Sound- and/or pressure-induced vertigo due to bone dehiscence of the superior semicircular canal

OBJECTIVES

To present symptoms, patterns of nystagmus, and computed tomographic scan identification of patients with sound- and/or pressure-induced vertigo due to dehiscence of bone overlying the superior semicircular canal. To describe anatomical findings and outcome in 2 patients undergoing plugging of the superior semicircular canal for treatment of these symptoms.

DESIGN AND SETTING

Prospective study of a case series in a tertiary care referral center.

PATIENTS AND RESULTS

Eight patients with vertigo, oscillopsia, and/or disequilibrium related to sound, changes in middle ear pressure, and/or changes in intracranial pressure were identified in a 2-year period. Seven of these patients also had vertical-torsional eye movements induced by these sound and/or pressure stimuli. The direction of the evoked eye movements could be explained by excitation or inhibition of the superior semicircular canal in the affected ear. Computed tomographic scans of the temporal bones identified dehiscence of bone overlying the affected superior semicircular canal in each case. Disabling disequilibrium in 2 patients prompted plugging of the dehiscent superior canal through a middle cranial fossa approach. Symptoms were improved in each case. One patient developed recurrent symptoms requiring an additional plugging procedure and developed sensorineural hearing loss several days after this second procedure.

CONCLUSIONS

We have identified patients with a syndrome of vestibular symptoms induced by sound in an ear or by changes in middle ear or intracranial pressure. These patients can also experience chronic disequilibrium. Eye movements in the plane parallel to that of the superior semicircular canal were evoked by stimuli that have the potential to cause ampullofugal or ampullopetal deflection of this canal's cupula in the presence of a dehiscence of bone overlying the canal. The existence of such deshiscences was confirmed with computed tomographic scans of the temporal bones. Surgical plugging of the affected canal may be beneficial in patients with disabling symptoms.

Vascular inner ear partition: a concept for some forms of sensorineural hearing loss and vertigo

The results of a series of scanning electron microscopical studies were used to construct a model for the vascular pathways in the inner ear. Corrosion cast preparations of the vessels of the inner ear of the adult rat were used in this study. The inner ear is, like a hand, an end organ containing four sense organs (cochlea, saccule, utricle and the cristae ampullaris). All these specific inner ear structures have their own vascular supply. We have developed a blood flow diagram of the inner ear. This model was used for a classification of different types of ischemia in the inner ear and forms a concept for some forms of sensorineural hearing loss and vertigo. Four types of inner ear ischemia are proposed. In type I (a or b) of inner ear ischemia only the vessels of the cochlea are involved resulting in two types of hearing loss without vertigo. Type II is characterized by ischemia of a part of the cochlea and a part of the vestibular system. In type III (a or b) only the vestibular system is involved, while in type IV no blood circulation will be present in the inner ear resulting in total deafness and severe vertigo. Inner ear partition at ultramicroscopical level of these structures may be possible in the future and new imaging techniques will probably support the vascular schematic model presented in this study.

An unusual cause of acute labyrinthine failure

We report a case of a 40-year-old man presenting with acute vertigo and deafness. Computed tomography (CT) scanning at initial presentation was normal. However, one year later he developed numbness on the right side of his face and examination revealed fifth, seventh and eighth cranial nerve palsies as well as cerebellar dysfunction. Magnetic resonance imaging (MRI) demonstrated a cerebellopontine angle lesion. He underwent near total excision followed by neuro-axis irradiation. The main mass of the tumour projected into the cerebellopontine angle. Histology showed this to be a medulloblastoma. All features of this case are unusual; hence we discuss the pathogenesis and management of this very rare tumour.

False perception of motion in a patient who cannot compensate for eye movements

We are usually unaware of the motion of an image across our retina that results from our own movement. For instance, during slow-tracking eye movements we do not mistake the shift of the image projected onto the retina for motion of the world around us, but instead perceive a stable world. Following early suggestions by von Helmholtz, it is commonly believed that this spatial stability is achieved by subtracting the retinal motion signal from an internal reference signal, such as a copy of the movement command (efference copy). Object motion is perceived only if the two differ. Although this concept is widely accepted, its anatomical underpinning remains unknown. Here we describe the case of a patient with bilateral extrastriate cortex lesions, suffering from false perception of motion due to an inability to take eye movements into account when faced with self-induced retinal image slip. This is indicated by the fact that during smooth-pursuit eye movements, he perceives motion of the stationary world at a velocity that corresponds to the velocity of his eye movement; that is, he perceives the raw retinal image slip uncorrected for his own eye movements. We suspect that this deficiency reflects damage of a distinct parieto-occipital region that disentangles self-induced and externally induced visual motion by comparing retinal signals with a reference signal encoding eye movements and possibly ego-motion in general.

