Pathogenesis and surgical correction of involuntary contraction of the occipitofrontalis muscle that causes forehead wrinkles

Histological analysis of the dermal and hypodermal layers of the face and correlation with high-frequency 24 MHz ultrasonography and elastosonography

Knowledge of the structure of the face is of fundamental importance. In fact, the face is treated in many areas of medicine, from dermatology, to maxillofacial surgery, to otorhinolaryngology, to ophthalmology, etc. and anti-aging aesthetic treatments, and those for the resolution of blemishes are on the increase. For ethical reasons it is not possible to take biopsy samples for facial analysis in the aesthetic field. The main aim of this study was to demonstrate that a high-resolution bimodal ultrasound examination, combined with elastosonography, could be a valid tool for pre-treatment morphological evaluation. To achieve this goal, skin samples were taken from the forehead, zygomatic area, nasolabial fold, upper and lower lip from cadavers to histologically characterize their structure. Subsequently, these same areas were evaluated in vivo using conventional B-mode ultrasound with a 24 MHz high-frequency probe, and elastosonography. The data obtained with the different techniques were compared, in order to state that modern ultrasound techniques can provide similar histological information. The analysis showed that the superficial hypodermis presented a different shape and structure in the different areas, with the exception of the areas of the upper and lower lip, which appeared similar. With aging, the forehead and zygomatic area showed a volumetric increase in the superficial hypodermic layer, while the lip showed non-structural changes. The morphology of the nasolabial fold remained unchanged. When it is not possible to perform histological investigations on the face, to understand its characteristics and dynamics, ultrasound with a 24 MHz probe would seem to be the most suitable method, while elastosonography could be a valid method for evaluating the stiffness of the structural components.

"Predicting Facial Changes After Blepharoplasty"

INTRODUCTION

The primary goal of blepharoplasty for blepharoptosis and blepharochalasis is to elevate the upper eyelid to restore a full field of vision, although many surgeons also aim to provide a better aesthetic outcome. Several facial configuration changes may occur following blepharoplasty. This study examined the effectiveness of vessel clips to preoperatively predict facial configuration alterations.

METHODS

We retrospectively enrolled 93 consecutive patients who underwent blepharoplasty correction for blepharoptosis and blepharochalasis with eyebrow elevation. Frontal portrait images were taken at the initial examination without load, preoperatively with vessel clips, and without load at 6 months postoperatively for evaluations of eyebrow height, forehead wrinkle length, and procerus area wrinkle length. Subjective outcomes were also surveyed by questionnaires and interviews at 6 months post-surgically.

RESULTS

No significant differences were detected between preoperative measurements with vessel clips and recordings at 6 months postoperatively. Significant correlations were identified among the addition/reduction values for preoperative and postoperative measurements (eyebrow height and forehead wrinkle length: r=0.402, p<0.001; eyebrow height and procerus area wrinkle length: r=-0.327, p<0.01; forehead wrinkle length and procerus area wrinkle length: r=-0.488, p<0.001). Women more frequently described notable changes in wrinkles than men.

CONCLUSIONS

Postoperative facial change outcomes for blepharoplasty may be predicted using the simple but effective vessel clip test. A better understanding of surgical results can relieve patient anxiety and contribute to increased satisfaction.

Frontalis Muscle Contraction and the Role of Visual Deprivation and Eyelid Proprioception

PURPOSE

To determine if frontalis muscle contraction can be induced by manipulating visual and eyelid proprioceptive inputs through simulating visual deprivation and ptosis.

METHODS

Volunteers without prior eyelid or forehead pathologic study were recruited for this nonrandomized, prospective study. Baseline and study phase brow positions were documented. The first phase was to simulate visual deprivation and the second to simulate ptosis. The dominant eye was used for each phase. As a proxy to simulate visual field deprivation, a black contact lens was placed on the eye, which reduced vision to light perception. As a proxy to simulate ptosis, an external eyelid weight was placed on the upper eyelid. Brow position ratios were calculated at various points along the brow and statistical analysis was performed.

RESULTS

Fifteen subjects participated. The average brow position ratio was 1.00 ± 0.08 for the visual deprivation group, which was not different from baseline (p = 0.86). The average brow position ratio for the external eyelid weight group was 1.13 ± 0.07, which was statistically significant compared with baseline and the visual deprivation group (p < 0.001).

