Blink reflex abnormalities in diabetes mellitus

Alterations in blink and masseter reflex latencies in older adults with neurocognitive disorder and/or diabetes mellitus

BACKGROUND

Blink and masseter reflexes provide reliable, quantifiable data on the function of the central nervous system: Delayed latencies have been found in patients with neurocognitive disorder (ND) and type 2 diabetes mellitus (T2DM), but this has not been studied in patients with both pathologies.

AIM

To investigate if older adults with ND plus T2DM have prolonged latencies of blink and masseter-reflex and if they were associated with disease progression.

METHODS

This cross-sectional study included 227 older adults (> 60 years) from Colima, Mexico. Neurocognitive disorder was identified by a neuropsychological battery test, and T2DM identified by medical history, fasting glucose, and glycosylated hemoglobin. Latencies in the early reflex (R1), ipsilateral late (R2), and contralateral late (R2c) components of the blink reflex were analyzed for all subjects, and 183 subjects were analyzed for latency of the masseter reflex.

RESULTS

In 20.7% of participants, ND was detected. In 37%, T2DM was detected. Latencies in R1, R2, and R2c were significantly prolonged for groups with ND plus T2DM, ND, and T2DM, compared with the control group (P < 0.0001). The masseter reflex was only prolonged in older adults (regardless of T2DM status) with ND vs controls (P = 0.030). In older adults with ND and without T2DM, the more the cognitive impairment progressed, the more prolonged latencies in R2 and R2c presented (P < 0.01).

CONCLUSION

These findings suggest that blink and masseter reflexes could be used to evaluate possible changes in brainstem circuits in older adults with ND and T2DM.

Changes of Blink Reflex in Type 2 Diabetes Mellitus

Blink reflex provides an objective assessment of the cranial and central nervous systems. However, the relationships between body mass index, dizziness, and BR have not been explored in patients with type 2 diabetes mellitus (T2DM). Moreover, R2 duration, one of the parameters of the blink reflex, has not been studied to date. In the present study, we aimed to investigate the characteristics and influencing factors of blink reflex in patients with T2DM. We included 45 healthy subjects and 105 hospitalized patients with T2DM. The relationships between these parameters and sex, age, body mass index, duration of T2DM, hemoglobin A1c, distal symmetrical polyneuropathy (DSPN), and dizziness symptoms were analyzed. The results showed that blink reflex latencies (including R1, ipsilateral R2, and contralateral R2 latency) were negatively associated with body mass index but were positively correlated with the duration of T2DM. There were no correlations between blink reflex parameters and sex, age, and hemoglobin A1c. Patients with DSPN had longer blink reflex latencies and shorter R2 durations than those without DSPN. Patients with dizziness had longer latencies (including R1, ipsilateral R2, and contralateral R2 latencies) and shorter R2 durations (including ipsilateral R2 and contralateral R2 durations) than those without dizziness. R2 duration was also a predictive factor for blink reflex abnormality. R2 latency was the most sensitive factor and the optimal predictor of dizziness. These results demonstrate that patients with T2DM with low body mass index, longer duration of T2DM, DSPN, and dizziness-related symptoms had more abnormal blink reflex parameters, indicating more serious injuries to the cranial nerves or the central nervous system.

The role of blink reflex R1 latency as an electrophysiological marker in diabetic distal symmetrical polyneuropathy

OBJECTIVE

Studies showed a relatively prolonged blink R1 latency in patients with diabetic distal symmetrical polyneuropathy (DSPN) compared to that without DSPN. We tested the hypothesis that blink R1 latency would provide a diagnostic alternative to nerve conduction studies (NCS) in DSPN and act as a marker of the severity of NCS abnormalities in DSPN.

METHOD

A total of 109 patients with type 2 diabetes underwent blink reflex studies and NCS. We used the composite amplitude scores of nerve conductions (CAS), which consisted of motor (tibial, peroneal and ulnar) and sensory (sural and ulnar) amplitudes for estimating the severity of NCS.

RESULTS

Patients with DSPN had longer blink R1, R2, and contralateral R2 latencies (P < 0.0001, P = 0.001, and P = 0.031, respectively) and higher CAS (P < 0.0001). Area under curve on receiver operating characteristic curve analysis in diagnosing occurrence of DSPN in blink R1 latency was 0.772 (P < 0.0001). Multiple linear regression analysis showed that blink R1 latency was independently associated with CAS.