Particulate matter in the posterior semicircular canal

The pathoetiology of benign paroxysmal positional vertigo (BPPV) is controversial. Particulate matter within the posterior semicircular canal has been identified intraoperatively in patients with BPPV but has also been reported in non-BPPV patients at the time of translabyrinthine surgery (Parnes LS, McClure JA. Free-floating endolymphatic particles: a new operative finding during posterior semicircular canal occlusion. Laryngoscope 1992;102:988-92; Schuknecht HF, Ruby RRF. Cupulolithiasis. Adv Otorhinolaryngol 1973;20: 434-43; Kveton JF, Kashgarian M. Particulate matter within the membranous labyrinth: pathologic or normal? Am J Otol 1994;15:173-6). The nature of the particulate matter remains unknown. The purpose of this study was to prospectively examine the posterior semicircular canal of patients with and without a clinical history of BPPV for the presence of particulate matter. Seventy-three patients without BPPV symptoms undergoing labyrinthine surgery (vestibular schwannoma excision or labyrinthectomy) and 26 patients with BPPV undergoing the posterior semicircular canal occlusion procedure were compared. Additionally, 70 archived temporal bones without a history of BPPV were examined microscopically for the presence of particulate matter within the lumen of the membranous labyrinth. No particles were observed intraoperatively in any of the 73 patients without a history of BPPV. Particulate matter was observed in 8 of 26 patients at the time of the posterior semicircular canal occlusion procedure for intractable BPPV. Of the 70 temporal bones examined, 31 did not show significant postmortem changes and also did not demonstrate cupulolithiasis or canalithiasis. Particulate matter from within the membranous posterior semicircular canal was removed from one patient at the time of posterior semicircular canal occlusion for intractable BPPV symptoms and was examined by scanning electron microscopy. The particulate matter appeared morphologically consistent with degenerating otoconia. These data show a statistically significant association between the presence of particles within the posterior semicircular canal in this study and the symptom complex of BPPV.

[Benign paroxysmal positional vertigo: follow-up of 165 cases treated by Semont's liberating maneuver]

The purpose of the present work has been to evaluate the effectiveness of the Semont's liberatory maneuver in treating benign paroxysmal positional vertigo (BPPV) stemming from lithiasis of the posterior semicircular canal. After taking an overview of the history, epidemiology and clinical manifestation of this pathology, the cases studied are presented: 165 cases of BPPV of the posterior semicircular canal diagnosed between September 1992 and December 1994 at the Audiology and E.N.T. Clinic of the Santo Spirito Hospital in Casale Monferrato, Italy. Diagnosis was based on careful examination of the case history and the finding of typical paroxysmal positional vertigo. Among the 1096 patients who came under observation for vertigo or instability, the incidence of BPPV was rather high: approximately 23%, predominantly females (64% of the cases). In 56% of the cases the right labyrinth was involved while the left labyrinth was involved in 39% (in 5% the form was bilateral). The average age of the patients was 60 years, with incidence being greatest in the 6th and 7th decades of life. In 10% of the cases the etiology was traumatic (cranial, cervical trauma or post otological or general surgery), in 5% it was of viral origin, in 1% of vascular origin; however, in the vast majority of cases (84%) it was idiopathic. All the patients were treated with the Semont's liberatory maneuver (repeated 1-3 times in subsequent sessions at 48 hour intervals). A full 62% of the patients treated were freed of the disorder after a single maneuver and 95.5% after 3 treatments. In 5% of the cases (3 very elderly patients), the disorder persisted even after rehabilitation with Brand Daroff's exercises. To evaluate the evolution in time, all the patients were sent a written questionnaire aimed at determining the progression of symptoms, any recurrences, the number of recurrences, and the length of time from the date of treatment. In the case of positive response, the patients were invited in for a clinical-instrumental check-up. This follow-up ranged from 6 to 30 months. At the end of May 1995 the case breakdown was as follows: 80.7% of the patients were still symptom free, most being quite satisfied with the results; 18% had had one or more recurrence of the paroxysmal positional vertigo which were successfully treated by one or more application of the Semont's maneuver.

