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Neurophysiology and MRI in late-infantile metachromatic leukodystrophy
D I Zafeiriou1, E E Kontopoulos, H M Michelakakis
1First Pediatric Clinic, Aristotle University of Thessaloniki, Greece.
Abstract:
We present serial clinical, radiologic, and neurophysiologic findings of a patient with late-infantile metachromatic leukodystrophy who was first admitted at 30 months of age because of gait disturbance. The neurologic findings were consistent with mild spastic diplegia (occasionally with toe walking). Magnetic resonance imaging disclosed diffuse high intensity in the cerebral white matter on T2-weighted images. Nerve conduction velocity studies and evoked-potential studies were markedly abnormal. Assay of arylsulfatase A activity in leukocyte culture disclosed a marked deficiency of the enzyme, confirming the diagnosis of late-infantile metachromatic leukodystrophy. Serial neurophysiologic studies demonstrated a marked decrease of nerve conduction velocities, both motor and sensory, as well as prolongation or disappearance of brainstem auditory-, visual-, and somatosensory-evoked potential latencies. Magnetic resonance imaging studies revealed initially diffuse increased signal intensity of periventricular and subcortical white matter on T2-weighted images, progressing to cortical atrophy with involvement of the arcuate fibers and the cerebellar white matter, correlating with the clinical deterioration (severe spastic tetraplegia with optic atrophy and epilepsy).
Insights
Late-infantile metachromatic leukodystrophy (MLD) presents with gait issues and abnormal neurophysiology. Early diagnosis via enzyme assays and MRI is crucial for managing this progressive white matter disorder.
Area of Science:
- Neurology
- Biochemistry
- Medical Imaging
Background:
- Late-infantile metachromatic leukodystrophy (MLD) is a rare genetic disorder affecting the white matter of the brain.
- It is caused by a deficiency in the enzyme arylsulfatase A, leading to the accumulation of sulfatides.
- Early diagnosis and understanding disease progression are critical for patient management.
Observation:
- A patient presented at 30 months with gait disturbance, progressing to spastic diplegia.
- Clinical course showed deterioration to severe spastic tetraplegia, optic atrophy, and epilepsy.
- Serial neuroimaging and neurophysiologic studies tracked disease progression.
Findings:
- Magnetic resonance imaging (MRI) revealed diffuse white matter hyperintensities on T2-weighted images, progressing to cortical atrophy.
- Nerve conduction velocity studies showed markedly reduced motor and sensory nerve conduction.
- Evoked potential studies demonstrated prolonged or absent latencies in brainstem auditory, visual, and somatosensory pathways.
- Leukocyte arylsulfatase A assay confirmed a marked enzyme deficiency, diagnosing late-infantile MLD.
Implications:
- This case highlights the utility of serial clinical, radiologic, and neurophysiologic assessments in diagnosing and monitoring MLD.
- Neuroimaging and neurophysiological findings correlate with clinical deterioration, aiding in prognosis.
- Understanding the natural history of MLD through such case studies is vital for developing therapeutic strategies.