S. Izumo

The clinical and pathological features of peripheral neuropathy accompanied with HTLV-I associated myelopathy

We describe the clinical and pathological studies in HTLV-I associated myelopathy (HAM)/tropical spastic paraparesis (TSP) patients with peripheral neuropathy as proven by sural nerve biopsy. Sural nerve pathology in HAM/TSP patients revealed that the most common type of pathologic change is a combination of both demyelination and remyelination and axonal degeneration and regeneration, and this change is modified by the complications. The pathologic changes were correlated with neither the duration of disease nor human T lymphotropic virus type I (HTLV-I) proviral load. This study suggests that peripheral nerves could be involved in HAM/TSP.

The main HTLV-I-harboring cells in the muscles of viral carriers with polymyositis are not macrophages but CD4 + lymphocytes

Abstract We have analyzed muscle biopsy specimens from polymyositis patients who are also positive for human T cell lymphotropic virus type I (HTLV-I) using both immunohistochemistry for surface antigens of lymphocytes and macrophages and in situ polymerase chain reaction for HTLV-I proviral DNA on the same sections. We found HTLV-I in CD4+ cells but not in macrophages. This finding suggests that most of the HTLV-I-containing CD4+ cells are not macrophages but lymphocytes.

Pathological changes in skeletal muscle in HTLV-I-associated myelopathy

The main lesion site of HTLV-I-associated myelopathy or tropical spastic paraparesis (HAM/TSP) is the pyramidal tract. In some HAM patients, clinical symptoms and findings indicate neuromuscular involvement, such as muscular atrophy, fasciculation, elevated serum creatine kinase (CK) or significant electrophysiological data. Cases of HAM/TSP complicated with polymyositis or motor neuron disease have been reported. But no investigation has been directed to muscular pathology in many patients of HAM/TSP. We conducted muscle biopsies on 13 HAM patients. Four patients showed neurogenic changes. Six patients showed histological findings indicative of inflammatory myopathy. We investigated surface marker of invading cells in these 6 patients. In all patients, T lymphocytes were more predominant than B lymphocytes and in three of them T helper/inducer cells were more predominant than T suppressor cells. In 2 patients, only slight myopathic change could be seen, such as variation in fiber diameter and increase in the number of internal nuclei. In 1 patient, type 2 fiber atrophy was seen, and was possibly the result of disuse. Disturbance of secondary motor neurons or inflammatory myopathy is thus shown to be possibly associated with HAM/TSP.

Polyneuropathy induced by m-tolyl methyl carbamate intoxication

SummaryA 55-year-old woman who attempted suicide by ingesting 200 ml of m-tolyl methyl carbamate (MTMC) is reported. She was comatose for 3 days and, upon recovery, had notable paraesthesia in her lower limbs and difficulty in walking. Neurological examination revealed sensorimotor polyneuropathy. Sural nerve biopsy revealed marked axonal degeneration with a moderate decrease of myelinated fibres.

Experimental germanium myopathy

SummaryThe long-term administration of germanium dioxide (GeO2) to rats produced Ge myopathy characterized by the formation of ragged-red fibers. The earliest pathological changes in experimental Ge myopathy were a decrease in cytochrome c oxidase activity and accumulation of high electron-dense materials in mitochondria. These findings suggest that a mitochondrial dysfunction may be most important in the genesis of experimental Ge myopathy, which could be a useful animal model for the investigation of and therapeutic trials for human mitochondrial myopathies.

Dominantly inherited motor and sensory neuropathy with excessive myelin folding complex

The two patients in a family having the clinical and electrodiagnostic features of hereditary motor and sensory neuropathy (HMSN) are described. The main histological features of sural nerve were segmental demyelination and remyelination with moderate to marked loss of myelinated fibers, and myelin folding complex along all of the large and small myelinated fibers. These features appeared morphologically similar to those observed in HMSN with excessive myelin outfolding, or globular neuropathy. Southern blot analysis suggests that there were neither duplication nor deletion of the peripheral myelin protein-22 gene in the patients. The presented two patients may be a rare form of dominantly inherited HMSN with myelin folding complex.

