Nervous control of eyelid function. A review of clinical, experimental and pathological data

Neural control of blinking

Blinking is a motor act characterized by the sequential closing and opening of the eyelids, which is achieved through the reciprocal activation of the orbicularis oculi and levator palpebrae superioris muscles. This stereotyped movement can be triggered reflexively, occur spontaneously, or voluntarily initiated. During each type of blinking, the neural control of the antagonistic interaction between the orbicularis oculi and levator palpebrae superioris muscles is governed by partially overlapping circuits distributed across cortical, subcortical, and brainstem structures. This paper provides a comprehensive overview of the anatomical and physiological foundations underlying the neural control of blinking. We describe the infra-nuclear apparatus, as well as the supra-nuclear control mechanisms, i.e., how cortical, subcortical, and brainstem structures regulate and coordinate the different types of blinking.

Lesion network mapping of eye-opening apraxia

Apraxia of eyelid opening (or eye-opening apraxia) is characterized by the inability to voluntarily open the eyes because of impaired supranuclear control. Here, we examined the neural substrates implicated in eye-opening apraxia through lesion network mapping. We analysed brain lesions from 27 eye-opening apraxia stroke patients and compared them with lesions from 20 aphasia and 45 hemiballismus patients serving as controls. Lesions were mapped onto a standard brain atlas using resting-state functional MRI data derived from 966 healthy adults in the Harvard Dataverse. Our analyses revealed that most eye-opening apraxia-associated lesions occurred in the right hemisphere, with subcortical or mixed cortical/subcortical involvement. Despite their anatomical heterogeneity, these lesions functionally converged on the bilateral dorsal anterior and posterior insula. The functional connectivity map for eye-opening apraxia was distinct from those for aphasia and hemiballismus. Hemiballismus lesions predominantly mapped onto the putamen, particularly the posterolateral region, while aphasia lesions were localized to language-processing regions, primarily within the frontal operculum. In summary, in patients with eye-opening apraxia, disruptions in the dorsal anterior and posterior insula may compromise their capacity to initiate the appropriate eyelid-opening response to relevant interoceptive and exteroceptive stimuli, implicating a complex interplay between salience detection and motor execution.

Müller Muscle-Conjunctival Resection for Treatment of Contralateral Ptosis following Unilateral External Levator Advancement

BACKGROUND

One of the main causes of unsatisfactory outcomes after unilateral blepharoptosis surgery is asymmetry of the upper eyelid height, which occurs as a result of a contralateral eyelid droop. Therefore, the authors evaluated the efficacy of Müller muscle-conjunctival resection (MMCR) for the treatment of contralateral ptosis following unilateral external levator advancement (ELA).

METHODS

This study analyzed 26 eyelids of 26 patients with upper eyelid height asymmetry following unilateral ELA who underwent contralateral MMCR retrospectively. The phenylephrine test was performed before ELA and before MMCR. The main outcome measures were symmetry outcomes and clinical outcomes.

RESULTS

The mean patient age was 55.81 ± 7.98 years (range, 44 to 70 years); 15 were female (57.7%). The Hering dependency was observed in 13 of the patients (50%) before ELA. An adequate response to phenylephrine was observed before MMCR but not before ELA. Symmetry outcomes after MMCR were perfect (<0.5 mm), good (≥0.5 mm and <1 mm), and fair (≥1 mm) in seven, 17, and two patients, respectively. An optimal upper eyelid height was noted in 47 of the 52 eyelids after the MMCR, whereas three of the 52 eyelids had minimal overcorrection, and two eyelids had undercorrection. The mean change in marginal reflex distance 1 of the contralateral eyelid droop was greater for patients with than without the Hering dependency ( P < 0.0001) after ELA but not after MMCR. Two patients (7.6%) underwent revision ELA surgery.

CONCLUSION

MMCR and use of the phenylephrine test to predict the eyelid position may represent an alternative approach in patients who require management of contralateral ptosis following unilateral ELA.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Validating a Portable Device for Blinking Analyses through Laboratory Neurophysiological Techniques

Blinking analysis contributes to the understanding of physiological mechanisms in healthy subjects as well as the pathophysiological mechanisms of neurological diseases. To date, blinking is assessed by various neurophysiological techniques, including electromyographic (EMG) recordings and optoelectronic motion analysis. We recorded eye-blink kinematics with a new portable device, the EyeStat (Generation 3, blinktbi, Inc., Charleston, SC, USA), and compared the measurements with data obtained using traditional laboratory-based techniques. Sixteen healthy adults underwent voluntary, spontaneous, and reflex blinking recordings using the EyeStat device and the SMART motion analysis system (BTS, Milan, Italy). During the blinking recordings, the EMG activity was recorded from the orbicularis oculi muscles using surface electrodes. The blinking data were analyzed through dedicated software and evaluated with repeated-measure analyses of variance. The Pearson’s product-moment correlation coefficient served to assess possible associations between the EyeStat device, the SMART motion system, and the EMG data. We found that the EMG data collected during the EyeStat and SMART system recordings did not differ. The blinking data recorded with the EyeStat showed a linear relationship with the results obtained with the SMART system (r ranging from 0.85 to 0.57; p ranging from <0.001 to 0.02). These results demonstrate a high accuracy and reliability of a blinking analysis through this portable device, compared with standard techniques. EyeStat may make it easier to record blinking in research activities and in daily clinical practice, thus allowing large-scale studies in healthy subjects and patients with neurological diseases in an outpatient clinic setting.

