Blink Reflex Test Research Articles

Supratentorial multiple sclerosis lesions affect the blink reflex test.

IntroductionThe Blink Reflex Test (BRT) is a neurophysiological examination used for evaluation of brainstem reflex circuits. MRI is the most precise modality for evaluation of MS lesion anatomy. Our study objective was to investigate how the functional results of the neurophysiological BRT relate to the anatomy of MS lesions in routine MRI studies.Methods65 MS patients underwent the BRT within 2 months of a brain MRI showing demyelinating lesions.Results The overall sensitivity of the BRT was 90.8%, while in patients with at least one brainstem lesion and no brainstem lesions it was 91.4% and 90%, respectively.Discussion The presence of brainstem lesions does not significantly affect BRT sensitivity. This points to the influence of supratentorial MS lesions on the BRT. Gender, age, disease duration, type of MS, acuteness of an MS event and whether MS diagnosis was recent or not were not variables affecting the results.

Facial synkinesis after experimental compression of the facial nerve comparing intratemporal and extratemporal lesions

The anatomical configuration of the facial nerve differs greatly between the intratemporal and extratemporal portions. The purpose of this study was to investigate the incidence of facial synkinesis and misdirection on clamping the facial nerve at the intratemporal or extratemporal portion of the facial nerve in guinea pigs. Experimental study. In 16 guinea pigs, the facial nerve was clamped with microsurgical needle forceps at either the extratemporal (group A) or intratemporal (group B) segment. Facial nerve function was evaluated 1 week postoperatively using electroneurography (ENoG), and the incidence of facial synkinesis was evaluated 15 weeks postoperatively using an evoked blink reflex test. Fifteen weeks postoperatively, two retrograde fluorescent tracers (Dil [1-1'-dioctodecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate] and True Blue) were injected into the facial muscles to observe reorganization of the facial nucleus. No significant difference in the ENoG threshold was observed between groups A and B. In group A, none of the animals developed facial synkinesis and the somatotopic organization of the facial nucleus was not disturbed. In contrast, synkinesis occurred and the somatotopic organization was disturbed in group B. A lack of funicular structure within the intratemporal facial nerve increases the possibility of misdirected regenerating axons and synkinesis.

Recovery of Facial Movement and Facial Synkinesis in Bell's Palsy Patients

We examined the relationship between the time course of development of facial synkinesis in patients with Bell's palsy and the severity of facial nerve damage. Retrospective study. Tertiary referral center. Thirty-nine consecutive patients with Bell's palsy who developed synkinesis. Diagnostic. Subjects were divided into groups A (electroneurographic [ENoG] value, <10%; n = 31) and B (ENoG value, > or =10%; n = 8). Development of facial synkinesis was assessed based on the appearance of synkinetic potentials from the orbicularis oris muscle on the blink reflex test. Times to appearance of facial synkinesis in groups A and B were compared. The proportion of patients who developed facial synkinesis after complete recovery of facial movement was also assessed in 14 patients whose facial movement recovered completely. The mean time to maximal recovery of facial movement was significantly longer in group A than in group B (p < 0.001), whereas the duration between the appearance of facial synkinesis and the onset of facial paralysis did not differ significantly between the 2 groups (p = 0.72). The proportion of patients who developed facial synkinesis after complete recovery of facial movement was significantly greater in group B than in group A (p = 0.015). During the course of recovery from Bell's palsy, the patients with an ENoG value of 10% or greater have a higher risk of developing facial synkinesis after complete recovery of facial movement.

Blink Reflex in Hypothyroidism

Aim: 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. Materials and Methods: Forty-two patients (3 males, 39 females), mean age 40 (±11), with newly diagnosed primary hypothyroidism and 30 healthy control subjects were included in the study. In all patients, the cause of hypothyroidism was chronic autoimmune thyroiditis. 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 Kohden/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 (R2Y) 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 R1, R2Y, and R2C did not correlate with 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.

Neurophysiologic and quantitative sensory testing in the diagnosis of trigeminal neuropathy and neuropathic pain

