Nerve conduction in children suffering insulin dependent diabetes mellitus

Prevalence of peripheral neuropathy and associated risk factors in children with type 1 diabetes

AIM

To detect the prevalence of diabetic polyneuropathy (DPN) in children with type 1 diabetes (T1D) and to identify associated the risk factors.

METHODS

This cross-sectional study evaluated children aged between 2 and 16y with T1D for ≥2 y. Detailed neurological examination, neuropathy symptom score, and nerve conduction studies were done in all children to assess nerve dysfunction. Disease-related factors were evaluated for the prediction of neuropathy.

RESULTS

Sixty-six children (67% boys) were enrolled. The mean age at the time of diagnosis of T1D was 7.1 ± 2.6 years. The mean duration of diabetes was 4 ± 1.8 years. None of the patients had neuropathy on clinical examination or on the neuropathy symptom score. The prevalence of subclinical DPN was 18.2% (n = 12/66). The type of neuropathy was pure motor (n = 11, 91.6%) and mixed sensorimotor (n = 1, 8.3%). The common peroneal nerve was most commonly affected (n = 6, 50%), followed by the tibial (n = 4, 33.3%) nerve. The most common patterns of nerve involvement were mixed axonal and demyelination (n = 7, 58.3%), followed by axonal (n = 3, 25%) and demyelinating type (n = 2, 16.6%). Children with subclinical DPN had a significant reduction in velocity of tibial, common peroneal, median motor, and ulnar motor nerves; delayed latency in common peroneal, median motor, ulnar motor, and median sensory nerves compared to those without DPN (p value <0.05). A higher body mass index predicted the development of subclinical DPN (p value <0.05).

CONCLUSION

Nearly one-fifth of children with T1D have subclinical neuropathy as early as two years of the disease. A higher body mass index is significantly associated with DPN. Electrophysiological studies should be performed regularly to screen for nerve dysfunction and its progression.

Homozygosity of the Z-2 polymorphic variant in the aldose reductase gene promoter confers increased risk for neuropathy in children and adolescents with Type 1 diabetes

BACKGROUND

Diabetic neuropathy (DN) is the least recognized complication of diabetes mellitus and may start early in the course of the disease. Aldose reductase (AKR1B1) gene promoter Z-2/Z-2 polymorphism increases the expression of AKR1B1 enzyme and may contribute to DN.

SUBJECTS

We evaluated 108 Type 1 diabetes (T1D) children and adolescents (mean ± SD age: 13.5 ± 3.46 years, disease duration: 5.3 ± 3.4 years) and 150 healthy controls (age: 11.9 ± 2.7 years).

METHODS

In both groups, pupillary dilation (PD) in darkness, postural blood pressure test (PBPT), and vibration sensation thresholds (VST) in upper and lower limbs were estimated as indices of autonomic and peripheral neuropathy, respectively. Nerve conduction studies (NCS) were performed in patients as peripheral neuropathy index. The polymorphisms of AKR1B1 gene were evaluated using microsatellite (AC)n sequence Z.

RESULTS

PBPT, PD, and VST impairments were more frequent in patient group compared with controls, while 38.6% of patients exhibited NCS abnormality. Gender, age, pubertal status, height, body mass index, diabetes duration, HbA1c, and anti-GAD titers were associated with neuropathy indices in patients. There was a strong correlation between PD and NCS in patients, while homozygous patients for Z-2 AKR1B1 gene polymorphism had higher prevalence of abnormal NCS (83.3% vs. 34.6%), PD (62.5% vs. 31.5%), and PBPT values compared with heterozygous or negative patients. Homozygous AKR1B1 status predicted PD, NCS, and PBPT variance, while PD, VST, NCS, and PBPT parameters accurately discriminated homozygous AKR1B1 patients.

CONCLUSIONS

Impaired indices of peripheral and autonomic DN were present in a significant proportion of young T1D patients. PD, VST, NCS, and PBPT parameters were simultaneously associated with homozygous state of AKR1B1 Z-2 gene polymorphism, implicating polyol metabolism with both autonomic and peripheral neuropathies.