Characterization of Postanoxic Tonic Eyelid Opening: A Poorly Recognized Prognostic Sign

Background

Postanoxic myoclonus is a known poor prognostic sign, and other postanoxic spontaneous movements have been reported but poorly described. We aim to describe the electroclinical phenomenon of postanoxic eyelid openings in context of its possible prognostic value.

Methods

We collected clinical data on postcardiac arrest patients with suspicious eyelid movements noted on continuous EEG monitoring. The eyelid movements captured on the video were correlated with the EEG findings and final clinical outcome. Neuroimaging data were reviewed when available. We also conducted a thorough literature review on this topic.

Results

A total of 10 patients (5 females) with average age of 56.1 (±14.4) years were included. The mean cardiopulmonary resuscitation duration was 18.9 (±11.3) minutes. Postanoxic eyelid-opening movements occurred at variable intervals (0.5-570 seconds) in each individual. Close examination of eyelid opening (available in 6 patients) revealed them to be tonic movements, lasting an average of 3 (±0.8) seconds and always succeeded the onset of burst of EEG activity in a burst-suppression background. This is a transient phenomenon, lasting a median duration of 30 (interquartile range 7.75-36) hours. MRI findings in 3 patients demonstrated diffuse cortical ischemic injury with relative sparing of the brainstem. All patients died within 2-7 days following cardiac arrest.

Conclusions

Contrary to previous descriptions, the postanoxic tonic eyelid openings (PATEO) are repetitive but nonperiodic, nonmyoclonic movements. Their close and specific temporal correlation with the burst of EEG activity suggests that this could be considered an ictal phenomenon requiring an intact midbrain based on MRI findings.

Macaque monkey trigeminal blink reflex circuits targeting levator palpebrae superioris motoneurons

For normal viewing, the eyes are held open by the tonic actions of the levator palpebrae superioris (levator) muscle raising the upper eyelid. This activity is interrupted during blinks, when the eyelid sweeps down to spread the tear film or protect the cornea. We examined the circuit connecting the principal trigeminal nucleus to the levator motoneurons by use of both anterograde and retrograde tracers in macaque monkeys. Injections of anterograde tracer were made into the principal trigeminal nucleus using either a stereotaxic approach or localization following physiological characterization of trigeminal second order neurons. Anterogradely labeled axonal arbors were located both within the caudal central subdivision, which contains levator motoneurons, and in the adjacent supraoculomotor area. Labeled boutons made synaptic contacts on retrogradely labeled levator motoneurons indicating a monosynaptic connection. As the eye is also retracted through the actions of the rectus muscles during a blink, we examined whether these trigeminal injections labeled boutons contacting rectus motoneurons within the oculomotor nucleus. These were not found when the injection sites were confined to the principal trigeminal nucleus region. To identify the source of the projection to the levator motoneurons, we injected retrograde tracer into the oculomotor complex. Retrogradely labeled cells were confined to a narrow, dorsoventrally oriented cell population that lined the rostral edge of the principal trigeminal nucleus. Presumably these cells inhibit levator motoneurons, while other parts of the trigeminal sensory complex are activating orbicularis oculi motoneurons, when a blink is initiated by sensory stimuli contacting the face.

Bilateral Cerebral Ptosis in a Patient with Subdural Hemorrhage: a Case Report

Although cerebral ptosis is rare, it is commonly associated with unilateral right cerebral hemisphere lesions. We report a case of a 79-year-old woman who presented with bilateral complete ptosis after a traumatic right fronto-temporo-parietal subdural hemorrhage (SDH). Bilateral ptosis was the primary manifestation of the acute right SDH, and the patient had no parenchymal lesion. Her prognosis was good, and she made a complete recovery. Right hemispheric hypoperfusion, as demonstrated on brain perfusion single-photon emission computed tomography, implied that the lateralization of eyelid control was in the right hemisphere, in line with previous reports.

Apraxia of Lid Opening in Subthalamic Nucleus Deep Brain Stimulation for Parkinson's Disease-Frequency, Risk Factors and Response to Treatment

Background

New-onset apraxia of lid opening (ALO) is reported to occur in Parkinson's disease (PD) patients following Deep Brain Stimulation (DBS). There are only few systematic studies on this uncommon disorder of eyelid movements.

Objectives

We aimed to examine the frequency, temporal evolution, predisposing factors and response to treatment, of new-onset ALO in PD patients who underwent bilateral subthalamic nucleus (STN) DBS.

Methods

We retrospectively reviewed the data of patients who underwent STN DBS at our centre between 1999 and 2017, with a minimum of 2 years of follow up after surgery.

Results

New-onset ALO was seen in 17 (9.1%) of the 187 patients after an average of 16.9 months (Range - 6-36 months). Comparison of the groups with and without ALO revealed that ALO occurred more often in older patients, both at the onset of PD symptoms and at surgery and in those with non-tremor dominant subtypes of PD and freezing of gait at baseline. The extent of levodopa dose reduction after surgery and the pre-operative severity of motor symptoms were not risk factors. Response to adjustments of dopaminergic medications and stimulation parameters was ill-sustained or nil. Botulinum toxin therapy resulted in satisfactory improvement in the majority.