This study investigated the utility of neurophysiologic examination and thermal quantitative sensory testing (QST) in the diagnosis of trigeminal neuropathy and neuropathic pain. Fifty-eight patients (14 men), 34 with sensory deficit within the inferior alveolar nerve (IAN) and 24 within the lingual nerve (LN) distribution, were included. Twenty-six patients (45%) reported neuropathic pain. Patients underwent blink reflex (BR) test and thermal QST; sensory neurography was done to the IAN patients. Results of clinical sensory testing were available from the charts of 48 patients revealing abnormal findings in 77% of the IAN and in 94% of the LN patients. The BR test was abnormal in 41%, neurography in 96%, and QST in 91% of the IAN patients. In the LN group, BR was abnormal in 33%, and QST in 100% of the patients tested. Neurophysiologic tests and QST verified the subjective sensory alteration in all but 2 IAN patients, both with old injuries, and 4 LN patients who did not undergo QST. When abnormal, thermal QST showed elevation of warm and cold detection thresholds (hypo/anesthesia), hypoalgesia was less marked, and heat allodynia was only occasionally present. Contralateral thermal hypoesthesia after unilateral injury was found in 14 patients. It was associated with the occurrence of neuropathic pain ( P=0.016). Axonal Aβ afferent damage was less severe in the IAN patients with pain than in those without pain ( P=0.012). Neurophysiologic tests and thermal QST provide sensitive tools for accurate diagnosis of trigeminal neuropathy and study of pathophysiological features characteristic to human neuropathic pain.

A case of Mobius syndrome—radiological and electrophysiological findings

Mobius syndrome is characterized by congenital bilateral facial palsy and abducens nerve paralysis, but reports of radiological and electrophysiological findings are scarce. A 4-year-old boy presented with mask-like facies noted at birth after a 34-week pregnancy. Examination revealed bilateral facial and abducens nerve paralysis with no other neurological abnormalities. Computed tomography revealed bilateral absence of facial nerve canal in the middle ear. Brain magnetic resonance imaging indicated a narrow than expected nerve in the internal auditory canal (IAC). Evoked electromyography and blink reflex testing to evaluate facial nerve function yielded no responses bilaterally. Facial palsy thus appears to be caused by facial nerve dysplasia or aplasia.

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.

Using the Blink Reflex as Measured by Electromyogram to Assess Cranial Nerve Involvement in People Affected by Leprosy

Damage to the peripheral nervous system is particularly frequent in leprosy patients. Trigeminal and facial nerves are among the most commonly affected. The aim of our study was to evaluate the efficacy of the blink reflex as a method for diagnosis of cranial nerve involvement in people affected by leprosy. We studied 37 affected people (mean age: 38 yrs, 20 female and 17 male) and 35 age-matched healthy subjects (mean age: 34 yrs, 20 female and 15 male). Blink reflexes were obtained after unilateral electrical stimulation of the supraorbital nerve for quantitative analysis of 3 responses, early ipsilateral phasic component (R1), late ipsilateral tonic component (R2i), and late contralateral tonic component (R2c). Nerve conduction parameters were studied in all subjects. The latencies of both the ipsilateral early phasic component (R1) and bilateral late tonic components (R2i and R2c) in people affected by leprosy were significantly prolonged compared with the controls. Out of 37 people affected by leprosy, 22 (59%) showed abnormalities R1 latency, 28 (75%) R2i latency and 31 (83%) R2c latency. No correlation was observed between prolonged latencies and duration of the disease. We conclude that blink reflex testing, which can be easily and rapidly performed in an EMG laboratory using standard equipment, can provide useful and objective information for the diagnosis of cranial nerve lesions and for the determination of the degree thereof.

Blink reflex alterations in recently diagnosed diabetic patients

Objective. The aim of the present study was to determine the frequency of blink reflex alterations and to examine the influence of hyperglycemia in inducing the alterations in recently diagnosed Type 2 diabetes mellitus patients. Methods. A cross-sectional study was carried out on patients having asymptomatic diabetes with a period of evolution under 10 years. In all 47 patients (26 women and 21 men), serum glycemia levels were determined and the latency onset of the blink reflex components were measured. Results. The average patient age was 44.5±11.0 (mean ± SD) years with a diabetes evolution period of 4.3±2.9 (mean ± SD) years. After a fasting serum glucose test, the diabetic patients were catalogued as normoglycemic (⩽126 mg/dl) or as hyperglycemic (>26 mg/dl) and subjected to a blink reflex test. The results obtained from the diabetic patients were compared with those from a non-diabetic control group. 14.8–31.9% of the diabetic patients showed alterations in blink reflex component latencies. The differences compared with the control group were significant ( p<0.05). Conclusions. Diabetes, as is well-known, can affect the central and peripheral nervous system and there does not appear to be a link between glycemic levels and blink reflex components. However, blink reflex alterations were present even in diabetic patients with a relatively short period of disease evolution.

