Elsevier

Clinical Neurophysiology

Volume 118, Issue 10, October 2007, Pages 2172-2175
Clinical Neurophysiology

Evaluation of atrophy of foot muscles in diabetic neuropathy – A comparative study of nerve conduction studies and ultrasonography

https://doi.org/10.1016/j.clinph.2007.06.019Get rights and content

Abstract

Objective

To evaluate the relation between the findings at nerve conduction studies and the size of small foot muscles determined by ultrasonography.

Methods

In 26 diabetic patients the size of the extensor digitorum brevis muscle (EDB) and of the muscles between the first and second metatarsal bone (MIL) was determined. Motor nerve conduction studies of the peroneal and tibial nerves were performed with determination of the amplitudes of the CMAPs and of the nerve conduction velocities (NCV). Further, a standardised clinical examination was performed providing a neurological impairment score.

Results

Seventeen patients fulfilled the criteria for diabetic neuropathy. The cross-sectional area of the EDB muscle and the thickness of the MIL muscle were 116 ± 65 mm2 and 29.6 ± 8.2 mm, respectively. Close relations were established between muscle size and the amplitude of the CMAP of the peroneal (r = 0.77, p < 0.001) and of the tibial nerve (r = 0.70, p < 0.01). Further there were close relations between the muscle size and the NCV of the peroneal (r = 0.62, p < 0.01) and of the tibial nerve (r = 0.71, p < 0.001).

Conclusions

The amplitude of the CMAP of the peroneal and of the tibial nerves is closely related to the size of the small foot muscles as determined by ultrasonography.

Significance

In diabetic patients motor nerve conduction studies can reliably determine the size of small foot muscles.

Introduction

Diabetic polyneuropathy is characterised by axonal loss combined with demyelination (Malik, 1997). This is reflected in the typical neurophysiological findings including reduced amplitudes of the compound muscle action potentials (CMAP) combined with slowed nerve conduction. The neurophysiological parameters are highly reproducible and reflect the neuropathic process, therefore, they are widely used in clinical studies of diabetic polyneuropathy. Further, longitudinal assessment of the amplitude of the CMAP combined with nerve conduction velocities is used to evaluate the efficacy of treatment (Dyck et al., 1997, Dyck et al., 2005, Kramer et al., 2005).

Using magnetic resonance imaging atrophy of small foot muscles has been found in diabetic patients with polyneuropathy in several studies (Bus et al., 2002, Andersen et al., 2004, Greenman et al., 2005). In one study this was found even in patients without any definite sign of polyneuropathy suggesting that atrophy of small foot muscles may be a sensitive parameter for the detection of neuropathy (Boffeli et al., 2002). Muscle atrophy is an indirect evidence of axonal loss, nevertheless, in diabetic patients atrophy of small foot muscle has attracted great interest because this leads to altered biomechanical properties of the foot such as prominence of the metatarsal heads and clawing of the toes (Boffeli et al., 2002). These changes may ultimately lead to the neuropathic end points foot ulcers and amputation (Rathur and Boulton, 2005). At the hand and foot the CMAPs are recorded from superficially situated muscles and, therefore, the size of the CMAP probably reflects the size of the muscle, however, studies are lacking combining nerve conduction studies with techniques that enable quantification of the target muscles.

In this study the aim was to evaluate whether motor nerve conduction studies provide information about the size of foot muscle. Diabetic patients without and with various degrees of neuropathy were included and the size of the foot muscles was determined by ultrasonography and compared with the findings at conduction studies of the peroneal and the tibial nerve.

Section snippets

Methods

Twenty-six diabetic patients (22 type 1, 4 type 2) were recruited from the out patient diabetes clinic. Care was taken to include patients without and with various degrees of neuropathy, however, no effort was made to include patients with motor symptoms or deficits. The diabetes duration was 32 (8–42) years (median, range). Patients were examined clinically and examined according to a neurological impairment score that includes activity of tendon reflexes, strength of all major muscle groups

Results

Seventeen patients fulfilled the minimal criteria for diabetic neuropathy and for all patients the neurological impairment score was 14 (0–40). The amplitude of the CMAP was 2.9 ± 2.8 mV (mean ± SD) for the peroneal and 6.2 ± 6.0 mV for the tibial nerve. Correspondingly, the area of the CMAP for the peroneal and the tibial nerve was 8.0 ± 8.7 and 14.6 ± 11.8 msmV, respectively. Nerve conduction velocities were 33.8 ± 12.1 m/s for the peroneal and 35.2 ± 11.8 m/s for the tibial nerve. In 3 and 2 patients,

Discussion

The main finding of this study is that the amplitude of the CMAP and the NCV of the peroneal and the tibial nerve are closely related to the size of small foot muscles determined by US. For the peroneal nerve the relation was closer for the size of the CMAP (amplitude and area) as compared to the NCV indicating that CMAP more closely reflects atrophy of the EDB muscle.