Conclusions

New-onset ALO is an uncommon phenomenon that manifests months after STN DBS. Development of ALO is likely to be due to the effects of chronic stimulation of basal ganglia-thalamo-cortical or brain stem circuits controlling lid movements in susceptible patients. Botulinum toxin therapy offers relatively better relief of symptoms than other strategies.

Müller Muscle-conjunctival Resection with or without Tarsectomy and Combined with Bandage Contact Lens Use in Ptosis Patients with Corneal Graft

PURPOSE

To examine the efficacy of ptosis correction with a Müller muscle-conjunctival resection with or without tarsectomy (MMCR±T), combined with bandage contact lens (BCL) use, in corneal graft patients.

METHODS

Seven patients with corneal grafts who underwent MMCR±T for treatment of ptosis were evaluated retrospectively. A BCL was applied to the grafts at the end of the surgery. The collected data included preoperative and postoperative visual acuity, marginal reflex distance 1 (MRD-1), presence of Hering's dependency by the phenylephrine test, symmetry outcomes, and complications after MMCR±T.

RESULTS

The average duration between the penetrating keratoplasty and MMCR±T was 14 months, with a follow-up time of 10.4 months after MMCR±T. Hering's dependency was observed in four (57.2%) patients before MMCR±T, and MRD-1 was increased in all patients based on preoperative phenylephrine tests. The mean preoperative MRD-1 was -0.14 ± 0.55 mm, and the mean postoperative MRD-1 was 2.35 ± 0.89 mm (p < 0.0001). Symmetry outcomes of perfect (<0.5 mm), good (0.5-1 mm), and fair (≥1 mm) were noted after MMCR±T in three, three, and one patients, respectively. During the follow-up, no obvious corneal epitheliopathy, keratitis, or corneal graft rejection/failure were noted in any cases. BCL use was well tolerated by all patients.

CONCLUSIONS

Most patients achieved good surgical outcomes with the application of the BCL to protect the graft and with the use of the phenylephrine test and Hering's dependency to predict the final eyelid position and symmetry. MMCR±T combined with BCL may therefore represent an alternative approach for correction of ptosis in patients with corneal graft.

Painful stimulation increases spontaneous blink rate in healthy subjects

Spontaneous blink rate is considered a biomarker of central dopaminergic activity. Recent evidence suggests that the central dopaminergic system plays a role in nociception. In the present study, we aimed to investigate whether pain modulates spontaneous blink rate in healthy subjects. We enrolled 15 participants. Spontaneous blink rate was quantified with an optoelectronic system before and after: (1) a painful laser stimulation, and (2) an acoustic startling stimulation. In control experiments, we investigated whether laser stimulation effects depended on stimulation intensity and whether laser stimulation induced any changes in the blink reflex recovery cycle. Finally, we investigated any relationship between spontaneous blink rate modification and pain modulation effect during the cold pressor test. Laser, but not acoustic, stimulation increased spontaneous blink rate. This effect was independent of stimulation intensity and negatively correlated with pain perception. No changes in trigeminal-facial reflex circuit excitability were elicited by laser stimulation. The cold pressor test also induced an increased spontaneous blink rate. Our study provides evidence on the role of dopamine in nociception and suggests that dopaminergic activity may be involved in pain modulation. These findings lay the groundwork for further investigations in patients with pathological conditions characterized by dopaminergic deficit and pain.

After stroke, apraxia of eyelid opening is associated with high mortality and right hemispheric infarction

INTRODUCTION

Apraxia of eyelid opening (AEO) refers to impaired voluntary eyelid elevation of supranuclear origin. AEO is well-described in neurodegenerative disorders, but its frequency in stroke is unknown.

METHODS

To investigate the frequency of AEO after stroke, we enrolled patients with an anterior circulation occlusion admitted for endovascular thrombectomy (EVT). Exclusion criteria were posterior circulation stroke, impaired consciousness and ophthalmological disorders. Forty-eight hours after EVT, patients were screened for AEO, conjugated gaze palsies and cortical ptosis. Neurological deficits were classified using the National Institute of Health Stroke Scale (NIHSS). A blinded neuroradiologist analyzed CT brain 24 h after EVT using the Alberta Stroke Program Early CT Score.

RESULTS

Ninety-eight EVT patients were included in 9 months. Six patients had AEO (6%), 37 conjugated gaze palsy (38%) and 16% cortical ptosis (16%). AEO was associated with higher median NIHSS compared to no eye symptoms (18.5 vs. 3; p < 0.001) and gaze palsy or cortical ptosis (18.5 vs. 7; p = 0.003). The median modified Rankin Scale (mRS) after 3 months was 2 in patients without AEO, but 6 in patients with AEO (mRS in AEO patients nr. 1-6: 3, 4, 6, 6, 6, and 6; p = 0.015; no longer significant after adjustment for stroke severity), including 4 deaths (66%) in AEO patients. All patients with AEO had right hemisphere stroke (6/6 vs. 43/98 in total, p = 0.006).

CONCLUSION

AEO was observed in 6% of EVT patients who showed poor survival and outcome. AEO occurred exclusively in right hemispheric infarctions, suggesting that supranuclear eyelid control is under the influence of the right cerebral hemisphere.

Ocular Motor Dysfunction Due to Brainstem Disorders

BACKGROUND

The brainstem contains numerous structures including afferent and efferent fibers that are involved in generation and control of eye movements.

