A Case of Positional Nystagmus of the So-Called Benign Paroxysmal Type and the Effects of Treatment by Intracranial Division of the VIIIth Nerve

A case of apogeotropic horizontal canal benign paroxysmal positional vertigo that transformed to the geotropic variant during treatment with Appiani maneuver, followed by successful treatment with Gufoni maneuver

Lesions at three possible sites can masquerade as apogeotropic horizontal semicircular canal benign paroxysmal positional vertigo (HSC-BPPV), namely: 1) short anterior (ampullary) arm canalolithiasis; and 2) culpulolithiasis, which may be either canal (Cup-C) or utricle-sided (Cup-U). There are no clinical methods or investigations to determine the exact pathological site when a patient with a history compatible with HSC-BPPV is found to have apogeotropic positional nystagmus on the supine roll test. Therefore, the treatment of apogeotropic variant of HSC-BPPV not only poses difficulties but the therapeutic options need to be tailored according to the ostensible localization of the pathology. If the apogeotropic HSC-BPPV is transformed into the geotropic variant, it becomes relatively easier to treat, as the treatment options for the latter are very well established. There are reports of cases of the apogeotropic variant of HSC-BPPV being transformed inadvertently during diagnostic positional tests as well as during therapeutic (intention-to-treat) positional maneuvers. I report here a case of an apogeotropic variant of right HSC-BPPV, that transformed into a geotropic variant during the therapeutic (intention-to-treat) Appiani maneuver, which was subsequently successfully treated with two sequences of Gufoni maneuver after transformation. The patient was followed up at one and 24 hours after the second sequence of Gufoni maneuver with a diagnostic supine roll test, which was negative. The case report is supported by seven videos of the diagnostic and therapeutic positional maneuvers revealing positional nystagmus, its appearance, change, and disappearance as clinical events unfolded during the examination and treatment.

Effectiveness of Canal Occlusion for Intractable Posterior Canal Benign Paroxysmal Positional Vertigo: A Systematic Review

Objectives

A last resort for therapy for intractable benign paroxysmal positional vertigo (BPPV) is mechanical occlusion of the posterior semicircular canal. The aim of this review was to assess the effect of posterior canal occlusion for intractable posterior canal BPPV on vertigo and to determine the risk of loss of auditory or vestibular function.

Data Sources

A systematic literature search according to the PRISMA statement was performed on PubMed, the Cochrane Library, Embase, Web of Science, and CINAHL. The last search was conducted in June 2018.

Review Methods

Cohort studies with original data and case reports describing >5 cases were included if they analyzed the effect of posterior semicircular canal obliteration in adults with intractable posterior BPPV on vertigo. Two authors screened titles and abstracts for eligibility. The first author screened full texts and analyzed the data.

Results

Eight retrospective studies met the eligibility criteria. The quality of all individual studies was rated fair. Canal occlusion was performed on 196 patients. All studies reported complete resolution of BPPV in all patients (100%). Among postoperatively tested patients, total loss of auditory function and vestibular function was reported in 2 of 190 (1%) and 9 of 68 (13%), respectively.

Conclusion

Posterior semicircular canal plugging resulted in 100% resolution of BPPV in patients with intractable BPPV in all studies. However, the strength of evidence was weak. Potential serious complications, such as deafness and loss of vestibular function, should be taken into account.

Benign Paroxysmal Positional Vertigo (BPPV): History, Pathophysiology, Office Treatment and Future Directions

BPPV is the most common cause of vertigo. It most often occurs spontaneously in the 50 to 70 year age group. In younger individuals it is the commonest cause of vertigo following head injury. There is a wide spectrum of severity from inconsistent positional vertigo to continuous vertigo provoked by any head movement. It is likely to be a cause of falls and other morbidity in the elderly. Misdiagnosis can result in unnecessary tests. The cardinal features and a diagnostic test were clarified in 1952 by Dix and Hallpike. Subsequently, it has been established that the symptoms are attributable to detached otoconia in any of the semicircular canals. BPPV symptoms can resolve spontaneously but can last for days, weeks, months, and years. Unusual patterns of nystagmus and nonrepsonse to treatment may suggest central pathology. Diagnostic strategies and the simplest "office" treatment techniques are described. Future directions for research are discussed.

Revisiting benign paroxysmal positional vertigo pathophysiology

Benign paroxysmal positional vertigo is the most common peripheral cause of vertigo. Although its pathophysiologic mechanisms remain unclear, different locations have been attributed throughout the last century, from the days of Bárány. Disease was initially located by Dix and Hallpike in the utricle, but later, Schuknecht's works elicited the cupulolithiasis and canalolithiasis theories, localizing the pathology to the semicircular canal system and mainly to the posterior one. However, conflicting evidences from temporal bone studies accumulated against this theory, which suggest other explanations. Although this clinical entity is well defined, and can usually be effectively treated with certain physical maneuvers, its pathophysiology is still obscure and is being critically discussed in this article, which reviews the milestones of benign paroxysmal positional vertigo understanding.

Charles Skinner Hallpike and the beginnings of neurotology

Although the symptom of vertigo had been well-recognized for several thousand years, it was not until the pioneering work of Prosper Ménière in the mid-19th century that it was appreciated that vertigo could originate from damage to the inner ear. Before that time, patients with vertigo (regardless of the cause) were said to have "cerebral congestion," a condition resulting from excessive blood filling the brain. Bloodletting and leeches to relieve the congestion were the treatment of choice. The discovery of endolymphatic hydrops in temporal bone specimens from patients with Ménière's disease by Hallpike and Cairns in 1938 marked the beginning of modern neurotology. For the first time, vertigo was correlated with specific pathophysiology. Propelled by his temporal bone work, Charles Hallpike received an appointment at the National Hospital at Queen Square, where he developed an internationally renowned neurotology clinic. His bithermal caloric test and positional tests are still routinely used in evaluation of the vertiginous patient.

