Pupillary size in children and adolescents with type 1 diabetes

Corneal nerve and nerve conduction abnormalities in children with type 1 diabetes

OBJECTIVE

In vivo corneal confocal microscopy (CCM) is a novel, rapid, and non-invasive technique that identifies early small fiber damage and can predict the progression and development of clinical neuropathy in adults with type 1 diabetes. However, its usefulness in children is not well established. This study compared corneal confocal microscopy with neuropathic symptoms, signs, and objective measures of neuropathy for the diagnosis of diabetic neuropathy in children with type 1 diabetes.

RESEARCH DESIGN AND METHODS

A total of 83 children with type 1 diabetes and 83 healthy participants of similar age underwent assessment of neuropathy symptoms, signs, nerve conduction studies, quantitative sensory and autonomic function testing, and in vivo CCM.

RESULTS

Only of 3/83 (4%) children with type 1 diabetes had subclinical neuropathy. However, corneal nerve fiber density (p = 0.001), branch density (p = 0.006), fiber length (p = 0.002), tibial motor nerve amplitude and conduction velocity, and sural sensory nerve amplitude and conduction velocity (all p < 0.004) were lower in participants with type 1 diabetes than in the controls. Vibration, cooling, and warm perception thresholds and deep breathing heart rate variability were not found to be different (all p > 0.05) between children with type 1 diabetes and healthy controls. Multivariate regression analysis identified a possible association between body mass index and decreased corneal nerves.

CONCLUSIONS

Decreased corneal nerves and abnormal nerve conduction were found in children with type 1 diabetes. CCM may allow rapid objective detection of subclinical diabetic neuropathy in children and adolescents with type 1 diabetes.

Can dynamic and static pupillary responses be used as an indicator of autonomic dysfunction in patients with obstructive sleep apnea syndrome?

PURPOSE

We aimed to reveal whether static and dynamic pupillary responses can be used for the detection of autonomic nervous system (ANS) dysfunction in patients with obstructive sleep apnea syndrome (OSAS).

METHODS

We included in this study patients with OSAS, who were divided into three groups according to the apnea-hypopnea index (AHI) (group 1, mild [n = 20]; group 2, moderate [n = 20]; and group 3, severe [n = 20]), and healthy controls (group 4, n = 20). Pupillary responses were measured using a pupillometry system.

RESULTS

Static (mesopic PD, P = 0.0019; low photopic PD, P = 0.001) and dynamic pupil responses (resting diameter, P = 0.004; amplitude of pupil contraction, P < 0.001; duration of pupil contraction, P = 0.022; velocity of pupil contraction, P = 0.001; and velocity of pupil dilation, P = 0.012) were affected in patients with different OSAS severities. Also, AHI was negatively correlated with mesopic PD (P = 0.008), low photopic PD (P = 0.003), resting diameter (P = 0.001), amplitude of pupil contraction (P < 0.001), duration of pupil contraction (P = 0.011), velocity of pupil contraction (P < 0.001), and velocity of pupil dilation (P = 0.001).

CONCLUSION

We detected pupil responses innervated by the ANS were affected in the OSAS patients. This effect was more significant in the severe OSAS patients. Therefore, the pupillometry system can be an easily applicable, noninvasive method to detect ANS dysfunction in the OSA patients.

Diabetic neuropathy in children and adolescents with type 1 diabetes mellitus: Diagnosis, pathogenesis, and associated genetic markers

Diabetic neuropathy (DN) is a common long-term complication of type 1 (T1D) and type 2 (T2D) diabetes mellitus, with significant morbidity and mortality. DN is defined as impaired function of the autonomic and/or peripheral nervous system, often subclinical, particularly in children and adolescents with T1D. Nerve conduction studies (NCS) and skin biopsies are considered gold-standard methods in the assessment of DN. Multiple environmental and genetic factors are involved in the pathogenesis of DN. Specifically, the role of metabolic control and glycemic variability is of paramount importance. A number of recently identified genes, including the AKR1B1, VEGF, MTHFR, APOE, and ACE genes, contribute significantly in the pathogenesis of DN. These genes may serve as biomarkers to predict future DN development or treatment response. In addition, they may serve as the basis for the development of new medications or gene therapy. In this review, the diagnostic evaluation, pathogenesis, and associated genetic markers of DN in children and adolescents with T1D are presented and discussed.

