Evidence of ancillary trigeminal innervation of levator palpebrae in the general population

Marcus-Gunn jaw winking syndrome: case series study and management algorithm

PURPOSE

To identify a rationale for treatment of patients with Marcus Gunn jaw winking syndrome (MGJWS).

METHODS

Retrospective review of 38 consecutive patients with MGJWS referred to a single tertiary institution. Clinical data included visual acuity, ocular motility, side of jaw-wink, presence or absence of ptosis, levator function, clinical photographs, and management undertaken. Thirty-two patients were operated on with customized surgery by a senior surgeon (FQL).

RESULTS

Cases with no ptosis or mild ptosis were managed conservatively. Levator advancement (LA) was successful in case of moderate ptosis and negligible synkynesis but resulted in a more evident synkinesis. Levator resection (LR) in patients with severe ptosis was associated with high rate of ptosis recurrence. Ptosis was adequately corrected in all patients submitted to uni- or bilateral levator excision (LE) and bilateral frontalis suspension (FS) or unilateral frontalis flap (FF). Jaw winking resolved in all patients submitted to LE but recurred in three cases at a later stage. Strabismus surgery was performed simultaneously in case of associated esotropia or hypotropia.

CONCLUSIONS

Moderate ptosis can be corrected with LA, but success is not related to levator function and synkinesis becomes more evident postoperatively. In severe ptosis, LR showed unpredictable results. In case of severe ptosis and severe synkinesis, uni- or bilateral LE and bilateral FS are recommended; unilateral FF is an alternative in patients who refuse bilateral treatment, as the cosmetic outcome is usually better than after unilateral FS.

Mesencephalic trigeminal nucleus neurons with collaterals to both eyelid and masseter muscles shown by fluorescent double-labeling, revealing a potential mechanism for Marcus Gunn Syndrome

Poking palpebral conjunctiva evoked upper-eyelid retraction during ophthalmic surgery. Iatrogenic eyelid ptosis occurred if eyelid branch of lachrymal nerve was sectioned. Mesencephalic trigeminal nucleus (Vme) neurons were labeled when tracer injected into lachrymal nerve innervating eyelid Mueller's muscle. Masseter afferent Vme neurons projecting to oculomotor nucleus (III) was observed in toad and rat, which helps amphibians to stare prey when they open mouth widely to prey. We hypothesized single Vme neurons may have peripheral collaterals to both eyelid and masseter muscles. WGA-594 was injected into upper eyelid, and WGA-488 was simultaneously delivered into ipsilateral masseter muscle in the same rat. Then, double labeled Vme neurons were found under both conventional and confocal microscope. Meanwhile, contact of WGA-594 positive eyelid afferent Vme neurons with WGA-488 labeled masseter afferent ones were observed sometimes. Combined with our previous observation of oculomotor projection Vme neurons, we thought WGA-594/488 double labeled Vme cells, at least some of them, are oculomotor projecting ones. Contact between eyelid and masseter afferent Vme neurons are supposed to be electrotonically coupled, based on a line of previous studies. If exogenous or genetic factors make these Vme neurons misinterpret masseter input as eyelid afferent signals, these Vme neurons might feedforward massages to eyelid retractor motoneurons in the III. Besides, oculomotor projecting Vme neurons might be co-fired by adjacent masseter afferent Vme neurons through electrotonic coupling once the masseter muscle is activated. In these cases, Marcus Gunn Syndrome might occur. This finding leads to a new hypothesis for the Syndrome.

