Preprocessing and time-frequency analysis of newborn EEG seizures

Neurological disease or dysfunction in newborn infants is often first manifested by seizures. Prolonged seizures can result in impaired neurodevelopment or even death. In adults, the clinical signs of seizures are well defined and easily recognized. In newborns, however, the clinical signs are subtle and may be absent or easily missed without constant close observation. This article describes the use of adaptive signal processing techniques for removing artifacts from newborn electroencephalogram (EEG) signals. Three adaptive algorithms have been designed in the context of EEG signals. This preprocessing is necessary before attempting a fine time-frequency analysis of EEG rhythmical activities, such as electrical seizures, corrupted by high amplitude signals. After an overview of newborn EEG signals, the authors describe the data acquisition set-up. They then introduce the basic physiological concepts related to normal and abnormal newborn EEGs and discuss the three adaptive algorithms for artifact removal. They also present time-frequency representations (TFRs) of seizure signals and discuss the estimation and modeling of the instantaneous frequency related to the main ridge of the TFR.

Myelin proteolipid protein - the first 50 years

Myelin proteolipid protein (PLP), the most abundant protein of central nervous system (CNS) myelin, is a hydrophobic integral membrane protein. Because of its physical properties, which make it difficult to work with, progress towards determining the exact function(s) and disease associations of myelin PLP has been slow. However, recent molecular biology advances have given new life to investigations of PLP, and suggest that it has multiple functions within myelin and is of importance in several neurological disorders. (C) 2002 Elsevier Science Ltd. All rights reserved.

Complex language functions and subcortical mechanisms: evidence from Huntington's disease and patients with non-thalamic subcortical lesions

The neuropathological changes associated with Huntington's disease (HD) are most marked in the head of the caudate nucleus and, to a lesser extent, in the putamen and globus pallidus, suggesting that at least part of the language impairments found in patients with HD may result from non-thalamic subcortical (NTS) pathology. The present study aimed to test the hypothesis that a signature profile of impaired language functions is found in patients who have sustained damage to the non-thalamic subcortex, either focally induced or resulting from neurodegenerative pathology. The language abilities of a group of patients with Huntington's disease (n=13) were compared with those of an age- and education-matched group of patients with chronic NTS lesions following stroke (n=13) and a non-neurologically impaired control group (n=13). The three groups were compared on language tasks that assessed both primary and more complex language abilities. The primary language battery consisted of The Western Aphasia Battery and The Boston Naming Test, whilst the more complex cognitive-linguistic battery employed selected subtests from The Test of Language Competence-Expanded, The Test of Word Knowledge and The Word Test-Revised. On many of the tests of primary language function from the Western Aphasia Battery, both the HD and NTS participants performed in a similar manner to the control participants. The language performances of the HD participants were significantly more impaired (p<0.05 using modified Bonferroni adjustments) than the control group, however, on various lexico-semantic tasks (e. g. the Boston Naming Test and providing definitions), on both single-word and sentence-level generative tasks (e. g. category fluency and formulating sentences), and on tasks which required interpretation of ambiguous, figurative and inferential meaning. The difficulties that patients with HD experienced with tasks assessing complex language abilities were strikingly similar, both qualitatively and quantitatively, to the language profile produced by NTS participants. The results provide evidence to suggest that a signature language profile is associated with damage to the non-thalamic subcortex resulting from either focal neurological insult or a degenerative disease.

Noninvasive measurement of cerebral bioimpedance for detection of cerebral edema in the neonatal piglet

The association of sustained cerebral edema with poor neurological outcome following hypoxia-ischaemia in the neonate suggests that measurement of cerebral edema may allow early prediction of outcome in these infants. Direct measurements of cerebral impedance have been widely used in animal studies to monitor cerebral edema, but such invasive measurements are not possible in the human neonate. This study investigated the ability of noninvasive cerebral impedance measurements to detect cerebral edema following hypoxia-ischaemia. One-day-old piglets were anaesthetized, intubated and ventilated. Hypoxia was induced by reducing the inspired oxygen concentration to 4-6% O-2. Noninvasive cerebral bioimpedance was measured using gel electrodes attached to the scalp. Cerebral bioimpedance was also measured directly by insertion of two silver-silver chloride electrodes subdurally. Noninvasive and invasive measurements were made before, during and after hypoxia. Whole body impedance was measured to assess overall fluid movements. Intracranial pressure was measured continuously via a catheter inserted subdurally, as an index of cerebral edema. There was good agreement between noninvasive and invasive measurements of cerebral impedance although externally obtained responses were attenuated. Noninvasive measurements were also well correlated with intracranial pressure. Whole body impedance changes did not account for increases in noninvasively measured cerebral impedance. Results suggest that noninvasive cerebral impedance measurements do reflect intracranial events, and are able to detect cerebral edema following hypoxia-ischaemia in the neonate. (C) 2002 Elsevier Science B.V. All rights reserved.

