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Byline: Asma Jabeen, Nazia Dildar, Bushra Nayyar and Sara Khan


Objective: To specify the value of brain MRI in the diagnostic workup of unexplained mental retardation/delayed milestones in children.

Study Design: A descriptive study.

Place and Duration of Study: Armed Forces Institute of Radiological Imaging, Rawalpindi from, October 2013 to March 2014.

Material and Methods: This study included 100 patients of both sexes from 2-10 years of age, who presented with delayed milestones /mental retardation, where no etiological diagnosis could be made following clinical examination and preliminary investigations. MRI machine 1.5 Tesla was used.

Results: One hundred children were included in the study. Age range of patients was 2-10 years with average age of 5.24 years (SD = 2.48). Majority of patients were males i.e. 60%. Radiological study was normal in 33% patients. Major radiological diagnosis was leukodystrophy in 30% patients followed by cerebral atrophy in 16% patients, congenital malformation in 15% patients and non specific findings in 6% patients. Comparison of radiological diagnosis between both the gender and age groups was done. It was noted that leukodystrophy occurs with equal frequency in both male and female children. However in cases of cerebral atrophy and congenital malformations males were affected more than females. In cases of cerebral atrophy 10% were female and 20% were male children. While in children with congenital malformations 3% were female and 20% were male. Age wise comparison shows that leukodystrophy is mostly seen in children between ages of 2-7 years.

Whereas cerebral atrophy and congenital malformations occur almost involving all age groups.

Conclusion: MRI is an important part of the comprehensive evaluation of children with developmental delay, as many specific etiologic and pathophysiologic conditions that lead to developmental delay can be detected easily. However, children with mild neuro developmental delay frequently have normal brain MRI examination. This article is going to highlight importance of MRI as imaging modality of choice.

Keywords: Developmental delay, Leukodystrophy, Magnetic resonance imaging.


Developmental delay/mental retardation are common, affecting 1-3% of the population1. It is defined as an incomplete or insufficient general development of mental capacity with sub average intellectual functioning (IQ less than 70)2. Others however call it as a significant delay (more than two standard deviations below the mean) in one or more of the following developmental domains3.

Gross motor, Vision and fine motor, Hearing, speech and language, Social, emotional and behavioral, Developmental delay is a descriptive term used for children whose difficulties are apparent earlier in childhood, where a cause is not yet established4. It does not imply a particular organic or syndromic cause. Early identification of affected children is important so that they may benefit from early intervention programs. An additional goal in the evaluation of developmental delay in children is the determination of a specific cause for disability5,6. This can provide information regarding the possible pathogenesis and prognosis. Several studies suggest that a definite cause for developmental delay can be identified in 40-60% of all patients undergoing evaluation7. Multiple etiological factors including prenatal, perinatal and postnatal are involved.

Therefore the history of pregnancy, labour and delivery has to be investigated for clues of both intrinsic and extrinsic influences on the fetus and infant development8,9.

We conducted this study to determine the diagnostic yield of MRI in a cohort of children with developmental delay of unknown origin.


This descriptive study was conducted in Armed Forces Institute of Radiological Imaging; Rawalpindi in collaboration of pediatric department.Duration of study was 6 months with effect from October 2013 to March 2014. MRI brain was done in 100 children. Patients of both genders ranging from 2 to 10 years, with delayed milestones, where no etiological diagnosis could be made were included in the study. Cases with known history of CNS malformation, like meningitis, encephalitis, obvious malformations like hydrocephalus and recognized syndromes, known to cause developmental delay/ mental retardation were excluded from the study. Patients were included in the study through non probability convenience sampling. The decision to perform MRI evaluation was based on the clinical judgment of the referring pediatrician.

Table-1: Gender-wise comparison of radiological diagnosis of patients (n=100).

Radiological diagnosis###Female (n=40)###Male (n=60)###p-value

Normal study###16 (40%)###17 (28.3%)###0.224

Leukodystrophy###15 (37.5%)###15 (25%)###0.181

Cerebral Atrophy###4 (10%)###12 (20%)###0.181

Congenital Malformation###3 (7.5%)###12 (20%)###0.086

Nonspecific findings###2 (5%)###4 (6.7%)###0.731

Table-2: Age-wise comparison of radiological diagnosis of patients (n=100).