EVIDENCE ACQUISITION

These structures give rise to distinct patterns of abnormal eye movements when damaged. Defining these ocular motor abnormalities allows a topographic diagnosis of a lesion within the brainstem.

RESULTS

Although diverse patterns of impaired eye movements may be observed in lesions of the brainstem, medullary lesions primarily cause various patterns of nystagmus and impaired vestibular eye movements without obvious ophthalmoplegia. By contrast, pontine ophthalmoplegia is characterized by abnormal eye movements in the horizontal plane, while midbrain lesions typically show vertical ophthalmoplegia in addition to pupillary and eyelid abnormalities.

CONCLUSIONS

Recognition of the patterns and characteristics of abnormal eye movements observed in brainstem lesions is important in understanding the roles of each neural structure and circuit in ocular motor control as well as in localizing the offending lesion.

Hydrocephalus due to aqueductal stenosis presenting with acute bilateral ptosis: case report

Hydrocephalus may cause Parinaud's syndrome which consists of vertical gaze palsy, convergence palsy, lid retraction and pupil light-near dissociation. We are aware of only two prior reports of hydrocephalus presenting with bilateral ptosis. Both were cured by ventriculoperitoneal shunts. We report a 28-month-old girl who presented acute bilateral ptosis but full eye movements both sides. Neuroimages revealed chronic hydrocephalus and aqueductal stenosis. The bilateral ptosis resolved quickly after endoscopic third ventriculostomy (ETV).

Anteromedial thalamic infarct: a rare presentation

We report a rare presentation of an anteromedial thalamic infarct in a 50-year-old woman with acute onset left eye ptosis, vertical gaze paresis and confusion. MRI identified an acute left anteromedial thalamic infarct with a severe left P1 stenosis. Thalamic infarcts are associated with marked neurobehavioural disturbances with dominant thalamic lesions causing language deficits, verbal perseveration, memory disturbances, abulia and disorientation. Ocular movement deficits can also be present and typically accompany paramedian lesions. Rarely, patients can develop an ipsilateral ptosis. We discuss these symptoms and review the literature.

Sleep-Induced Apraxia of Eyelid Opening

BACKGROUND

Apraxia of eyelid opening (AEO) primarily has been described as bilateral loss of volitional ability to open the eyes at certain times and often associated with neurodegenerative disease. Rarely, it can occur in isolation and as an idiopathic phenomenon. There are a few reports of unilateral AEO only on awakening from sleep. We report an additional 11 patients with this unusual variation of AEO.

METHODS

Retrospective, observational case series of patients collected from 3 separate neuro-ophthalmology practices.

RESULTS

All 11 patients were Caucasian women with a mean age of 59 years (range 35-80 years). All experienced AEO on awakening from sleep. Eight patients had unilateral AEO, and 3 had bilateral symptoms. The duration of episodes ranged from 3 weeks to several years. Ten of the patients reported manually elevating the eyelid to open it, while 1 patient waited for the eyelid to open spontaneously. After initial manual elevation, all patients reported normal function and position of the eyelids for the remainder of the day. Seven patients had a history of autoimmune disease. Slit-lamp and fundus examinations were negative for ocular pathology to explain the patients' symptoms, and 9 patients had unremarkable brain imaging.

CONCLUSIONS

AEO occurring only on awakening from sleep is a rare entity. Neuroimaging and extensive laboratory testing are not indicated without associated neurologic or ocular findings. There may be a Caucasian female preponderance and autoimmune link in patients with AEO, but further studies are required.

High Double Eyelid Fold Correction Using Wide Dual-Plane Dissection

Background

The ability to correct unnatural-appearing, high, and deep double eyelid folds has been limited by the lack of redundant upper eyelid skin and the presence of prior incision line scars in patients.

Methods

From January 2000 to September 2011, 256 patients with high and deep double eyelid folds underwent our fold-lowering procedure. The first dissection was made at the superficial layer between the orbicularis oculi muscle and orbital septum/retroorbicularis oculi fat. The second dissection was at a deeper layer between the preaponeurotic fat and levator aponeurosis. The dissection proceeded 7 to 8 mm farther cephalad to the prior fold line to separate the upper flap and the floor from the prior fold line. The lower flap was undermined caudally to obtain normal skin tension, and the lower flap was secured to the septoaponeurosis junctional thickening or pretarsal tissue. Six months after surgery, the correction of the high fold scar and change in fold height (with eyes closed) was documented.

Results

Using the authors' technique, unnatural-appearing, high, and deep double eyelid folds were converted to lower nondepressed folds. Although prior high fold incision scars could be seen postoperatively on close examination, they were not easily visible. Complications included fold height asymmetry in 10 cases, persistence of the prior fold in 5 cases, and redundant upper flap skin that needed further excision in 25 cases.

Conclusions

Using a wide double-layer dissection, high folds were lowered successfully even in situations where there was no redundant upper eyelid skin for excision.