CONCLUSION

Blink R1 latency may be valuable in auxiliary diagnosis and in determining the severity of NCS abnormalities in DSPN.

SIGNIFICANCE

Blink R1 latency can be added as a supplemental marker of severity of NCS in DSPN, especially if the patient's sural amplitudes has a floor effect.

Trigeminal nociceptive function and oral somatosensory functional and structural assessment in patients with diabetic peripheral neuropathy

This case-control study primarily compared the trigeminal nociceptive function, the intraoral somatosensory profile and possible structural nerve changes between diabetic peripheral neuropathy (DPN, n = 12) patients and healthy participants (n = 12). The nociceptive blink reflex (nBR) was recorded applying an electrical stimulation over the entry zone of the right supraorbital (V1R), infraorbital (V2R) and mental (V3R) and left infraorbital (V2L) nerves. The outcomes were: individual electrical sensory (I₀) and pain thresholds (I_P); root mean square (RMS), area-under-the-curve (AUC) and onset latencies of R2 component of the nBR. Furthermore, a standardized full battery of quantitative sensory testing (QST) and intraepidermal nerve fibre density (IENFD) or  nerve fibre length density (NFLD) assessment were performed, respectively, on the distal leg and oral mucosa. As expected, all patients had altered somatosensory sensitivity and lower IENFD in the lower limb. DPN patients presented higher I₀, I_P, RMS and AUC values (p < 0.050), lower warm detection thresholds (WDT) (p = 0.004), higher occurrence of paradoxical heat sensation (PHS) (p = 0.040), and a lower intraoral NFLD (p = 0.048) than the healthy participants. In addition, the presence of any abnormal intraoral somatosensory finding was more frequent in the DPN patients when compared to the reference group (p = 0.013). Early signs of trigeminal nociceptive facilitation, intraoral somatosensory abnormalities and loss of intraoral neuronal tissue can be detected in DPN patients.

Sensory Ganglionopathy and the Blink Reflex: Electrophysiological Features

Background: Sensory ganglionopathy (SG) is characterised by asymmetrical sensory fibre degeneration, with the primary pathology occurring at the level of the dorsal root ganglion. It is seen in the context of autoimmune, paraneoplastic, and degenerative disorders. There is limited literature examining the electrophysiological correlate of the trigeminal ganglion and associated pathways, the blink reflex (BR), in cases of SG. Previous work has suggested that the BR is preserved in cases of SG associated with paraneoplasia. Methods: The local clinical neurophysiology database was searched for patients diagnosed with SG from peripheral nerve conduction studies in whom the BR was performed. Twenty-six patients were included in the final analysis. Results: Sjögren’s syndrome constituted the most common SG aetiology (8/26), followed by idiopathic cases (7/26) and paraneoplasia (5/26). BR abnormalities were seen in 9 of the 26 patients (34.6%) across all aetiologies. No patients reported sensory disturbance in the distribution of the trigeminal nerve, indicating that the changes noted are subclinical. Three patients showed abnormality of the R1 response; in the remaining six patients, only R2 responses were affected. Conclusions: Subclinical abnormalities of both R1 and R2 can be seen in the context of SG of varying aetiologies, including paraneoplasia. Performing the BR in patients with suspected of having SG may be helpful in providing additional evidence of patchy sensory fibre involvement that is characteristic of the disease.

Blink reflex in type 2 diabetes mellitus

PURPOSE

An evaluation of the extent of damage of the central nervous system in diabetes mellitus is of high value in current research. Electrophysiological abnormalities are frequently present in asymptomatic patients with diabetes mellitus. Diabetic cranial neuropathy is one of the complications of the disease. Blink reflex is used to diagnose subclinical cranial neuropathy. The objective is to test the utility of blink reflex in detecting subclinical cranial nerve involvement in patients with type 2 diabetes mellitus.

METHODS

Forty patients with type 2 diabetes mellitus, aged from 30 to 60 years examined clinically and neurologically. Blink reflex and nerve conduction studies for the upper and lower limbs were performed and compared with 20 matched normal controls.

