Reduction of neuronal specific protein and some neurotransmitters in the infantile neuroaxonal dystrophy (INAD)

Infantile neuroaxonal dystrophy: diagnosis by skin biopsy

A child who shows progressive motor and mental deterioration after the first year of life, who has pyramidal signs, marked muscle hypotonia, but no seizures, suggests to have infantile neuroaxonal dystrophy (INAD). Beyond the age of two years, the EEG also entails characteristic findings. Diagnosis may be obtained by an ultrastructural examination of biopsied skin. The respective clinical and morphological findings are recorded and illustrated from four patients in this report.

Substructures of neurofilaments

The results of this investigation indicate that neurofilaments of mammals (human and rabbit) are composed of four protofilaments each of which is formed of globular units connected by longitudinal bars. A cross-view of neurofilaments reveals the presence of four globular units, 20-25 A in diameter, connected by four transverse bars, 25-30 A in length. Two of the transverse bars appear more electron-dense (darker) than the remaining two. A longitudinal view of neurofilaments shows two protofilaments bonded by the darker of the transverse bars to form a two-stranded band. The remaining two protofilaments form a band in a similar manner. The two two-stranded bands, wrapped helically, form a four-stranded neurofilament. The axial periodicity between twists along each neurofilament ranges from 200 A to 270 A. A three-dimensional diagram of neurofilament structure is presented.

Infantile neuroaxonal dystrophy in an albino girl. A cliniconeuropathologic study

We present a cliniconeuropathologic study of infantile neuroaxonal dystrophy (INAD) in a 5-year-old Black girl with albinism. The clinical picture shows progressive psychomotor deterioration, beginning after 1 year of age, with hypotonia, pyramidal signs, optic atrophy, and deafness. Light-microscopic examination of the brain reveals wide distribution of spheroids, cerebellar atrophy, and neuronal loss with astrocytosis. This is the first described case of the combination of INAD with albinism.

Aluminum-induced neurofibrillary changes in axons and dendrites

We examined the chronic effect of aluminum on the rabbit central nervous system (CNS) and documented the occurrence of axonal swellings (spheroids) and dendritic thickening in spinal cord neurons in addition to the accumulation of neurofibrillary material in the perikaryon. The axonal swellings always occurred at the first heminode, and the neurofilaments appeared disorganized, whereas in dendrites the neurofilaments generally retained their longitudinal arrangements. Although neurofibrillary tangles were present in cortical neurons, no axonal swellings were observed. Thickening of segments of apical dendrites proximal to the cell body affected by neurofibrillary changes was present. The axonal swellings resembled those observed in IDPN intoxication, and in amyotrophic lateral sclerosis, and may be useful as a model for studying these diseases.