Histopathology of idiopathic chronic recurrent vertigo

Vestibular neuritis is a degenerative neuropathy of the peripheral vestibular system. The etiology of this condition is uncertain, although it is generally believed to be viral. A small percentage of patients with vestibular neuritis have chronic recurrent episodes of vertigo. Detailed cytologic descriptions of acute or chronic vestibular neuritis are lacking, and no previous studies have reported evidence of chronic inflammation in human temporal bone specimens. The authors of this study examined temporal bone specimens from three patients with a history of chronic recurrent vertigo of unknown cause. Varying degrees of inflammation and destruction were seen in the vestibular system, and mild involvement of the cochlear system was noted. These findings are consistent with postinfectious inflammatory changes of the cochlear-vestibular system analogous to a postinfectious syndrome involving the central nervous system.

Particle repositioning for benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo is a common condition that can be severely incapacitating. The causative mechanism is usually displaced dense particles (canaliths) in a semicircular canal. By means of canalith repositioning, these particles can be moved into the utricle and the symptoms completely resolved in a high percentage of cases. The protocol for procedure is discussed as well as the management of complications and recurrences.

Update on posterior canal occlusion for benign paroxysmal positional vertigo

Most, if not all, cases of BPPV appear to result from free-floating posterior semicircular canal endolymph particles. Particle repositioning alleviates symptoms and findings in the vast majority of patients. For the small intractable group of nonresponders, posterior semicircular canal occlusion remains a safe and highly efficacious procedure. This new technique has also paved the way for even newer and most invasive inner ear procedures.

Basophilic deposits on the cupula: preliminary findings describing the problems involved in studies regarding the incidence of basophilic deposits on the cupula

In this study, the possibility of whether basophilic deposits adhered to the cupulas in the semicircular canals was investigated histologically. Results indicated that basophilic deposits were present in all three cupulas of the semicircular canals. The overall incidence of basophilic deposits in the superior, lateral and posterior semicircular canal cupulas was 26%, 41% and 37%, respectively. The incidence of basophilic deposits bound to the cupulas increased with age. The possible origin of these basophilic deposits on the cupulas and the increased incidence of basophilic deposits with increasing age are discussed.

Repetitive paroxysmal nystagmus and vertigo

A 55-year-old woman had paroxysms of vertigo and visual blurring associated with complex combined torsional, horizontal, and vertical nystagmus. These episodes occurred regularly at 2-minute intervals, each attack lasting for 15 seconds. Between attacks, there was a much finer asymptomatic nystagmus whose components were in the opposite direction to those associated with the paroxysmal attacks. A brain MRI revealed an arteriovenous malformation in close proximity to the left vestibular nucleus, with evidence of previous bleeding. Caloric testing demonstrated a left-sided vestibular paresis. We suggest that neurons in this patient's damaged left vestibular nucleus are usually underactive but regularly produce pathologic brief bursts of hyperactivity causing episodic reversal and gross exacerbation of her resting nystagmus. Treatment with low-dose carbamazepine was successful in abolishing both the paroxysms of nystagmus and the symptoms of vertigo and visual disturbance.

MR imaging features of an intracochlear acoustic schwannoma

We present a very unusual case of an acoustic neuroma involving the left cochlea and internal auditory canal of a 24-year-old man. Clinical suspicion was aroused when the patient presented with a left total sensorineural hearing loss and continuing vertigo. The diagnosis was made pre-operatively with MRI after initial CT scanning was normal. The tumour was removed via a transotic approach. This case report demonstrates the MRI features of an intracochlear schwannoma and emphasizes the importance of MRI in patients with significant auditory and clinical abnormalities with normal CT scans of the relevant region.