Lateralization of pupillary light reflex parameters

OBJECTIVE

The aim of this study was to determine differing reactions of the left and right eyes with regard to pupillary light reflex (PLR) parameters.

METHODS

All together 90 healthy subjects were included. In the first test series, 34 subjects were investigated on both eyes (left eye was tested first, three tests per day and one reliability test). In the second test series, 32 subjects were studied while changing the beginning side. In the last test series, 29 subjects were investigated 12 times each within 1h (beginning side changed, without spoken advice). Infrared pupillometry was used to study pupil diameter, latency time, relative amplitude, contraction/dilation velocity, and pupil redilation time.

RESULTS

The study demonstrated significant differences of PLR parameters between both eyes. In contrast to the pupil diameter of the left eye the parasympathetically-dominated right eye was not influenced by vocal instructions or by changing the beginning side.

CONCLUSIONS

PLR parameters might indicate functional lateralization of autonomic function in the central nervous system. High sensitivity of the procedure (arousal due to spoken advice, time of day) is advantageous for various psychophysiological investigations.

SIGNIFICANCE

Differences between both eyes might point towards cortical lateralization of central autonomic function.

Pupillary autonomic denervation with increasing duration of diabetes mellitus

BACKGROUND/AIMS

The autonomic pupillary changes in type I and II diabetic patients without clinical evidence of diabetic autonomic neuropathy (DAN) were compared with age matched controls. The relation between pupillary and cardiovascular autonomic function was assessed in the diabetic patients.

METHODS

A case-control study was performed with diabetics grouped according to type and duration of diabetes. Static infrared pupillography was used to compare mean dark adapted pupil size and mean percentage changes in pupil size with pilocarpine 0.1% and cocaine 4% in the diabetic and control groups. All diabetic patients underwent cardiovascular autonomic function assessment using the Valsalva ratio, the 30:15 ratio, and testing for orthostatic hypotension.

RESULTS

In total, 72 type I and 69 type II diabetic patients were compared with 120 controls. Mean dark adapted pupil size was significantly smaller in diabetic groups than controls. Except for type I diabetics with disease for less than 5 years, all patient groups had significantly greater mean percentage constriction in pupil size in response to dilute pilocarpine than controls. There was no significant difference between the mean percentage dilatation in response to cocaine 4% in diabetics and controls. A high proportion of patients had normal cardiovascular autonomic function particularly when this was assessed with the Valsalva ratio.

CONCLUSIONS

Denervation hypersensitivity to dilute pilocarpine is a result of damage to the pupillary parasympathetic supply of diabetic patients. This occurs before the pupillary sympathetic pathway is affected, it can be detected early in the disease, and it may be a possible explanation for the small pupil size seen in diabetic patients. Pupillary autonomic dysfunction occurs before cardiovascular autonomic changes and detection of pupil denervation hypersensitivity to dilute pilocarpine is an inexpensive way to detect early DAN.

Aldose reductase inhibition ameliorates pupillary light reflex and F-wave latency in patients with mild diabetic neuropathy

OBJECTIVE

The present study was conducted to investigate the effect of an aldose reductase inhibitor, epalrestat, on autonomic and somatic neuropathy at an early stage in type 2 diabetic patients by assessing the pupillary light reflex and minimum latency of the F-wave.

RESEARCH DESIGN AND METHODS

A total of 30 diabetic patients with subclinical or mild diabetic neuropathy were randomly allocated to a control group (n = 15) and epalrestat (150 mg/day) group (n = 15). After 24 weeks, the pupillary light reflex test, cardiovascular autonomic function tests, and nerve conduction study were performed.

RESULTS

The beneficial effect of epalrestat on the pupillary light reflex was observed in the minimum diameter after light stimuli (P = 0.044), constriction ratio (P = 0.014), and maximum velocity of constriction (P = 0.008). Among cardiovascular autonomic nerve functions, the ratio of the longest expiratory R-R interval to the shortest inspiratory R-R interval during deep breathing was significantly improved by epalrestat (P = 0.037). Minimum latencies of F-wave of median and tibial motor nerves were significantly shortened by epalrestat (P = 0.002 and P = 0.001, respectively); however, no significant effects were observed in motor or sensory nerve conduction velocity.

CONCLUSIONS

These observations suggest that epalrestat may have therapeutic value at the early stage of diabetic neuropathy and that the pupillary light reflex and minimum latency of F-wave may be useful indicators of diabetic neuropathy.

