Neurologic defects are not exclusively seen among the patients of cerebrovascular accidents, CVA. This can also be observed on patients without CVA medical history. As reported, based on magnetic resonance imaging or MRI, 11% of cerebral damages were noted on non-CVA patients. On the other hand, the neurologic complications of the sickle-cell disease such as seizures, paralysis, and even death pose risk to affected individuals. However, the extent of cerebral defects brought by the disease can be hardly described due to the limited sampling designs of the researches conducted on this matter.
Hence, the Cooperative Study of the Sickle Cell Disease, CSSCD, carried out MRI brain assessment on children with ages of six years old and above with clinical records since their six-month old period (Moser et. al. , 1996). Results MRI techniques were employed on 312 subjects aged 6 to 14 years of whom 200 have sickle-cell anemia or Hb SS while 97 have Hb SC or sickle-cell disease. As such, 70 subjects have atrophy, ischemia or infarction lesions while a single Hb SS case with both hemorrhage and infarction was noted.
Among the 242 subjects who were diagnosed without any atrophy, ischemia or infarction, two were examined respectively with contusion and cerebellar arteriovenous defect. In addition, ischemia or infarction lesions were observed on 52 Hb SS patients and 3 Hb Sc patients. As well, 16 Hb SS patients were found with CVA medical history. Prior to MRI assesstment, CVA was experienced by Hb SS patients. Also, cerebral ischemia or infarction changes were observed in 17% additional Hb SS patients. Likewise, among Hb SC patients, 3% had lesions even without CVA background.
Furthermore, ischemia or infarctions were observed on both extensive and localized brain areas of the Hb SC patients. While localized lesions were seen in inner white matter, extensive lesions were detected on both inner white matter and in the cortical regions. On the other hand, the extensive lesions among Hb SS patients were detected on both inner white matter and on the cortical regions of temporal, frontal, and parietal lobes as the localized lesions were observed on the inner matter of the temporal, frontal and parietal lobes.
Still, cortical lesions were typically detected on subjects with CVA history denoting the association of the overt symptoms of the disease with the large-vessel vasculopathy than with the occurrence of lesions in the border zones. Nevertheless, cortical lesions in the absence of white matter were only observed on two patients who had CVA prior to MRI evaluation. Meanwhile, brain atrophy was detected on 35 subjects of whom 20 have ischemia or infarction lesions.
The brain atrophies of the 20 subjects were attributed to death of neurons with associated infarctions. However, the cause of the atrophy was still unknown and could only be hypothesized with ischemic injury. Cognitive Impairment in Children with Hemoglobin SS Sickle Cell Disease: Relationship to MR Imaging Finding and Hematocrit Introduction Silent infarction is the ischemic alteration on the brain tissues of the individuals, without medical stroke history, detected through MRI or magnetic resonance imaging.
This infarction is typically observed in cases of sickle-cell disease in children and has been correlated with the impairment in cognitive functions. Also, as showed by contemporary studies, the sickle-cell disease patients without any focal brain defect have been observed with cognitive impairments. Moreover, the cases of mild mental defects in a sample of sickle-cell disease patients, without medical stroke history, was increased by eleven folds while the hematocrit was postulated to be related to their respective IQ or intelligence quotient.
This signifies that the cerebral hypoxia due to sickle-cell disease directly affects cognitive functions among children. Hence, Steen, Miles, Helton, Strawn, Wang, Xiong and Mulhern (2003) conducted a study to determine the relationship between hematocrit and IQ among children with Hb SS or hemoglobin sickle-cell anemia by means of MRI techniques. Results Fourty-nine Hb SS patients, without medical stroke history, were chosen as subjects of this study.
The modified Wechsler scale was utilized for the evaluation of the cognitive attributes of the subjects while MRI techniques were employed for the assessment of hematocrit and brain structures. Then, the respective score of the subjects on Wechsler scale was correlated to their hematocrit data and MRI observations. As such, it was revealed that MRI data, even though were found as significantly related with the impairment of the cognitive functions the intervening effect of the brain injury, was also recognized.
