapid eye movements (REMs) during REM sleep, although he exhibited REMs during wakefulness. The average numbers of both REMs and bursts of REMs in REM sleep in the other six breath holders were significantly lower than those in age-matched controls. The breath holders showed no airway obstruction, desaturation, or sleep fragmentation. Since the rapid ocular activity in REM sleep is generated in the brain stem, we hypothesized that a functional brainstem disturbance is involved in the occurrence of breath-holding spells.

ACTH activates rapid eye movement-related phasic inhibition during REM sleep in patients with infantile spasms.

OBJECTIVES: Phasic inhibition index (PII) is the rate of the simultaneous occurrence of phasic chin muscle activity (PCMA) and rapid eye movement bursts during rapid-eye-movement sleep (REMS). In naive patients with infantile spasms (IS), the PII value was found to reflect their prognosis. We studied the effects of adrenocorticotropic hormone (ACTH) on REMS components including PII in IS. METHODS: REMS parameters were examined in 18 IS patients before and after ACTH treatment. The effects of corticosteroids (CSs) were examined in 3 patients with congenital adrenal hyperplasia (CAH) and 3 with nephrotic syndrome (NS). RESULTS: ACTH decreased PII and PCMA in IS patients. In CAH patients, physiological doses of CSs corrected the increased intrinsic ACTH level and increased PII. In NS patients, therapeutic doses of CSs suppressed PCMA without affecting PII. CONCLUSION: ACTH suppressed PCMA through CSs, and reduced PII directly. ACTH was hypothesized to eliminate IS through these dual modes of action.

Immunohistochemical analysis of brainstem lesions in infantile spasms.

Whether the cerebral or subcortical lesions are involved in the pathogenesis in infantile spasms (IS) remains to be determined. To investigate the functional lesions of the subcortical structures in IS, the brainstem expression of neurotransmitters, neuropeptides and calcium-binding proteins in IS autopsy cases of lissencephaly and of perinatal hypoxic ischemic encephalopathy (HIE/IS) was investigated. The IS patients consisted of four subjects each of lissencephaly and HIE. They suffered from both West and Lennox-Gastaut syndromes. The healthy and disease controls were composed of four subjects without neuromuscular disorders and six cases of HIE (HIE/C), neither of whom had the epileptic syndrome. In these subjects the expressions of tryptophan hydroxylase (TrH), tyrosine hydroxylase (TH), parvalbumin (PV), methionine-enkephalin (ME) and substance P (SP) were immunohistochemically determined in serial sections of the midbrain, pons and medulla oblongata. The immunoreactivity of neurons and neuronal processes for TH was altered in the mesencephalic periaqueductal gray matter, locus ceruleus, and dorsal vagal nucleus in the patients. The HIE/IS cases showed reduced TrH-immunoreactivity in the medullary raphe nuclei. The brainstem auditory tract was poorly discernible on anti-PV immunostaining in the IS patients. The immunoreactivity for ME in the spinal trigeminal nucleus was severely affected in the IS patients, while that for SP was comparatively well preserved. It is suggested that the presence of common brainstem lesions in IS is irrespective of etiologies. It is intriguing that some of the changes seemed to be interrelated with the neurophysiological abnormalities being reported in IS patients.

REM sleep components predict the response to initial treatment of infantile spasms.

PURPOSE: The phasic inhibition index (PII) is the rate of the simultaneous occurrence of rapid eye movement bursts (RBs) and phasic chin muscle activity (PCMA) during rapid eye movement sleep (REMS). PII is low insofar as physiologically occurring REM-related phasic inhibition acts on chin muscles. Previously we found that PII was significantly higher in patients with infantile spasms (ISs) who had a recurrence of convulsions than in patients with ISs who exhibited no recurrence. We aimed to predict the response of patients with ISs to conventional anticonvulsants (AEDs) by means of REMS components including PII, expecting to facilitate avoidance of potentially hazardous hormonal therapy. METHODS: REMS, recorded before the beginning of any medication, was retrospectively examined in 15 patients with ISs. The patients were classified into two groups according to the response to initial treatment with conventional AEDs. Conventional AEDs were enough to control the spasms in six good responders (GRs), whereas further hormonal therapy was required in nine poor responders (PRs) to control the spasms. RESULTS: The amount of REMS was significantly lower in patients with ISs than in controls. GRs had less REMS than did PRs, although no significant difference was observed. Although the frequencies of RB and PCMA showed no significant differences among GRs, PRs, and controls, the average PII value in PRs (12.6+/-3.4; mean+/-SD) was significantly (p < 0.001) higher than that in GRs (6.1+/-1.7). CONCLUSIONS: PII is a useful parameter for differentiating GRs from PRs.