An evaluation of clinical and electrophysiologic tests in nerve injury diagnosis after mandibular sagittal split osteotomy

The yield of clinical sensory tests and electrophysiologic tests in the diagnostics of inferior alveolar nerve (IAN) damage after bilateral sagittal split osteotomy (BSSO) was studied. The diagnostic value of these tests was evaluated by comparing the test results to the degree of nerve damage at the end of the operation as documented by means of the intraoperative nerve conduction recording of the IAN. Twenty patients undergoing BSSO were analysed preoperatively and 2 weeks postoperatively. The frequency of the IAN disturbance ranged from 10% to 94% depending on the test method and the test site used. Of the clinical sensory tests, the touch detection threshold (TD) test was the most sensitive and clinically useful test. It also correlated best with the electrophysiologically verified intraoperative nerve damage (R=−0.603,P =0.017 on the right, R=−0.626, P=0.01 on the left). The blink reflex and quantitative cold detection threshold tests were almost as often abnormal as the TD-test, but nerve conduction study (NCS) was the most sensitive (88%) of all clinical and electrophysiologic tests. The frequency of abnormal findings in the electrophysiologic tests indicating IAN injury, 75% on the right side and 90% on the left side, corresponded exactly with the figures of subjective sensory alteration. Almost all electrophysiologic tests showed obvious associations with the objectively verified IAN damage. All tests, except the NCS, showed only moderate sensitivity. Specificity of the tests was generally high, the only exceptions being the TD test and the NCS. To increase the diagnostic accuracy of the testing and to detect different types of damage in different nerve fibre populations, a combination of different sensory and electrophysiologic tests is recommended.

Pathophysiology of facial nerve paralysis induced by herpes simplex virus type 1 infection.

Herpes simplex virus type 1 (HSV-1) has been proven to be a cause of Bell's palsy; however, the underlying pathophysiology of the facial nerve paralysis is not fully understood. We established a mouse model with facial nerve paralysis induced by HSV-1 infection simulating Bell's palsy and investigated the pathophysiology of the facial nerve paralysis. The time course of the R1 latency in the blink reflex tests paralleled the recovery of the facial nerve paralysis well, whereas electroneurographic recovery tended to be delayed, compared to that of the paralysis; these responses are usually seen in Bell's palsy. On histopathologic analysis, intact, demyelinated, and degenerated nerves were intermingled in the facial nerve in the model. The similarity of the time course of facial nerve paralysis and the electrophysiological results in Bell's palsy and the model strongly suggest that the pathophysiological basis of Bell's palsy is a mixed lesion of various nerve injuries.

Blink reflex abnormalities in diabetes mellitus.

Damage of the peripheral nervous system is particularly frequent in diabetes mellitus (DM), but somatic cranial neuropathies usually presenting as mononeuropathies are rare. Oculomotor and facial nerves are among the most commonly affected, whereas the Vth, IXth and Xth cranial nerves are less often affected. While existing neurophysiological tests in the subclinical diagnosis of damage to the peripheral nerve in diabetic patients have advanced, the same does not hold true for the subclinical diagnosis of the central nervous system (CNS). Electrophysiological studies such as the blink reflex was shown to be an effective method for revealing subclinical involvement of cranial nerves in generalised neuropathies. 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 diabetic patients frequently affected with peripheral neuropathy. Twenty diabetic patients with electrophysiologically confirmed neuropathy were included in the present study for the evaluation of blink reflex. Patients with earlier cranial nerve involvement were excluded. Abnormal blink reflex responses were found in 55% of patients studied. R2Y and R2C latencies in diabetic patients were prolonged relative to controls (p<0.001 and p<0.001, respectively). However R1 values in diabetic patients did not differ significantly from those of normal controls (p<0.5). R2Y and R2C prolongation showed a positive correlation with the duration of disease (p=0.015 and p=0.009, respectively). However the same correlation could not be found with R1 values. No correlations were found between R1, R2Y, R2C values and HbA(1c) nor between R1, R2Y, R2C values and patients' age. We suggest that blink reflex testing is a useful method for obtaining early diagnosis of cranial nerve compromise in diabetic patients who do not show any clinical symptoms or signs of CNS involvement.

Electrically induced blink reflex and facial motor nerve stimulation in beagles.

Electrophysiologic assessment of the blink reflex test and the muscle-evoked potentials evoked by stimulation of the facial nerve were performed in 15 healthy adult Beagles before and after supraorbital (trigeminal) and facial anesthetic nerve blocks performed by lidocaine injections. Unilateral electrical stimulation of the supraorbital nerve elicited 2 ipsilateral (R1 and R2) and a contralateral (Rc) reflex muscle potential in orbicularis oculi muscles. Electrical stimulation of the facial nerve elicited 2 muscle potentials (a direct response [D] and a reflex faciofacial response [RF]) in the ipsilateral orbicularis oculi muscle. Anesthetic block of the left supraorbital nerve resulted in bilateral lack of responses upon left supraorbital nerve stimulation, but normal responses in right and left orbicularis oculi muscles upon right supraorbital stimulation. Right facial anesthetic block produced lack of responses in the right orbicularis oculi muscle regardless the side of supraorbital nerve stimulation. Results of this study demonstrate that the blink reflex can be electrically elicited and assessed in dogs. Reference values for the blink reflex responses and for the muscle potentials evoked by direct facial nerve stimulation in dogs are provided. The potential usefulness of the electrically elicited blink reflex test in the diagnosis of peripheral facial and trigeminal dysfunction in dogs was demonstrated.

