Intractable Persistent Direction-Changing Geotropic Nystagmus Improved by Lateral Semicircular Canal Plugging

Abstract

Antigravitational deviation of the cupula of the lateral semicircular canal, which is also called light cupula, evokes persistent direction-changing geotropic nystagmus with a neutral point. No intractable cases of this condition have been reported. In our case, a 67-year-old man complained of positional vertigo 3 months after developing idiopathic sudden hearing loss in the right ear with vertigo. He showed a persistent direction-changing geotropic nystagmus with a leftward beating nystagmus in the supine position. The nystagmus resolved when his head was turned approximately 30° to the right. He was diagnosed with light cupula of the right lateral semicircular canal and was subsequently treated with an antivertiginous agent. However, his symptoms and positional nystagmus did not improve, so the right lateral semicircular canal was plugged by surgery. One month after surgery, his positional vertigo and nystagmus were completely resolved. We speculated that the cause of the patient's intractable light cupula was an enlarged cupula caused by his idiopathic sudden hearing loss.

Persistent Positional Vertigo in a Patient with Sudden Sensorineural Hearing Loss: A Case Report

“…Recently, it was reported that the condition of light cupula may be responsible for the positional vertigo which is accompanied by ipsilateral SSNHL [ 3 14 ]. The pathophysiology of light cupula still remains unclear.…”

The Light Cupula Phenomenon: A Scoping Review

“…In 2015, Seo and colleagues reported a case of a patient with sudden sensorineural hearing loss who had incurable, persistent geotropic DCPN for more than 6 months and was treated with HSCC plugging surgery. They suggested that the cause of the intractable light cupula might be related to an irreversible morphological change in the cupula (enlarged cupula) In other words, it was assumed that the density of the cupula decreased due to the enlargement of the cupula while the mass of the cupula remained constant [25].…”

The Light Cupula: An Emerging New Concept for Positional Vertigo

“…Bergenius and Tomanovic [ 4 ] suggested that an altered homeostasis of these macromolecules may change the relative specific gravity of the endolymph to the cupula. Seo, et al [ 19 ] reported a patient with sudden sensorineural hearing loss showing persistent geotropic DCPN whose positional vertigo was intractable and persisted for more than 6 months. They suspected that the light cupula in that patient was caused by an irreversible morphological change in the cupula (enlarged cupula).…”

“…Though a null plane was not sought to be identified in the study, we can assume that a null plane might have been identified on the unaffected side from the nystagmography results in all 3 patients [ 26 ]. Patients with sudden sensorineural hearing loss [ 2 , 4 , 19 , 21 , 24 , 27 ] and acute otitis media complicated by serous labyrinthitis [ 28 ] may exhibit persistent geotropic DCPN. Compared to patients with light cupula without associated labyrinthine disorders, a null plane may not be identified in patients with such association on the same side with the inner ear disorder, and the conversion from geotropic to apogeotropic nystagmus may occur more frequently in the latter group [ 22 , 28 ].…”

“…Symptoms of vertigo and positional nystagmus resolve spontaneously within 2 weeks in most patients with light cupula [ 3 , 8 ]. However, in some cases in whom persistent geotropic DCPN is accompanied by sudden sensorineural hearing loss, positional vertigo may persist for several months or even longer [ 19 , 27 ], and surgery such as LSCC plugging may be required in some cases, to treat intractable positional vertigo [ 19 ].…”