[Auditory brainstem responses in group A xeroderma pigmentosum].

Xeroderma pigmentosum has been known to result from disturbance in the repair of injured DNA caused by the ultra violet light. According to cell fusion studies, this disease is classified into 8 groups. Among these groups, group A (A-XP) shows the most severe type of neurological disturbance. Slowly progressive diffuse impairment both in the central and the peripheral nervous systems has been reported. Although hearing loss occurs in all the patients, few papers have described the chronological changes of this disability. This study aimed to clarify the development of audiological abnormalities in A-XP patients. We recorded auditory brainstem evoked responses (ABRs) in 20 Japanese children with A-XP. All patients had homozygous intron 3 splicing mutations of xeroderma pigmentosum group A complementing gene, the most common type mutations in Japan. ABR threshold, peak latency of 5th wave and the peak interval latency between the 1st and 5th waves (I-V interpeak latency) were measured, and were compared with those obtained from age-matched controls. ABRs were well detected in all patients examined under 4 years old. The I-V interpeak latencies became shorter with age as in the controls. In 3 ears, the 5th wave was recorded without 1st wave. In 4 ears which no ABRs were detected with 90 dBHL stimulation, the only 5th wave was detected. No waves were obtained from the patients aged over 10 years. The current study revealed that ABR disturbance in A-XP patients became obvious after 4 years of age. In addition, no ABR was found to be identified after 10 years of age. During 4 to 10 years of age, some patients showed the elevation of the threshold of the 5th wave. In A-XP patients, the peripheral nerve was hypothesized to be affected earlier than the central pathway involved in ABR.

Video analysis of gross body movements during sleep.

Gross body movements (GM) during sleep, classified into four GM types by the involved parts of body, were evaluated using two-dimensional video analysis in five normal children aged 4-12 years. The rate of occurrence of all GM types showed apparent sleep stage dependency. Among four GM types, GM-1 (GM with axial rotation) was the most frequent. Averaged duration of GM-1 was the longest. A total of 77.2% of GM-1 started with the contraction of chin muscle and 35% of total sleep changes (tSC) were related to GM. A total of 5.6% of tSC following GM shifted to the deeper stage. Further evaluation is necessary in order to understand the physiological mechanism of GM.

Maturation of motility and motor inhibition in rapid-eye-movement sleep.

OBJECTIVE: To describe the age-related changes in the number of movements in rapid eye movement (REM) sleep, and to quantify the functional maturation of motor inhibition. STUDY DESIGN: Gross movements, phasic mentalis muscle activity (PMMA), and a new index that expressed the shortness of PMMA (the proportion of short PMMA among all PMMA) were examined cross-sectionally in 87 healthy children from premature babies to preadolescents by means of a single (all-night) polysomnography. RESULTS: The incidence of gross movements and long PMMA decreased with age, whereas that of short PMMA increased with age. The new index exhibited an age-related increase, with the highest correlation with age among sleep parameters examined, and reached an adult level after 6 years of age. CONCLUSION: We found that the age-related reduction of PMMA duration, which was expressed by a new index, occurred in parallel with the maturation of the inhibitory system that is tonically activated during REM sleep. We named this index the tonic inhibition index and concluded that the neuronal system involved in motor inhibition during REM sleep was still maturing during early childhood. We propose the tonic inhibition index as a useful quantitative indicator for the maturity of the inhibitory system.

Sleep development in children with congenital and acquired hypothyroidism.

To determine how thyroid hormone deficiency before birth influences early development of the human central nervous system, we examined sleep development in children with congenital hypothyroidism using all-night polysomnography. Although the sleep-wakefulness circadian rhythm was not disturbed, two patients under 1 year of age showed mild decreases of REM sleep. Rapid eye movements during REM sleep were significantly decreased in one patient in whom thyroxine replacement was delayed. Regarding phasic body movements during sleep, generalized gross movements were more frequently disturbed than localized muscle twitches, and even after L-thyroxine replacement, they were significantly reduced when compared with those in controls. Children with acquired hypothyroidism and neonatal transient hyperthyrotropinemia showed no severe abnormalities of the sleep parameters examined here. Sleep development in patients with congenital hypothyroidism is believed to be useful for regional evaluation of the brain impairment in congenital hypothyroidism.

[Disturbance of active sleep components in neonates with congenital hypothyroidism].