Eyelid Dysfunction in Neurodegenerative, Neurogenetic, and Neurometabolic Disease

Eye movement abnormalities are among the earliest clinical manifestations of inherited and acquired neurodegenerative diseases and play an integral role in their diagnosis. Eyelid movement is neuroanatomically linked to eye movement, and thus eyelid dysfunction can also be a distinguishing feature of neurodegenerative disease and complements eye movement abnormalities in helping us to understand their pathophysiology. In this review, we summarize the various eyelid abnormalities that can occur in neurodegenerative, neurogenetic, and neurometabolic diseases. We discuss eyelid disorders, such as ptosis, eyelid retraction, abnormal spontaneous and reflexive blinking, blepharospasm, and eyelid apraxia in the context of the neuroanatomic pathways that are affected. We also review the literature regarding the prevalence of eyelid abnormalities in different neurologic diseases as well as treatment strategies (Table 1).

Neuroimaging correlates of blinking abnormalities in patients with progressive supranuclear palsy

OBJECTIVE

We aimed to identify the possible relationship between blinking abnormalities and neuroimaging changes in patients with progressive supranuclear palsy.

METHODS

We studied 18 patients with progressive supranuclear palsy and 13 healthy subjects. Voluntary and spontaneous blinking were recorded using kinematic techniques. Changes in brain structures were detected by T1-weighted magnetic resonance imaging and voxel-based morphometry. We then sought possible correlations between blinking and neuroimaging abnormalities in patients.

RESULTS

Kinematic analysis indicated several abnormalities during voluntary blinking and a markedly reduced spontaneous blink rate in patients compared with healthy subjects. Neuroimaging showed gray matter loss in cortical and subcortical structures and lower white matter volume in the brainstem. Gray matter loss in subcortical structures correlated with the prolonged pause duration between the closing and opening phases, during voluntary blinking.

CONCLUSIONS

This study provides a more specific insight into the pathophysiological mechanisms underlying blinking abnormalities in progressive supranuclear palsy.

The Effect of Hering's Law on Different Ptosis Repair Methods

BACKGROUND

The Hering's law effect has significant importance in surgical planning and outcomes of eyelid surgery.

OBJECTIVES

The current study examined the preoperative and intraoperative effect of Hering's law in Mullerectomy and levator aponeurosis advancement.

METHODS

A retrospective analysis was conducted of 52 patients with unilateral ptosis who underwent surgical repair from January 2011 through June 2013. Patients underwent levator aponeurosis advancement or Mullerectomy with or without tarsectomy. Preoperative and postoperative clinical documentation and photographs were evaluated. Preoperative Hering's dependency and postoperative changes in positioning of the non-operated eyelid were measured. The decision to operate on the ptotic eye alone or on both eyelids was based on preoperative Hering's dependence and intraoperative changes in the contralateral eyelid.

RESULTS

Fifty-two patients with unilateral ptosis were included. Average age was 63.3 ± 20.1 years (range, 22-88 years; median, 61 years); 34 (65.4%) were female. The 14 cases that were not aponeurotic (either congenital, secondary to trauma, or due to postoperative ptosis) did not need contralateral repair (p = .000). In 4 (19%) cases of Mullerectomy and in 9 (52.9%) cases of levator advancement, both eyelids required surgery (p = .029). Hering's law effect was significantly more apparent in the levator advancement approach than in Mullerectomy.

CONCLUSIONS

Levator surgery resulted in a higher incidence of combined intraoperative and postoperative Hering's law effect than did Mullerectomy. Cases with poor levator function or congenital ptosis can be repaired unilaterally with no need for contralateral surgery. The fibrotic levator palpebrae muscle and its special innervations probably explain this phenomenon. This should be considered in surgical planning.

Quantitative assessment of the impact of blood pulsation on images of the pupil in infrared light

Pulsation in the blood vessels of the eye has a big impact on the dynamics of the entire eyeball and its individual elements. Blood pulsation in the retina can be recorded by the pupil, whose size is also subject to dynamic changes. The study involved synchronous measurements of pupil size using a high-speed camera, and blood pulsation using a pulse oximeter placed on the ear lobe. In addition, there were no metrologically significant differences in the phase shift between the average brightness of the individual pupil quadrants. Blood pulsation in other ocular tissues can affect the dynamics of the optical properties of the eye. As demonstrated in this paper, it affects the pupil behavior and its parameters to a considerable extent.

Simultaneous loss of bilateral voluntary eyelid opening and sustained winking response following bilateral posterior cerebral artery infarction

Spontaneous opening and closing of both eyes usually occurs in the normal awake state, unless a deliberate and voluntary attempt is made to open only one eye. We present a rare case of a male patient who was unable to open both eyes simultaneously after bilateral posterior cerebral artery infarction. He was able to close both eyes voluntarily. However, he was unable to keep both eyes open simultaneously and either the right or left eye remained closed. Upon a verbal command to open both eyes, the opened eye closed and the contralateral eye opened. When the closed eye was forced open, the opened eye closed. We thus presented a case of right-left dissociation of voluntary eyelid opening following bilateral posterior cerebral artery infarction, which was treated with botulinum toxin type A injection. Differential diagnosis to other movement disorders of the eyelids was discussed.

