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Biomedical subjects

A S Harvey

Publications and source records attributed to A S Harvey.

At least 19 recordsLinked to original sources
PubMed2005

Prefrontal lesions and attentional skills in childhood.

Despite the potential impact on development, few studies have examined the influence of prefrontal lesions occurring prior to maturation of the central nervous system. This study investigates the effect of prefrontal lesions in general, as well as the impact of lesion laterality, with respect to attentional abilities. The sample comprised 36 children with prefrontal lesions and 40 healthy controls. Attentional function was assessed across four domains: selective, shifting and divided attention, and processing speed. Group mean performances for children with prefrontal lesions indicated global attentional deficits, with greatest difficulties for "higher-order" skills including shifting and divided attention. Children with left prefrontal lesions performed similarly to controls, with a specific deficit characterized by difficulties with on-line processing of auditory-verbal information. Right prefrontaj lesions were primarily associated with impairments in day-to-day executive functions, including reduced monitoring, poor shifting attention and disinhibition. Children with bilateral prefrontal lesions performed worse than controls on tasks requiring greater cognitive resources. These results provide evidence of the important role played by prefrontal cortex in the development of attentional skills, and the particular role of the right prefrontal cortex. The pattern of attention deficits observed following early prefrontal lesions suggests some lateralization of function within the frontal lobes, even during childhood.

Adolescent↗
PubMed2004

Language cortex activation in normal children.

OBJECTIVE: To describe a protocol for use in young children and adolescents for determining language representation. METHODS: We performed 130 fMRI studies in 48 children and 17 adults. Verb generation (VG) and orthographic lexical retrieval (OLR) were used. The localization and lateralization of activation was rated visually. Regional voxel counts measured asymmetry and extent of activation. RESULTS: Activation was predominantly left-lateralized (children 85%, adults 94%), and there was no difference in the localization of activation for either paradigm. Children's typical sites of activation included mesial (96%), inferior (94%) and middle frontal (92%) gyri, the inferior (85%) and superior (65%) temporal cortex, and the cerebellum (67%). Less frequently activated sites were insular (50%) and posterior parietal (48%) cortices. Quantitative asymmetry index scores and visual inspection of laterality were concordant. Greater quantitative asymmetry for VG than OLR occurred in children. Laterality was not related to age, sex, task proficiency, or handedness. Frontal region voxel counts lower in children than adults and left sided counts correlated with task proficiency. CONCLUSIONS: Language fMRI can be performed in young children using resources available to clinical centers. The similarity in frequency of left language lateralization between children and adults suggests that language representation establishes early in development. The reduced amount of frontal region of interest activation in task-specific regions in children may reflect different levels of ability. However, the left-right distribution of activation does not appear to depend on task performance or age. These normative data provide a basis for decisions about language laterality in pediatric patients.

Adolescent↗
PubMed2004

Longitudinal study of MRS metabolites in Rasmussen encephalitis.

This study analyses the evolution of metabolite changes in an 8-year-old boy with focal Rasmussen encephalitis. Five MRI examinations, including magnetic resonance spectroscopy (MRS) were performed over 9 months. Following complex partial status, T2-weighted imaging showed transient dramatic signal increase in the left superior temporal gyrus and mesial temporal structures. Subsequent scans showed resolution of the swelling and signal normalization, with development of slight focal atrophy. MRS after status showed a reduction in N-acetylaspartate, total creatine and trimethylamines. Subsequent scans showed complete resolution of these metabolite abnormalities, followed later by development of further abnormal metabolite values. Lactate and glutamine/glutamate were elevated after status. After surgery, ex vivo high-field (1)H and (31)P MRS confirmed metabolite abnormalities (elevated choline and decreased aspartate, N-acetylaspartate, [(1)H]glutamate together with altered [(31)P]phospholipid ratios. These findings suggested active disease process in the anterior region of the excised superior temporal gyrus. We conclude that Rasmussen encephalitis is a combination of progressive encephalitic damage and fluctuating seizure effects, in which neuronal injury and recovery can occur. MRS measurements at a single time point should consider the fluctuating metabolite profile related to seizure activity.

Child↗
PubMed2003

Hypertensive encephalopathy: antecedent to hippocampal sclerosis and temporal lobe epilepsy?

