Otoneurological expert system for vertigo.

We have developed an otoneurological expert system (ONE) to aid the diagnostics of vertigo, to assist teaching and to implement a database for research. The ONE database is set to harvest data on patient history, signs and test results necessary for diagnostic work with vertiginous patients. A method based on pattern recognition was used in the reasoning process. Questions about symptoms, signs and test results are weighted and scored for each disease and the most likely disease is recognized from defined disease profiles. Missing information and uncertainties are solved with a method resembling fuzzy logic. ONE was validated by comparing diagnoses assessed by physicians with those provided by the system. It proved to be a valid decision-maker by solving 65% of the cases correctly, while the physicians' mean was 69%. To improve ONE further, a follow-up should be implemented for the patients, since diagnosing sudden deafness and Meniere's disease during the first visit is often impossible. We aim to obtain new information on diseases involving vertigo by applying adaptive computer applications, such as genetic algorithms, to the reasoning process.     

Experiences of otoneurological expert system for vertigo

We have developed an OtoNeurological Expert system (ONE) to aid the diagnostics of vertigo, to assist teaching and to implement the database for research. The database contains detailed information on the patient history, signs and test results necessary for the diagnostic work with vertiginous patients. The pattern recognition method was used in the reasoning process. Questions regarding symptoms, signs and test results are weighted and scored for each disease, and the most likely disease is recognized from the defined disease profiles. Uncertainties in reasoning, caused by missing information, were solved with a method resembling fuzzy logic. We have also applied adaptive computer applications, such as genetic algorithms and decision trees, in the reasoning process. In the validation the expert system ONE proved to be a sound decision maker, by solving 65% of the cases correctly, while the physicians' mean was 69%. To improve the expert system ONE further, a follow-up should be implemented for the patients, to ease the diagnostic work of some difficult diseases. The six diseases were detected with high accuracy also with adaptive learning methods and discriminant analysis. An expert system is a practical tool in otoneurology. We aim to construct a hybrid program for the reasoning, where the best reasoning method for each disease is used.     

Discovering diagnostic rules from a neurotologic database with genetic algorithms.

Data on patients with Meniere's disease, vestibular schwannoma, traumatic vertigo, sudden deafness, benign paroxysmal positional vertigo, or vestibular neuritis were retrieved from the database of otoneurologic expert system ONE for the development and testing of a genetic algorithm (GA). The accuracy of the diagnostic rules in solving the test cases was 81%, 91%, 92%, 95%, 96%, and 98% for the respective diseases. The best rules retrieved from the GA were described by a set of questions with the most likely answers. The most important questions concerned the duration of hearing loss and the occurrence of head injury. The validity and structure of the rules created with a GA can be analyzed in detail. For rare diseases, some other reasoning process can be used, for example, case-based reasoning.     

Production of diagnostic rules from a neurotologic database with decision trees

A decision tree is an artificial intelligence program that is adaptive and is closely related to a neural network, but can handle missing or nondecisive data in decision-making. Data on patients with Meniere's disease, vestibular schwannoma, traumatic vertigo, sudden deafness, benign paroxysmal positional vertigo, and vestibular neuritis were retrieved from the database of the otoneurologic expert system ONE for the development and testing of the accuracy of decision trees in the diagnostic workup. Decision trees were constructed separately for each disease. The accuracies of the best decision trees were 94%, 95%, 99%, 99%, 100%, and 100% for the respective diseases. The most important questions concerned the presence of vertigo, hearing loss, and tinnitus; duration of vertigo; frequency of vertigo attacks; severity of rotational vertigo; onset and type of hearing loss; and occurrence of head injury in relation to the timing of onset of vertigo. Meniere's disease was the most difficult to classify correctly. The validity and structure of the decision trees are easily comprehended and can be used outside the expert system.     