RESULTS

Diabetic patients with peripheral neuropathy showed significant prolonged distal latency and reduced amplitudes of the R2C response compared with the control, patients without peripheral neuropathy showed insignificant changes. Alteration of R2 correlated with the type of treatment and the duration of the disease. In patients without peripheral neuropathy, ulnar sensory distal latencies showed significant positive correlation with R2I latency, whereas its Conduction Velocity (CV) showed significant positive correlation with R2C amplitudes and negative correlation with R2C latency.

CONCLUSIONS

R2C is the most sensitive parameter in the blink reflex, which can help in the diagnosis of subclinical diabetic cranial neuropathy.

Is There a Relation between Reticular Formation and Storage Symptoms in Men

OBJECTIVE

To reveal brainstem originated pathology in men with different types of lower urinary tract symptoms blink reflex latency times were assessed.

METHODS

A total of 32 men, 16 with storage and 16 with voiding symptoms, were enrolled in the study. Blink reflex latency times were analyzed through electrical stimulation of the supraorbital nerve. Two responses in the orbicularis oculi muscle were recorded: the latency times for the early ipsilateral response, R1, and the late bilateral responses, R2.

RESULTS

The mean ages of the patients with storage and voiding symptoms were 57.31 ± 6.87 and 58.06 ± 6.29 years, respectively. The R2 latency times were significantly longer in men with storage symptoms. However, the R1 latency times were similar for the two groups.

CONCLUSION

Late blink latency times were long only in patients who had storage symptoms. An oligosynaptic path through the trigeminal nuclei, which includes one or two interneurons, is responsible for early response; however, late response is relayed through a polysynaptic path, including neurons in the reticular formation. It has also been shown that stimulation of the pontine reticular formation inhibits the micturition contraction. In some patients, storage symptoms may result from pathology that originates with the reticular formation and this pathology may lead to increases in late blink latency times. Additional studies are needed on other reflexes that are mediated through reticular formation, in order to show the possible dysfunction of the reticular formation in men with storage symptoms.

Electromyographic evaluation of blink reflex as a tool for early diagnosis of neurological dysfunction in patients of hypothyroidism

BACKGROUND

Neurological dysfunction is an important consequence of hypothyroidism. Some of the neurologic manifestations of hypothyroidism include somnolence, lethargy, impaired memory and concentration, depression and entrapment neuropathy. Rarer but reversible neurological manifestations include cerebellar ataxia, psychosis, dementia and myxedema coma.

PURPOSE

The aim of the present study was to evaluate the usefulness of the blink reflex as a method for obtaining an early diagnosis of central nervous system dysfunction in hypothyroid patients who do not have signs or symptoms of nervous system dysfunction.

METHODS

Forty-eight patients with mean age 40 (± 11), with newly diagnosed primary hypothyroidism and 20 healthy control subjects were included in the study. The patients were divided into subclinical and overt hypothyroidism. Patients with normal T3/T4 with elevated TSH were considered subclinical hypothyroids. For blink reflex testing, subjects lay supine on a bed in a warm room with eyes gently closed. Recordings were performed with an EMG machine (Nihon Kohdeni'Neuropack), with a filter setting of 20 Hz to 10 kHz, using an analysis time of 50 ms. Recordings were performed with surface recording electrodes (Dantec 13K60, Copenhagen, Denmark).

RESULTS

Second ipsilateral response (R2I) and second contralateral response (R2C) latencies in hypothyroidism were prolonged relative to controls, and the differences were statistically significant (P<0.001 and P<0.001, respectively). Latency of Rl, R2I, and R2C did not correlate linearly free T3, free T4, or TSH values in the hypothyroid group.

CONCLUSION

The finding of abnormal blink reflex responses in hypothyroid individuals raises the notion that they may be useful in detecting early changes and in the follow-up of the patients with the disorder.

Blink reflex alterations in diabetic patients with or without polyneuropathy

The main aim of this study is to evaluate the role of blink reflex for early diagnosis of cranial neuropathy in diabetic patients with or without polyneuropathy. Ninety-five diabetic patients were included in the present study for the evaluation of blink reflex. The diabetic patients were divided into two groups according to having diabetic neuropathy or not. Both R1, R2i and R2c latencies in all diabetic patients with or without polyneuropathy were prolonged relative to controls and the differences were statistically significant (p < .001). R1 latencies in diabetic patients with polyneuropathy were prolonged relative to diabetic patients without polyneuropathy and the differences were statistically significant (p < .001). These findings presumably reflect that facial nerve is severly involved in diabetic polyneuropathy. Finally blink reflex is of value in detection of clinically silent intraaxial brainstem functional abnormalities or extraaxial lesions in diabetic patients before peripheral neuropathy.

