Awareness and management of oculonasal synkinesis: case reports Open Access

Abstract

Introduction

Oculonasal synkinesis (OS) is a rare and benign condition characterized by momentary involuntary alar wing movement triggered by voluntary or involuntary blinking. This condition is often observed bilaterally [1]. It is related to the relationship between the temporal and zygomatic branches of the facial nerve; these branches innervate the orbicularis oculi muscle and the superior buccal branch of the facial nerve, which in turn innervates the compressor narium minor (CNM) muscle [2]. OS may occur due to nerve misdirection following physical trauma, surgery, or inflammation. While it can be associated with these conditions, most documented cases are congenital and idiopathic [3]. Treatment options for OS include botulinum toxin injections, chemodenervation, selective neurectomy, and open or closed rhinoplasty [4]. In our report, we discuss the treatment of two OS cases using open rhinoplasty and Botox injections, noting the disappearance of OS in both patients during follow-up.

Case presentation 1

A 26-year-old female patient presented with nasal congestion. Examination revealed drooping of the nose tip, slight left septal deviation, and bilateral inferior turbinate hypertrophy. During the examination, a sudden collapse of the lateral crus of the lower lateral cartilage occurred simultaneously with blinking (Video 1). The patient was unaware of this condition and had no other complaints. All laboratory tests and images appeared normal. An electromyography (EMG) was conducted for OS and reported as normal. The patient had no known additional diseases and no family history of similar symptoms. She was diagnosed with idiopathic congenital OS and treated with 5 IU of Botox injected into both CNM muscles. One week later, OS had resolved.

Case presentation 2

A 28-year-old female presented with cosmetic concerns about a nasal deformity. Endoscopic examination revealed minimal right septal deviation, with no other abnormalities. Simultaneous collapse of the bilateral lower lateral cartilage crura was observed with blinking (Video 2). The patient was unaware of this condition. Detailed laboratory tests were normal, and the patient declined EMG. A diagnosis of congenital idiopathic OS was made. Open rhinoplasty was performed, with careful attention to the direction of the CNM muscle. Postoperative examination confirmed the disappearance of OS.

Discussion

Synkinesis is described as the simultaneous contraction of muscles. OS, although rare, is a well-documented phenomenon [1]. The orbicularis oculi muscle, consisting of palpebral and orbital parts, enables eyelid closure [3]. The CNM muscle, alongside the anterior dilator narium muscle, performs eccentric and concentric movements at the nasal tip and compresses the nostril [3]. In OS, simultaneous contraction of the orbicularis oculi and CNM muscles occurs during blinking.

OS was first described by Guyuron et al. in 1994. This study, being the largest case series to date, comprised 13 cases, all of whom were female. The literature typically presents small case series. Although few cases have been published, Palazi et al. suggested that OS may be more common than previously thought, emphasizing that careful observation can detect more cases. Patients are usually unaware of this condition and often do not have any related complaints. Professionals often encounter patients with different primary complaints. No male patients have been documented in the literature, which might be due to female patients more frequently seeking cosmetic surgeries, thereby leading specialists to detect and diagnose OS during pre-procedural evaluations. Both of our cases were female and exhibited bilateral symptoms, as commonly reported.

Although the exact cause of OS is unclear, it is thought to be associated with conditions such as trauma, tumors, surgical injuries, and congenital factors [3]. OS may result from facial nerve damage due to trauma or tumor compression and subsequent aberrant nerve fiber regeneration. However, there are no documented cases of OS definitively caused by nerve regeneration following trauma in the literature. While there are cases in the literature of OS developing after rhinoplasty, this scenario is somewhat contradictory. It is more plausible that OS was present before the surgery but only became noticeable afterwards as the patient and their relatives paid more attention to the nose. Neither of our patients had a history of trauma. In both cases, OS was determined to be congenital idiopathic [4]. Guyuron et al. classified contractions seen in patients with OS as strong, moderate, or mild [5]. We believe that this classification, which does not rely on objective data, may not be appropriate. External contractions of the CNM muscle can vary depending on factors such as skin thickness, nasal cartilage, and muscle structure. Beyond visual inspection, a detailed EMG study may be appropriate to determine the strength of contraction.

Regarding treatment, although there is no consensus, dissecting the CNM muscle during surgery offers a permanent solution. This procedure is safe and does not lead to nasal valve issues. The dissection can be executed using either closed or open rhinoplasty techniques. Kozin and Palazi recommended subperichondrial or subperiosteal dissection. Notably, there is a documented case in the literature of a patient who still exhibited OS symptoms after undergoing closed rhinoplasty twice. It was also observed that improvement was unilateral in a bilateral OS patient who underwent open rhinoplasty without careful attention to CNM muscle dissection. These examples show that dissection of the CNM muscle should be performed meticulously when using either open or closed techniques for the treatment of OS.

A non-surgical treatment option is botulinum toxin injection, which is non-permanent and requires repeated injections. In our first case, where the patient had nasal obstruction without cosmetic demands, we suggested botulinum toxin injections. Five units of botulinum toxin were applied to the CNM muscles. Because cosmetic complaints were prominent in the second case, we performed open rhinoplasty and dissected the CNM muscles bilaterally. OS disappeared in both cases. Our findings support the literature in terms of etiology, pathogenesis, and treatment determination.

In conclusion, facial plastic surgery specialists should be aware of this condition. Recognizing and documenting OS preoperatively, particularly since patients tend to focus on the nose following surgery, can help protect physicians from potential legal issues. To the best of our knowledge, this case report is among the few in the literature that includes video documentation.

Conflict of interest statement

None declared.

Funding

None declared.

References