Sonographic Imaging of the Peripheral Nerves in Patients with Type 2 Diabetes Mellitus

Abstract

The World Health Organization estimates that more than 220 million people worldwide have diabetes mellitus (DM). This figure is estimated to more than double by 2030 (Wild et al., 2004). In Japan, the number of diabetic patients has increased to 8 million, and it is assumed that 35% to 45% of diabetic patients have diabetic symmetric polyneuropathy (DPN). Advanced DPN causes serious complications, such as diabetic foot ulcers, gangrene, and Charcot joint, all of which worsen the quality of life of diabetic patients (Ogawa et al., 2006). Therefore, early detection of nerve dysfunction is important to provide appropriate care for patients with DPN (Chudzik et al., 2007). The diagnosis of diabetic neuropathy is based primarily on characteristic symptoms and is confirmed with nerve conduction studies (NCS), which are time-consuming, slightly invasive, and occasionally not well tolerated for repeated evaluations (Colak et al., 2007). In contrast, ultrasonographic examinations can be performed to assess peripheral nerves with less discomfort and have already been used for the evaluation of several disorders of the peripheral nervous system such as carpal tunnel syndrome (Wiesler et al., 2006a; Abe et al., 2004; Jayaraman et al., 2004; Duncan et al., 1999; Lee et al., 1999), cubital tunnel syndrome (Okamoto et al., 2000; Wiesler et al., 2006b), and traumatic nerve lesions (Cartwright., 2007; Peer et al., 2001). High-resolution diagnostic ultrasonography (US) has improved greatly, allowing for evaluation of minute peripheral nerves (Fornage., 1993; Solbiati et al., 1985). We previously showed that the cross-sectional area (CSA) of the median nerve in the carpal tunnel of patients with DPN is greater than that of controls and correlates with NCS (Watanabe et al., 2009). Furthermore, it appears that the percentage of the hypoechoic area of the peripheral nerves was significantly greater in patients with lower motor nerve conduction velocity (MCV) and DM than in controls or patients with higher MCV and DM (Watanabe et al., 2010). The purpose of this chapter is to review the current knowledge regarding the overview and diagnosis of the most common forms of neuropathy in type 2 DM. Furthermore, our current sonographic technique and preliminary studies are presented for some cases. In this chapter,