Clinical picture of vestibular schwannoma

PURPOSE: To characterize the clinical picture with vestibular schwannoma, we retrieved 122 patients with vestibular schwannoma from the vestibular unit of the Helsinki University Central Hospital. PROCEDURES: The patients filled out a questionnaire concerning their symptoms, earlier diseases, accidents, and the use of tobacco and alcohol. This information was then completed with results of audiometric, neurotologic and imaging studies. The data were prospectively stored to the database of neurotologic expert system called ONE. RESULTS: The average tumor size was 21 mm. Most of the patients had hearing loss (94%) and tinnitus (83%) but only half of them (49%) had vertigo attacks. The most common initial symptom was hearing loss combined with tinnitus (34%, n=44). Vertigo only was the initial symptom for 12 patients. The mean duration of a vertigo attack was from 5 min to 4 h and the intensity of the attack was regularly mild (37%) or moderate (32%). The vertigo of the vestibular schwannoma patients differed from vertigo in other diseases by the absence (63%) or low intensity (18%) of nausea. Spontaneous nystagmus was present in 56 patients (46%), and caloric asymmetry (>25%) was observed in 66% (n=69). Caloric asymmetry increased with tumor size. The prevalence of headache was 18% (n=21). Sudden slips seldom (7%) occurred. CONCLUSION: Hearing loss and tinnitus are the main symptoms of vestibular schwannoma. Only half of patients have vertigo. Screening to detect vestibular schwannoma is more yielding in sudden deafness patients rather than in patients with Meniere's disease.     

Postural Control and Glycerol Test in Me´nie`re's Disease

Ménière's disease is a clinical disorder, characterized by fluctuating hearing loss, recurrent spontaneous episodic vertigo, tinnitus and aural fullness, which may be defined as the idiopathic syndrome of endolymphatic hydrops. The most important test for diagnosis of Ménière's disease is the glycerol test. This is a simple and rapid method and several authors have confirmed its efficiency for identifying endolymphatic hydrops. This test provides information on the cochlear response to the osmotic changes produced by glycerol in the inner ear, whereas modifications in the vestibular labyrinth are usually not evaluated. The aim of this study was to evaluate the effects of glycerol on postural control during attacks of Ménière's disease, and to correlate this data with data on cochlear function. After the glycerol test, an improvement in postural control was recorded in 70% of patients, with all patients reporting a recovery of vertigo. The impairment of postural control during endolymphatic hydrops could be related to a pressure increase in the labyrinth, which interferes with the normal dynamics of the endolymph, and a rapid functional recovery could occur during an osmotic depletion. Dynamic posturography improves the sensitivity of the glycerol test and may therefore be useful in the diagnosis and staging of Me´nie &#164 re's disease.     

Recurrent vestibulopathy

Recurrent vestibulopathy is defined as an illness of unknown cause characterized by more than a single episode of vertigo of duration characteristic of that occurring with hy-drops but without auditory or clinical neurological symptoms or signs. Eighty-six patients with this condition were diagnosed in the Dizziness Unit, and data on age and sex distribution, natural history and caloric pattern are presented. On follow-up of mean duration 3.5 years, 6 cases evolved to classic Ménière's disease, and 4 to benign positional vertigo, but none developed brain disease. The prognosis regarding vertigo is generally good. We consider the term recurrent vestibulopathy a logical designation of a distinctive clinical disorder with unknown cause but with probable peripheral vestibular origin, and hope that its use would spur research into previously unrecognized causes of recurrent vertigo.     

Relevance of function tests in the diagnosis of vestibular disorders

The diagnostic value or relevance of a vestibular function test is dependent on the whole clinical and functional context of each particular case. It is not the ability to show‘abnormality’in a high number of patients complaining of whatever kind of vertigo, that indicates the relevance of a function test. Neither is relevance of a test based upon the possibility that this test can re-categorize some patients in the same way as has been done by other tests. Each test evaluates some particular functional aspect and this is very different from one test to another. A test is more relevant, i. e. indicates more abnormality when the type of vertigo caused by the dysfunction is also considered. These statements are confirmed by experience in peripheral vestibular disorders, especially benign paroxysmal positional vertigo (BPPV). A paroxysmal positional nystagmus (ppn) (nystagmus and vertigo elicited by movements and manoeuvres) is linked to the problem of provoked vertigo and gives a confirmation of this vertigo by reproducing it in some manoeuvres. Some inconstancy in the reproduction of this ppn may cause difficulties in diagnosis. Caloric tests are the clue for diagnosis of sudden unilateral loss (so-called neuronitis), whereas they give only complementary information for patients with BPPV. Posturography adds information in all categories concerning the standing position and can be interesting in the scope of rehabilitation treatment. The findings of a retrospective study in patients with BPPV (n= 95), compared with patients with Ménière's disease (n= 89) and others with sudden unilateral loss syndrome (n= 48), illustrate these concepts.     