Transient evoked otoacoustic emissions in children studying in special schools

Objectives: The present study aimed to investigate the feasibility and practicalities or testing children in special school settings using transient evoked otoacoustic emissions (TEOAE) and tympanometry. Children studying in special schools, particularly those with intellectual impairment, may be highly susceptible to hearing pathologies and can be difficult to assess using traditional test batteries. Researchers have recently suggested the possible applicability of TEOAE testing. in lieu of conventional behavioral methods, as a hearing screening device for persons with intellectual impairment. However, to date. few publications have detailed the particulars and results of such testing. Methods: A total of 489 children, with a mean age of 9.6 years, were tested in 15 special schools. Case information was obtained regarding birth history, medical history and type,degree of impairment, for later comparison with screening results. TEOAEs were collected using Quickscreen mode of the ILO292 Otodynamics Analyzer, whilst tympanometry was performed utilizing a Madsen Zodiac 901 Middle Ear Analyzer. Results: In total, 80% of students were able to be tested using TEOAEs. Average test time per ear was 2 min. However, a large proportion (40 of those able to be tested) failed TEOAE testing in at least one ear. No significant effects were found between could-not-test (CNT) cases and case history factors, A significant difference in TEOAE failure rates was found across history of neonatal special care nursery residency and history of parental concern regarding possible hearing impairment. Failure rates were higher for those who indicated positive histories. A total of 74% of subjects could be tested using tympanometry, with 25% of those able to be tested failing in at least one ear. Notably, neither type nor degree of impairment had any significant bearing on CNT or failure rates for tympanometry or TEOAE screening. Conclusions: Findings of the present investigation lend support to the review of hearing screening programs for children in special schools. with TEOAEs presenting as a potential alternative procedure. Further examination of the performance measures of protocols incorporating TEOAEs would now be advantageous. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

A Case Study of Partial Agenesis of the Corpus Callosum: Audiological Implications

This case study presents four and a half years of audiological observations, testing and aural habilitation of a female child with a partial agenesis of the corpus callosum (ACC). The ACC was diagnosed by MRI scan performed at 6 months of age to eliminate neurological causes for the developmental delay. This child was also born with a cleft palate and was diagnosed with Robinow Syndrome at 3 years and 3 months of age. The audiological results showed an improvement in hearing thresholds over the 4-year period. The child’s ophthalmologist also reported an improvement in visual skills over time. The most interesting aspect of the child’s hearing was the discrepancy between the monaural and the binaural results. That is, when assessed binaurally she often presented with a mild to moderate mixed loss and, when assessed monaurally, she showed a moderate to severe mixed loss for the right ear and a severe mixed loss for the left ear. Over time, the discrepancy between the monaural and binaural results changed. When assessed binaurally, the loss decreased to normal low frequency hearing sloping to a mild high frequency loss. When assessed monaurally, the most recent results showed a mild loss for the right ear and a moderate loss for the left ear. This discrepancy between binaural and monaural results was evident for both aided and unaided tests. For the most recent thresholds, the binaural results were consistent with the right monaural thresholds for the first time over the four and a half years. Parental reports of the child’s hearing were consistent with the binaural clinical results. This case indicates the need for audiologists to (1) carefully monitor the hearing of children with ACC, (2) obtain monaural and binaural hearing and aided thresholds results, and (3) compare these children’s functional abilities with the objective test results obtained. This case does question whether hearing aids are appropriate for children with ACC. If hearing aids are deemed to be appropriate, then hearing aids with compression characteristics should be considered.