Electrophysiological Characterization of Neuropathy Complicating Type 1 Diabetes Mellitus

Diabetic peripheral neuropathy (DPN) involves sensory and motor nerves, resulting in demyelination as well as axonal degeneration. This study was conducted to describe the pattern of lower limb nerve involvement in children with type 1 diabetes mellitus (DM) based on the parameters of nerve conduction study (NCS). This cross-sectional study recruited 50 children with type 1 DM having mean disease duration of 4.92 ± 3.84 years who attended the referred clinic in Sudan Childhood Diabetes Center. Their mean age was 15.00 ± 2.19 years, 42% were males, and 58% were females. Twenty six matched healthy control subjects were involved; their mean age was 13.88 ± 2.46 years, 38.46% were males, and 61.54% were females. Bilateral NCS of the sensory and motor lower limb nerves was performed using Medelec Synergy machine. Interpretation of the patients' results was based on our own control reference values. Data was analysed using IBM SPSS statistics. Out of the 50 diabetic patients, 44 (88%) had electrophysiological evidence of peripheral neuropathy (abnormalities in at least two of the electrophysiological parameters). The majority (68.2%) had motor involvement and 31.8% had sensorimotor, while none of them (0%) had pure sensory involvement. Regarding abnormal NCS parameters (conduction velocity vs. amplitude of the compound action potential), conduction slowing feature predominated in 61.4% and only few (6.8%) showed amplitude reduction, while 31.8% showed mixed features. The most frequently affected nerve was the common peroneal, followed by posterior tibial, and the least was the sural nerve. The most sensitive parameter was the common peroneal conduction velocity. Motor precedes sensory nerve involvement. The most frequent neurophysiological abnormality was the conduction slowing, and the common peroneal was the most vulnerable nerve. These findings signify generation of a protocol for early screening of neuropathy in children with type 1 diabetes.

High Prevalence and Incidence of Diabetic Peripheral Neuropathy in Children and Adolescents With Type 1 Diabetes Mellitus: Results From a Five-Year Prospective Cohort Study

BACKGROUND

In this prospective cohort study, we investigated the prevalence of diabetic peripheral neuropathy at baseline and after five years of follow-up in children and adolescents with type 1 diabetes mellitus using both measurements of nerve conduction velocity and clinical neurological examination.

METHODS

A total of 38 patients who underwent insulin pump or intensive insulin therapy were included. The subjects averaged 12.6 ± 2.4 years of age and their diabetes duration averaged 5.6 ± 3.2 years. All patients underwent a detailed physical, neurological, and electrophysiological examination, as well as laboratory testing at their annual checkup.

RESULTS

At baseline, the prevalence of diabetic peripheral neuropathy diagnosed using neurological examination was 13.2%, whereas nerve conduction velocity testing revealed diabetic peripheral neuropathy in 31.6%, highlighting a high prevalence of subclinical diabetic peripheral neuropathy. During follow-up, there was a strong increase in the prevalence of clinically diagnosed diabetic peripheral neuropathy, which reached 34.2% (P = 0.039) after five years; the proportion of patients with subclinical diabetic peripheral neuropathy even reached 63.2% (P = 0.002). The most significant changes in electrophysiological parameters were observed in the tibial sensory nerve (P = 0.001).

CONCLUSIONS

The prevalence of diabetic peripheral neuropathy in children and adolescents with type 1 diabetes mellitus was high, and there was a rapid increase in the prevalence of diabetic peripheral neuropathy during a five-year follow-up interval. Importantly, our data show that a mere clinical evaluation is not sensitive enough to diagnose diabetic peripheral neuropathy in these patients. Nerve conduction velocity measurement, which is regarded as the gold standard for the assessment of diabetic peripheral neuropathy, should be applied more broadly.

Validity of the neurological examination in diagnosing diabetic peripheral neuropathy

The aim of this study was to evaluate the prevalence of diabetic peripheral neuropathy in children and adolescents with type 1 diabetes mellitus and examine whether the neurological examination validly diagnoses diabetic peripheral neuropathy as compared with the gold standard of nerve conduction velocity in these patients. Nerve conduction velocity was measured in an unselected consecutive series of patients aged 8-18 years who had been suffering from type 1 diabetes mellitus for at least 1 year. For the neurological examination, neuropathy disability scores and neuropathy sign scores were used. Of the 39 patients, six (15%) had clinically evident diabetic peripheral neuropathy, whereas nerve conduction velocity testing revealed diabetic peripheral neuropathy in 15 (38%) patients. Sensitivity and specificity of the neurological examination for the diagnosis of diabetic peripheral neuropathy were 40% and 100%, respectively. The corresponding positive and negative predictive values were 100% and 72.7%, respectively. This conclusions from this study are that in children and adolescents with type 1 diabetes mellitus, diabetic peripheral neuropathy is highly prevalent, but in the majority of patients it is subclinical. Sensitivity and negative predictive values of the neurological examination are low. Therefore, routine nerve conduction velocity measurement for the assessment of diabetic peripheral neuropathy appears to be warranted in these patients.