Apraxia of eyelid opening after brain injury: a case report

Apraxia of eyelid opening (AEO) is a syndrome characterized by the patient's difficulty in initiating eyelid elevation spontaneously. Most of the reported cases were associated with extrapyramidal diseases. We report a case of AEO presented after traumatic brain injury, not with extrapyramidal diseases, and improved by dopaminergic treatment. A 49-year-old man underwent a traffic accident and was transferred to the emergency room in an unconscious state. Brain computed tomography (CT) revealed a subdural and epidural hemorrhage at right temporal and bilateral frontal lobes, and he received burr-hole trephination. After receiving comprehensive treatment including occupational therapy, cognition and mobility gradually improved, but he could not open his eyes voluntarily. With dopaminergic treatment (levodopa/benserazide 200/50 mg), he started to open his eyes spontaneously, especially when eating and undergoing physical training. This case showed that AEO may occur after brain injury and that dopaminergic treatment is beneficial also in AEO patients without extrapyramidal diseases.

Delineation of motoneuron subgroups supplying individual eye muscles in the human oculomotor nucleus

The oculomotor nucleus (nIII) contains the motoneurons of medial, inferior, and superior recti (MR, IR, and SR), inferior oblique (IO), and levator palpebrae (LP) muscles. The delineation of motoneuron subgroups for each muscle is well-known in monkey, but not in human. We studied the transmitter inputs to human nIII and the trochlear nucleus (nIV), which innervates the superior oblique muscle (SO), to outline individual motoneuron subgroups. Parallel series of sections from human brainstems were immunostained for different markers: choline acetyltransferase combined with glutamate decarboxylase (GAD), calretinin (CR) or glycine receptor. The cytoarchitecture was visualized with cresyl violet, Gallyas staining and expression of non-phosphorylated neurofilaments. Apart from nIV, seven subgroups were delineated in nIII: the central caudal nucleus (CCN), a dorsolateral (DL), dorsomedial (DM), central (CEN), and ventral (VEN) group, the nucleus of Perlia (NP) and the non-preganglionic centrally projecting Edinger–Westphal nucleus (EWcp). DL, VEN, NP, and EWcp were characterized by a strong supply of GAD-positive terminals, in contrast to DM, CEN, and nIV. CR-positive terminals and fibers were confined to CCN, CEN, and NP. Based on location and histochemistry of the motoneuron subgroups in monkey, CEN is considered as the SR and IO motoneurons, DL and VEN as the B- and A-group of MR motoneurons, respectively, and DM as IR motoneurons. A good correlation between monkey and man is seen for the CR input, which labels only motoneurons of eye muscles participating in upgaze (SR, IO, and LP). The CCN contained LP motoneurons, and nIV those of SO. This study provides a map of the individual subgroups of motoneurons in human nIII for the first time, and suggests that NP may contain upgaze motoneurons. Surprisingly, a strong GABAergic input to human MR motoneurons was discovered, which is not seen in monkey and may indicate a functional oculomotor specialization.

Is Hering's law as important in congenital blepharoptosis as in acquired ptosis?

BACKGROUND

Although Hering's law has significant importance in the planning and outcomes of eyelid surgery, it has not been applied in all cases of ptosis.

OBJECTIVES

The authors evaluate whether cases of unilateral congenital ptosis require surgery on the contralateral eyelid, in keeping with Hering's law.

METHODS

The records of 35 consecutive patients with unilateral congenital ptosis who had surgical repair between 2007 and 2012 were retrospectively analyzed. All patients underwent either levator resection or frontalis sling surgery. Preoperative and postoperative clinical documents and photographs were evaluated for each case, including preoperative Hering's dependence and postoperative measurements of the change in position of the nonoperated eyelid.

RESULTS

There were 19 women and 16 men, and the average patient age was 9.7 ± 10 years. The mean preoperative levator function and marginal reflex distance were 6.7 ± 4.7 mm and 0.3 ± 0.47 mm, respectively. There were significant differences in age, preoperative levator function, and marginal reflex distance between patients who underwent levator resection and those who had frontalis sling surgery. In all patients, the preoperative Hering's dependence of eyelid position did not show any decrease, and the position of the contralateral eyelid postoperatively did not differ from the baseline position.

CONCLUSIONS

This research shows that Hering's law does not apply to cases of congenital ptosis. This is likely due to the fibrotic levator palpebrae muscle and its special innervations. Thus, it is not necessary to perform levator resection or a frontalis sling operation on the unaffected eyelid.

Eyelid contour detection and tracking for startle research related eye-blink measurements from high-speed video records

Using the positions of the eyelids is an effective and contact-free way for the measurement of startle induced eye-blinks, which plays an important role in human psychophysiological research. To the best of our knowledge, no methods for an efficient detection and tracking of the exact eyelid contours in image sequences captured at high-speed exist that are conveniently usable by psychophysiological researchers. In this publication a semi-automatic model-based eyelid contour detection and tracking algorithm for the analysis of high-speed video recordings from an eye tracker is presented. As a large number of images have been acquired prior to method development it was important that our technique is able to deal with images that are recorded without any special parametrisation of the eye tracker. The method entails pupil detection, specular reflection removal and makes use of dynamic model adaption. In a proof-of-concept study we could achieve a correct detection rate of 90.6%. With this approach, we provide a feasible method to accurately assess eye-blinks from high-speed video recordings.

