Muscular atrophy in diabetic neuropathy: a stereological magnetic resonance imaging study

Abstract

Motor dysfunction develops in advanced cases of diabetic polyneuropathy [1,2]. In the clinic it is most frequently detected by inability to walk on heels which indicates a preponderance for the dorsal flexors of the ankle. Recently weakness of both the ankle dorsal and plantar flexors and of the knee extensors and flexors was found in long-term insulin-dependent diabetic (IDDM) patients with peripheral neuropathy at isokinetic dynamometry [3]. Furthermore, the weakness at the ankle and knee was closely related to the severity of neuropathy assessed clinically, electrophysiologically and at quantitative sensory examination.The present study was performed in order to clarify whether muscle weakness in diabetic patients with polyneuropathy is associated with muscular atrophy and secondly if present how the atrophy is topographically distributed. A non-invasive quantitative method for analysis of muscle volume was applied in the present study. Assessment of muscle morphology can be obtained with ultrasonomyography, X-ray computed tomography (CT), and magnetic resonance imaging (MRI) [4][5][6][7]. Ultrasonomyography is Diabetologia (1997) Summary Diabetic patients with polyneuropathy develop motor dysfunction. To establish whether motor dysfunction is associated with muscular atrophy the ankle dorsal and plantar flexors of the non-dominant leg were evaluated with magnetic resonance imaging in 8 patients with symptomatic neuropathy, in 8 nonneuropathic patients and in 16 individually matched control subjects. In the neuropathic patients the muscle strength of the ankle dorsal and plantar flexors was reduced by 41 % as compared to the non-neuropathic patients (p < 0.005). Volume of the ankle dorsal and plantar flexors was estimated with stereological techniques from consecutive cross-sectional images of the lower leg. The neuropathic patients had a 32 % reduction in volume as compared with the nonneuropathic patients (p < 0.005). To determine the regional distribution of atrophy cross-sectional magnetic resonance images were performed at predetermined levels of the lower leg in relation to bone landmarks. In the neuropathic patients there was an insignificant increase of 3 % of muscle area at the proximal lower leg level, whereas the atrophy was 43 % (p < 0.002) at the mid lower leg level and 65 % (p < 0.002) distally. Analysis of individual muscles confirmed that the atrophy predominated distally. We conclude that muscular atrophy underlies motor weakness at the ankle in diabetic patients with polyneuropathy and that the atrophy is most pronounced in distal muscles of the lower leg indicating that a length dependent neuropathic process explains the motor dysfunction. [Diabetologia (1997[Diabetologia ( ) 40: 1062[Diabetologia ( -1069

Abnormal viscoelastic behaviour of passive ankle joint movement in diabetic patients: an early or a late complication?

“…In the absence of appropriate active tension and decreased ROM, the contribution of passive components to the joint movement will increase [3]. It is well known that the strength of calf muscles [6] and ROM [9] are reduced in diabetic patients. This suggests that a greater proportion of the ankle moment during gait may come from passive structures.…”

“…It is known that under conditions of decreased active tension, such as ankle dorsal and plantar flexor weakness and atrophy resulting from diabetic neuropathy, passive tension may make a greater contribution to the total tension than that found in healthy individuals [6]. So in the absence of appropriate active tension, it is possible that a considerable portion of the ankle moment during gait may come from passive structures.…”

Atrophy of Foot Muscles

“…Previous studies on motor function in diabetic neuropathy have relied on simple clinical tests such as the ability to stand on heels (1) and neurophysiological examinations of motor nerves (2). In a series of experiments in long-term diabetic patients, we have observed that muscle weakness in the lowerleg muscles occurs to a substantial degree in chronic neuropathic patients, closely related to muscle atrophy, whereas nonneuropathic patients have normal muscle strength and striated muscle mass (3). In the more distally situated intrinsic foot muscles, Brash et al (4) observed atrophy in neuropathic diabetic patients using a specific magnetic resonance imaging (MRI) contrast sequence; however, the atrophy was not quantified.…”

“…Muscle fascia, tendons, and blood vessels were excluded. At each image, the crosssectional area of all muscles was estimated by a single observer using a stereological point-counting method as described previously (3,5). The total volume of striated muscle (in cubic centimeters) was calculated by multiplying the distance between the sections by the total cross-sectional area, the first section being randomly placed within the first interslice 10-mm interval.…”

Reproducibility of foot structure measurements in neuropathic diabetic patients using magnetic resonance imaging

“…Because of its multiplanar imaging capability and inherent superiority in tissue contrast, magnetic resonance imaging (MRI) is increasingly being used as a tool to assess structural pathology in the foot or lower leg of diabetic patients with peripheral neuropathy (5,(7)(8)(9)(10)(11). These assessments are considered important for improving our understanding of the relationship between structure and function in the foot and the pathogenesis of foot ulceration.…”