The authors describe three patients with refractory temporal lobe epilepsy (TLE) following an episode of hypertensive encephalopathy as their only identified antecedent event. All patients had typical MR features of hippocampal sclerosis (HS), and the two operated cases had typical HS histology and became seizure-free postoperatively. These cases suggest that hypertensive encephalopathy may be a rare form of initial precipitating injury, leading to TLE and HS.

Anterior Temporal Lobectomy↗
PubMed2003

Generalized epilepsy in hypothalamic hamartoma: evolution and postoperative resolution.

OBJECTIVE: To better understand the epileptogenesis of symptomatic generalized epilepsy in patients with hypothalamic hamartoma and intractable epilepsy, many of whom experience remission of generalized seizures and slow spike-wave discharges following surgery. METHODS: The authors documented the evolution of symptomatic generalized epilepsy in 12 of 20 children who underwent transcallosal microsurgical hypothalamic hamartoma resection. In seven patients they recorded intraoperative EEG from the hamartoma and simultaneously from the scalp and frontal cortex before, during, and after resection. RESULTS: Gelastic seizures began on average at 6 months of age (range birth to 3 years); tonic seizures began at 6 years (range 2 months to 9 years). Normal EEG were reported in early childhood; thereafter, abnormalities were progressive. Interictal spike-wave was recorded intraoperatively over the scalp and cortex in six patients, but not from the hypothalamic hamartoma. Hamartoma resection had no immediate effect on cortical spike-wave, but waking spike-wave was absent in seven patients on subsequent postoperative EEG. Tonic seizures ceased in 11 of 12 patients, but 6 of these had postoperative generalized seizures that resolved over 1 to 6 months. CONCLUSION: Gelastic seizures in hypothalamic hamartoma arise from the hamartoma itself; the interictal spike-wave does not. The evolution of EEG abnormalities, the development of generalized seizures years after onset of gelastic seizures, and the postoperative running down of interictal spike-wave and generalized seizures in these patients may reflect secondary epileptogenesis.

Child↗
PubMed2001

Clinical and neuroradiologic features of acute disseminated encephalomyelitis in children.

OBJECTIVE: To identify the clinical and neuroradiologic features of acute disseminated encephalomyelitis (ADEM) in childhood. METHODS: A retrospective review was conducted of the medical records and MRI of children who presented to the Royal Children's Hospital in Melbourne with ADEM between January 1993 and December 1998. RESULTS: Of the 31 patients included in this study, 22 (71%) experienced a prodromal illness. Two patients (6%) had received hepatitis B vaccine 3 to 6 weeks before developing their illness. Symptoms and signs typically evolved over several days. Ataxia was the most common presenting feature, occurring in 20 patients (65%). MRI findings were variable, but lesions were most commonly seen bilaterally and asymmetrically in the frontal and parietal lobes. The authors found a high incidence of the corpus callosal and periventricular changes more typically associated with MS, but they also found a high rate of deep gray matter involvement (61% of patients). The use of high-dose IV methylprednisolone was usually associated with rapid recovery. Eighty-one percent of patients recovered completely, with only mild sequelae recorded in the remaining children. CONCLUSION: In the absence of a biological marker, the distinction between ADEM and MS cannot be made with certainty at the time of first presentation, but the authors suggest that a viral prodrome, early-onset ataxia, high lesion load on MRI, involvement of the deep gray matter, and absence of oligoclonal bands are more indicative of ADEM.

Adolescent↗
PubMed2001

Neuropsychological profile of a 9-year-old child with subcortical band heterotopia or 'double cortex'.

Subcortical band heterotopia (SBH) or 'double cortex', is a congenital brain abnormality that results from aberrant migration of neurons during development of the cortex. MRI shows a continuous band of heterotopic grey matter located between the cortex and ventricular walls, separated from them by a thin layer of white matter. The condition is quite rare, found predominantly in females, and is occasionally familial with an X-linked dominant inheritance. Current research has focused on genetic and neurological correlates, with cognitive assessment restricted to a global measure of general intellectual functioning. This paper describes in detail the results of a neuropsychological assessment of a 9-year-old female recently diagnosed with SBH. Predominant features were a significantly reduced speed of processing for visuomotor and oral output and reduced immediate registration of information. This difficulty has functional implications affecting skill acquisition, learning in the classroom, and social interaction.

Attention↗
PubMed2001

Severe myoclonic epilepsy of infancy: extended spectrum of GEFS+?