Paroxysmal positional vertigo

Paroxysmal positional vertigo (PPV) is the peripheral vertiginous syndrome that is most frequently encountered in clinical practice. It is characterised by paroxysmal vertiginous attacks that are triggered by head movements and last no more than a few seconds, and is often accompanied by nausea and vomiting. The aim of this review is to provide a complete and updated description of the two principal manifestations of the syndrome: posterior semicircular canal (PSC-PPV) and horizontal semicircular canal PPV (HSC-PPV).

Pathophysiology and management of cupulolithiasis

Substantial support for the concept that the posterior semicircular canal is responsible for benign paroxysmal positional vertigo comes from four sources: clinical observations, temporal bone histopathology, experimental observations, and results of selective denervation of the posterior canal crista (singular neurectomy). The complete immediate relief of the positional vertigo and nystagmus that resulted from 39 of 40 singular neurectomies establishes this procedure as an effective management for patients with the chronic disabling form of cupulolithiasis. The ocular response in cupulolithiasis and the release nystagmus that follows singular neurectomy are explained by neural pathways that have been previously elucidated by anatomic and physiologic techniques. Although sensorineural hearing loss followed surgery three times among the first 15 patients, hearing loss has not occurred in the last 25 operations for cupulolithiasis.

Cupulolithiasis and posterior ampullary nerve transection

Schuknecht's description of a degenerated otoconial mass embedded in the cupula of the posterior canal crista of the downmost ear in the Hallpike test has been termed cupulolithiasis to reflect the pathophysiology in the syndrome described by Barany. The hypothesis that the otoconial mass renders the cupula of the posterior canal gravity-sensitive has received considerable experimental and clinical support. Clinical support is provided here by the observation that complete relief of the paroxysmal positional vertigo followed transection of the posterior ampullary nerve (singular nerve) in 31 ears of 29 patients complaining of chronic cupulolithiasis. Two patients in the series exhibited bilateral cupulolithiasis and were relieved by sequential bilateral singular neurectomies. Twenty-seven patients were relieved by unilateral singular neurectomy. Although there were three instances of sensorineural hearing loss following surgery in the first 15 patients, no hearing loss has been observed following surgery in the last 16 operations. This low incidence of sensorineural hearing loss has resulted from modifications in surgical technique.

Disabling positional vertigo

We have identified a group of patients with vestibular disorders whose symptoms are not consistent with the commonly recognized syndromes such as Meniere's disease, benign paroxysmal positional vertigo, and vestibular neuronitis. These patients have a constant positional vertigo and are often nauseated to an extent that makes them disabled. Their symptoms do not respond to conventional medical treatment or habituating therapy. We have found specific clinical-pathological signs in these patients that indicate that the vestibular nerve is compressed intracranially by blood vessels. Treatment of nine such patients by microvascular decompression of the eighth nerve brought total relief of symptoms in eight patients and improvement in one. We suggest that this syndrome be named disabling positional vertigo.

Some observations on the localizing significance of ear-dependent positional nystagmus

Seventy-one patients who demonstrated unilateral ear-dependent positional nystagmus and unilateral labyrinthine weakness were studied to test the hypothesis that ear-dependent positional nystagmus almost always occurs on the side of unilateral labyrinthine impairment. Little, if any, correlation was found between these two parameters. The results of this study with regard to the critical question of selecting the correct ear for surgery in patients with incapacitating benign paroxysmal postural vertigo are discussed.

Effect of vestibular deafferentation upon positional nystagmus in the squirrel monkey

Seventeen of eighteen squirrel monkeys, under a restrained condition, showed positional nystagmus in different body positions. Good repeatability and consistency of the nystagmus were found, especially at the left-lateral, right-lateral, and head-hanging positions. Positional nystagmus was not observed after the subject underwent bilateral labyrinthectomy. However, one subject in which part of the crista ampullaris posterior remained, continuously showed a positional nystagmus. Therefore, the existence of a minimal vestibular imput from the crista ampullaris could provoke the nystagmus. Some changes occurred in positional nystagmus after bilateral macular ablation; however, the nystagmus did not completely disappear. Even though imput from the crista ampullaris is essential to provoke positional nystagmus in squirrel monkeys, the positional nystagmus probably results from a central dyscoordination between vestibulo-oculomotor function, spino-oculomotor function, vestibular and brain circulation, and psychological condition.

Transection of the posterior ampullary nerve for the relief of benign paroxysmal positional vertigo

Five patients with incapacitating benign paroxysmal positional vertigo (BPPV) for one year or longer were managed surgically by transection of the posterior ampullary nerve. An approach to this nerve was devised based upon a careful study of the posterior ampullary nerve in temporal bone dissections and specimens of the inner ear. Using the round window membrane as the principal landmark, the singular canal was exposed in the round window niche via a tympanotomy approach under local anesthesia. Transection of the posterior ampullary nerve promptly and completely relieved the signs and symptoms of BPPV in all five patients. A severe sensorineural hearing loss was produced in one case as a result of traumatic labyrinthitis. Transection of the posterior ampullary nerve in the round window niche is recommended to: 1) relieve severe BPPV of one or more years duration, and 2) add to the completeness of transcanal labyrinthectomy by denervating the inaccessible posterior canal crista.