What is the MRI signature of Alexander disease?

Type I (infantile): frontal-predominant white matter lesions with frontoparietal gradient, periventricular garland, and basal ganglia signal change; Type II (adult/juvenile): brainstem atrophy with dentate nucleus and posterior fossa predominance.

What GFAP mutation type determines phenotype severity?

De novo dominant GFAP mutations cause Type I infantile Alexander disease; Type II (adult onset) has more mutations throughout the gene; R79H is most common and causes Type I; mutations cluster around IF domains.

What are Rosenthal fibers and their diagnostic significance?

Rosenthal fibers are aggregates of GFAP protein in astrocyte foot processes; they are the pathological hallmark of Alexander disease; they can also be seen in other conditions (pilocytic astrocytoma, reactive gliosis).

What bulbar features occur in Type II Alexander disease?

Palatal myoclonus, dysarthria, dysphagia, nystagmus, and autonomic dysfunction are characteristic of adult-onset (Type II) Alexander disease, reflecting brainstem and cerebellar involvement.

Are seizures common in all forms of Alexander disease?

Infantile form has frequent and often refractory seizures (especially infantile spasms and tonic-clonic); adult-onset typically lacks significant epilepsy; seizure management is symptomatic with conventional AEDs.

Alexander Disease MRI Severity and Clinical Staging

Stages Alexander disease using MRI white matter abnormality severity score, Rosenthal fiber distribution, bulbar/brainstem dysfunction severity, and seizure burden to guide supportive care planning.

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Alexander Disease MRI Severity and Clinical Staging

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Frequently Asked Questions

What is the MRI signature of Alexander disease?

What GFAP mutation type determines phenotype severity?

What are Rosenthal fibers and their diagnostic significance?

What bulbar features occur in Type II Alexander disease?

Are seizures common in all forms of Alexander disease?