Cognitive Deficits and MRI in Sickle Cell Disease

J Gordon Millichap
1999 Pediatric Neurology Briefs  
brain tumor surgery should be avoided when possible, especially if cranial irradiation is planned. In a randomized prospective study of carbamazepine or phenytoin in 276 post-craniotomy patients, 37% suffered at least 1 seizure during a 6-24 month trial period, and the incidence of status epilepticus in the first week following surgery was higher in AED-treated patients than in untreated controls (8% cf 2%). The occurrence of seizures in the first post-operative week did not increase the
more » ... increase the likelihood of late epilepsy. Acute allergic skin rashes occurred in 13% of patients The risk of subtle brain abnormalities in children with sickle cell disease (SCD) and their relationship to blood hematocrit was determined by prospective comparison of 50 patients and 52 controls studied at St Jude Children's Research Hospital, Memphis, TN. Using quantitative magnetic resonance imaging to measure T1 (spin-lattice relaxation time) in basal ganglia, and the Wechsler test of intelligence, patients by age 4 years showed a significantly lower T1 (evidence of structural changes at the cellular level) in basal ganglia and cortex, but not in white matter, and mild mental deficiency (IQ, 50-70) in 33%, compared to a published prevalence of 1.45% in controls. Routine conventional MRIs were read as normal. Both the subtle T1 abnormalities on MRI and cognitive deficits were associated with a low hematocrit (Hct). Patients with an Hct of less than 27% had significantly lower IQ, scores and significantly lower gray matter Tl, than those with an Hct >27%. SCD was associated with a 23-fold increase in risk of mild mental deficiency. (Steen RG, Xiong X. Mulhern RK, Langston JW, Wang WC. Subtle brain abnormalities in children with sickle cell disease: relationship to blood COMMENT. Young children with sickle cell disease and low hematocrits are at risk of subtle brain abnormalities, only detected by quantitative MRI, and complicated by mild mental deficiency. Brain hypoxia is proposed as the mechanism of this subtle brain damage demonstrated in patients with SCD who are spared more obvious brain pathology, including stroke. Psychometric tests of intelligence can be more sensitive to subtle neurological abnormalities than conventional MRI scanning in SCD. In the absence of quantitative MRI, the Wechsler IQ, test should be used routinely to follow children with SCD, not affected by stroke. The authors suggest that aggressive prophylactic therapy should be considered for possible prevention of brain damage and cognitive impairments in young children with SCD. In an Editorial in the same issue, Dr GJ Dover of Johns Hopkins University School of Medicine discusses the progressive nature of the neuropathology of SCD (Ann Neurol March 1999;45:277-8). Steen and associates, in the present article, demonstrate the earliest detectable evidence of diffuse tissue hypoxia in the gray matter, as measured by quantitative MRI and IQ, tests. Heretofore, the progression of brain pathology in SCD was documented in three ways: 1) subclinical largevessel occlusion shown by Doppler; 2) clinical and subclinical infarcts seen on CT/MRI radiographic imaging; and 3) increased incidence of massive intracranial 23
doi:10.15844/pedneurbriefs-13-3-10 fatcat:qfocwbhphjeelgyb7yqoelmihe