Specifically, low hematocrit among children imparted greater cognitive impairment. Also, hematocrit and MRI brain features are both predictors of IQ among the subjects. Thus, cognitive impairment is brought by various factors as the cerebral hypoxia is crucial to the sickle-cell disease’s pathophysiology. Neurocognitive Development of Young Children with Sickle Cell Disease Through Three Years of Age Introduction
Children with sickle-cell disease are under the threat of neurocognitive defects due to infarction of the major arteries of the brain which resulted from the chronic state of the disease. This condition is directly correlated to a low scholastic performance because of the cognitive impairments brought by the disease as well as poor brain oxygenation. As estimated, about 5 to 10% of children with sickle-cell disease with ages below 15 years have infarctions in the central nervous system while around 16 to 22% children have silent infarctions.
In addition, children with medical stroke history experienced impairment of the cognitive functions while academic delays and mild cognitive defects were associated with children with mild cognitive defects. Thus, Thompson, Gustafson, Bonner, and Ware (2002) intended to extend the evaluation of neurocognitive attributes among children with sickle-cell disease from infancy to preschool level. Their study was anchored on the stress and cognitive processing parenting model. Results The subjects of their study were composed by 89 children with their parents from African-American families.
The psychomotor and cognitive attributes of the children were measured during their 6th, 12th, 24th and 36th month-old as their respective parents assessed the cognitive implications of psychological stress, stress, family functioning, and attributions. As such, Thompson, Gustafson, Bonner, and Ware (2002) found that as the children progress from infancy to preschool stage, a decreased in their cognitive functions were observed while their psychomotor attributes were not affected.
Further, low cognitive function during the 24th month-old of the children was ascribed with biomedical risk, parenting, and attributional style. On the other hand, 24% of the parents reported psychological stress, poor adjustment, and inadequate knowledge on the complications of the disease and child growth and development. Analysis and Conclusion Sickle-cell disease, a class of genetic disorders, is principally caused by the formation of sickle-cell hemoglobin or Hb S that affects normal blood flow leading to the injury of the ischemic tissues and the development of hemolytic anemia (Moser et.
al. , 1996). In connection to this, the brains of Hb SS patients are much prone to ischemic injury due to the sickle-cell obstruction on both small and large blood vessels and red-cell blockage resulting to infarctions in the border-zone fields. On the other hand, brain lesions in the border-zone fields can be attributed to cerebral vessels’ vasoocclusion or to the perfusion pressure’s fluctuations. As well, the hypovolemic or hypoxic incidence may possibly occur as perfusion pressure undergoes a transient decreased.
This episode is mostly ascribed with seizure, chest syndrome, sequestration problem, or aplastic (Moser et. al. , 1996). Further, endothelial hyperplasia along with occlusion and vessel stenosis are predictors of extensive infarctions which characterized the cerebral vasculopathy (Moser et. al. , 1996). While, the non-correlation of age with the lesions’ increased implied the development of lesion during childhood years, the increased of lesions with age, regardless of CVA history, indicate the progress of injury with time.
In addition, low hematocrit level causes greater cognitive impairments, thus, along with MRI brain features it directly predicts IQ level (Steen et. al. , 2003). Nonetheless, as the sickle-cell disease directly impairs the cognitive functions of infants and preschoolers, it does not affect the psychomotor development (Thompson, Gustafson, Bonner, and Ware, 2002). Therefore, the production of sickle-shape hemoglobin results to the obstruction of normal flow of the blood in cerebral arteries which results to the ischemic injury.
Then, the brain experiences insufficient blood circulation that leads to inadequate supply of oxygen and nutrients. These events eventually affect the metabolism of the neuron cells and the physiology of the whole brain, impairing cognitive functions. References Moser, F. G. , Miller, S. T. , Bello, J. A. , Pegelow, C. H. , Zimmerman, R. A. , Wang, W. C. , Ohene-Frempong, K. , Schwartz, A. , Vichinsky, E. P. , Gallagher, D. , and Kinney, T. R. (1996). The Spectrum of Brain MR Abnormalities in Sickle-Cell Disease: A Report from the Cooperative Study of Sickle Cell Disease.
American Journal of Neuroradiology, 17, 965-972. Steen, R. G. , Miles, M. A. , Helton, K. J. , Strawn, S. , Wang, W. , Xiong, X. , and Mulhern, R. K. (2003). Cognitive Impairment in Children with Hemoglobin SS Sickle Cell Disease: Relationship to MR Imaging Finding and Hematocrit. American Society of Neuroradiology, 24, 382-389. Thompson, R. J. , Gustafson, K. E. , Bonner, M. J. , and Ware, R. E. (2002). Neurocognitive Development of Young Children with Sickle Cell Disease Through Three Years of Age. Journal of Pediatric Psychology, 27 (3), 235-244.