继发性后半规管良性阵发性位置性眩晕的诊治

目的 探讨继发性良性阵发性位置性眩晕(BPPV)的诊断和治疗。方法研究继发性后半规管BPPV的内耳疾病6例病历资料,诊断依据为病史及Dix-Hallpike试验诱导出现的眼震结果。结果 6例内耳疾病(分别为突发性聋3例, 梅尼埃病2例, 前庭神经元炎1例)伴有后半规管良性阵发性位置性眩晕被确诊,通过Dix-Hallpike试验诱发出垂直扭转型眼震。结论 继发性BPPV临床较少见,常为后半规管受累,通过Dix-Hallpike试验和Epley手法复位可以确诊和治愈。     

Ménière's--an inner ear seizure.

Data of 27 signs, symptoms or findings were collected on 125 confirmed cases of Meniere's disease. Statistical association, plus the percentage prevalence of these findings were studied to perform a cluster analysis. These findings were used to obtain a statistical picture of the disease in terms of the recorded variable (signs, symptoms and findings). The major finding was the existence of a group of variables (a central core) of high percentage occurrence. They consisted of intermittent rotational vertigo, intermittent to constant nerve hearing impairment, tinnitus, pressure in the ears, positional vertigo, nausea, abnormal caloric nystagmus, headache and normal laterotorsion. The first four are the classic criteria of Meniere's disease, the remainder are additions. The average patient had 8 of the 9 conditions; 44% had all 9. A graphic multi-factor analysis of the signs, symptoms and findings suggests that these patients had a disease of a specific central origin. An alternative suggestion is that of several closely related diseases arising from adjacent central locations. No indication was found that influenza, hypertension, arteriosclerosis or diabetes were consistent precursors of Meniere's disease. Spontaneous, positional, gaze and optokinetic (tracking) nystagmus showed no demonstrable relationship to the Meniere's signs and symptoms. They showed the ordinary population prevalence except for spontaneous nystagmus which was slightly higher. The possibility of using these associations as a guide for correlation of the disease manifestations with neuroatomic tracts and areas is suggested.     

Results of Vestibular Autorotation Testing at the End of Intratympanic Gentamicin Treatment for Méniére's Disease

Objective--The vestibular autorotation test (VAT) examines the ocular response to voluntary horizontal and vertical head movements at frequencies for which the vestibular system is the main source for eye stabilization. The purpose of this study was to analyse the VAT results in patients with disabling Méniére's disease and to evaluate the change in VAT values once treatment with intratympanic gentamicin had terminated and clinical signs of vestibular hypofunction could be observed. Material and methods--The 30 study subjects were patients diagnosed with definitive unilateral Méniére's disease that could not be controlled with medication. The vestibulo-ocular reflexes of each patient were evaluated by means of the VAT before the first injection of gentamicin and after the last injection. Results--The pattern of abnormalities found in this population conformed to the selection criteria and the findings reflected a severe disabling process, with major modifications in the vestibulo-ocular reflex. At the end of treatment there was a reduction in the peak frequency of head oscillation. Furthermore, we commonly found that, in the horizontal VAT, gain and phase were reduced while in the vertical VAT some subjects registered a normal response. The phase in the horizontal and vertical VATs was most significantly reduced for oscillation frequencies of 2-3.7 Hz. Conclusion--This study provides further evidence that effective control of vertigo in patients with Méniére's disease can be achieved by administering intratympanic gentamicin.     

Is recurrent loss of low frequency tone perception--without vertigo--a precursor of Meniere disease?