CONCLUSIONS

Inducing visual deprivation with a black contact lens does not lead to a change in brow position. However, placing an external eyelid weight does lead brow elevation, with an average increase of 13% from baseline. This suggests a likely role for proprioceptive or sensory inputs in frontalis muscle contraction in the setting of eyelid ptosis.

Proprioceptive Phenomenon With Involutional Ptosis: Evidential Findings in Anophthalmic Ptosis

PURPOSE

To determine the effect of ptosis on compensatory frontalis contraction in patients without visual input and to identify if a sensory stimulus contributes to brow elevation.

METHODS

A prospective study. Clinical photographs were measured by 2 masked oculoplastic surgeons to determine brow height in 8 patients with unilateral ocular prosthesis in 3 conditions: at baseline, after a gold weight was applied to the upper eyelid inducing acute ptosis, and with the gold weight plus topical anesthetic. The measured brow height was then compared between the 3 scenarios.

RESULTS

Mean brow height increased after application of the gold weight when compared with baseline, and this difference reached significance (p = 0.012). After topical anesthetic was applied, the mean brow height decreased but not back to baseline. When mean brow height during the gold weight with topical anesthesia was compared with baseline and with the gold weight only scenarios, the difference was not significant (p > 0.05).

CONCLUSIONS

Frontalis contraction is observed when acute ptosis is simulated in anophthalmic patients, confirming that a contracted visual field cannot be the only stimulus for compensatory brow elevation. A sensory or proprioceptive mechanism is suggested but not confirmed by the trend of reduction in brow elevation with topical anesthesia.

Eyelid Opening with Trigeminal Proprioceptive Activation Regulates a Brainstem Arousal Mechanism

Eyelid opening stretches mechanoreceptors in the supratarsal Müller muscle to activate the proprioceptive fiber supplied by the trigeminal mesencephalic nucleus. This proprioception induces reflex contractions of the slow-twitch fibers in the levator palpebrae superioris and frontalis muscles to sustain eyelid and eyebrow positions against gravity. The cell bodies of the trigeminal proprioceptive neurons in the mesencephalon potentially make gap-junctional connections with the locus coeruleus neurons. The locus coeruleus is implicated in arousal and autonomic function. Due to the relationship between arousal, ventromedial prefrontal cortex, and skin conductance, we assessed whether upgaze with trigeminal proprioceptive evocation activates sympathetically innervated sweat glands and the ventromedial prefrontal cortex. Specifically, we examined whether 60° upgaze induces palmar sweating and hemodynamic changes in the prefrontal cortex in 16 subjects. Sweating was monitored using a thumb-mounted perspiration meter, and prefrontal cortex activity was measured with 45-channel, functional near-infrared spectroscopy (fNIRS) and 2-channel NIRS at Fp1 and Fp2. In 16 subjects, palmar sweating was induced by upgaze and decreased in response to downgaze. Upgaze activated the ventromedial prefrontal cortex with an accumulation of integrated concentration changes in deoxyhemoglobin, oxyhemoglobin, and total hemoglobin levels in 12 subjects. Upgaze phasically and degree-dependently increased deoxyhemoglobin level at Fp1 and Fp2, whereas downgaze phasically decreased it in 16 subjects. Unilateral anesthetization of mechanoreceptors in the supratarsal Müller muscle used to significantly reduce trigeminal proprioceptive evocation ipsilaterally impaired the increased deoxyhemoglobin level by 60° upgaze at Fp1 or Fp2 in 6 subjects. We concluded that upgaze with strong trigeminal proprioceptive evocation was sufficient to phasically activate sympathetically innervated sweat glands and appeared to induce rapid oxygen consumption in the ventromedial prefrontal cortex and to rapidly produce deoxyhemoglobin to regulate physiological arousal. Thus, eyelid opening with trigeminal proprioceptive evocation may activate the ventromedial prefrontal cortex via the mesencephalic trigeminal nucleus and locus coeruleus.

