Mental retardation and seizure disorder in Schimke immunoosseous dysplasia

Mechanisms of cognitive dysfunction in CKD

Cognitive impairment is an increasingly recognized major cause of chronic disability and is commonly found in patients with chronic kidney disease (CKD). Knowledge of the relationship between kidney dysfunction and impaired cognition may improve our understanding of other forms of cognitive dysfunction. Patients with CKD are at an increased risk (compared with the general population) of both dementia and its prodrome, mild cognitive impairment (MCI), which are characterized by deficits in executive functions, memory and attention. Brain imaging in patients with CKD has revealed damage to white matter in the prefrontal cortex and, in animal models, in the subcortical monoaminergic and cholinergic systems, accompanied by widespread macrovascular and microvascular damage. Unfortunately, current interventions that target cardiovascular risk factors (such as anti-hypertensive drugs, anti-platelet agents and statins) seem to have little or no effect on CKD-associated MCI, suggesting that the accumulation of uraemic neurotoxins may be more important than disturbed haemodynamic factors or lipid metabolism in MCI pathogenesis. Experimental models show that the brain monoaminergic system is susceptible to uraemic neurotoxins and that this system is responsible for the altered sleep pattern commonly observed in patients with CKD. Neural progenitor cells and the glymphatic system, which are important in Alzheimer disease pathogenesis, may also be involved in CKD-associated MCI. More detailed study of CKD-associated MCI is needed to fully understand its clinical relevance, underlying pathophysiology, possible means of early diagnosis and prevention, and whether there may be novel approaches and potential therapies with wider application to this and other forms of cognitive decline.

Reversible Cerebral Vasoconstriction Syndrome: A Novel Mechanism for Neurological Complications in Schimke Immuno-osseous Dysplasia

BACKGROUND

Schimke immuno-osseous dysplasia is a rare autosomal recessive disease resulting from biallelic SMARCAL1 mutations. It presents in early childhood and is characterized by short stature, nephropathy, and immunodeficiency. Approximately 50% of those affected have neurological complications including migraines, transient ischemic attacks, and strokes.

METHODS

We present a six-year-old boy with Schimke immuno-osseous dysplasia without evidence of atherosclerosis with recurrent episodes of severe headache, fluctuating hemiparesis, and aphasia.

RESULTS

Magnetic resonance imaging and angiography were normal during the initial episode; multiple areas of reversible restricted diffusion with decreased perfusion and arterial stenosis were seen with subsequent attacks.

CONCLUSIONS

This constellation of symptoms and imaging findings is suggestive of reversible cerebral vasoconstriction syndrome, which we propose as a mechanism for the transient ischemic attacks and infarcts seen in some patients with Schimke immuno-osseous dysplasia, as opposed to accelerated atherosclerosis alone. This new insight may provide a basis for novel preventative therapy in this rare disorder.

Primary immunodeficiency diseases associated with neurologic manifestations

Primary immunodeficiency diseases (PID) are a heterogeneous group of inherited disorders of the immune system, predisposing individuals to recurrent infections, allergy, autoimmunity, and malignancies. A considerable number of these conditions have been found to be also associated with neurologic signs and symptoms. These manifestations are considered core features of some immunodeficiency syndromes, such as ataxia-telangiectasia and purine nucleoside phosphorylase deficiency, or occur less prominently in some others. Diverse pathological mechanisms including defective responses to DNA damage, metabolic errors, and autoimmune phenomena have been associated with neurologic abnormalities; however, several issues remain to be elucidated. Greater awareness of these associated features and gaining a better understanding of the contributing mechanisms will lead to prompt diagnosis and treatment and possibly development of novel preventive and therapeutic strategies. In this review, we aim to provide a brief description of the clinical and genetic characteristics of PID associated with neurologic complications.