Volitional eyes opening perturbs brain dynamics and functional connectivity regardless of light input

The act of opening (or closing) one's eyes has long been demonstrated to impact on brain function. However, the eyes open condition is usually accompanied by visual input, and this effect may have been a significant confounding factor in previous studies. To clarify this situation, we extended the traditional eyes open/closed study to a two-factor balanced, repeated measures resting state fMRI (rs-fMRI) experiment, in which light on/off was also included as a factor. In 16 healthy participants, we estimated the univariate properties of the BOLD signal, as well as a bivariate measure of functional connectivity and multivariate network topology measures. Across all these measures, we demonstrate that human brain adopts a distinctive configuration when eyes are open (compared to when eyes are closed) independently of exogenous light input: (i) the eyes open states were associated with decreased BOLD signal variance (P-value=0.0004), decreased fractional amplitude of low frequency fluctuation (fALFF. P-value=0.0061), and decreased Hurst exponent (H. P-value=0.0321) mainly in the primary and secondary sensory cortical areas, the insula, and the thalamus. (ii) The strength of functional connectivity (FC) between the posterior cingulate cortex (PCC), a major component of the default mode network (DMN), and the bilateral perisylvian and perirolandic regions was also significantly decreased during eyes open states. (iii) On the other hand, the average network connection distance increased during eyes open states (P-value=0.0139). Additionally, the metrics of univariate, bivariate, and multivariate analyses in this study are significantly correlated. In short, we have shown that the marked effects on the dynamics and connectivity of fMRI time series brought by volitional eyes open or closed are simply endogenous and irrespective of exogenous visual stimulus. The state of eyes open (or closed) may thus be an important factor to control in design of rs-fMRI and even other cognitive block or event-related experiments.

Effects of cold pressor stress on the human startle response

Both emotion and attention are known to influence the startle response. Stress influences emotion and attention, but the impact of stress on the human startle response remains unclear. We used an established physiological stressor, the Cold Pressor Test (CPT), to induce stress in a non-clinical human sample (24 student participants) in a within-subjects design. Autonomic (heart rate and skin conductance) and somatic (eye blink) responses to acoustic startle probes were measured during a pre-stress baseline, during a three minutes stress intervention, and during the subsequent recovery period. Startle skin conductance and heart rate responses were facilitated during stress. Compared to baseline, startle eye blink responses were not affected during the intervention but were diminished afterwards. These data describe a new and unique startle response pattern during stress: facilitation of autonomic stress responses but no such facilitation of somatic startle eye blink responses. The absence of an effect of stress on startle eye blink responsiveness may illustrate the importance of guaranteeing uninterrupted visual input during periods of stress.

Myoelectric signals of levator palpebrae superioris as a trigger for FES to restore the paralyzed eyelid

Some closed loop FES systems have been designed to restore the blinking function of facial paralysis patients. All of them used myoelectric signal of orbicularis oculi at the normal side as the trigger to stimulate the paralyzed side. They were limited to the one side facial paralysis. Here we proposed that the myoelectric signal of levator palpebrae superioris could be used as the trigger to stimulate the paralyzed orbicularis oculi. Because the levator palpebrae superioris and the innervating nerve are intact, the myoelectric signal of the paralyzed side still could be used as the trigger. It will be more acceptable for the patients and have the potential to resolve the bilateral facial paralysis.

Effects of varying subthalamic nucleus stimulation on apraxia of lid opening in Parkinson's disease

Apraxia of lid opening (ALO) is a non-paralytic inability to open the eyes or sustain lid elevation at will. The exact pathophysiological mechanisms underlying the syndrome are still unknown. ALO has been reported in patients with Parkinson's disease (PD) after subthalamic nucleus (STN) deep brain stimulation (DBS), suggesting a possible involvement of the basal ganglia. We aimed to assess the effects of varying STN stimulation voltage on ALO in PD patients. Seven out of 14 PD patients with bilateral STN stimulation consecutively seen in our centre presented with ALO. We progressively increased voltage on each STN, using either 130 Hz (high-frequency stimulation, HFS) or 2 or 3 Hz (low-frequency stimulation, LFS). In five patients, HFS induced ALO time-locked to stimulation in 7 out of 10 STNs at a voltage higher than that used for chronic stimulation. LFS induced myoclonus in the pretarsal orbicularis oculi muscle (pOOm) with a rhythm synchronous to the frequency. In the other two patients with ALO already present at the time of the study, HFS improved ALO in 3 out of 4 STNs. ALO recurred within minutes of stimulation arrest. Our findings show that STN-DBS can have opposite effects on ALO. On the one hand, ALO is thought to be a corticobulbar side effect due to lateral current spreading from the STN, in which case it is necessary to use voltages below the ALO-inducing threshold. On the other hand, ALO may be considered a form of off-phase focal dystonia possibly improved by increasing the stimulation voltages.

Effects of subthalamic nucleus deep brain stimulation and L-DOPA on blinking in Parkinson's disease

In this study we asked whether subthalamic nucleus deep brain stimulation (STN-DBS) alone, or in combination with l-dopa, modifies voluntary, spontaneous and reflex blinking in patients with Parkinson's disease (PD). Sixteen PD patients who underwent STN-DBS were studied in four experimental conditions: without STN-DBS and without l-dopa, STN-DBS alone, l-dopa alone and STN-DBS plus l-dopa. The results were compared with those obtained in 15 healthy controls. Voluntary blinking was assessed by asking participants to blink as fast as possible; spontaneous blinking was recorded during two 60s rest periods; reflex blinking was evoked by electrical stimulation of the supraorbital nerve. Blinking were recorded and analysed with the SMART motion system. STN-DBS increased the peak velocity and amplitude for both the closing and opening voluntary blink phases, but prolonged the inter-phase pause duration. l-dopa had no effects on voluntary blinking but reversed the increased inter-phase pause duration seen during STN-DBS. Spontaneous blink rate increased after either STN-DBS or l-dopa. Reflex blinking kinematics were not modified by STN-DBS or l-dopa. The STN-DBS effects on voluntary blinking kinematics and spontaneous blinking rate may occur as results of changes of cortico-basal ganglia activity. The prolonged pause duration of voluntary blinking indicates that STN-DBS has detrimental effects on the cranial region. These results also shed light on the pathophysiology of eyelids opening apraxia following STN-DBS.