PURPOSE: Recurrent low-frequency sensory hearing loss is one characteristic sign of Meniere's disease. It is therefore often assumed to be a prodromal sign of Meniere's disease. METHODS: We report on 81 patients with recurrent low-frequency sensory hearing loss who did not previously suffer from vertigo. All patients underwent a follow-up examination after at least 1 year up to more than 10 years after the onset of the disease [average: 64.65 months (SD 56.33)]. CONCLUSIONS: Only 3.7% of these patients developed the typical signs of Meniere's disease with labyrinthine vertigo, whereas 25.9% suffered from recurrent hearing loss and an unspecific vertigo, which could be diagnosed and treated as psychogenic vertigo; 3.7% showed a typical benign positional vertigo. We can thus conclude that although almost every patient with Meniere's disease suffers from recurrent hearing loss, only a few patients with recurrent hearing loss will develop Meniere's disease. However, many patients with low-frequency sensory hearing loss develop anxiety and psychogenic dizziness in expectation of "imminent" Meniere's disease. Therefore, it is important to counsel the patients carefully that the probability of this occurring is not very high.     

Rezidivierende Tiefton-Hörverluste ohne Schwindel – ein eigenes Krankheitsbild?

Background

Besides the typical attacks of dizziness, recurrent low-frequency sensory hearing loss—together with mostly low-frequency tinnitus—is also a characteristic sign of Menière’s disease. It is therefore often assumed to be a prodromal sign of Menière’s disease, even without dizziness.

Methods

During our longitudinal study, which was started in 1995, we reported that there were 81 patients with recurrent low-frequency hearing loss with no initial vertigo in the first suspense year of 1999. After a further 6 years, we investigated 46 (57%) of these original 81 patients in the second suspense year, 2005, for new components of vertigo, with the questions of development of Menière’s disease and further development of the patients’ hearing ability and psychic situation in mind.

Results

In all, 12 (26%) of the 81 former patients suffered from vertigo, but only 4 (9%) had developed the typical signs of full-blown Menière’s disease with the typical labyrinthine vertigo. Of the 12 patients who suffered from vertigo, 6 (13% of the 81 with vertigo) were diagnosed with psychogenic vertigo, 1 (1%) suffered from benign and treatable paroxysmal positional vertigo and 1 (1%) had developed vertigo after acoustic neurinoma surgery.

Conclusions

We conclude from our observations that, although almost every patient with Menière’s disease suffers from recurrent low-frequency hearing loss, only a few patients with recurrent hearing loss develop Menière’s disease. However, many patients with low-frequency sensory hearing loss develop anxiety leading to psychogenic dizziness in fearful expectation of “imminent” Menière’s disease. We found that26% of the patients had persisting bilateral normacusis in the low-frequency ranges, while 34% had unilateral hearing loss that was sufficiently severe to affect their lives and 39%, bilateral hearing loss; however, none of the patients became completely deaf.     

半规管阻塞技术的初步临床应用

目的初步探讨临床应用半规管阻塞技术治疗位置性眩晕与梅尼埃病的安全性与有效性。方法回顾性分析1994-2000年间半规管阻塞技术临床应用的资料,其中,后半规管位置性眩晕2例,水平半规管位置性眩晕1例,内淋巴囊阻塞术后5年复发的梅尼埃病1例,男1例,女3例,年龄39-58岁。梅尼埃病患者行三半规管阻塞及内淋巴乳突腔分流术,位置性眩晕患者行相应的半规管阻塞术。结果位置性眩晕患者术后随访1.5-7年,全部患者位置性眩晕得到解除,术后纯音测听、中耳功能分析、听觉脑干电反应测试、耳声发射等听觉功能检查结果显示耳蜗功能与术前完全一致,水平半规管阻塞的患者双耳冷热试验结果显示手术消除了水平半规管的功能,后半规管阻塞的患者双耳冷热试验结果显示手术后以水平半规管为代表的其它前庭末梢器官的功能得到良好的保存。内淋巴囊阻塞术后5年复发的梅尼埃病患者术后随访2年,眩晕得到完全控制。结论半规管阻塞技术可有效控制位置性眩晕与梅尼埃病患者的眩晕,半规管阻塞对患者耳蜗功能及所阻塞半规管以外的其它前庭末梢器官功能没有影响,半规管阻塞技术可望成为位置性眩晕和梅尼埃病安全、有效的治疗手段,符合现代外科学对手术微创的要求。     

Postural control and glycerol test in Ménière's disease.