PURPOSE: Severe myoclonic epilepsy of infancy (SMEI) is an intractable epilepsy of early childhood of unknown etiology. It is often associated with a family history of seizure disorders, but epilepsy phenotypes have not been well described. We sought to characterize the seizure phenotypes of relatives to better understand to the genetic basis of SMEI. METHODS: Probands with SMEI were identified, and systematic family studies were performed. Epilepsy syndromes were characterized in affected family members. RESULTS: Twelve probands with SMEI were identified. Eleven of the 12 probands with SMEI had a family history of seizures, and the twelfth was the result of a consanguineous marriage. We found that 16.7% of full siblings and 8.3% of parents had definite seizures. A total of 39 affected family members was identified. The most common phenotype was febrile seizures in 14, febrile seizures plus in seven, partial epilepsy in two, and there were single individuals with SMEI, myoclonic-astatic epilepsy, Lennox-Gastaut syndrome, and 13 cases with unclassified or unconfirmed seizures. CONCLUSIONS: The family history of seizures in SMEI is in keeping with the spectrum of seizure phenotypes seen in generalized epilepsy with febrile seizures plus (GEFS+). Our findings suggest that SMEI is the most severe phenotype in the GEFS+ spectrum.

Adolescent↗
PubMed2001

Surgical resection for intractable epilepsy in "double cortex" syndrome yields inadequate results.

PURPOSE: To analyze the results of surgical treatment of intractable epilepsy in patients with subcortical band heterotopia, or double cortex syndrome, a diffuse neuronal migration disorder. METHODS: We studied eight patients (five women) with double cortex syndrome and intractable epilepsy. All had a comprehensive presurgical evaluation including prolonged video-EEG recordings and magnetic resonance imaging (MRI). RESULTS: All patients had partial seizures, with secondary generalization in six of them. Neurologic examination was normal in all. Three were of normal intelligence, and five were mildly retarded. Six patients underwent invasive EEG recordings, three of them with subdural grids and three with stereotactic implanted depth electrodes (SEEG). Although EEG recordings showed multilobar epileptic abnormalities in most patients, regional or focal seizure onset was recorded in all. MRI showed bilateral subcortical band heterotopia, asymmetric in thickness in three. An additional area of cortical thickening in the left frontal lobe was found in one patient. Surgical procedures included multiple subpial transections in two patients, frontal lesionectomy in one, temporal lobectomy with amygdalohippocampectomy in five, and an additional anterior callosotomy in one. Five patients had no significant improvement, two had some improvement, and one was greatly improved. CONCLUSION: Our results do not support focal surgical removal of epileptogenic tissue in patients with double cortex syndrome, even in the presence of a relatively localized epileptogenic area.

Adolescent↗
PubMed2001

Near-total absence of the cerebellum.

We report five cases of near-total absence of the cerebellum with accompanying pontine hypoplasia. The cerebellar remnant in each case comprised only antero-superior masses, the posterior fossa being otherwise fluid filled. Three of these patients, two teenagers and an infant, presented a fairly consistent clinical and neuroradiological phenotype, and a few similar cases are recorded in the literature. The cerebellar remnant was irregular and asymmetrical, and no ventral pontine prominence was discernible. In at least the older two, cerebellar motor functions were not greatly compromised, and intellectual handicap was of a mild degree. We propose that these cases represent a distinct entity of "near-total absence of the cerebellum with flat ventral pons, and relatively mild clinical affection". All cases have been sporadic, implying that the risk of recurrence within a family may be low. Quite different clinical pictures, of considerably greater severity, are demonstrated in the remaining two cases. One had pontocerebellar hypoplasia type 2, while the other had a complex cerebellar and cerebral malformation.

Adolescent↗
PubMed2001

Transcallosal resection of hypothalamic hamartomas, with control of seizures, in children with gelastic epilepsy.

