MRI in Pediatric Inherited Neurodegnerative Changes

Pediatric inherited neurodegenerative diseases are non-homogenous group of diseases caused by inborn errors of metabolism (IEMs) that mainly impact the central nervous system. They typically affect newborns and infants . Genetic defects causing specific enzyme deficiencies that lead to deficiency or toxic accumulation of essential metabolites with specific biochemical and molecular abnormalities are the cause of these diseases .

Inborn errors of metabolism are uncommon, which leads to a lack of experience for most neuroradiologists to diagnose these disorders easily. Moreover, most of these disorders manifest in nonspecific manner, creating a diagnostic difficulty for pediatricians, neurologists, and geneticists .

Clinical presentation may be confusing and potentially lead to a delay in the diagnosis and treatment. Incidence of these disorders may vary from one region to another, being higher in communities with consanguineous marriages, ranging from 1.2 to 2 per 100,000 live births. Most exhibit an autosomal recessive mode of inheritance and fewer exhibit an X-linked mode of inheritance.

Multiple methods can be used to classify neurometabolic diseases according to their clinical presentation, biochemical features, impacted cellular organelle, or involved location of the brain.

As a non-invasive means, neuroimaging approaches play a major role in increasing diagnostic accuracy and patient follow-up in IEM by assessing the timing, degree, reversibility, and brain injury.

Imaging based classification includes leukodystrophy (primary involvement of white matter due to genetic abnormality), leukoencephalopathy (secondary involvement of white matter either due to genetic or acquired systemic disorder), poliodystrophy (predominant involvement of grey matter), and pandystrophy (mixed involvement of both white and grey matter).

White matter of the central nervous system is usually affected due to many pathological processes such as delayed myelination (myelin maturation delayed for expected age), hypomyelination (scarcity of myelin or arrest in myelination process), dysmyelination (deposition of abnormally composed fragile myelin), demyelination (secondary loss of myelin that may have been previously normal) and myelinopathy (vacuolation due to deranged brain iron and water hemostasis).

The preferred method for evaluating pediatric inherited neurodegenerative disorders is magnetic resonance imaging (MRI). Examining MRI patterns and clinical indicators aids in narrowing the differential and customizing further laboratory (focused metabolomics) or genetic research.

Magnetic resonance imaging (MRI) can be useful and even crucial for prompt treatment before the receipt of expensive and time-consuming results from genetic or biochemical tests.

Inclusion criteria

• Patients with clinical suspicion of neuro-developmental delay and metabolic disease consulted for or referred to pediatric neurology.
• Patients known to have inherited neurodegenerative diseases under follow-up.

Exclusion criteria

• Patients with prior histories of perinatal ischemia or stroke, hypoxic-ischemic encephalopathy, birth trauma or accident, or known systemic diseases (congenital heart disease, renal failure, or autoimmune disorders) will be excluded.