Hemifacial Spasm in an Argus II Retinal Prosthesis Patient

Abstract

Purpose:

A 59-year-old man with retinitis pigmentosa, who received an Argus II retinal prosthesis in the left eye 3 years prior, presented with left-sided involuntary facial contractions that occurred only after turning on the Argus II device.

Methods:

A case report.

Results:

Given that this patient's reported and visualized lower eyelid twitching corresponds to the location of the external region of the implanted coil, we hypothesize that heat or wirelessly transmitted electrical signals from the external coil to the implanted coil may induce spasm of the facial nerve and thus play a role in hemifacial spasm onset.

Conclusions:

To our knowledge, this is the first report of hemifacial spasm associated with Argus II use.

Introduction

A 59-year-old man with retinitis pigmentosa received an Argus II retinal prosthesis in the left eye 3 years prior and presented to our clinic with symptoms of a “twitching eyelid” in that left eye during use of the Argus II system. His visual acuity is light perception in both eyes. Anterior segment examination of both eyes revealed posterior chamber intraocular lenses. Posterior segment examination demonstrated waxy pallor of both nerves, attenuated vessels, and peripheral bone spicules. The macula of the left eye had an Argus II implant in good position. His past medical history was unremarkable, and his social history was significant for 3 cups of coffee daily and a present-day smoker with a 20-year, half-pack per day history. There was no associated pain, and he was not significantly bothered by these twitching occurrences. He reported that these episodes occurred only while the device was turned on, typically presented several minutes after initiating the device, and resolved spontaneously within seconds to minutes after turning off the device. He had never experienced similar episodes prior to Argus II implantation.

In clinic, after 3 to 5 minutes of continuous Argus II use, he demonstrated involuntary clonic contractions of the left side of the face, including the orbicularis oculi muscle of the left lower eyelid and the zygomaticus, leading to an upturning of the corner of the mouth (see Supplemental Video). Owing to the involuntary twitching in the upper and lower face, the patient was diagnosed with hemifacial spasm associated with Argus II use.

Methods

Case Report

Hemifacial spasm is a disorder of the seventh cranial nerve that leads to unilateral involuntary twitching of the facial muscles. ^1,2 Hemifacial spasm can be primary or secondary, with primary hemifacial spasm often due to intracranial vascular compression of the seventh nerve, leading to an upper face spasm that may travel to the lower face. ³ Secondary causes, on the other hand, typically present with simultaneous involvement of the upper and lower face, as seen with our patient. ⁴ Our patient did not demonstrate the classic involuntary undulating, rippling movements seen in facial myokymia. ⁵ His simultaneous involuntary contractions in the upper and lower face occurred only with use of the Argus II and the spasms were not distractible, leading to a diagnosis of hemifacial spasm rather than any psychogenic spasm.

Hemifacial spasm is a chronic condition for which mild cases can be observed with conservative management to reduce exposure to risk factors such as stress. ^6,7 When therapy is desired, botulinum toxin is preferred although microvascular decompression has been performed in cases caused by vascular compression. ¹ To our knowledge, there have been no reports of hemifacial spasms associated with Argus II use, nor is there a known link between facial spasms and ocular implants.

Results

The Argus II is composed of a camera that captures images, a video processor unit that converts information from the camera into electrical signals, and an external coil that wirelessly transmits signals to the implanted secondary coil (located inferotemporally under the lateral rectus) and epiretinal electrode array. ^8,9 Although the patient’s caffeine use and smoking history are known risk factors for eyelid myokymia, these risk factors are not classically associated with hemifacial spasm and the patient’s symptoms occur only when actively using the Argus II and did not occur prior to implantation. ¹⁰ These risk factors, however, may help incite his symptoms. ¹¹ Hemifacial spasm, a pathology of the facial nerve, and its potential temporal relationship to the use of the Argus II is not fully understood. Given that this patient’s reported and visualized lower eyelid twitching corresponds to the location of the external region of the implanted coil, we hypothesize that heat or wirelessly transmitted electrical signals from the external coil to the implanted coil may induce spasm of the facial nerve and thus play a role in hemifacial spasm onset. ¹²

Conclusions

This patient’s hemifacial spasm symptoms occur only while the Argus II device is turned on, last for a few minutes, and resolve within 30 seconds after discontinuation of device use. No therapy was recommended, and he was advised to manage symptoms conservatively by taking breaks as necessary during use of the retinal prosthesis.