Ménière's disease is a clinical disorder, characterized by fluctuating hearing loss, recurrent spontaneous episodic vertigo, tinnitus and aural fullness, which may be defined as the idiopathic syndrome of endolymphatic hydrops. The most important test for diagnosis of Ménière's disease is the glycerol test. This is a simple and rapid method and several authors have confirmed its efficiency for identifying endolymphatic hydrops. This test provides information on the cochlear response to the osmotic changes produced by glycerol in the inner ear, whereas modifications in the vestibular labyrinth are usually not evaluated. The aim of this study was to evaluate the effects of glycerol on postural control during attacks of Ménière's disease, and to correlate this data with data on cochlear function. After the glycerol test, an improvement in postural control was recorded in 70% of patients, with all patients reporting a recovery of vertigo. The impairment of postural control during endolymphatic hydrops could be related to a pressure increase in the labyrinth, which interferes with the normal dynamics of the endolymph, and a rapid functional recovery could occur during an osmotic depletion. Dynamic posturography improves the sensitivity of the glycerol test and may therefore be useful in the diagnosis and staging of Ménière's disease.     

Effect of edaravone on acute brainstem–cerebellar infarction with vertigo and sudden hearing loss

We report 2 cases with acute brainstem and brainstem–cerebellar infarction showed improvement of their signs and symptoms after administration of edaravone. Case 1, a 74-year-old woman who experienced sudden vertigo, also had dysarthria and left hemiplegia. Magnetic resonance imaging (MRI) showed an abnormal region in the right ventrolateral medulla oblongata. The patient's vertigo and hemiplegia improved completely after treatment. Case 2, a 50-year-old man who experienced sudden vertigo and sensorineural hearing loss (SNHL), developed dysarthria after admission. MRI revealed acute infarction in the right cerebellar hemisphere. Magnetic resonance angiography revealed dissection of the basilar artery and occlusion of the right anterior inferior cerebellar artery. The patient's vertigo and hearing remarkably improved. We have described 2 patients whose early symptoms were vertigo and sudden SNHL, but who were later shown to have ischemic lesions of the central nervous system. Edaravone is neuroprotective drug with free radical-scavenging actions. Free radicals in the ear are responsible for ischemic damage. Edaravone, a free radical scavenger, may be useful in the treatment of vertigo and SNHL.     

Isolated directional preponderance of caloric nystagmus: I. Clinical significance

OBJECTIVES: To determine the clinical significance of an isolated directional preponderance (DP) on bithermal caloric testing. An isolated caloric DP was defined as a DP, calculated according to the standard Jongkees formula, of > or = 40%, with a spontaneous nystagmus (SN) in darkness of < or = 2 degrees/s and a canal paresis (unilateral weakness) of < or = 25%. STUDY DESIGN: A retrospective analysis of all 15,542 bithermal caloric tests performed in the authors' department in the previous 10 years to identify all tests with an isolated DP of > or = 40%. This was followed by a review of the clinical data on the 144 patients identified with such a result and then by a telephone or postal follow-up study of these patients. The study group eventually comprised 114 patients; these were patients in whom a clinical diagnosis could be made at the time the caloric test was done, or who responded to requests for follow-up information. The 34 patients in whom a clinical diagnosis could not be made at the time of the caloric test, and who did not respond to requests for follow-up information, were excluded. STUDY SETTING: A balance disorders clinic in a tertiary referral hospital. INTERVENTION: All patients underwent standard bithermal caloric testing. Some of the patients also underwent rotational testing. OUTCOME MEASURES: A clinical diagnosis for the cause of the isolated DP, made either at the time of the caloric test or on the basis of information supplied at follow-up by the patient or by the referring physician. RESULTS: Of 114 patients, 39 had benign paroxysmal positioning vertigo, 14 had Ménière's disease, and 5 had migrainous vertigo. Five patients had central nervous system (CNS) disorders, and this was clinically apparent at the time of the caloric test in 4, so that only 1 patient with an isolated DP developed evidence of a CNS disorder after the caloric test was done. In the other 54 patients, no definite diagnosis could be made, but 41 of these 54 were either completely well or much better at follow-up. CONCLUSIONS: An isolated DP on caloric testing is usually a transient, benign disorder. About half the patients with an isolated DP have either Ménière's disease or benign paroxysmal positioning vertigo; in most of the other half, no definite diagnosis is made but most of these patients will do well. Only approximately 5% have a CNS lesion and in almost all this is apparent at the time the caloric test is done. In a relapsing-remitting peripheral vestibular disorder such as benign paroxysmal positioning vertigo or Ménière's disease, the mechanism of an isolated DP could be enhanced dynamic gain of ipsilesional medial vestibular nucleus neurons, perhaps as a result of intermittent hyperfunction of primary semicircular canal vestibular afferents. The authors postulate that an isolated DP reflects a gain asymmetry between neurons in the medial vestibular nucleus on either side, caused either by increased sensitivity on one side or by reduced sensitivity on the other, perhaps as an adaptive change in response to abnormal input. In an accompanying article, the authors implement a realistic neural network model in which it is possible to simulate an isolated DP by adjusting the dynamic sensitivity of type 1 medial vestibular nucleus neurons on one side or of type 2 medial vestibular nucleus neurons on the other.     

