Biomedical subjects
Publications and source records attributed to D J Lacey.
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Status epilepticus (SE) is defined as a continuous seizure that lasts more than 30 minutes or as serial seizures in which the patient does not regain a premorbid level of consciousness. This condition exists primarily in two forms: convulsive (focal or generalized) and nonconvulsive (absence or partial complex) SE. Protracted or serial convulsive seizures represent a medical emergency with a current mortality rate of 10%. As in any urgent or life-threatening situation, the initial treatment is directed at support and maintenance of vital functions. Specific anticonvulsant management is usually begun with intravenous lorazepam. This benzodiazepine is replacing diazepam in many medical centers because it has a longer duration of action and causes less respiratory depression. Concurrent intravenous loading with phenytoin is usually necessary for sustained control of seizures. Phenobarbital may be required as a third drug if seizures persist or recur. In cases of refractory status epilepticus, barbiturate coma, continuous anticonvulsant intravenous infusion, or general anesthesia may be necessary.
A child born to a phenylketonuric (PKU) woman not on dietary treatment was microcephalic and had congenital heart and other physical anomalies consistent with the maternal PKU syndrome. After a repeat cardiac catherization at 3 months of age, he suffered an embolic left cerebral infarct and seizures. He was found by his mother dead in bed at 4 months of age; general autopsy revealed Klebsiella sepsis and pneumonia. Neuropathologic studies of the right cerebral hemisphere showed neuronal loss of the third cortical layer; Golgi studies revealed persistently immature cortical pyramidal cell somata and dendritic spines. This is the first report of specific neuronal abnormalities in a child with the maternal PKU syndrome and may, in part, account for the clinical features of microcephaly, mental retardation, and seizures seen in affected children.
Pregnant rats injected with phenylacetate produced pups who had structurally abnormal cortical pyramidal cell dendrites. Neurons whose perikarya were in layer 5 had apical dendritic arbors with reduced numbers of dendritic spines which were longer and thinner than controls. Pyramidal cells of other cortical layers, as well as hippocampal pyramidal cells, were qualitatively and quantitatively normal. These results may be pertinent to children born to mothers with hyperphenylalaninemia (untreated PKU), many of whom have microcephaly, seizures and mental retardation. Application of findings in this rat model of maternal PKU to affected human children is uncertain until human histologic data become available.
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Acquired movement disorders in children can present a diagnostic dilemma. Chorea, dystonia, and atypical seizures must be distinguished from simple or complex tics. The combination of chronic motor and vocal tics, Tourette syndrome, may in some children be associated with thought and behavioral disorders, sleep disturbances, headaches, and school difficulties (e.g., attention deficit disorder). The increasing numbers of children recognized as having Tourette syndrome, its broadening clinical spectrum and frequent familial nature are detailed in this review.
Although brainstem gliomas carry the worst prognosis of any brain tumor in children, with median survivals of 9 to 12 months, there may be a subgroup of long-term survivors. We have identified 12 children with brainstem gliomas, 5 of whom have survived greater than 6 years and 6 less than or equal to 12 months. Another child, alive and well 3 years following diagnosis, was considered in the long-term survivor group. Favorable prognostic factors included neurofibromatosis, symptoms greater than or equal to 12 months before diagnosis, calcification on CT, exophytic location, and pathology suggesting a low-grade tumor. Recognition that certain patients with brainstem gliomas may have prolonged survivals even in the absence of definitive treatment must be taken into consideration when new treatment regimens are being formulated.
EEGs were performed on 102 preterm low-birth-weight neonates within the first 7 days of life. Babies were later separated into those without intracranial hemorrhage, those who had only subependymal hemorrhage (SEH), and those with intraventricular/intracerebral hemorrhage. The incidence and types of EEG abnormalities, 42% overall and including positive rolandic sharp waves, did not differ in the three groups. The incidence and distribution of EEG abnormalities between groups were not influenced by perinatal events. Developmental follow-up of 73 patients was similarly not correlated with neonatal EEG results, although the most severe EEG abnormalities were associated with subsequent mortality or morbidity.
Increased numbers of apical dendritic spines are present on hippocampal CA1 pyramidal cells in rats injected with phenylacetate from 2 to 21 days of life if animals are sacrificed at 20-30 days. However, if sacrificed at 60-90 days, spine counts are not significantly different from saline injected controls. These results suggest that this increased spine density at 3-4 weeks represents retardation of normal maturational spine loss rather than an actual hyperplasia, and is reversible upon termination of the phenylacetate injections. Implications for human pathologic series of phenylketonuria are discussed.
