糖尿病患者における下肢・足部機能の特徴

Characteristics of Lower-Limb and Foot Function in Diabetic Patients

はじめに

　糖尿病足病変の診療を行うにあたっては，糖尿病患者に起こる下肢機能，足部機能の変化を理解しておく必要がある。糖尿病発症早期から高頻度に見られる糖尿病性神経障害は，両足の痺れや疼痛（陽性症状）だけでなく，感覚低下（陰性症状）や自律神経障害を通して足部に影響を与える 1）。糖尿病において，網膜症や腎症と同様に細小血管症として認識される神経障害は，糖尿病性多発神経障害（diabetic polyneuropathy：以下，DPN）と呼ばれ，慢性に生じる遠位対称性感覚運動性多発神経障害（distal symmetric sensorimotor polyneuropathy：以下，DSPN）と自律神経障害（diabetic autonomic neuropathy：以下，DAN）に分けられる 2）。DSPNは外傷や炎症による疼痛に気付きにくくなる感覚神経障害と，足部の小筋群の筋萎縮と筋力低下，バランス障害などをもたらす運動神経障害によって足部に大きな影響を与え，DANは足部の発汗低下による足部皮膚の乾燥や亀裂，動静脈シャント血管の開大によるシャルコー足の発生につながる。

　すなわち，感覚神経障害，運動神経障害，自律神経障害，すべての神経障害を素地として，足に繰り返し外的刺激が加わることにより足病変の発生が起こり得るのである。本章では糖尿病患者の下肢と足部に起こる変化と，それが糖尿病足病変発生につながる仕組みを概説する。

　Patients with diabetic polyneuropathy experience a variety of changes in the functions of one or both lower extremities and feet. In addition to changes in muscle strength, joint range of motion, and soft tissue, a loss of defensive perception, loss of dexterity, and diabetic retinopathy have occurred in this patient population. All of these contribute to the risk of developing diabetic foot lesions.

　Healing of foot ulcers is one goal of treatment. However, even if the ulcer is healed, it does not cure the loss of lower-extremity function. Over the long course of the chronic disease of diabetes, diabetic patients are at risk for foot lesions to recur again and again. Without understanding the changes that are occurring in diabetic patients and considering further interventions, it is not possible to prevent recurrence even once a wound has healed.

　Specific interventions may include screening at an appropriate frequency according to the risk, foot care, thorough orthotic unloading, and patient education. Rehabilitative interventions can also be offered for muscle weakness, joint range of motion loss, and gait instability. Interventions to prevent the recurrence of diabetic foot lesions will be even more effective if diabetic foot lesions are redefined as a musculoskeletal problem.