Coordination and movement pathology: models of structure and function

Here we consider the role of abstract models in advancing our understanding of movement pathology. Models of movement coordination and control provide the frameworks necessary for the design and interpretation of studies of acquired and developmental disorders. These models do not however provide the resolution necessary to reveal the nature of the functional impairments that characterise specific movement pathologies. In addition, they do not provide a mapping between the structural bases of various pathologies and the associated disorders of movement. Current and prospective approaches to the study and treatment of movement disorders are discussed. It is argued that the appreciation of structure-function relationships, to which these approaches give rise, represents a challenge to current models of interlimb coordination, and a stimulus for their continued development. (C) 2002 Elsevier Science B.V. All rights reserved.

Effects of intravenous injection of Clostridium perfringens type D epsilon toxin in calves

In cattle, a neurological lesion similar to that produced in sheep and goats by Clostridium perfringens type D enterotoxaemia has been reported. However, no causal relationship has been established between this disease and the lesion in cattle. The effects of single and multiple intravenous injections of epsilon toxin in three calves aged 6 months were studied. A further calf was inoculated intravenously with saline solution and used as a control. Epsilon toxin invariably produced neurological signs within 2-60 min of the end of the injection process. Clinical signs consisted of loss of consciousness, recumbency, convulsions, paddling, opisthotonus, hyperaesthesia and dyspnoea. Gross changes consisted of severe acute pulmonary oedema, which was particularly marked in the interlobular septa. The histological lesions consisted of intra-alveolar and interstitial oedema of the lung and variable degrees of perivascular proteinaceous oedema in the internal capsule, thalamus and cerebellar white matter. No clinical or post-mortem changes were observed in the control calf. These results show that calves are susceptible to the intravenous injection of epsilon toxin, and that they can show at least some of the histological lesions produced in sheep and goats by this toxin. (C) 2002 Harcourt Publishers Ltd.

Neuro-angiostrongylosis in wild Black and Grey-headed flying foxes (Pteropus spp)

Objective To identify nematodes seen in histological sections of brains of flying foxes (fruit bats) and describe the associated clinical disease and pathology. Proceedures Gross and histological examination of brains from 86 free-living flying foxes with neurological disease was done as part of an ongoing surveillance program for Australian bat lyssavirus. Worms were recovered, or if seen in histological sections, extracted by maceration of half the brain and identified by microscopic examination. Histological archives were also reviewed. Results There was histological evidence of angiostrongylosis in 16 of 86 recently submitted flying foxes with neurological disease and in one archival case from 1992. In 10 flying foxes, worms were definitively identified as Angiostrongylus cantonensis fifth-stage larvae. A worm fragment and third stage larvae were identified as Angiostrongylus sp, presumably A cantonensis, in a further three cases. The clinical picture was dominated by paresis, particularly of the hind-limbs, and depression, with flying foxes surviving up to 22 days in the care of wildlife volunteers. Brains containing fifth-stage larvae showed a moderate to severe eosinophilic and granulomatous meningoencephalitis (n = 14), whereas there was virtually no inflammation of the brains of bats which died when infected with only smaller, third-stage larvae (n = 3). There was no histological evidence of pulmonary involvement. Conclusion This is the first report of the recovery and identification of A cantonensis from free-living Australian wildlife. While anglostrongylosis is a common cause of paresis in flying foxes, the initial clinical course cannot be differentiated from Australian bat lyssavirus infection, and wildlife carers should be urged not to attempt to rehabilitate flying foxes with neurological disease.

The spread of Angiostrongylus cantonensis in Australia

Until the recent establishment of Angiostrongylus cantonensis in North America. Australia was the only developed region endemic for this parasite. Almost 50 years ago the life cycle was elucidated there, in the city of Brisbane, and the first human infections probably occurred in 1959. From the 1970s, increasing numbers of autochthonous infections have been reported along the central east coast of the continent (southeast Queensland and northern New South Wales), involving humans, rats, dogs, horses, flying foxes and marsupials. Ten years ago, the parasite was discovered in Sydney, almost 1,000 km to the south, in dogs. In that city, it has since been diagnosed as a cause of neurological disease in increasing numbers of dogs, flying foxes, marsupials and zoo primates. Presumably, these infections resulted from the ingestion of snails or slugs, and it seems that virtually all species of native and exotic terrestrial molluscs can serve as intermediate hosts. It is not known how the parasite was introduced to this continent, or how it has spread over such an extensive territory, although eventually its range could encompass the entire east coast, and potentially other regions. It is also not known if the almost identical, native species, A. mackerrasae, is able to infect people (or other non-rodent hosts). All worms recovered to date, from one fatal human case, and from many animal infections, have been confirmed as A. cantonensis.