In diabetic neuropathy NCV and CMAP are widely used to monitor the neuropathic process. Quantification of the size of the CMAP

References (16)

  • T.J. Boffeli et al.

    Biomechanical abnormalities and ulcers of the great toe in patients with diabetes

    J Foot Ankle Surg

    (2002)
  • H. Andersen et al.

    Atrophy of foot muscles a measure of diabetic neuropathy

    Diabetes Care

    (2004)
  • R. Beekman et al.

    Ultrasonography shows extensive nerve enlargements in multifocal motor neuropathy

    Neurology

    (2005)
  • S.A. Bus et al.

    Intrinsic muscle atrophy and toe deformity in the diabetic neuropathic foot: a magnetic resonance imaging study

    Diabetes Care

    (2002)
  • S.A. Bus et al.

    Plantar fat-pad displacement in neuropathic diabetic patients with toe deformity: a magnetic resonance imaging study

    Diabetes Care

    (2004)
  • P.J. Dyck et al.

    The Rochester Diabetic Neuropathy Study: reassessment of tests and criteria for diagnosis and staged severity

    Neurology

    (1992)
  • P.J. Dyck et al.

    Longitudinal assessment of diabetic polyneuropathy using a composite score in the Rochester Diabetic Neuropathy Study cohort

    Neurology

    (1997)
  • P.J. Dyck et al.

    Monotonicity of nerve tests in diabetes: subclinical nerve dysfunction precedes diagnosis of polyneuropathy

    Diabetes Care

    (2005)
There are more references available in the full text version of this article.

Cited by (45)

  • Motor dysfunction in diabetes

    2022, Diabetic Neuropathy
  • Neuromuscular maturation in the neonate: Combined electroneurographic and ultrasonographic study

    2020, Early Human Development
    Citation Excerpt :

    The combination of the three methods adds to the information on function provided by ENG-EMG by adding data on morphology, as provided by ultrasonography (US). Severinsen and Andersen [6] conducted a study of patients with type II diabetes mellitus and found a linear correlation between the maximum amplitude of the compound motor action potential and the thicknesses of the small muscles of the lower limb. To the best of our knowledge, no studies on neonates have been performed to evaluate the relationship between nerve conduction and muscle size.

  • High-resistance strength training does not affect nerve cross sectional area – An ultrasound study

    2017, Clinical Neurophysiology Practice
    Citation Excerpt :

    The reason why we did not see the same result in muscle thickness when comparing trained and untrained men and women separately is probably due to the number of participants being too low when dividing the cohort into subgroups. The finding that the CMAP amplitude of the EDB muscle correlates with muscle thickness in the whole cohort is in line with a previous study (Seok et al., 2016), and similar correlations has also been found in foot muscles of diabetic patients (Severinsen and Andersen, 2007). One drawback of the study was that the untrained group was older than the trained group.

  • Evaluation of extensor digitorum brevis thickness in healthy subjects: A comparative analysis of nerve conduction studies and ultrasound scans

    2016, Clinical Neurophysiology
    Citation Excerpt :

    These findings suggest that EDB thickness measured by ultrasound is a relatively less variable measure of distal muscle biology than CMAP. Taken together with prior studies (Mohseny et al., 2015; Hamjian and Walker, 1994; Severinsen and Andersen, 2007) that have shown a relationship between the size of small distal muscles and function it is possible that EDB thickness could be useful in evaluating fibular nerve pathology. The present study also determined normal reference values of muscle thickness (EDB, TA, and AHB) and demonstrated a relationship with gender and BMI on the thickness of all three muscles.

View all citing articles on Scopus

Disclosures: The authors have no disclosures.

View full text