Temporal bone pathology in a case of Cogan's syndrome

Cogan's syndrome (CS) presents typical and atypical types. Typically, there are episodes of nonsyphilitic keratitis and audiovestibular dysfunction. Atypically, there are inflammatory changes in other eye structures and other organ systems, particularly the cardiovascular system. The temporal bone pathology in a case of CS shows changes that are similar to those observed in other autoimmune disorders associated with audiovestibular dysfunction. The following pathologic features characterize autoimmune inner ear disease: 1. acute labyrinthitis resulting in atrophy of inner ear tissues including the sense organs and their supporting structures; 2. endolymphatic hydrops; 3. focal and diffuse proliferation of fibrous tissue and bone; and 4. retrograde neuronal degeneration. These pathologic findings are consistent with an inflammatory (and possibly ischemic) attack on the membranous labyrinth.

Particulate matter within the membranous labyrinth: pathologic or normal?

Recent reports have suggested that particulate matter identified within the membranous portion of the posterior semicircular canal is responsible for the development of positional vertigo. To further investigate this claim, a posterior canal fenestration was carried out in ten patients undergoing acoustic tumor removal via a translabyrinthine approach. Particles were identified in the membranous labyrinth in nine patients. One of these patients described positional vertigo preoperatively. Electron microscopy demonstrated particles within the membranous labyrinth that appeared to be of mixed proteinaceous and mineral content. These data suggest that further studies must be undertaken before the theory of endolymphatic particle migration can be confirmed as the etiology of positional vertigo.

Magnetic resonance examination of the inner ear and cerebellopontine angle in patients with vertigo and/or abnormal findings at vestibular testing

The inner ears of 167 patients with vertigo and/or abnormal findings at vestibular testing were studied using magnetic resonance (MR). Pathology potentially explaining vertigo was found in 54 patients, and was detected in the posterior fossa (28%), the internal auditory canal (28%) and the membranous labyrinth (44%). The overall percentage of pathology and the percentage of pathology found in the membranous labyrinth was high and was probably influenced by the referral pattern in our hospital where high resolution MR of the inner ear (three dimensional Fourier transformation-constructive interference in steady state sequence; 3DFT-CISS sequence) is available. Unenhanced, and especially gadolinium (Gd)-enhanced T1-weighted spin-echo images, are needed to detect most of the pathology inside the internal auditory canal, and some of the lesions inside the membranous labyrinth. 3DFT-CISS images are the only images that can show fibrous obliteration of the intralabyrinthine fluid spaces, and are therefore necessary to recognise most of the intralabyrinthine pathology. Finally, T2-weighted spin-echo images are best suited to demonstrate cerebellar or brain stem infarction. An additional MR-angiography sequence (three dimensional Fourier transformation-fast imaging with steady precession; 3DFT-FISP) is used when vascular compression of the cochleovestibular nerve is suspected. MR is the method of choice to look for pathology in patients with vertigo, and allows detection of pathology that remains invisible with other imaging techniques. However, well adapted sequences are needed to detect these lesions.

Benign paroxysmal positioning vertigo with indeterminate cerebellar lesion: case report

Of the numerous causes of dizziness, those that represent a life-threatening condition are rare. Physicians must guard against missing these rare but serious conditions while controlling the cost of the evaluation of patients who present with dizziness. This case study involving a 41-year-old female was written to illustrate the importance of systematic case history taking and of obtaining an ENG. The patient presented with classic symptoms of benign paroxysmal positioning vertigo (BPPV). The managing physician performed an MRI, which showed a cerebellar lesion. Results of a biopsy were negative. The patient's symptoms persisted, and she travelled to our clinic for further assessment. An ENG demonstrated a classic response to the Dix-Hallpike maneuvers, and a canalith repositioning maneuver was performed. The positioning dizziness resolved, and when contacted several months later, the patient stated she had remained asymptomatic.

Vertigo and the anterior inferior cerebellar artery syndrome

We present two patients with clinical features of infarction in the distribution of the anterior inferior cerebellar artery (AICA) who had vertigo as an isolated symptom for several months prior to infarction. Both had risk factors for cerebrovascular disease and other episodes of transient neurologic symptoms not associated with vertigo. At the time of infarction they developed vertigo, unilateral hearing loss, tinnitus, facial numbness, and hemiataxia. MRI identified hyperintense lesions in the lateral pons and middle cerebellar peduncle on T2-weighted images. Audiometry and electronystagmography documented absent auditory and vestibular function on the affected side. Since the blood supply to the inner ear and the vestibulocochlear nerve arises from AICA, a combination of peripheral and central symptoms and signs is characteristic of the AICA infarction syndrome. The vertigo that preceded infarction may have resulted from transient ischemia to the inner ear or the vestibular nerve.