Diagnosis of common causes of vertigo using a structured clinical history

The structured clinical history is the most sensitive test for diagnosing vertigo. Its diagnostic effectiveness on the first visit was analyzed and key signs and symptoms with high predictive value for common causes of vertigo were identified. One hundred outpatients who complained of dizziness or loss of balance were evaluated using a structured clinical interview. Each questionnaire was examined independently by three blinded investigators, who assigned a diagnosis and identified the elements of the history that figured most prominently in the diagnosis. The gold standard was defined as independent selection of the same diagnostic category by all three investigators. A first-visit diagnosis was obtained in 40% of patients (95% confidence interval 30-50%): 38% women and 42% men. Causes included benign positional paroxysmal vertigo (BPPV, 13 patients), headache-associated vertigo (9), Meniere disease (7), cervical vertigo (3), psychiatric dizziness (2), post-traumatic vertigo (2), vertebro-basilar transient ischemic attack (1), vestibular neuritis (1), convulsive seizure (1), and presyncope (1). The best predictors of BPPV were the precipitating mechanism (specificity [SP] 100%), positional nystagmus (sensitivity [SE] 90%, SP 63%), and the Dix-Hallpike test (SE 82%, SP 71%). Elements predictive of headache-associated vertigo were duration of the attack (minutes) and a personal history of headache (both, SP 100%). Other predictors were facial hypoesthesia (SE 92%, SP 47%) and associated neurological disease (SE 82%, SP 58%).     

Concordance and discordance in patient and provider perceptions of dizziness

PurposeThe purpose of the present investigation was to determine whether there are significant differences in patient/healthcare provider perceptions of patient's dizziness severity, dizziness disability/handicap, anxiety, and signs of autonomic system activation.Materials and methodsThis was a prospective investigation of 30 patient–provider dyads drawn as a sample of convenience from an otology clinic in a large, tertiary care, medical center. Patients completed both the Dizziness Handicap Inventory (DHI) and the Vestibular Symptom Scale (VSS) prior to vestibular function testing. Providers were instructed to complete the same measures following the patient's clinic visit from what they estimated was the patient's point of view. The two measures were analyzed for concordance and discordance.ResultsPatient/provider differences in DHI and VSS vertigo subscale scores were not significantly different. However, difference scores on the VSS anxiety/autonomic subscale indicated that providers significantly under-estimated patient anxiety and symptoms of autonomic system activation.ConclusionsThe results suggest that providers may be missing information pertinent to the role anxiety and autonomic system activation may play in patient visits for complaints of dizziness. We suggest that this problem can be mitigated by administrating to patients prior to their clinic visit a standardized measure that quantifies patient self-report dizziness, vertigo, anxiety and autonomic system arousal. Patterns of response by patients on these measures can enable providers to diagnose correctly dizziness disorders that are rooted in clinically significant anxiety either related to, or unrelated to, a history of vestibular system impairment.