Electrophysiological findings of acute peripheral facial palsy in diabetic and non-diabetic patients

The aim of this study is to investigate the role of diabetes mellitus on the clinical and electrophysiological findings of peripheral facial palsy (PFP), the effect of the diabetes duration and polyneuropathy on the electrophysiological parameters. A total of 32 diabetic and 40 non-diabetic patients with peripheral facial palsy were included. All patients were divided into two subgroups based on the time of electrophysiological examinations: within the first 15 days versus within 16-30 days. Neuropathy symptoms and the results of neurological examinations and electrophysiological findings were recorded. The findings of electroneurography (EnoG), blink reflex (BR) evaluation, and needle electromyography (EMG) indicated statistically significant blink reflex abnormalities in diabetic patients compared to non-diabetics. Delay in the latency was more remarkable in the R2 component than in the R1 (p<0.001). The delay in the R1 latency was also observed in the non-affected side for diabetic patients. The longer duration of the diabetes caused significant delay on the blink reflex latency on both the affected and non-affected sides for R1 component (p=0.019, p=0.041, respectively). In contrary, neither the diabetes duration nor the age of the patients correlated with the clinical severity of facial palsy, fiber loss, fibular nerve compound muscle action potential amplitudes, and the nerve conduction velocities.

Role of blink reflex in diagnosis of subclinical cranial neuropathy in diabetic mellitus type II

BACKGROUND AND OBJECTIVES

Peripheral neuropathy (PN) is one of the late complications of diabetes mellitus. Cranial nerves III, VII, and V are among the most commonly affected in diabetic patients. Traditional electrodiagnosis (Edx) studies are a useful method for diagnosis of PN and symptomatic cranial neuropathy, and may not be useful for detecting subclinical involvement of cranial nerves. The main objective of this study is to evaluate the role of blink reflex (BR) for early diagnosis of cranial neuropathy in diabetic patients with PN.

DESIGN

A prospective study was performed on NIDDM patients with PN. One hundred eighty-eight subjects were included in our study in which 142 acted as healthy subjects and 46 as diabetic patients. Patients were excluded with prior history of cranial nerve lesions, stroke, or any other disease with polyneuropathy or drug-induced neuropathy. Routine nerve conduction studies were performed, and only patients with PN were included in this study.

RESULTS

Abnormalities were found in 54.4% of patients. R1, IR2, and CR2 were prolonged relative to the healthy group. Statistically there was no significant difference in R/D ratio of patients (P=0.201). Also, there was a positive correlation between R1, IR2, and CR2 latencies with duration of diabetes and severity of polyneuropathy, but not for R/D. The greatest correlation was shown in R1 latency (69.9% abnormality).

CONCLUSION

BR is a noninvasive and very useful method for the evaluation and diagnosis of subclinical cranial nerve involvement in diabetic patients.

Blink Reflex Abnormalities in Chronic Alcoholics

PURPOSE

The aim of the present study was to evaluate the efficacy of blink reflex as a method for obtaining early diagnosis of cranial nerve involvement in alcoholic patients.

MATERIALS AND METHODS

The study was conducted on 30 male alcoholics with a mean age of 43 years. They had histories of alcohol abuse for at least 6 years (mean: 25). At the time of recording, they had undergone detoxification treatment for a mean of 27 days.

RESULTS

R1 (early response), R2Y (second ipsilateral response), and R2C (second contralateral response) latencies in alcoholics were prolonged relative to controls and the differences were statistically significant (p < 0.02, p < 0.001, p < 0.001, respectively). According to the defined criteria, 40% of the patients had abnormal responses, and the most common abnormality was the unilateral prolongation of R1 (13%).

CONCLUSION

Finding abnormal blink reflex responses in alcoholic patients has suggested that blink reflex testing is a useful method for the evaluation of subclinical cranial nerve involvement in alcoholic patients. Blink reflex testing may be useful in detecting early changes and in the follow-up of alcoholic disorder.