Physiological oculo-auricular-facial-mandibular synkinesis elicited in humans by gaze deviations

Integrated motor behaviors involving ocular motion-associated movements of the head, neck, pinna, and parts of the face are commonly seen in animals orienting to a visual target. A number of coordinated movements have also been observed in humans making rapid gaze shifts to horizontal extremes, which may be vestiges of these. Since such integrated mechanisms point to a non-pathological co-activation of several anatomically separate cranial circuits in humans, it is important to see how the different pairs of integrative motor behaviors with a common trigger (i.e., ocular motion) manifest in relation to one another. Here, we systematically examined the pattern of eye movement-induced recruitment of multiple cranial muscles in humans. Simultaneous video-oculography and bilateral surface electromyograms of transverse auricular, temporalis, frontalis, and masseter muscles were recorded in 15 healthy subjects (8 females; 29.3±5.2 years) while they made head-fixed, horizontal saccadic, pursuit and optokinetic eye movements. Potential chin laterotrusion linked to contractions of masticator muscles was captured with a yaw-fixed accelerometer. Our findings objectively show an orchestrated aural-facial-masticatory muscle response to a range of horizontal eye movements (prevalence of 21-93%). These responses were most prominent during eccentric saccades. We further reveal distinctions between the various observed activation patterns in terms of their profile (transient or sustained), laterality (with respect to direction of gaze) and timing (with respect to saccade onset). Possible underlying neural substrates, their atavistic behavioral significance, and potential clinical applications for monitoring sensory attention and designing attention-directed hearing aids in the future are discussed.

Long-term surgical outcomes of levator resection in patients with Marcus-Gunn jaw-winking ptosis

Purpose: To report long-term surgical outcomes of a series of MGJWS patients with moderate ptosis who underwent levator resection.Materials and Methods: A retrospective review of medical records of 10 MGJWS patients with moderate ptosis who underwent levator resection was performed in two major eye centers in Riyadh, Saudi Arabia from January 1987 to December 2019. Clinical features, pre-operative and post-operative data of the 10 patients were recorded.Outcome Measures: Long-term upper eyelid position.Results: The mean patient age at presentation was 5.4 years. Seven patients were female and three were male. All patients had moderate ptosis with marginal reflex distance ranged from 1 to 2 mm. The mean age at surgery was 9.5 years. After initial good ptosis correction for all patients, seven of them had a recurrence of ptosis several months after levator resection.Conclusions: Levator resection in MGJWS patients with moderate ptosis and good levator function is associated with a high rate of ptosis recurrence and less predictable surgical results.

The rare phenomenon of Marcus-Gunn jaw winking without ptosis: Report of 14 cases and review of the literature

Purpose:

To report a rare case series of 14 patients of the Marcus-Gunn jaw-winking phenomenon (MGJWP) without ptosis.

Methods:

This was a retrospective noninterventional case series. The medical records of all patients diagnosed with MGJWP over the past 10 years were retrieved. Patients with documented evidence of absence of ptosis were segregated and analyzed for visual acuity, the severity of Marcus-Gunn, the presence of squint and amblyopia, and the presence of other aberrant regenerations.

Results:

A total of 207 patients were diagnosed with MGJWP, out of which 14 (6.76%) patients had isolated MGJWP without blepharoptosis. The mean age of presentation was 9.5 years and males and females were equally affected. The left eye was involved more commonly (57.2%) than the right eye. Twelve patients were congenital and two were presumed to be of traumatic origin. The most common refractive error in this cohort was astigmatism (10, 71.42%), followed by hyperopia (5, 35.71%). One patient had anisometropic amblyopia. Marcus-Gunn was found to be mild (≤2 mm of lid excursion) in all cases. None of the patients had strabismus or any other aberrant innervations. None of the patients underwent surgery and did not develop ptosis or worsening or improvement of Marcus-Gunn after a mean follow-up period of 2.3 years.

Conclusion:

Isolated MGJWP in the absence of ptosis is a very rare entity and this is the largest series to date to report such an occurrence. All patients had a mild form of MGJWP with no intervention required in any of the cases.

Is there a primitive reflex residue underlying Marcus Gunn Syndrome? Rat electrophysiology

AIM

To make an electrophysiological demonstration of a possible jaw muscle afferents-oculomotor neural pathway that was proposed by our previous works on rats, which substantiates an early "release hypothesis" on pathogenesis of human Marcus Gunn Syndrome (MGS).