The 2000 Ogura Lecture: Olfactory neural cells: An untapped diagnostic and therapeutic resource

Objective. This is an over-view of the cellular biology of upper nasal mucosal cells that have special characteristics that enable them to be used to diagnose and study congenital neurological diseases and to aid neural repair. Study Design: After mapping the distribution of neural cells in the upper nose, the authors' investigations moved to the use of olfactory neurones to diagnose neurological diseases of development, especially schizophrenia. Olfactory-ensheating glial cells (OEGs) from the cranial cavity promote axonal penetration of the central nervous system and aid spinal cord repair in rodents. The authors sought to isolate these cells from the more accessible upper nasal cavity in rats and in humans and prove they could likewise promote neural regeneration, making these cells suitable for human spinal repair investigations. Methods: The schizophrenia-diagnosis aspect of the study entailed the biopsy of the olfactory areas of 10 schizophrenic patients and 10 control subjects. The tissue samples were sliced and grown in culture medium. The ease of cell attachment to fibronectin (artificial epithelial basement membrane), as well as the mitotic and apoptotic indices, was studied in the presence and absence of dopamine in those cell cultures. The neural repair part of the study entailed a harvesting and insertion of first rat olfactory lamina propria rich in OEGs between cut ends of the spinal cords and then later the microinjection of an OEG-rich suspension into rat spinal cords previously transected by open laminectomy. Further studies were done in which OEG insertion was performed up to 1 month after rat cord transection and also in monkeys. Results: Schizophrenic patients' olfactory tissues do not easily attach to basement membrane compared with control subjects, adding evidence to the theory that cell wall anomalies are part of the schizophrenic lesion of neurones. Schizophrenic patient cell cultures had higher mitotic and apoptotic indices compared with control subjects. The addition of dopamine altered these indices enough to allow accurate differentiation of schizophrenics from control patients, leading to, possibly for the first time, an early objective diagnosis of schizophrenia and possible assessment of preventive strategies. OEGs from the nose were shown to be as effective as those from the olfactory bulb in promoting axonal growth across transected spinal cords even when added I month after injury in the rat. These otherwise paraplegic rats grew motor and proprioceptive and fine touch fibers with corresponding behavioral improvement. Conclusions. The tissues of the olfactory mucosa are readily available to the otolaryngologist. Being surface cells, they must regenerate (called neurogenesis). Biopsy of this area and amplification of cells in culture gives the scientist a window to the developing brain, including early diagnosis of schizophrenia. The Holy Grail of neurological disease is the cure of traumatic paraplegia and OEGs from the nose promote that repair. The otolaryngologist may become the necessary partner of the neurophysiologist and spinal surgeon to take the laboratory potential of paraplegic cure into the day-to-day realm of clinical reality.

Dental and skeletal pathology in lungfish jaws and tooth plates

Many lungfish of the tooth plated lineage, both fossil and living, are affected by dental and skeletal pathologies including dental caries, abscesses and cysts within the bone or tooth plate, osteopenia, bone hypertrophy, and malocclusion. These conditions, while influenced in part by structural relationships of soft and hard tissues in the tooth plates, jaw bones and surrounding oral tissues, can also be used as indicators of the kind of environment inhabited by the fish. The disease processes have specific structural consequences, related either to the pathology or to attempts to heal the damage, and usually alter the form and function of the tooth plate or bone. Consequently they can be distinguished from postmortem diagenetic or taphonomic effects, which alter the structure in less specific ways and show no sign of healing. Dental caries, the most common pathological condition in dipnoan dentitions, is recognisable in lungfish from the Devonian of Western Australia, the Tertiary of South Australia and the Northern Territory and from living lungfish in south east Queensland. Other pathologies have a more sporadic occurrence.

Neonatal respiratory therapy in the new millennium: Does clinical practice reflect scientific evidence?