OBJECTIVE: Hypothalamic hamartomas (HHs) are associated with precocious puberty and gelastic epilepsy; the seizures are often refractory to antiepileptic medications and associated with delayed development and disturbed behavior. The current opinion is that surgery to treat intrahypothalamic lesions is formidable and that complete excision is not technically achievable. We report our experience with a transcallosal approach to the resection of HHs. METHODS: Five children (age, 4-13 yr) with intractable epilepsy and HHs underwent preoperative clinical, electroencephalographic, and imaging evaluations. Two patients experienced only gelastic seizures, and three patients experienced mixed seizure disorders with drop attacks; all experienced multiple daily seizures. Patients were evaluated with respect to seizures, cognition, behavior, and endocrine status 9 to 37 months (mean, 24 mo) after surgery. The HHs were approached via a transcallosal-interforniceal route to the third ventricle and were resected using a microsurgical technique and frameless stereotaxy. RESULTS: Complete or nearly complete (>95%) excision of the HHs was achieved for all patients, with no adverse neurological, psychological, or visual sequelae. Two patients experienced mild transient diabetes insipidus after surgery. Two patients developed appetite stimulation, but no other significant endocrinological sequelae were observed. Three patients are seizure-free and two patients have experienced only occasional, brief, mild gelastic seizures after surgery, all with reduced antiepileptic medications. On the basis of parental reports and our own subjective observations, the children also exhibited marked improvements in behavior, school performance, and quality of life. CONCLUSION: Complete or nearly complete resection of HHs can be safely achieved via a transcallosal approach, with the possibility of seizure freedom and neurobehavioral improvements.

Child Behavior↗
PubMed2001

Awake craniotomy in an adolescent.

We present our approach to management of awake craniotomy for epilepsy surgery for an adolescent. The importance of patient selection and preoperative preparation is stressed. Anaesthetic management included regional scalp block and preincisional surgical infiltration of local anaesthetic and light sedation with propofol, fentanyl and midazolam. The patient remained responsive to voice for all but a small part of the procedure.

Adolescent↗
PubMed2000

Sudden unexpected death in epilepsy in Victoria.

Sudden unexpected death in epilepsy (SUDEP) refers to sudden unexpected death in patients with epilepsy in whom autopsy fails to reveal an anatomic or toxicological cause of death. The purpose of this study was to examine associated factors and mechanisms relating to SUDEP in Victoria. The study was a retrospective study based on data from questionnaires completed by treating doctors and coronial files including police reports of death, autopsy and toxicology reports. The deaths were of people with epilepsy in Victoria that were referred to the coroner between 1991 and 1997. There were 15,751 coronial autopsies of which 357 had epilepsy and 50 (14%) were SUDEPs. The SUDEP rate was approximately 1 per 3000 epileptics per year. This study suggested the following associations: young age, tonic-clonic seizures, seizure frequency greater than 10/year, duration of epilepsy greater than 10 years, mental retardation, psychiatric disease and alcohol abuse. Antiepileptic drug (AED) compliance was rated by treating doctors as good in 24 cases. One or more postmortem AED drug levels was subtherapeutic in 30 of 50 cases. Only 5 were receiving psychotropic drugs; only 1 of these was receiving more than one of these drugs. A history of recent unusually stressful life event was present in only 4 cases. At least 11 showed evidence of terminal seizure, and the majority of events occurred in sleep. These observations support the hypothesis that seizures are the mechanism of many cases of SUDEP. The associations observed were largely in agreement with previous studies. However, seizure frequency was greater and duration of epilepsy greater than most previous studies. The role of factors such as AED compliance, psychotropic drug prescription and recent unusually stressful life event is less clear. This highlights the need for case-control studies of risk factors for SUDEP.

Adolescent↗
PubMed1999

Clinical and imaging features of cortical malformations in childhood.

OBJECTIVE: To determine the types, relative frequencies, clinical features, and MRI characteristics of malformations of cortical development (MCD) occurring in a cohort of children referred to a tertiary pediatric center. METHODS: Original MR images were reviewed by two investigators, who were blinded to clinical details, to determine the elemental imaging features of each malformation and to label these malformations according to an existing system of classification. Clinical information was collected by a review of hospital records. RESULTS: A total of 109 children with MCD were identified. There were 58 boys and 51 girls, age 8 days to 18 years at initial imaging (mean age, 5 years). Seizures were present in 75%, developmental delay or intellectual disability in 68%, abnormal neurologic findings in 48%, and congenital anomalies apart from the CNS malformation in 18%. The main malformations identified were heterotopic gray matter (19%), cortical tubers (17%), focal cortical dysplasia (16%), polymicrogyria (16%), agyria/pachygyria (15%), schizencephaly/cleft (5%), transmantle dysplasia (5%), and hemimegalencephaly (4%). Eight patients had features of more than one malformation. Most lesions were multilobar (47%), with the frontal lobe being the most common lobe involved (78%). A total of 68% of patients had other cerebral malformations including ventricular dilatation or dysmorphism (46%) and abnormalities of the corpus callosum (29%). CONCLUSIONS: This study illustrates the spectrum of MCD in a pediatric cohort and highlights some of the differences between pediatric and adult patients. Patients with MCD presenting in childhood have a wider spectrum of malformations and more varied, often more severe, clinical manifestations. The lesions are frequently multifocal or generalized and many are associated with noncortical developmental brain anomalies.