METHODS

Extracellular unit discharge recording was applied and both orthodromic and spontaneous unitary firing were recorded in the oculomotor nucleus (III), and the complex of pre-oculomotor interstitial nucleus of Cajal and Darkschewitsch nucleus (INC/DN), following electric stimulation of the ipsilateral masseter nerve (MN) in rats.

RESULTS

Extracellular orthodromic unit discharges, with latencies of 3.7±1.3 and 4.7±2.9ms, were recorded unilaterally in the III, and the INC/DN neurons, respectively. Spontaneous unit discharges were also recorded mostly in the INC/DN and less frequently in the III. Train stimulation could prompt either facilitation or inhibition on those spontaneous unit discharges. The inhibition pattern of train stimulation on the spontaneous discharging was rather different in the III and INC/DN. A slow inhibitory pattern in which spontaneous firing rate decreased further and further following repeated train stimulation was observed in the III. While, some high spontaneous firing rate units, responding promptly to the train stimuli with a short-term inhibition and recovered quickly when stimuli are off, were recorded in the INC/DN. However, orthodromic unit discharge was not recorded in the III and INC/DN in a considerable number of experiment animals.

CONCLUSION

A residual neuronal circuit might exist in mammals for the primitive jaw-eyelid reflex observed in amphibians, which might not be well-developed in all experimental mammals in current study. Nonetheless, this pathway can be still considered as a neuroanatomic substrate for development of MGS in some cases among all MGS with different kind of etiology.

Eye movements in relation to rhythmic masticatory muscle activities in patients with sleep bruxism

OBJECTIVES

To characterize eye movements during rhythmic masticatory muscle activities (RMMAs) in patients with sleep bruxism (SB).

METHODS

Polysomnographic (PSG) recordings were performed on SB patients and normal controls during sleep (n = 8 for each group) and wakefulness (n = 9 for each group). The eye movements associated with episodes of RMMAs/SB during sleep and jaw movements during wakefulness were analyzed.

RESULTS

During sleep, all episodes of RMMAs/SB in the SB patients and controls were associated with eye movements and most of the RMMAs/SB related slow eye movements (SB patients: 96.29%, 1583/1644; Controls: 97.49%, 543/557) were horizontal in the SB patients and controls. During wakefulness, all of the series of jaw movements were associated with eye movements. Most of cycles of jaw movements (SB patients: 88.89%, 200/225; Controls: 95.11%, 214/225) were associated with slow eye movements and most of the eye movements (SB patients: 52.50%, 105/200; Controls: 61.21%, 131/214) were vertical. There were significant correlations between the durations of episodes of eye movements and RMMAs/SB during sleep and between the duration of episodes of eye movements and duration of series of jaw movements during wakefulness in the SB patients and controls.

CONCLUSIONS

Most of RMMAs/SB episodes during sleep and jaw movements during wakefulness are associated with eye movements in SB patients and normal controls.

Marcus Gunn (jaw-winking) phenomenon in pediatric otorhinolaryngology practice

Marcus Gunn phenomenon (MGP) is a rare form of congenital facial synkinesis known as jaw-winking or pterygoid-levator synkinesis. The MGP is the raising of the affected eyelid is synchronous and proportionate to the opening of the mouth. The etiology is unclear. Most authors claim that a branch of trigeminal nerve has been congenitally misdirected into position of the oculomotor nerve which supplies the levator muscle of the upper lid. The MGP deals with number of problems which have to be manage by ENT doctors, but they are not well‑documented. We describe the first time Marcus Gunn phenomenon associated with an olfactory nerve disturbance. We have especially emphasized laryngological aspect of MGP diagnosis and the need for deeper interdisciplinary diagnostics in each child with olfactory dysfunction.

Is Marcus Gunn jaw winking a primitive reflex? Rat neuroanatomy

AIM

To investigate a possible trigeminal proprioceptive-oculomotor neural pathway and explore possible synaptic connections between neurons in this pathway. Attempt to bring a new insight to mechanism of Marcus Gunn syndrome (MGS).

METHODS

Anterograde and retrograde tract tracing was applied and combined with immunofluorescent stain in rats. After electrophysiological identifying mesencephalic trigeminal nucleus (Vme) neurons, intracellular injection of tracer was performed to trace axon trajectory.