Electrically elicited blink reflex in horses with trigeminal and facial nerve blocks

Abstract Objective To reassess reference values for the components of the electrically induced blink reflex, document reference values for facial motor nerve conduction velocity, and demonstrate usefulness of the blink reflex as a diagnostic tool in peripheral facial and trigeminal nerve dysfunction in horses. Animals 10 healthy adult horses (8 males, 2 females) without neurologic abnormalities. Procedure Blink reflex tests were performed by electrical stimulation of the supraorbital nerve and facial (auriculopalpebral) nerve. Reflex and direct muscle-evoked potentials of the orbicularis oculi muscles were recorded from concentric needle electrodes inserted bilaterally in these muscles. Supraorbital and auriculopalpebral nerve blocks were performed by lidocaine hydrochloride injections. Results Supraorbital nerve stimulation elicited 2 or 3 ipsilateral and 1 contralateral reflex muscle potential in the orbicularis oculi muscles. Auriculopalpebral nerve stimulation elicited a direct and a reflex potential in the ipsilateral orbicularis oculi muscle. After left supraorbital nerve block, no responses could be elicited ipsilaterally or contralaterally upon stimulation of the blocked nerve, but bilateral responses were obtained upon stimulation of the right supraorbital nerve. After right auriculopalpebral nerve block, no responses were recorded from the right orbicularis oculi muscle upon stimulation of left or right supraorbital nerves. Conclusions and Clinical Relevance Reference values for the components of the blink reflex and facial motor nerve conduction velocity will allow application of these tests to assist in the diagnosis of equine neurologic disorders involving the trigeminal and facial nerves, the brainstem, and the cranial end of the cervical segment of the spinal cord. This study reveals the usefulness of the blink reflex test in the diagnosis of peripheral trigeminal and facial nerve dysfunction in horses. (Am J Vet Res 1999;60:1287–1291)

Blink reflex in cerebral palsy: evaluation of late components in patients with normal auditory brainstem responses.

The electrically elicited blink reflex was examined and evaluated quantitatively in 60 controls and seven patients with cerebral palsy due to perinatal asphyxia who exhibited normal auditory brainstem responses. In the controls, the early component (R1) latency changed slightly from infancy to adulthood, and the late component (R2 and R2') latencies decreased to adult values by 4 to 6 years of age. The electromyographic activity of R2 and R2' increased later and became mature in the young adolescent period. Prolonged R2 latency and decreased R2 amplitude were observed more frequently than R1 abnormalities in the patients. The electromyographic activity of R2 in the patients was lower than that in control subjects more than 13 years old. Almost all patients showed bilateral cerebral atrophy and dilated lateral ventricles, but only one patient exhibited distinct pontine atrophy on cranial computed tomographic scan. These electrophysiologic abnormalities suggest that decreased excitability of interneurons of the reflex arc was present in the patients, particularly in older ones. The blink reflex test seems to be more sensitive than the auditory brainstem response for detecting brainstem dysfunction in patients with cerebral palsy due to neonatal asphyxia.

The mental nerve blink reflex in the diagnosis of lesions of the inferior alveolar nerve following orthognathic surgery of the mandible

The purpose of this study was to evaluate the diagnostic value of a new modification of the blink reflex test with stimulation of the distribution of the mental nerve in iatrogenic lesions of the inferior alveolar nerve. The test was performed on 23 patients undergoing orthognathic surgery of the mandible, most of them (20) with bilateral sagittal split osteotomies. The function of the inferior alveolar nerve was studied preoperatively, and 2 weeks, 2 months, 6 months and 1 year postoperatively with both mental nerve blink reflex test and clinical neurosensory testing. The objective electrophysiological test proved to be useful in the diagnosis and follow-up of sensory impairment of the inferior alveolar nerve. The results of the mental nerve blink reflex test and clinical neurosensory testing were closely related. The results of the two tests did not differ statistically significantly in the two first postoperative examinations. The positive predictive value of the mental nerve blink reflex test was better than that of clinical neurosensory testing: an initially abnormal reflex response predicted persistent subjective sensory symptoms after one year more reliably than did altered sensation at the first two examinations. Irrespective of the possible coexistent sensory symptoms and signs, a normal mental nerve blink reflex within 2 months after operation also predicted a reasonably good sensory recovery at 1 year.