Brain↗
PubMed1999

The impact of spinal cord injury on men's time use.

BACKGROUND: Despite evidence of the relationship between time use and health and well-being, and the World Health Organization's recognition of activity limitation as a measure of dis-ability, there has been limited investigation into the activity patterns of persons with disabilities. METHODS: Interviews and time diaries to provide preliminary descriptive and analytical information about the daily time use patterns of men with a spinal cord injury (SCI) living in the community (n=312) compared with the time use data of able-bodied men (n=3617) collected as part of the 1992 Canadian General Social Survey. The study also examined relationships between time use by men with SCI and selected factors (severity of disability and socioeconomic status). FINDINGS: Statistically different time use patterns between the SCI and able-bodied subjects. The men with spinal cord injury spent on average 7.2 h in leisure activities (able-bodied men=6.0 h); 4.7 (7.7) h in productivity; 3.7 (2.3) h in personal care; and 8.5 (8.0) h sleeping. The SCI men's lesser productivity time was accounted for largely by the lack of time spent in paid work. The average time use of the SCI sample showed the most time spent in passive leisure pursuits such as watching TV and listening to the radio. The sample rated their satisfaction with their time use as mediocre, but levels of adjustment to disability were moderate to high. Regression analysis revealed that severity of disability (lesion level, functional independence, environment) did not predict the amount of time spent in personal care, productivity, leisure, or sleep. Socioeconomic status had a mild predictive relationship with time allocation. IMPLICATIONS: The findings suggest men with SCI are socially isolated relative to their able-bodied peers. Recommendations are made and include both methodological considerations for further time use studies with persons with SCI, and policy recommendations. The latter focus on the need for rehabilitation, education and resources that go beyond functional independence such that persons with SCI can expand both their leisure and productivity roles and become better socially and economically integrated into society.

Activities of Daily Living↗
PubMed1998

Paroxysmal tonic upgaze: a reappraisal of outcome.

Paroxysmal tonic upgaze (PTU) of childhood is a distinctive neuro-ophthalmological syndrome of unknown etiology and pathogenesis that is characterized by episodes of sustained upward deviation of the eyes, often with incomplete downward saccades on attempted downgaze. It is generally regarded as having a benign outcome. We observed 16 children with PTU, from 10 months to 11 years from onset (mean, 5.4 years), to study the natural history and possible etiology. Five cases were from two unrelated families. Onset of PTU occurred either during or after an intercurrent infection or vaccination in 5 children. No antecedent was identifiable in the rest. PTU had completely resolved in 10 children (62%) (mean age at offset, 2.5 years), whereas 2 children intermittently manifest a modified form of the disorder. At follow-up, 11 children (69%) had developmental delay, intellectual disability, or language delay and 9 (56%) had ocular motility problems other than PTU. Only 3 children (19%) had normal development and neurological findings. PTU is a heterogeneous syndrome with respect to associations and outcome and may simply be an age-dependent manifestation of a variety of disorders affecting corticomesencephalic control of vertical eye movement. This disorder may be an early sign of more widespread neurological dysfunction.

Adolescent↗
PubMed1998

Cortical malformations: a significant cause of paediatric neurological morbidity.

Disorders of cortical development are a significant cause of epilepsy, developmental delay and congenital neurological deficits in children of all ages. Disruption of neuronal proliferation, differentiation, migration and organization during the middle trimester are recognized as the basis of most of these disorders. With advances in magnetic resonance imaging and increasing recognition of the characteristic radiological appearance of these lesions, a variety of lesions are now described. Furthermore, detailed clinical and genetic studies have lead to the recognition of clinicopathological syndromes of cortical maldevelopment with specific modes of inheritance. Our understanding of these disorders is increasing rapidly and will continue to do so with improvements in neuroimaging, advances in developmental neurobiology and heightened clinician awareness.

Brain↗