Infantile Neuroaxonal Dystrophy or Seitelberger’s Disease

Neuroaxonal dystrophy in infantile alpha-N-acetylgalactosaminidase deficiency

Morphologic alterations in biopsies of central and peripheral nervous tissue were investigated at the light-and electron-microscopic level in the first cases of lysosomal alpha-N-acetylgalactosaminidase deficiency. Widespread spheroid formation was observed in terminal and preterminal axons. Neocortical and peripheral autonomic axons contained tubulovesicular and lamelliform membranous arrays, prominent acicular clefts, and electron-dense axoplasmic matrix, the typical ultrastructural abnormalities corresponding to axonal spheroids in many inherited and acquired axonopathies. Central and peripheral membranous distal axonal spheroids were the only neuropathologic abnormality identified; other alterations resembling those in various neuronopathic lysosomal storage diseases were not observed. The morphologic findings and the distribution of the lesion in the present disorder are remarkably similar to those reported in the inherited infantile form of neuroaxonal dystrophy with normal alpha-N-acetylgalactosaminidase activity (Seitelberger disease).

Neuroaxonal dystrophy at birth with hypertonicity and basal ganglia mineralization

A full-term male infant exhibited rigidity of all extremities with hyperreflexia beginning soon after birth and lasting until his death at age 6 months. Head circumference remained at the 25th to 50th percentile. Distinct sleep-wake cycles and responsiveness to visual, auditory, and tactile stimuli developed. Metabolic studies, skin biopsy, electroencephalography, and electromyography produced normal results. Head computed tomographic and magnetic resonance imaging scans revealed mineralization of the basal ganglia and thalamus. Muscle and nerve biopsy results were consistent with axonal dystrophy. Autopsy showed widespread neuronal loss, with reactive gliosis, marked in the globus pallidus and brainstem reticulate core; spheroids in globus pallidus, nucleus cuneatus, and upper cervical cord; and mineralized neurons in the inner division of globus pallidus and thalamus. Neonatal hypertonia, rapid progression, and mineralization of the basal ganglia are unusual features of neuroaxonal dystrophy exhibited in this case.

Pathology of skeletal muscle and intramuscular nerves in infantile neuroaxonal dystrophy

Biopsies of the biceps muscle and sural nerve were taken from a girl aged 2 years with infantile neuroaxonal dystrophy (INAD). In addition to the typical axonal spheroid bodies in a number of the i.m. nerve fibers, the neuromuscular junctions (NMJs) and motor nerve endings also contained axonal swellings. The sural nerve, except for three dystrophic fibers, was almost completely normal. A teased nerve preparation showed four additional abnormal fibers with focal axonal enlargement similar to those in giant axonal neuropathy (GAN). These results suggest that a biceps muscle biopsy may be more useful than a sural nerve biopsy for the diagnosis of INAD, because the muscle contains abnormal peripheral nerves and NMJs in high frequency.

Diagnosis of infantile neuroaxonal dystrophy by skin biopsy

Skin biopsy with ultrastructural examination of cutaneous nerves showed dystrophic axons (spheroids), confirming a diagnosis of infantile neuroaxonal dystrophy. Independent of axonal changes, a few endoneurial and Schwann cells showed cytoplasmic inclusion bodies composed of structures similar to those seen in the spheroids.

Infantile neuroaxonal dystrophy and giant axonal neuropathy: are they related?

Light and electron microscopic findings from two sural nerve biopsies obtained at a one-year interval from a patient with the clinical features of Seitelberger's disease are described. Ballooned axons with accumulations of membranous profiles, vesicles, mitochondria, and a homogeneous center were present, and there were masses of 90 A filaments in endothelial, endoneurial, perineurial, and Schwann cells. These pathological alterations were less prominent in the second nerve biopsy, which showed a more pronounced decrease in myelinated fibers. The case shows that a generalized increase of 90 A filaments in structures of the peripheral nervous system is not a phenomenon exclusively occurring in patients with giant axonal neuropathy and, furthermore, that it may be a transitory feature.

Morphological investigations on axonal swellings and spheroids in various human diseases

Axonal swellings and spheroids in various human diseases were studied by light and electron microscopy. 4 cases of infantile neuroaxonal dystrophy, 2 of degenerative diseases, 2 brain tumors and 3 of cerebrovascular disease were examined. Ultrastructurally most spheroids in infantile neuroaxonal dystrophy consisted of interconnected tubules, stacked membranotubular profiles, alternating layered membranes and accumulations of neurofilaments. Combinations of these four constituents were seen only in infantile neuroaxonal dystrophy. "Torpedos" (fusiform swelling of the axon of a Purkinje cell) consisted exclusively of neurofilaments. Spheroids in case 6 (mental retardation) and 7 (atypical teratoma) consisted of interwoven skeins of neurofilaments and grouped mitochondria. Spheroids in case 8 (demyelination) and 9 (cerebrovascular disease) consisted of packed complex bodies and mitochondria. Spheroids in cases 10 and 11 (cerebrovascular disease) consisted of degenerating organelles only. The morphological differences between cases 9, 10 and 11 probably depends on the severity and timing of the cerebral injury. Most spheroids show similar histological and histochemical properties, but ultrastructural study may give some clue to the origin of the bodies.

Juvenile neuroaxonal dystrophy: clinical, electrophysiological, and neuropathological features

We describe 2 brothers with progressive myoclonus epilepsy that began in the second decade and was associated with cerebellar ataxia and intellectual deterioration. Electroencephalographic and cerebral evoked potential studies showed findings associated with myoclonus epilepsy. Neuropathological examination of 1 of the brothers, who died at age 23 years, revealed widespread changes of neuroaxonal dystrophy without pigment deposition in the basal ganglia. We propose the term juvenile neuroaxonal dystrophy (JNAD) to distinguish this condition on clinical grounds from infantile neuroaxonal dystrophy on the one hand, and on clinical and pathological grounds from Hallervorden-Spatz disease on the other hand. JNAD, while exceedinly rare, must be considered in the differential diagnosis of the progressive myoclonus epilepsies.