In order to investigate the effect of hypothyroidism during the early development on the functional brainstem maturation, polysomnograms were recorded on 7 patients with congenital hypothyroidism detected by neonatal screening before treatment. The following two sleep indices for phasic muscle activity during rapid eye movement (REM) sleep were evaluated: dissociation index (DI) and % body movements in REMs burst (% BM). The DI is defined as the ratio of the number of twitch movements (TMs) during REM sleep to the sum of TMs and localized movements (LMs) during REM sleep. The % BM is the percentage of TMs and LMs which occur during bursts of REMs in relation to the sum of TMs and LMs during REM sleep. The DI and % BM can reflect maturation of the tonic and phasic inhibitory system functioning during REM sleep, respectively. In congenital hypothyroidism, DI was lower than that in controls, while % BM was identical. The tonic inhibitory system was specifically involved, whereas the phasic one was preserved. It is suggested that thyroid hormone could play an important role on the functional brainstem maturation. We propose to investigate their neuropsychological development over the long term to elucidate the influence of hypothyroidism.

Phasic motor activity reduction occurring with horizontal rapid eye movements during REM sleep is disturbed in infantile spasms.

Single polysomnography was performed before treatment in 17 patients with infantile spasms (IS) (13 with a cryptogenic type and 4 with a symptomatic one). Their sleep components during rapid eye movement (REM) sleep were compared with those in 22 age-matched controls. The tonic muscle atonia during REM sleep was observed in all IS patients as in controls. The amount of REM sleep in IS patients was significantly lower, while the incidences of gross movements, phasic chin muscle activity, and bursts of horizontal rapid eye movements were identical with those in controls. The phasic inhibition index (PII), i.e., the rate of simultaneous occurrence of phasic chin muscle activity and bursts of horizontal rapid eye movements, was significantly higher in IS than in controls. The PII value was the only parameter that reflected our patients' prognosis among the obtained REM sleep parameters. We presume that the elevated PII in IS reflects the weakness of the phasic motor activity reduction occurring with horizontal rapid eye movements, and attribute this disturbance to a functional instability of the rostral pontine tegmentum. We propose that PII is a useful parameter for assessing the prognosis of IS. Considering the neural basis for elevated PII in IS, this index is expected to provide a clue for explaining the pathophysiology of IS.

Motor disturbance during REM sleep in group A xeroderma pigmentosum.

We investigated motor phenomena during rapid eye movement (REM) sleep in 13 patients with group A xeroderma pigmentosum aged from 11 to 39 months, and compared them with those obtained from 12 age-matched controls. At the time of sleep study, they had no abnormality on routine electrophysiological examinations. The amount of REM sleep and the incidence of motor phenomena during REM sleep in patients were similar to those in age-matched controls. However using the newly designated indices, we demonstrated disturbance on both the tonic motor inhibition occurring during the whole REM sleep period and the phasic one acting simultaneously with horizontal rapid eye movements in these patients. Since the motor inhibition during REM sleep is mediated by the subcortical structures, our study indicate that these structures are functionally impaired in group A xeroderma pigmentosum even during the early stage of the illness.

Impairment of respiratory rhythmogenesis and sequelae of bacterial meningitis.

A 9-year-old boy with respiratory disturbance associated with medullary lesions after pneumococcal meningitis is reported. Although he lives a normal daily life, he cannot cough or sneeze. A polysomnographic study revealed a low respiration rate and an irregular respiratory rhythm not only during REM sleep but also during slow wave sleep, and marked desaturation during sleep. Respiratory function tests including CO2 response revealed normal values. Magnetic resonance imaging demonstrated bilateral small lesions in the medulla. This patient is unusual because respiratory rhythm is impaired, without decreased ventilatory capacity or CO2 response, supporting the possibility that rhythmogenetic respiratory neurons are located in a limited area of the human medulla.

Phasic motor activity reduction occurring with horizontal rapid eye movements during active sleep in human.

We describe the phasic reduction of motor activity occurring with horizontal rapid eye movements (REMs) during active sleep in 15 children (12 healthy children and 3 patients with severe brain damage). A REM-related decrease in intercostal muscle activity was demonstrated by averaging integrated surface electromyograms. In the healthy subjects, this reduction had a mean latency from the REM onset of 37.1 ms and a duration of 225.9 ms. This phenomenon was also observed in the 3 patients who had lost cerebral function. We hypothesized a brainstem origin for the effect. A REM-related mentalis muscle activity loss, detected by averaging mentalis muscle twitches, was observed in 10 healthy children among the subjects. This loss began at 59.1 ms before the onset of REMs and lasted for 230.2 ms on average. In addition, a transient decrease in integrated REM activity surrounding mentalis muscle twitches (a twitch-related reduction of REMs) was observed. We discuss the similarity between REM-related phasic reduction of muscle activity obtained for intercostal and mentalis muscles and pontogeniculo-occipital (PGO) wave-related inhibitory postsynaptic potentials reported for feline lumbar and trigeminal motoneurons, respectively. We then assume the presence of a phasic event generator, functioning during active sleep in healthy humans, which triggers at least three generators; that is, the generator of PGO waves (or REMs), motor inhibition, and of motor excitation including muscle twitches.

