Case report: Inverse Bell’s phenomenon presents after frontalis sling surgery

The patient had bilateral ptosis and poor levator function with normal Bell's phenomenon before surgery.

Issue: December 10, 2016

ByDhivya Ashok Kumar, MD, FRCS, FICO, FAICO

ByAmar Agarwal, MS, FRCS, FRCOphth

Upward and outward movement of the eyeball on attempted voluntary lid closure is called Bell’s phenomenon, as named by Charles Bell. This is a common clinical finding in 75% of normal individuals. The significance of this is often felt in those eyes that have ptosis and require surgical correction.

Preoperative Bell’s phenomenon is often examined in eyes before surgery as a part of the preliminary workup. Downward movement of the eye on closure is known as inverse Bell’s. This has been known to happen after levator resection surgeries, as reported by Betharia and colleagues, and there have been a few more reports substantiating the chance of inverse Bell’s after supramaximal levator resection following congenital ptosis. However, there are no previous reports or literature showing the risk of inverse Bell’s after sling surgery. We report a case of congenital ptosis in which normal Bell’s changed to inverse Bell’s following simple frontalis sling surgery.

Inverse Bell’s after frontalis sling

A 26-year-old female patient came to our outpatient department with bilateral droopy eyes since childhood. On examination she had bilateral ptosis with poor levator function (3 mm). The vertical palpebral height was 5 mm in each eye. Marginal reflex distance was –2 mm in each eye. Extraocular movements were normal, and Bell’s was normal. There were no other ocular abnormalities observed in the anterior or posterior segment. She underwent bilateral frontalis sling in pentagon fashion using a silicone sling under local infiltration anesthesia. There were no intraoperative complications noted.

On day 1 postop, marginal reflex distance was 4 mm in each eye. There was significant lid edema, and prominent lagophthalmos was present. The sling was in position, and skin wound sutures were intact. Inverse Bell’s was noted (Figure 1), and other extraocular movements were normal. The patient had excessive lacrimation, lagophthalmos and early corneal epithelial defect on day 1. The Frost suture was retained in place, and copious lubricants in gel and drops formulations were given. A topical antibiotic for the skin wound and a serratiopeptidase oral formulation were also prescribed, with plans to review the patient again at 2 weeks. At 2 weeks, the Bell’s phenomenon had become normal (Figure 2), and there were no lacrimation or epithelial changes. Lagophthalmos was reduced, and the patient was asymptomatic.

Figure 1. Postoperative inverse Bell’s following frontalis sling surgery seen as eyes moving down and inward on lid closure.

Figure 2. Bell’s becoming normal seen as upward movement of eyes on lid closure at 2 weeks postoperative.

Figure 3. Preoperative (a), 2 weeks postoperative (b) and 4 weeks postoperative (c) palpebral aperture and lid position of the patient.

Theories for inverse mechanism

Residual surgery or repeat intervention is more prone for inverse Bell’s phenomenon, and levator resection is often identified as a common surgery before inverse Bell’s. It has also been noted in some normal populations and after conjunctival scarring. In our case, we noticed inverse Bell’s after frontalis sling surgery.

The proposed mechanism for inverse Bell’s after levator surgery has been extensive tissue manipulation and tissue plane dissection. However, tissue manipulation does not happen in frontalis sling surgery because the sling passes through one plane or axis only. However, there is excess tissue that is bundled up by the sling, which induces indirect trauma by causing edema and hemorrhage in the muscular and subcutaneous plane.

The frontalis sling is a silicone sling that is less traumatic and has been used in ptosis surgeries previously. However, the needle end of the sling can induce trauma to the tissues and induce acute edema and inflammation. As reported previously, large levator resections have led to inverse Bell’s. Similarly, in our case, the ptosis was severe, and we required more correction or elevation (Figure 3). Also similar to other cases, the inverse Bell’s resolved within 2 weeks after surgery without any additional treatment.

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Takagi and colleagues noticed that normal Bell’s phenomenon happens only during voluntary lid closure and not during blinks. According to Coppez, inverse Bell’s may be present in 2% of normal cases. But certain pathologic conditions, such as 7th cranial nerve palsy, tabes dorsalis, conjunctival scarring and ectropion of the upper lid, may increase the incidence. Very rarely malignant infiltration of the upper lid can also induce inverse Bell’s. Gupta and colleagues reported that 3rd and 7th cranial nerve nuclei on the same side are well connected, unlike the 4th and 7th nerve nuclei. Hence, the contraction of the orbicularis oculi muscle produces upward movement due to synergistic action of the superior rectus and inferior oblique. During abnormal situations such as trauma or scarring, the reflex arc involves the 4th cranial nerve nuclei along with the 3rd and 7th nerve, causing inverse phenomenon, ie, the eye rotates down instead of up. The clinical significance is increased when the inverse movement happens in after ptosis surgery because there is coexisting lagophthalmos. Therefore, utmost care is taken to prevent exposure keratopathy by maintaining the Frost suture and lubricating the eyes with liberal tear substitutes. Bell’s phenomenon became normal in our patient at 2 weeks, unlike malignancy or infiltration in which it is known to persist.

Conclusion

Examination of Bell’s phenomenon is vital in all lid surgeries. It has to be stressed that preoperative eye movement documentation and identification of postoperative ocular movement abnormalities are important in the learning curve. We believe that this report can add to the existing literature that inverse Bell’s can occur not only in levator resection surgery but also following frontalis sling surgery, and the surgeon should be well aware of such complication.

References:
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Gupta JS, et al. Am J Ophthalmol. 1965;doi:10.1016/0002-9394(65)93035-7.
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For more information:
Amar Agarwal, MS, FRCS, FRCOphth, is director of Dr. Agarwal’s Eye Hospital and Eye Research Centre. Agarwal is the author of several books published by SLACK Incorporated, publisher of Ocular Surgery News, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery and Presbyopia: A Surgical Textbook. He can be reached at 19 Cathedral Road, Chennai 600 086, India; email: dragarwal@vsnl.com; website: www.dragarwal.com.

Disclosure: No products or companies that would require financial disclosure are mentioned in this article.