Histopathological and ultrastructural features of feline hereditary cerebellar cortical atrophy: a novel animal model of human spinocerebellar degeneration

Abstract Human spinocerebellar degeneration is one of the intractable diseases. We studied the detailed neuropathology of cats with hereditary cerebellar degeneration obtained from the experimental breeding. The findings included almost total loss of Purkinje cells with an increase in Bergmann’s glia in the cerebellar hemisphere, preservation of some Purkinje cells in the vermis and moderate neuronal depletion of the olive nucleus. Cerebellar and pontine nuclei were normal. The cerebrum and spinal cord as well as the peripheral nervous system appeared normal. Electron microscopic examination revealed swelling of the distal dendrites of Purkinje cells in the less-affected nodule of the vermis, and clusters of presynaptic boutons without any synaptic contact in the severely affected folia where Purkinje cell bodies and dendrites disappeared. Prolonged existence of presynapses in the molecular and Purkinje cell layers was confirmed by positive immunoreactivity to anti-synaptophysin. Quantitative analysis using electron microscopy demonstrated an apparent increase in the density and mean size of presynapses in the molecular layer of the severely affected folia. These findings indicate that degeneration of Purkinje cells started at the most distal part of the dendrite in this animal model of cerebellar degeneration, and that presynapses, axon terminals of the granular cells and basket cells can exist for a long time even after complete degeneration of the Purkinje cells. Further investigation of this novel animal model may promote a better understanding of pathogenesis of human hereditary cerebellar degeneration.

Experimental germinaium dioxide-induced neuropathy in rats

We report and experimental model of germanium dioxide (GeO2)-induced neuropathy in rats. More than 6 months administration of GeO2 to young rats produced neuropathy characterized by segmental demyelination/remyelination and nerve edema. Electron microscopic studies demonstrated that changes in Schwann cells, such as an increased cytoplasmic volume or disintegration of the cytoplasm, were the earliest pathological findings. Schwann cell mitochondria contained high electron-dense materials. Subsequent removal of necrotic Schwann cell debris and myelin by invading macrophages was evident. These findings suggested that the Schwann cells themselves are the primary target of the toxin. The deposition of electron-dense granules in the intra-axonal vesicles, which was suggestive of glycogen granules in mitochondria, was observed in the advanced stage of the neuropathy. The findings of endoneurial edema with splitting of myelin lamellae were noted at the early stage of demyelination. Nerve edema may be the result of GeO2-induced endothelial cell injury.

An autopsied case of the Crow-Fukase syndrome: a neuropathological study with emphasis on spinal roots

SummaryAn autopsied case of the Crow-Fukase syndrome is reported. Neuropathological findings were as follows: (1) in the sural nerve, there was marked decrease of large and small myelinated fibers. Myelinated fibers showing axonal degeneration and segmental demyelination and remyelination were moderately increased. (2) In the lumbar spinal roots, myelinated fibers showing segmental demyelination and remyelination were frequently observed. The density of myelinated fibers of the ventral root was less at the dural site than the spinal site, while that of the dorsal roots was less at the spinal site than the dural site. (3) In the dorsal root ganglion, there were Nageottes residual nodules and satellitosis; (4) in the lumbar and thoracic spinal cord, there was pallor of the dorsal column; and (5) nerve cells showing central chromatolysis were frequently observed in the spinal anterior horn cells. Segmental demyelination and remyelination in the spinal roots and loss of myelinated fibers with axonal degeneration in the sural nerve are fibers with axonal degeneration in the sural nerve are main neuropathological features of this syndrome.

Chronic demyelinating neuropathy and intra-axonal polyglucosan bodies

SummaryIn this study we evaluated the relationship between polyglucosan bodies and peripheral nerve lesions. The biopsied sural nerve from a patient with late-onset chronic sensori-motor neuropathy showed many intra-axonal polyglucosan bodies and segmental demyelination/remyelination. The formation of Schwann cell hyperplasia around the demyelinated axons was found at the sites of polyglucosan bodies. These findings suggest that demyelinating neuropathy is a part of the spectrum of the diseases characterized by the accumulation of polyglucosan bodies within cellular compartments.