PS-5-3 Assessment of brain function by habituation of blink reflex and psycho-metric test in the various type of supratentorial lesions

PS-5-3 Assessment of brain function by habituation of blink reflex and psycho-metric test in the various type of supratentorial lesions

Evaluating function of the inferior alveolar nerve with repeated nerve conduction tests during mandibular sagittal split osteotomy

Purpose: This article evaluates a new intraoperative recording technique for measuring the sensory nerve conduction velocity (SNCV) of the human inferior alveolar nerve (IAN) during orthognathic surgery of the mandible to assess the effects of intraoperative strain on function of the IAN. Materials and Methods: The new test was successfully applied in 10 patients during bilateral sagittal split osteotomy of the mandible (20 IANs). The recordings were made with active wire electrodes at foramen ovale and stimulation was done at the mental foramen with two monopolar needle electrodes. The sensory nerve action potentials (SNAP) were recorded intraoperatively at three stages: 1) before the split, 2) after splitting of the mandible and possible mobilization of the IAN from the proximal bone fragment, and 3) at the end of the operation after fixation of the proximal and distal fragments with screws. Results: The SNCV values (mean 64.1 m/sec) were obtained in all 20 nerves at stage 1, with no significant differences between the sides in latency or amplitude of the SNAPs. The SNAPs remained stable in the IANs not exposed during the operation. In the remaining nerves, the most obvious and statistically significant changes indicating nerve injury occurred between stages 1 and 2. Partial transsection and mobilization of the IAN were equally potent in bringing about abnormal results in objective neurophysiologic tests as well as subjective sensory disturbances. The results of the intraoperative SNCV recordings correlated well with the findings of the mental nerve blink reflex tests conducted 2 weeks after the operation, whereas comparison of the results of clinical neurosensory testing with the intraoperative events and SNCVs were more inconsistent. Conclusions: Recording of the SNCV offers a useful objective tool for the examination of the IAN both intraoperatively and in clinical diagnosis.

Comprehensive Management of the Eye in Facial Paralysis

To determine guidelines for the management of paralyzed eyelids following facial palsy, including surgical indications, timing, and type of procedure(s). Prospective analysis of 60 patients diagnosed as having complete facial palsy. Follow-up ranged from 18 to 36 months. All subjects had a complete unilateral facial palsy of various origins. Ages ranged from 6 to 81 years. Forty patients underwent evoked electromyography and blink reflex testing of the facial nerve. Twenty additional patients had a known fifth-degree nerve injury that did not require testing. Lack of interval improvement in clinical results of examination and/or evoked electromyography, coupled with length of time from injury, were used to determine surgical candidacy. All patients with fifth-degree nerve injury were considered surgical candidates, with clinical examination results of eyelid function used to determine which procedure(s) to be performed. Of the 60 patients evaluated with facial palsy, 43 patients required surgical restoration of eyelid function. Forty-one patients required gold weight implants; 18 of these also required shortening of the lower eyelid. Two additional patients underwent eyelid shortening without gold weight implantation. Seventeen patients were treated only with corneal lubricants and moisturizers. No gold weights extruded; there were no infections. Two patients required revision of their lower eyelid surgery owing to progressive laxity. Four patients have had their gold weights removed an average of 9.5 months following insertion. The degree of neural injury and its associated regeneration time, determined clinically and by evoked electromyography, are useful factors to assist in patient selection, surgical timing, and type of procedure(s) necessary to fully rehabilitate the upper and lower eyelids following facial paralysis.

Clinical application of the blink reflex with stimulation of the mental nerve in lesions of the inferior alveolar nerve

We evaluated the clinical usefulness of a new modification of the blink reflex (BR) test with electrical stimulation of the innervation area of the mental nerve (MN). We studied the MN BR in 28 patients with traumatic lesions of the inferior alveolar nerve and compared the results with the clinical sensory examination. Within 3 months of the trauma, the MN BR was abnormal in 18 of 20 nerves. In lesions older than 3 months, the test was often normal (in 9 of 11 nerves) despite subjective sensory symptoms and mild clinical signs. Anatomic obstacles to nerve regeneration also gave rise to abnormal MN BR in two patients examined 2 and 4 years after the trauma. The MN BR responses were often absent after violently traumatic lesions, whereas milder injuries commonly produced only latency prolongation of the reflex components. The MN BR is a useful objective method in the diagnosis of sensory loss in the distribution of the MN.