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Demyelinating changes in sural nerve biopsy of patients with HTLV-I-associated myelopathy
K Sugimura1, A Takahashi, M Watanabe
1Department of Neurology, Nagoya University School of Medicine, Japan.
Insights
This study details sural nerve pathology in three patients with Human T-lymphotropic virus type I-associated myelopathy (HAM). Findings reveal specific demyelination patterns, suggesting a unique nerve damage process in HAM patients.
Area of Science:
- Neurology
- Pathology
- Virology
Background:
- Human T-lymphotropic virus type I-associated myelopathy (HAM) is a neurological disorder.
- Understanding peripheral nerve involvement in HAM is crucial for diagnosis and treatment.
Observation:
- Three HAM patients with significant myelopathy symptoms and high HTLV-I viral loads were studied.
- Sural nerve biopsies revealed decreased myelinated fiber density and frequent demyelination/remyelination.
- Degenerating fibers with unique globule-like myelin changes (Dyck's G change) were observed.
Findings:
- Globule-like myelin changes in sural nerves are associated with adjacent demyelinated segments.
- These globules result from repetitive myelin degeneration, representing a form of demyelination.
- The specific demyelination process with globule formation appears characteristic of HAM.
Implications:
- The findings suggest a distinct pathological mechanism in HAM's peripheral neuropathy.
- This specific nerve pathology could serve as a diagnostic marker for HAM.
- Further research into this demyelination process may reveal new therapeutic targets for HAM.
Abstract:
We describe the sural nerve pathology in 3 patients with HTLV-I-associated myelopathy (HAM). These patients showed remarkable symptoms of myelopathy and had high HTLV-I titers in the serum and CSF. The common pathologic findings in the sural nerves were as follows: slightly decreased density in myelinated fibers (6,567/mm2, 6,488/mm2, and 7,159/mm2; control 9,999 +/- 3,446/mm2), frequent occurrence of demyelinated and remyelinated fibers, and many degenerating fibers with globule-like myelin changes. Teased-fiber analysis indicated the globule-like changes (Dyck's G change) to be accompanied by the formation of adjacent demyelinated segments. The globules result from slowly repetitive degenerative changes of myelin and are considered to be a form of demyelination. However, they have seldom been found in other demyelinating neuropathies, indicating the demyelination process with globule formation in HAM to be rather specific for this disease.