Respiratory therapy has historically been considered the primary role of the physiotherapist in neonatal intensive care in Australia. In 2001 a survey was undertaken of all level three neonatal intensive care units in Australia to determine the role of the physiotherapist and of respiratory therapy in clinical practice. It appears that respiratory therapy is provided infrequently, with the number of infants treated per month ranging from 0 to 10 in 15 of the 20 units who provide respiratory therapy, regardless of therapist availability. The median number of respiratory treatments per month during the week was three, and on weekends it was one. Respiratory therapy was carried out by physiotherapists and nurses in 54.6% of units, by physiotherapists only in 36.4% of units, and by nurses only in the remaining 9% of units surveyed. There was also a diminution of the role of respiratory therapy in the extubation of premature infants. A review of the literature shows that overall the use of respiratory therapy reflects current evidence. The question remains whether it is possible to maintain the competency of staff and justify the cost of training in the current healthcare economic climate. It seems probable that the future role of physiotherapists in neonatal intensive care unit may be in the facilitation of optimal neurological development of surviving very low birth weight infants.

Variation in articulatory timing of three English consonants: An electropalatographic investigation

Increasingly, electropalatography (EPG) is being used in speech pathology research to identify and describe speech disorders of neurological origin. However, limited data currently exists that describes normal articulatory segment timing and the degree of variability exhibited by normal speakers when assessed with EPG. Therefore, the purpose of the current investigation was to use the Reading EPG3 system to quantify segmental timing values and examine articulatory timing variability for three English consonants. Ten normal subjects repeated ten repetitions of CV words containing the target consonants /t/, /l/, and /s/ while wearing an artificial palate. The target consonants were followed by the /i/ vowel and were contained in the carrier phrase 'I saw a __'. Mean duration of the approach, closure/constriction, and release phases of consonant articulation were calculated. In addition, inter-subject articulatory timing variability was investigated using descriptive graphs and intra-subject articulatory timing variability was investigated using a coefficient of variation. Results revealed the existence of intersubject variability for mean segment timing values. This could be attributed to individual differences in the suprasegmental features of speech and individual differences in oral cavity size and structure. No significant differences were reported for degree of intra-subject variability between the three sounds for these same phases of articulation. However, when this data set was collapsed, results revealed that the closure/constriction phase of consonant articulation exhibited significantly less intra-subject variability than both the approach and release phases. The stabilization of the tongue against the fixed structure of the hard palate during the closure phase of articulation may have reduced the levels of intra-subject variability.

Motor and functional skills of children with developmental coordination disorder: A pilot investigation of measurement issues

This paper reports on the motor and functional outcomes of 20 children with developmental coordination disorder (DCD) aged 4-8 years consecutively referred to a pediatric physiotherapy service. Children with a Movement ABC (M-ABC) score less than the 15th percentile, and with no concurrent medical, sensory, physical, intellectual or neurological impairments, were recruited. The Motor Assessment Outcomes Model (MAOM) [Coster and Haley, Infants and Young Children 4 (1992) 11] provided the theoretical base for measurement selection, and preliminary findings at the activities and participation levels of the model are reported in this article. Children with DCD performed at the lower end of the normal range on the Pea-body Developmental Motor Scales (fine motor total score) (M = 85.65, SD = 12.23). Performance on the Visual Motor Integration Test (VMI) standard scores was within the average range (M = 96.15, SD = 10.69). Videotaped observations of the children's writing and cutting indicated that 29% were left-handed and that a large proportion of all children (31%) utilized unusual pencil grasp patterns and immature prehension of scissors. Measurement at the participation level involved use of the Pictorial Scale of Perceived Competence and Social Acceptance (PCSA) and Pediatric Evaluation of Disability Inventory (PEDI). Overall, these young children rated themselves towards the more competent and accepted end of the PCSA over the dimensions of physical and cognitive competence and peer and maternal acceptance. The PEDI revealed generally average performance on social (M = 49.98, SD = 16.62) and mobility function (M = 54.71, SD = 3.99), however, self-care function was below the average range for age (M = 38.01, SD = 12.19). The utility of the MAOM as a framework for comprehensive measurement of functional and motor outcomes of DCD in young children is discussed. (C) 2003 Elsevier B.V. All rights reserved.