RESULTS

Following injections of anterograde tracers into the Vme, labeled terminals were observed ipsilateral in oculomotor and trochlear nuclei (III/IV), as well as in their premotor neurons in interstitial nucleus of Cajal and Darkschewitsch nucleus (INC/DN). Combining with choline acetyltransferase (ChAT) immunofluorescent stain, it showed that Vme projecting terminals contact upon ChAT positive III/IV motoneurons under confocal microscope. By retrograde labeling premotor neurons of the III, it showed that Vme neuronal terminals contact with retrogradely labeled pre-oculomotor neurons in the INC/DN. Axons of intracellularly labeled Vme neurons that respond to electric stimuli of the masseter nerve traveled into the ipsilateral III.

CONCLUSION

There may exist a trigeminal proprioceptive-oculomotor system neural circuit in the rat, which is probably related to vertical-torsional eye movements. Possible association of this pathway with MGS etiology was discussed.

Marcus Gunn Jaw-Winking Syndrome: A Comprehensive Review and Report of Four Novel Cases

PURPOSE

To report 4 cases of Marcus Gunn jaw-winking synkinesis (MGJWS) in the absence of ptosis.

METHODS

A retrospective review of patients with MGJWS and congenital ptosis was compiled from the public and private subspecialty adult and pediatric oculoplastic practices of the 2 senior authors (AAM, TGH). Clinical data collected on patients with MGJWS included visual acuity, stereopsis, ocular motility, side of jaw-wink, presence or absence of ptosis, levator function, clinical photographs and videos, and any management undertaken.

RESULTS

A total of 848 cases of congenital ptosis were seen. Of these, there were 72 consecutive patients with MGJWS, of which 4 cases (5.6%) had no ptosis. One patient had bilateral MGJWS, with ptosis on one side only. The authors found the incidence of MGJWS in our study population to be 8.5% of all congenital ptosis cases. When the authors excluded syndromic, neurogenic, and myopathic causes of congenital ptosis, the incidence was 12.1%. In addition, the authors found a trend toward females with simple congenital ptosis and MGJWS being affected on the left side, however this was not statistically significant.

CONCLUSIONS

The authors report the first case series of MGJWS in the absence of ptosis within the second largest series ever reported. These findings may help further our understanding of the etiology behind MGJWS.

Co-firing of levator palpebrae and masseter muscles links the masticatory and oculomotor system in humans

Simultaneous co-firing of the levator palpebrae (LP) and pterygoid muscles were recorded in Marcus Gann Syndrome (MGS) patients in early clinical studies. “Release hypothesis” proposed an intrinsic masticatory oculomotor neural circuit and this kind circuit, which, however, has been observed only in amphibian. On the other hand, congenital miswiring hypothesis has overwhelmed other interpretations. However, the same phenomenon visualized in MGS cases was unveiled in human subjects without any sign of congenital oculomotor disorder. To further study co-firing of the upper eyelid and jaw muscles, we applied non-invasive EMG recording of the upper eyelid and ipsilateral masseter muscle belly in nine healthy volunteers. LP activity was determined initially by looking upward and active retraction of upper eyelid with head fixed. Then, dual channel inputs from upper eyelid and masseter muscle was recorded during tooth occlusion motivated by isometric masseter muscle contraction without jaw and face moving. The EMG recorded from upper eyelid when the subjects retracted eyelid with head fixed exhibited the same pattern as that collected during tooth occlusion, but the pattern was completely different from EMG of active eye closure. This reflects tooth occlusion evoked LP activity. Then, simultaneous co-firing of the LP and masseter muscle was recorded simultaneously during tooth occlusion without jaw movement. Finally, the aforementioned co-firing was recorded when the subjects conducted rhythmic occlusion and synchronous EMG from both muscles was acquired. In conclusions, humans may also have an intrinsic masticatory oculomotor circuit and release hypothesis may apply, at least, to some cases of MGS.