Human cytomegalovirus DNA in cerebrospinal fluid.

To determine the involvement of human cytomegalovirus (CMV) in conditions of neurological impairment, detection of CMV DNA was attempted in cerebrospinal fluid obtained from 45 neurologically affected children aged from 1 month to 17 years by means of the polymerase chain reaction. Four patients (congenital CMV encephalopathy with West's syndrome, acute encephalitis, chronic epileptic encephalopathy, and lissencephaly) had CMV DNA in their cerebrospinal fluid. CMV DNA was absent in the cerebrospinal fluid of 11 neurologically unaffected controls aged from 1 month to 11 years. Three patients with acute CMV hepatitis had no CMV DNA in their cerebrospinal fluid. Among the four patients who had CMV DNA in their cerebrospinal fluid, two did not excrete CMV DNA or CMV antigen in the urine. The possible pathogenetic significance of CMV DNA in the cerebrospinal fluid is discussed. By applying the polymerase chain reaction to cerebrospinal fluid, the mode of brain invasion by CMV can be clarified further.

[Sleep disordered breathing in group A xeroderma pigmentosum].

We studied sleep disordered breathing (SDB) in 12 patients with group A xeroderma pigmentosum (XP) by means of respiratory inductive plethysmography (Respisomnograph:Nims) during polysomnographical examination. The subjects were 6 male and 6 female patients aged from 10 months to 25 years. Four out of the subjects had SDB:3 showed sleep apnea (apnea index ranged from 5.2 to 44.2/h) and 1 presented desaturation during sleep (desaturation time per total sleep time was 4.3%). All these patients were over 12 years. The patients below 14 years had mainly the central type of SDB, and the others aged over 16 years had both the central and obstructive types of SDB. Three of the 4 patients had daytime sleepiness or restless sleep, which seemed to be due to SDB. We discussed the pathophysiology of SDB with XP in relation with brain stem function and peripheral neuropathy. We must pay attention to SDB in patients with XP aged over 12 years.

[Polygraphical sleep study on typical absence: relationship between the effect of sodium valproate and nigrostriatal function].

In order to clarify the mechanism of the effect of sodium valproate (VPA) on absence seizures, we performed sleep polygraph recordings in 10 patients with typical absence. VPA was effective in six cases (group A), partially effective in two (group B), and ineffective in two (group C). In 5 of 9 cases, the tonic sleep components were abnormal. In 4 cases, the percentage of slow wave sleep increased before administration of VPA, and did not change remarkably by its administration. In group A and B, twitch movements (TM), one of the phasic sleep components detected in the mentalis muscle on surface EMG, decreased or were unchanged after administration of VPA, especially during the REM period. In contrast, TM increased in group C. We speculate that the changes of TM (especially in the REM periods) after administration of VPA are well related to its effectiveness. Since TMs are thought to be controlled by the nigrostriatal dopaminergic pathway, the different response of basal ganglia to VPA among cases with absence epilepsy would have some relation to the different effectiveness of VPA in controlling seizures.

Brainstem control of phasic muscle activity during REM sleep: a review and hypothesis.

For the generation of phasic muscle activity during rapid eye movement (REM) sleep, strong motor excitation to overcome both tonic and phasic inhibition is needed at the motoneuron level. Descending pathways originating in the rostral pons (cholinoceptive (nucleus reticularis pontis oralis-->nucleus reticularis gigantocellularis, peri-locus coeruleus pars alpha-->nucleus reticularis magnocellularis) and cholinergic (pedunculopontine tegmental nucleus-->nucleus reticularis paramedianus) pathways) are involved in motor inhibition during REM sleep. Since the origins of excitatory drives related to phasic muscle activity during REM sleep are also in the brainstem, the occurrence of phasic muscle activity can be said to be determined by brainstem activity. We review the basic and clinical studies on phasic muscle activity during REM sleep and propose the possibility that it can be a beneficial parameter for assessing brainstem activity, especially in relation to its maturation during early stage of life.