Radiological diagnosis###less than 5 years###5 - 7 years###> 7 years###p-value


Normal study###13 (31%)###14 (36.8%)###6 (30%)###0.813

Leukodystrophy###14 (33.3%)###14 (36.8%)###2 (10%)###0.087

Cerebral Atrophy###8 (19%)###3 (7.9%)###5 (25%)###0.187

Congenital Malformation###4 (9.5%)###7 (18.4%)###4 (20%)###0.421

Nonspecific findings###3 (7.1%)###0 (0%)###3 (15%)###0.067

MRI studies were carried out in AFIRI in 1.5 Tesla MR Unit. The children were sedated. The following protocol was used. T1WI axial, coronal and sagittal images, T2WI axial coronal and sagittal images and axial fluid attenuated inversion recovery FLAIR. The slice thickness was 5-6 mm on axial images and 3mm on coronal plane. The interspace gap varies from 0.3-0.6 mm. The field of view varied from 18-24 cm. The images on the coronal plane were oriented perpendicular to the hippocampus. All MRI were reported by the same radiologist.

All data collected had been analyzed using SPSS version 10. Descriptive statistics were used to describe the results.Chi square test was applied to compare radiological diagnosis between gender and between age groups. A p-value less than 0.05 was considered as significant.


One hundred children were included in the study. Age range of patients was 2 - 10 years with average age of 5.24 years (SD=2.48). Majority of patients were males i.e. 60%. Radiological study was normal in 33% patients. Major radiological diagnosis was leukodystrophy in 30% patients followed by cerebral atrophy in 16% patients, congenital malformation (agenesis of corpus callosum, hydrocephalus, dandy walker variant, cerebral aqueduct stenosis etc) in 15% patients and nonspecific findings (basal ganglia calcifications, arachnoid cysts, hemorrhagic infarct) in 6% patients. (Figure) comparison of radiological diagnosis between both the gender and age groups is shown in table-1 and table-2. Radiological diagnosis was similar between both the gender as well as between age group with insignificant difference.


The aim of investigating a child with mental retardation or developmental delay is to reach etiologic diagnosis. Though not always diagnostic, neuroimaging provides useful diagnostic information in a relatively high percentage of retarded children, where no other diagnostic clue is available11, 12. The sensitivity of neuroimaging in this study with a 66% rate of positivity exceeds that of other lab tests. These findings are comparable to those of study of Soto Ares who reported a 50% positivity of MRI in idiopathic developmental delay13. This can be attributed to the versatility of imaging in providing diagnostic information about a variety of conditions associated with abnormal morphology, structural malformation, metabolic disorders, vascular or infective insults14, 15.

In this study the most common finding was leukodystrophy i.e 30%, which is comparable to the study carried out by J. L. Bonkowsky where incidence of leukodystrophy was 26%16. The radiological findings in almost all of these patients was bilateral symmetrical confluent areas of signal change in periventricular white matter with sparing of subcortical U-fibers, which appear low on T1WI, high on T2WI and FLAIR sequence with usually no enhancement. However three patients showed a linear punctate enhancement pattern within the lesion. Leukodystrophies are disorders which are characterized by the progressive destruction of myelin owing to the accumulation of various catabolize depending on the specific enzyme deficiency. Children often present clinically with progressive mental or motor deterioration. Although most of these conditions are not treatable, establishing a diagnosis is valuable in providing a prognosis and enables parental genetic counseling.

The second most common causative factor for mental retardation was cerebral atrophy. It includes both cases with generalized cerebral atrophy and front temporal atrophy. One patient also had cerebellar atrophy. Findings which suggest cerebral atrophy was dilatation of intra and extra cerebral CSF spaces. Though very nonspecific generalized cerebral atrophy is also a feature of some metabolic disorders and its presence warrants a proper work up for a metabolic cause17,18.

Third group was of congenital malformations which include pachygyria, holoprosencephaly, dandy walker variant, hydrocephalus and agenesis of corpus callosum. Six out of hundred patients had nonspecific findings like basal ganglia calcifications.

The application of neuroimaging does not facilitate any specific management in the retarded children, nor does it alter the patient's developmental status. Nevertheless, it is immensely useful in providing valuable information regarding an etiological basis for retardation18,19. This greatly helps the clinician in counseling the concerned families. In addition an etiologic diagnosis provides for a more accurate prognosis20,21. In the present study, after neuroimaging, the positive results help the families in finding some solace that there was some physical factor in the brain beyond their control that accounted for this lifelong problem. Finding causes help them to accept the problem better and stop their efforts for diagnosis and pay more attention to training.


It is recommended that if an etiologic diagnosis is not readily apparent after a detailed history, examination and initial investigations, magnetic resonance imaging should be the standard clinical practice for a child with global developmental delay. MRI can easily detect many specific etiologic and pathophysiologic conditions that lead to mental retardation which will greatly help the clinician.


This study has no conflict of interest to declare. Abstract and results of this study were accepted and presented in an oral presentationat the International conference on Medical Education, organised by Association for Excellence in Medical Education(AEME) and held on 07th-09th March 2014 at University of Health Sciences(UHS) Lahore, Pakistan. No funding was received from any agency or institution.


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Publication:Pakistan Armed Forces Medical Journal
Article Type:Report
Date:Jun 30, 2016

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