Ultrastructural findings of peripheral nerve in a preclinical case of adult metachromatic leukodystrophy.

In a 13-year-old neurologically healthy boy from a family with adult-onset of metachromatic leukodystrophy (MLD) showing arylsulfatase A-deficiency in the adult, sural nerve biopsy probably was performed 2-3 decades before clinical manifestation of the disease could be expected. Ultrastructurally 4 basic types of inclusion bodies in Schwann cells could be demonstrated (pleo-morphic "zebra body"-like inclusions, double-lamellated inclusions, "tuff-stone"-like inclusions, granular osmiophilic inclusions). Additionally, endoplasmatic reticulum, mitochondria and lysosomes showed marked alterations. Advanced damage of myelin was only rarely seen, but initial segmental demyelination was a common finding. These early pathological changes in chronic MLD are thought to represent a subcellular metabolic insufficiency of Schwann cells in this disease.