Free-floating endolymph particles: a new operative finding during posterior semicircular canal occlusion

Most clinicians accept cupulolithiasis as the pathophysiological mechanism underlying benign paroxysmal positional vertigo (BPPV.) According to this theory, a cupular deposit induces a gravitational effect on the posterior canal crista. Posterior semicircular canal occlusion is a new operative procedure for treating incapacitating BPPV. It is postulated that canal occlusion abolishes endolymph movement within the canal, effectively fixing the cupula and rendering it unresponsive to both angular and linear acceleration (gravity). During two recent canal occlusions, abundant "free-floating particles" were identified within the posterior canal endolymph. When changing the position of the canal in the earth vertical plane, these free-floating particles would move under the influence of gravity. The hydrodynamic drag of the particles would induce endolymph movement with cupular displacement leading to the typical response. This finding supports an alternate explanation to cupulolithiasis as the pathophysiological mechanism underlying BPPV.

Cochleovestibular nerve compression syndrome. II. Vestibular nerve histopathology and theory of pathophysiology

The present study was undertaken to systematically examine and characterize pathological changes in vestibular nerve specimens obtained at surgery in patients with symptomatic cochleovestibular nerve compression syndrome (CNCS). Vestibular nerves were obtained in six cases of CNCS and were intermingled with vestibular nerves obtained in cases of Meniere's disease. All of the nerve specimens were coded and reviewed microscopically in a blind-study fashion by the neuropathologist. The vestibular nerves obtained from CNCS cases showed significant endoneurial fibrosis, compared to controls (specimens from patients with Meniere's disease). Based on observations in this study, as well as the clinical symptoms and audiovestibular test findings in these patients, a theory of pathophysiology in CNCS of the cochleovestibular nerve is proposed. The implications of this theory are discussed with respect to the diagnosis of CNCS.

High signal from the otic labyrinth on unenhanced magnetic resonance imaging

High signal from the otic labyrinth was observed on precontrast MR scan of two patients who presented with sudden hearing loss and vertigo. The authors suggest the possibility that the high signal was caused by hemorrhage but that clinical significance and therapeutic implications of this finding need further study.

Prognostic significance of hearing loss as a lateralizing indicator in the surgical treatment of vertigo

In patients with peripheral vertigo the presence of an asymmetrical hearing loss is an important lateralizing sign, having both diagnostic and prognostic significance. In a consecutive series of 83 patients undergoing retro-labyrinthine vestibular nerve section for uncontrolled vertigo, asymmetrical hearing loss was associated with an 83 per cent incidence of complete control of vertigo and a 49 per cent incidence of complete relief from dysequilibrium. In the absence of a lateralizing hearing loss, the figures were 50 per cent and 24 per cent respectively (p less than 0.01 and p less than 0.05). The explanation for this finding may be that the presence of a hearing loss is more often associated with an exclusively peripheral disorder (controllable by peripheral surgical ablation), whereas in patients with symmetrical hearing there may be an unrecognized central or contralateral pathology resulting in less effective results from a unilateral peripheral surgical approach. The bithermal caloric test did not give such useful diagnostic or prognostic information.

Longitudinal followup of patients with Menière's disease

The etiology, pathophysiology, and natural history of Menière's syndrome are poorly understood. The reported studies have had inadequate followup or insufficient numbers of patients to allow conclusions about the natural history. Our study group was 119 patients who had the classic symptom complex of episodic vertigo, tinnitus, and hearing loss in the year 1970. After initial review of these charts, follow-up information was obtained by questionnaire, telephone interview, chart review, or repeat examination, when possible, both in 1983 and in 1988, for a total followup of 18 years. In the patients with followups of at least 14 years, vertiginous episodes had disappeared completely in 50% of patients and somewhat resolved in 28%; hearing was absent in 48% and worse in 21%. Surprisingly, 43% of patients underwent surgery at some point for control of vertigo. Bilateral disease was present initially in 13% and developed subsequently in 45% of patients. Other areas reviewed included the efficacy of long-term medical treatment, frequency and severity of vertiginous attacks, and contralateral ear symptoms.

