糖尿病患者における腓腹神経の臨床病理学的検討—組織定量的所見と臨床所見との対比

CLINICOPATHOLOGICAL STUDIES OF BIOPSIED SURAL NERVES : HISTOMETRIC STUDIES AND THEIR CLINICAL CORRELATIONS

はじめに

　糖尿病患者の末梢神経障害は，（1） polyneuropathy型（主として下肢の左右対称性のsensory neuropathy），（2） mononeuritis multiplex型，（3） diabetic amyo—trophy型に大別される¹）。このうちpolyneuropathy型の頻度が高いが，臨床的観点からはその発症様式，感覚障害の程度，運動障害の有無，自律神経障害の有無などに大きな差異が認められる。文献上polyneuropathy型末梢神経障害例では，末梢神経の髄鞘形成細胞であり末梢神経軸索と共生状態にあるシュワン細胞の代謝障害によつて生じるとされている節性脱髄所見が，主な末梢神経の病理所見であるとされ，慢性例，重症例では軸索変性が生じるとする考えが広く信じられている^2〜7）。節性脱髄と軸索変性の両方の存在を認めいずれの病変が主であるか決定し難いかまたは軸索変性を重要な所見とする報告もある^8〜12）。文献上すでに糖尿病患者の末梢神経の組織病理学的検討は多数報告されているが，系統的な組織定量的研究は少ない。本報告では近年ほぼ確立された腓腹神経の組織定量的方法^13）を用い，（1） polyneuro—pathy型末梢神経障害例の神経線維病変の特徴，（2）腓腹神経内鞘内小血管壁の厚さの増大の有無，（3）有髄，無髄線維密度と臨床所見との相関関係を明らかにすることを目的とした。

Morphometric studies of biopsied sural nerves were performed among 16 diabetic patients (14 with polyneuropathy and 2 without polyneuropathy). Main clinical findings at the time of biopsy were reviewed retrospectively and the correlations be-tween clinical findings (the presence or absence of sensory disturbance, motor disturbance, retinopathy and pain, and the duration of sensory disturbance) and nerve fiber densities were analyzed. The follo-wing results and conclusions were obtained. 1) Dec-rease of densities of both myelinated and unmyelina-ted fibers was found in 9 out of 16 cases. Decrease of the density of unmyelinated fibers in diabetic patients was noticeable among over 100 cases of various neuropathies studied by us. Both mye-linated and unmyelinated fibers seem to be de-creased with the duration of sensory distubance. 2) In teased fiber analysis myelinated fibers showing axonal degeneration as well as segmental demyelin-ation were seen at relatively lower frequency. Onion bulb formation was found only in one case out of 16 cases. Therefore it was concluded that axonal degeneration is probably the main pathologi-cal change in sural nerves in this study, considering the decrease of nerve fiber densities as well. 3) The mean thickness of the perivascular space of endoneurial small vessels in diabetic patients was greater than that of the control (32 consecutive patients of various neuropathies). 4) No good cor-relations were found between the presence or absence of motor disturbance, pain and retinopathy, and the nerve fiber densities.