Forty children with partial agenesis of the corpus callosum have been prospectively identified and followed up for up to 15 years. Additional physical anomalies and diagnoses were frequent. At the time of diagnosis, the majority of children were developmentally delayed or retarded. If callosal agenesis was diagnosed during infancy, most children had or subsequently developed seizures. Older patients had a more favorable outcome and were less likely to develop epilepsy.
An increased concentration of dendritic spines was present in one region of the hippocampus in rats made hyperphenylalaninemic (phenylketonuria model). It is uncertain whether this finding resulted from an actual hyperplasia or a failure of maturational spine reduction. The result is unusual in that Golgi studies of most mental retardation syndromes and relevant animal models have shown loss of dendritic spines.
In an infant with Gaucher's disease, brainstem auditory evoked responses were abnormal on three separate occasions. Only waves I and II were typically present at standard intensity settings, although a third peak was elicited at 88 dB. Histologic studies demonstrated absence of neurons in the cochlear nuclei and a hypoplastic superior olivary complex. This neurophysiologic-pathologic correlation supports contentions that both brainstem auditory evoked response (BAER) waves I and II arise from the auditory nerve and that it may be capable of generating additional peaks.
We report on an autosomal dominant neonatal-infantile seizure disorder and offer criteria for establishing the diagnosis and guidelines for the evaluation and treatment of this disorder. Long-term anticonvulsant treatment usually is not required. The subsequent risk of a recurrent seizure disorder depends on whether other affected relatives developed a seizure disorder later in life. This disorder may have at least two different neonatally indistinguishable forms: one having an increased empiric risk (20%) of subsequent epilepsy, and a second which carries no increased risk. These familial neonatal-infantile seizures are termed "benign" since they are not associated with subsequent psychomotor retardation.
Electroencephalograms during light sleep were performed in controls and in infants with near-miss sudden infant death syndrome, in siblings of such infants, and in infants with recurrent apnea, all from 2 to 8 months of age. EEG background and multiple sleep spindle characteristics were compared for individual children in each of these groups. From 2 to 6 months of age, but not later, all at-risk groups differed from controls by the presence of excessive variability of sleep spindle frequency during sleep recordings. However, the three groups at risk for SIDS did not significantly differ from each other. It is concluded that careful analysis of routine sleep EEGs may in some cases help differentiate young infants at risk for apnea or SIDS from normal children.
The neuropathological and general pathological features of intraventricular hemorrhage are described in 32 neonates who had been born at term. Although the most common site of bleeding was the choroid plexus, a significant minority occurred in the subependymal germinal matrix. Associated neuropathological findings included meningeal venous congestion, periventricular white-matter necrosis and subarachnoid hemorrhage. Pulmonary hemorrhages, hyaline membranes and congenital heart-defects were common. Most of the infants had low Apgar scores at birth and lived for less than two days. Significant neurological findings included hypotonia, hyporeflexia, decreased activity level and seizures. Clinical signs had not been reliable enough to differentiate distressed neonates with intraventricular hemorrhage from those without. Intraventricular hemorrhage should be considered in both term and premature neonates who sustain perinatal asphyxia or who later develop evidence of neurological deterioration.
The hippocampus of the fence lizard (Sceloporus undulatus) is composed of two laminated regions that are readily distinguishable on the basis of position and perikaryal size in Nissl preparations: the small-celled (Hsc) and the large-celled (Hlc) hippocampal divisions. Based upon cellular and fibrillar characteristics, the layers of the Hsc are: (1) the superficial plexiform layer; (2) the cellular layer; (3) the deep plexiform layer; (4) the layer of deep fibers, or alveus; and, (5) the ventricular ependyma. The layers of the Hlc are: (1) the tangential layer; (2) the molecular layer; (3) the pyramidal layer; (4) the deep plexiform layer; (5) the alveus; and, (6) the ventricular ependyma. The neurons of each hippocampal layer were grouped into classes based upon somal position and appearance, and dentritic and axonal arborization patterns in Golgi sections. Neurons of the Hsc are more numerous and pleomorphic than those of the Hlc. Data do not suggest an intrinsic organization that closely parallels that found in the mammalian hippocampus.
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