Pathology of peripheral vestibular disorders in the elderly

A clinical classification of vertigo commonly seen in the elderly and caused by peripheral vestibular disorders is illustrated by case reports and temporal bone histopathology. The classification includes inducible transient vertigo and noninducible protracted vertigo. The peripheral vestibular pathology includes abnormalities of sensory, neural, and mechanical structures and is often asymmetric. The pathogenesis of these disorders is often speculative, but includes degenerative, infectious, neoplastic, and vascular insults to the vestibular labyrinth.

Lermoyez's syndrome: histopathologic report of a case

This paper reports findings in a pair of temporal bones from a patient with clinical evidence of Lermoyez's syndrome, a rare variant of Meniere's disease. Endolymphatic hydrops is limited to the basal turn of the cochlea and saccule in Lermoyez's syndrome, but more generalized in Meniere's disease.

In search of pathologic correlates for hearing loss and vertigo in Paget's disease. A clinical and histopathologic study of 26 temporal bones

Mixed sensorineural and conductive hearing loss is a common clinical manifestation of Paget's disease of the temporal bone, and while there are numerous clinical and pathologic reports on the condition, none have identified a consistent pathologic explanation for the hearing loss. We performed histologic studies on 26 temporal bones exhibiting Paget's disease from 16 persons, of whom 7 had audiometric testing performed. Contrary to common opinion, the conductive hearing loss is not caused by ossicular fixation; in fact, no cause could be found in the seven ears with documented conductive hearing losses. While the sensorineural hearing losses were greater than normal for age, we could not identify cochlear disorders that could be attributed to Paget's disease. It is concluded that the hearing losses in Paget's disease are caused by changes in bone density, mass, and form that serve to dampen the finely tuned motion mechanics of the middle and inner ears.

The pathology of peripheral vestibular disorders in the elderly

We describe a clinical classification of vertigo commonly seen in the elderly and caused by peripheral vestibular disorders. The classification includes inducible transient vertigo and noninducible protracted vertigo. The peripheral vestibular disorder includes abnormalities of sensory, neural, and mechanical structures and is often asymmetric. Determination of the pathogenesis of these disorders is often speculative. Pathogenesis may include degenerative, infectious, neoplastic, and vascular insults to the vestibular labyrinth.

Histopathologic consequences of surgical approaches to the singular nerve

Selective sectioning of the singular nerve has proven successful in the relief of incapacitating benign positional vertigo (BPV), presumably on the histopathologic basis of posterior ampullary cupulolithiasis. Although the surgical techniques of transmeatal and the recently introduced retrosigmoid IAC approach have been well described, little has been written about the singular nerve's anatomical relationships determined histologically for each surgical approach. The anatomical relationships of the singular nerve in both the transmeatal and retrosigmoid IAC approaches are discussed. Histologic evidence presented suggests that other mechanisms may also be ultimately responsible for improvement in the symptoms of BPV following transmeatal surgery. Moreover, the high incidence of injury to the endolymphatic duct during retrosigmoid surgery raises questions about the exact role of the endolymphatic duct and sac in inner ear homeostasis.

[Importance of the general radiograph of the cervical spine in vertigo and pathologic proprioceptive cervical nystagmus]

The general roentgenogram of the cervical spine often shows manifold pathological alterations by patients without any clinical complaints. On the other hand, there are cervical vertigo and different symptoms caused by the cervical spine, its joints, muscles and ligaments without any X-ray manifestation. Nevertheless, some connections are assumed to exist between vertigo and alterations of the cervical spine an assumption supported especially by the frequently successful elimination of cervical troubles by chirotherapy. We compared the X-ray manifestations in patients complaining of vertigo with any and without any pathological proprioceptive cervical nystagmus provoked by examination according to Moser and revealed by electronystagmography. The extended posture of the cervical spine seems to point to a possible cause of vertigo. Likewise, some degenerative alterations seem to exercise a pathological effect, provoking cervical vertigo additionally if both effects are combined. Uncovertebral arthroses seem to have the same effect without occurring in combination with other effects. The general roentgenogram of the cervical spine in the sloping, lateral and anterior-posterior direction may consequently point to some possible causes of cervical vertigo.