Surgical desensitisation of the mechanoreceptors in Müller's muscle relieves chronic tension-type headache caused by tonic reflexive contraction of the occipitofrontalis muscle in patients with aponeurotic blepharoptosis

Proprioceptively innervated intramuscular connective tissues in Müller's muscle function as exterior mechanoreceptors to induce reflex contraction of the levator and occipitofrontalis muscles. In aponeurotic blepharoptosis, since the levator aponeurosis is disinserted from the tarsus, stretching of the mechanoreceptors in Müller's muscle is increased even on primary gaze to induce phasic and tonic reflexive contraction of the occipitofrontalis muscle. It was hypothesised that in certain patients with aponeurotic blepharoptosis, the presence of tonic reflexive contraction of the occipitofrontalis muscle due to the sensitised mechanoreceptors in Müller's muscle, can cause chronic tension-type headache (CTTH) associated with occipitofrontalis tenderness. To verify this hypothesis, this study evaluated (1) what differentiates patients with CTTH from patients without CTTH, (2) how pharmacological contraction of Müller's smooth muscle fibres as a method for desensitising the mechanoreceptors in Müller's muscle affects electromyographic activity of the frontalis muscle, and (3) how surgical aponeurotic reinsertion to desensitise the mechanoreceptors in Müller's muscle electromyographically or subjectively affects activities of the occipitofrontalis muscle or CTTH. It was found that patients had sustained CTTH when light eyelid closure did not markedly reduce eyebrow elevation. However, pharmacological contraction of Müller's smooth muscle fibres or surgery to desensitise the mechanoreceptor electromyographically reduced the tonic contraction of the occipitofrontalis muscle on primary gaze and subjectively relieved aponeurotic blepharoptosis-associated CTTH. Over-stretching of the mechanoreceptors in Müller's muscle on primary gaze may induce CTTH due to tonic reflexive contraction of the occipitofrontalis muscle. Therefore, surgical desensitisation of the mechanoreceptors in Müller's muscle appears to relieve CTTH.

Evaluation of muscle hyperactivity of the grimacing muscles by unilateral tight eyelid closure and stapedius muscle tone

Muscle hyperactivity of grimacing muscles, including the orbicularis oculi and corrugator supercilii muscles that cause crow's feet and a glabellar frown line with ageing, cannot be accurately evaluated by surface observation. In 71 subjects, this study investigated the extent to which grimacing muscles are innervated by the bilateral motor cortices, whether the corticofacial projection to the grimacing muscles affects the facially innervated stapedius muscle tone by measuring static compliance of the tympanic membrane, and whether unilateral tight eyelid closure with contraction of the grimacing muscles changes static compliance. Unilateral tight eyelid closure and its subsequent change in the contralateral vertical medial eyebrow position revealed that motor neurons of the orbicularis oculi and corrugator supercilii muscles were innervated by the bilateral motor cortices with weak-to-strong contralateral dominance. The orbicularis oculi, corrugator supercilii, and stapedius muscles innervated by the bilateral motor cortices had increased muscle hyperactivity, which lowered the vertical medial eyebrow position and decreased the static compliance of the tympanic membrane more than those innervated by the unilateral motor cortex. Unilateral enhanced tight eyelid closure with contraction of the grimacing muscles in certain subjects ipsilaterally decreased the static compliance with increased contraction of the stapedius muscle, which probably occurs to immobilise the tympanic membrane and protect the inner ear from loud sound. Evaluation of unilateral tight eyelid closure and the subsequent change in the contralateral vertical medial eyebrow position as well as a measurement of the static compliance for the stapedius muscle tone has revealed muscle hyperactivity of grimacing muscles.

Upgaze eyelid position allows differentiation between congenital and aponeurotic blepharoptosis according to the neurophysiology of eyelid retraction

To differentiate between congenital and aponeurotic blepharoptosis, we investigated whether upgaze with stretching of the mechanoreceptor of Mueller muscle increases involuntary reflex contraction of the levator slow-twitch muscle fibers. In 50 cases each of unilateral congenital blepharoptosis and of asymmetric aponeurotic blepharoptosis, the mean increases by upgaze in the upper eyelid margin to the line between the medial and lateral canthi as upper eyelid retraction distance (UERD) of the ptotic eyelid 0.4 mm and 2.9 mm, respectively. These were significantly smaller and significantly larger than those of the corresponding nonptotic eyelid, 2.0 mm and 2.3 mm, respectively.Worsening of ptosis on upgaze is common in congenital ptosis and is an abnormal differentiating sign, lacking the involuntary reflex contraction. Improvement of ptosis on upgaze is common in aponeurotic blepharoptosis and likely represents a normal physiological process, restoring the involuntary reflex contraction.