Surgical outcomes in patients with bilateral ptosis and Hering's dependence

PURPOSE

To assess whether sequential or simultaneous ptosis repair yields a better postoperative outcome in patients with documented preoperative Hering's dependency.

DESIGN

Retrospective, case-control study.

PARTICIPANTS AND CONTROLS

Of the 216 patients who underwent bilateral ptosis surgery, 109 patients with documented Hering's dependency constituted the study group and the 107 patients with no Hering's dependency constituted the control group.

METHODS

The charts of patients who underwent levator advancement ptosis surgery between April 2002 and December 2004 by the same surgeon (R.C.K.) were reviewed retrospectively. Data regarding patient demographics, preoperative and postoperative margin-reflex distance values, levator function, presence of Hering's dependency, side of the initial operation, and reoperation status were collected from the charts. Patients demonstrating preoperative Hering's dependency of eyelid position operated simultaneously and sequentially were compared for postoperative symmetry and reoperation rates. Postoperative asymmetry was defined as a more than 1-mm difference between upper eyelid heights.

MAIN OUTCOME MEASURES

Postoperative asymmetry and reoperation rates.

RESULTS

In the Hering's dependency group (n = 109), 64 sequential surgeries that yielded 15 asymmetric results (23.4%) and 7 reoperations (10.9%) compared with the 45 simultaneous operations, which revealed 1 case of asymmetry (2.2%; P = 0.002) and 1 case of reoperation (2.2%; P = 0.137). Compared with the control group, sequentially operated Hering's dependency patients still showed higher postoperative asymmetry (P = 0.011), and the reoperation rate was similar (P = 0.134). Hering's dependency patients who had the initial operation on the left side demonstrated a significantly higher rate of postoperative asymmetry (42.3% vs. 10.5%; P = 0.006).

CONCLUSIONS

Bilateral ptosis cases with documented Hering's dependency yield better results when both eyes are operated in the same session, rather than delaying surgery for the second eyelid. Ocular dominance probably has a significant impact on Hering's dependency and postoperative outcome after unilateral operations.

A local, bottom-up perspective on sleep deprivation and neurobehavioral performance

Waking neurobehavioral performance is temporally regulated by a sleep/wake homeostatic process and a circadian process in interaction with a time-on-task effect. Neurobehavioral impairment resulting from these factors is task-specific, and characterized by performance variability. Several aspects of these phenomena are not well understood, and cannot be explained solely by a top-down (subcortically driven) view of sleep/wake and performance regulation. We present a bottom-up theory, where we postulate that task performance is degraded by local, use-dependent sleep in neuronal groups subserving cognitive processes associated with the task at hand. The theory offers explanations for the temporal dependence of neurobehavioral performance on time awake, time on task, and their interaction; for the effectiveness of task switching and rest breaks to overcome the time-on-task effect (but not the effects of sleep deprivation); for the task-specific nature of neurobehavioral impairment; and for the stochastic property of performance variability.

Normal and abnormal lid function

This chapter on lid function is comprised of two primary sections, the first on normal eyelid anatomy, neurological innervation, and physiology, and the second on abnormal eyelid function in disease states. The eyelids serve several important ocular functions, the primary objectives of which are protection of the anterior globe from injury and maintenance of the ocular tear film. Typical eyelid behaviors to perform these functions include blinking (voluntary, spontaneous, or reflexive), voluntary eye closure (gentle or forced), partial lid lowering during squinting, normal lid retraction during emotional states such as surprise or fear (startle reflex), and coordination of lid movements with vertical eye movements for maximal eye protection. Detailed description of the neurological innervation patterns and neurophysiology of each of these lid behaviors is provided. Abnormal lid function is divided by conditions resulting in excessive lid closure (cerebral ptosis, apraxia of lid opening, blepharospasm, oculomotor palsy, Horner's syndrome, myasthenia gravis, and mechanical) and those resulting in excessive lid opening (midbrain lid retraction, facial nerve palsy, and lid retraction due to orbital disease).

Concomitant presentation of three rare mesencephalic syndromes: case report

We describe a unique case of concomitant presentation of three rare mesencephalic syndromes. A 48-year-old man with an acute stoke was found to have an unusual combination of three rare mesencephalic syndromes after detailed neuro-ophthalmic evaluation: the plus-minus lid syndrome, the vertical one-and-a-half syndrome, and Claude's syndrome. We discuss the clinical and anatomical localization of these syndromes. This was corroborated by magnetic resonance imaging (MRI) which revealed areas of infarction at the thalamo-mesencephalic junction and the right rostral midbrain involving the third nerve fascicle and the red nucleus. Our case highlights the importance of a careful ocular motility examination as a tool which has a highly localizing value in the diagnosis of stroke.