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.

Otoconia in health and disease. A review

Mammalian otoconia are made up of inorganic calcium carbonate crystallites and organic substance, which is thought to be sulfated glycosaminoglycans and glycoprotein. Mouse otoconia are formed in situ, and the primitive otoconia assume spindle, trigonal, dumbbell, or quadrilobed forms. As the otoconia mature, they assume the typical barrel-shaped body with pointed tips formed by three surfaces. A variety of otoconial disorders have been reported. Otoconial degeneration can result from ototoxic drugs, infection, trauma, and aging. Abnormal otoconia are also known to occur as a result of genetic mutation, as well as ototoxicity. Otoconial deficiency may be genetic or caused by certain drugs, such as carbonic anhydrase inhibitors or tetracycline, or manganese deficiency during the critical period of gestation when the otoconia are formed in utero. Otoconial deficiency has been found to produce head tilting, swimming difficulty, and reduction or failure of the air-righting reflexes in animals.

Pathology as it relates to ear surgery II. Labyrinthectomy

Five human temporal bones and three surgical VIIIth nerve biopsies from patients who had previously undergone labyrinthectomy, five months to ten years before examination, were studied by light and electron microscopy. Post-labyrinthectomy dizziness could be explained on the bases of inadequate surgical removal of the vestibular sense-organs, neuroma formation in the vestibule, and high regenerative potential of the vestibular nerve. Post-labyrinthectomy pressure sensation and tinnitus are most probably due to cochlear endolymphatic hydrops and need cochlear neurectomy. The severe atrophy in the sensorineural structures of the cochlea was not associated with retrograde degeneration of the cochlear nerve central axons. This may be of significance in the artificial electrical stimulation of the cochlear nerve in deaf patients.

Behavior of the vestibular nerve following labyrinthectomy

Transtympanic labyrinthectomy was performed on 24 cats, and after survival times of one month to three years, the temporal bones were prepared for light microscopic study. The operated ears showed mean neuronal losses of 12% in six months, 24% in 1 year, 35% in 2 years, and 53% in 3 years. These was no evidence of regeneration of vestibular nerve fibers nor of formation of traumatic neuromata. The temporal bones of two human subjects who had undergone transtympanic labyrinthectomy are also presented; one shows atrophy of the vestibular nerves while the other exhibits proliferation of nerve fibers not resembling a neuroma. It is concluded that the afferent vestibular nerves undergo slow but progressive atrophy following labyrinthectomy and that they have no potential for the creation of amputation neuromata. The evidence suggests that excision of the vestibular nerves may have no therapeutic advantage over labyrinthectomy in the treatment of intractable vertigo.

Demyelinating disease as the assumed cause of hearing loss and vertigo. A case report with light- and electron-microscopic findings

A patient initially presenting typical symptoms of idiopathic sudden deafness later developed disabling episodic vertigo, which led to translabyrinthine eighth nerve transection. Morphological examination of the removed cochlear nerve specimen revealed a demyelinating process in the neuroglial portion of the nerve. The major part of the peripheral, neurolemmal portion of the cochlear nerve was normal. The inferior vestibular nerve was fibrotic. The major part of the superior vestibular nerve was normal. Some of its peripheral bundles showed increased endoneurial fibrosis. It is suggested that a demyelinating process was the cause of the patient's symptoms.

Electron microscopic observations of the utricle and ampullae in a case of dizziness of suspected saccular origin

Electron microscopic observation was reported on the utricle and ampullae of a case, a 36-year-old male, with dizziness attack due to suspected saccular origin. After the removal of the utricle and ampullae, the dizziness recurred, and finally the saccular nerve section relieved the dizziness attack of this case. So the actual lesion was localized in the saccule and was not in the specimens obtained at the first surgery. Though most of hair cells appeared normal, there were a few with many vacuoles or shrinkage of the cytoplasm distributing sparsely throughout the sensory epithelia. The distribution of the pathological hair cells in the utricle was more general than in the ampullae. The sensory hair cells without pathology and the presynaptic structures were similar to those found in the experimental animals. Nerve and nerve endings showed normal structures. The findings may be physiological at this age group or an extension of the pathology of the dizziness-causing lesion.