Prevalence of microvascular and neurologic abnormalities in a population of diabetic children

One hundred and twenty-nine (87%) of a total county population of 150 eligible diabetic children together with 144 age- and sex-matched control children participated in a longitudinal, epidemiological study of the evolution of diabetic microvascular disease. At enrollment the median (range) age of the diabetic children was 12.5 (3.7-16.8) years with a median diabetes duration of 2.9 (0.1-13.4) years and a median HbAl of 11.1 (6.8-17.9)%. Two sets of measurements were made over a period of 18 months for all indices of microvascular disease, while autonomic function was studied on one occasion. Urinary albumin excretion in diabetic children was assessed from all voidings during two timed 48-h urine collections and was expressed as urinary albumin/creatinine ratios (ACR). Blood pressure (BP) was measured using a random zero sphygmomanometer. Autonomic function was assessed by pupillary adaptation in darkness, using a portable Polaroid pupillometer, and by heart rate (HR) variation recorded by dedicated computer. Vibration sensation thresholds (VST) (as indices of peripheral neuropathy) were recorded using a Biothesiometer. Limited joint mobility (LJM) was assessed by the "prayer sign". Five (3.9%) diabetic children presented raised mean ACR in more than two of four 24-h urine collections. Fourteen (10.8%) diabetic children were identified as having persistently raised BP during both study periods. Impaired HR response in one HR test was observed in 20 (15.5%) diabetic children, while ten (7.7%) diabetic children demonstrated abnormalities in two or more HR tests. Reduced pupillary adaptation in darkness was found in eight (7.9%) diabetic children. Persistent vibration sensation impairment (VST) in lower limbs was detected in eight (6.2%) diabetic children, while LJM was present in 12 (9.3%) diabetic children. Eight of the 129 diabetic children (6.2%) were found to have abnormality in two and one in three indices of microvascular and autonomic function. Six of nine children had coexistence of impaired autonomic neuropathy and nephropathy. These nine children were diagnosed at a younger age than the rest of the diabetic population (5.1 vs 8.0 yr, p=0.002). Four of nine were aged >11 yr and five of nine had had diabetes for >5 yr. Thus, a constellation of microvascular and neurological abnormalities were demonstrable in a small proportion of diabetic children, who were younger than the rest of the population at the time of onset of their disease. Longitudinal study of this population will demonstrate the clinical significance of these findings.

Consistency of microvascular and autonomic abnormalities in diabetes

The progression of early measures of microvascular disease and autonomic neuropathy were studied in a group of 81 children with insulin dependent diabetes mellitus over a mean interval of 4.2 years. Repeated measurements were made of blood pressure, albumin excretion, joint mobility, and pupillary dilatation in darkness. Over the years between the first and the second study, systolic and diastolic blood pressure showed positive tracking correlations (r = 0.38 and r = 0.32) with a small but significant deviation from normality; albumin/creatinine ratio was significantly increased (0.79 v 0.55); a greater number of children were identified in the second study as having limitation of mobility of the fifth metacarpophalangeal joint; and pupillary dilatation in darkness significantly decreased (61.5% v 62.9%); 62% of the children with one or more abnormal measurements in the first study were found to have measurements outside the normal ranges in the second study, indicating a consistency in observations over time. It remains to be seen with what accuracy these measurements predict adult onset clinical disease.

The prospective assessment of autonomic nerve function by pupillometry in adolescents with type 1 diabetes mellitus

The study aimed to compare the longitudinal assessment of automatic nerve function by computerized infrared pupillometry and standard cardiovascular tests in adolescents with diabetes. Adolescents (n = 150) were assessed at two time points (T1 and T2). The median time interval between assessments was 1.5 (range 0.9-3) years. At T1 the median age was 14.5 (range 8.3-19.5) years and the median duration was 6.5 (range 1.1-16) years. The pupillary variables assessed included the resting pupil diameter, the maximum constriction velocity, and the reflex amplitude of constriction. Heart rate reflexes were assessed in response to deep breathing, the Valsalva manoeuvre, and on standing from a lying position (30/15 ratio). Between visits there was a significant decrease in maximum constriction velocity (6.0 mm s-1 vs 6.3 mm s-1, p = 0.0001) and resting pupil diameter (6.2 mm vs 6.3 mm, p = 0.001). At reassessment pupillary abnormalities increased from 32 (21%) to 45 (30%), with 17 (54%) of the initial abnormalities persisting. Adolescents with abnormally slow maximum constriction velocity compared to those with normal maximum constriction velocity had a higher glycated haemoglobin (HbA1c%) at T2 (p = 0.02) and between assessments (p = 0.01). Cardiovascular test abnormalities did not increase between visits and the persistence of initial abnormalities was low (21%). In summary, pupillometry appears a more sensitive test of automatic nerve dysfunction in adolescents with diabetes than assessment of cardiovascular reflexes.

Pupil size in diabetes

Sympathetic function was studied in 101 diabetic children and 102 age and sex matched control children, as part of a longitudinal study of the evolution of microvascular disease in the population of diabetic children and adolescents in Avon County. The median (range) age of the diabetic population was 13.5 (6.0-17.2) years, the duration of diabetes was 4.0 (0.4-13.9) years, and glycated haemoglobin (HbA1) was 10.9 (7.0-18.1)%. Pupillary adaptation in darkness, as an index of sympathetic neuropathy, was measured using a Polaroid portable pupillometer. Diabetic children had a significantly smaller median pupillary diameter, measured as the pupil/iris ratio and expressed as a percentage, than control children (median (range) 62.9 (50.3-72.1) v 65.9 (52.2-73.8)). Pupillary diameter was significantly related to diabetes duration (r = -0.22), HbA1 (r = -0.34), systolic blood pressure (r = -0.25), diastolic blood pressure (r = -0.49), and mean albumin/creatinine ratio on random urine samples (r = -0.26). Pupillary diameter was not related to age (r = -0.1). Eight (7.9%) diabetic and four (3.9%) control children were identified as having abnormal pupillary dilation in darkness. In comparison with the rest of the diabetic population, these diabetic children had longer diabetes duration and poorer glycaemic control. Polaroid pupillometry has demonstrated subclinical autonomic neuropathy in a population of diabetic children and adolescents. These abnormalities were related to poor metabolic control, long diabetes duration, and also to other indices of microvascular disease.

Effect of actual glycaemia on pupillary function in children with type 1 diabetes

The objective was to study the effect of actual glycaemia on autonomic function. Autonomic function was assessed by computerised infrared video-pupillometry in 10 children with type 1 diabetes (age 10.5-15.8, median 13.7 years, diabetes duration 1.1-10.0, median 3.8 years) on 6 occasions (07:30, 12:00, 17:30 h on days 1 and 10, respectively). Blood glucose was measured by a reflectance meter immediately prior to each pupillometry study. To allow for inter-individual differences in pupillary variables (resting pupil diameter (RPD), reflex amplitude (RA), maximum constriction velocity (MCV)) the variation of each variable from the mean for the individual (difference between the actual value and the mean value from the 6 measurements (delta RPD, delta RA, delta MCV)) was used in calculations. None of the three pupillary variables showed a significant correlation with the blood glucose value (delta RPD: r = 0.072, P = 0.59; delta RA: r = -0.008, P = 0.96; delta MCV: r = -0.080, P = 0.55). It is concluded, that autonomic function in children with Type 1 diabetes as determined by computerised infrared video-pupillometry is not affected by actual glycaemia.

Urinary bladder dysfunction in diabetic children with and without subclinical cardiovascular autonomic neuropathy

The aim of this study was to assess the relationship between bladder dysfunction and impaired cardiovascular reflexes in diabetic children with no clinical symptoms of autonomic neuropathy. After 15 ml/kg of water intake, the time to first sensation to void, the voiding volume, the voiding time, the average and maximum urinary flows, and the time to maximum urinary flow were estimated by sonography and uroflowmetry in diabetic children with and without cardiovascular autonomic dysfunction (CAD), and in a healthy control group. The three groups of children were matched for age, weight and height. CAD was considered to be present if the results of cardiovascular tests were more than 2SD from the mean of healthy controls. Diabetic children with and without CAD had increased time to first sensation to void, voiding volume, and average urinary flow when compared with healthy children. Voiding volume and average and maximum urinary flows were higher in diabetic children with CAD than in those without CAD. Diabetic children with CAD had also a higher maximum urinary flow than diabetic children without CAD and healthy children. Diabetic children with CAD had a longer diabetes duration and a higher mean fructosamine level during the preceding 3 years than those without CAD. These findings suggest that diabetic children may have diminished sensation of bladder filling independent of impaired cardiovascular reflexes, however, the degree of bladder dysfunction parallels with CAD, both depending on diabetes duration and long-term glycaemic control.