Cerebellar-pontine angle tumors. Results of quantitative vestibulo-ocular testing.

A new quantitative vestibulo-ocular test battery was evaluated in 12 patients with surgically confirmed cerebellar-pontine angle tumors. The battery consisted of precise vestibular and visual stimuli and digital computer analyses of responses. Eleven of 12 patients, including all patients with acoustic neurolemmomas, had significant vestibular deficits on the tumor side (P less than .01). Contrary to previous reports, rotatory tests (impulse and sinusoidal acceleration) reliably identified the side and magnitude of vestibular deficit. Eight of nine patients with surgically confirmed brain stem compression had significantly impaired smooth pursuit (P less than .05). Optokinetic nystagmus was impaired in five of nine patients with brain stem compression (P less than .05). By combining the results of the entire test battery with standard clinical evaluation, a good prediction of tumor size, location, and type was possible.

Vestibulo-ocular function in patients with cerebellar atrophy.

Eye movement abnormalities were quantiatively assessed in four patients with clinically pure cerebellar atrophy (group A), six patients with brainstem plus cerebellar atrophy (group B), and five patients with Friedreich's ataxia (group C). Twelve patients had one or more types of spontaneous nystagmus; eight gaze nystagmus, three rebound nystagmus, wo positional nystagmus, and one vestibular nystagmus. Catoric-induced and rotatory-induced nystagmus was hyperactive in group A and diminished in group C. Group B had mixed responses. All patients demonstrated significant fixation instability and impaired smooth pursuit. There was dysmetria of voluntary saccades, with flutter and "rebound" saccades. Nine of 15 patients had significant slowing of induced saccades, including two patients in group A. It is concluded that quantitative vestibulocular tests can be useful in classifying the cerebellar atrophy syndromes.

The saccade velocity test.

Scatter plots showing the amplitude versus velocity (maximum and average) relationship of horizontal saccades in 25 normal subjects and four groups of patients were statistically compared. Three patients with "subclinical" medial longitudinal fasciculus syndromes had significant slowing of adducting saccades, and two of these patients had unsuspected slowing of abducting saccades (although to a lesser degree). Five patients with olivopontocerebellar degeneration and three patients with myotonic dystrophy had significant slowing of saccades in both directions. Five patients with surgically documented acoustic neuromas did not have significant slowing despite brain-stem compression in three. It is concluded that the saccade velocity test can be a useful clinical tool in addition to its potential in clinical research.

Age-related changes in levels of tyrosine kinase B receptor and fibroblast growth factor receptor 2 in the rat inferior colliculus: implications for neural senescence.

Brain-derived neurotrophic factor and fibroblast growth factor 2, and their respective binding sites, tyrosine kinase B receptor and fibroblast growth factor receptor 2, are known to regulate neurite outgrowth and antioxidant enzyme activity. Several studies suggest that brain-derived neurotrophic factor and fibroblast growth factor are contained in the inferior colliculus. Previous work in our laboratories revealed dendritic and synaptic losses in the inferior colliculus of aged Fischer-344 rats, along with coincident increases in lipid peroxidation possibly linked to a decrease in activity of antioxidant enzymes. In an effort to identify potential causal mechanisms underlying age-related synaptic and dendritic losses that occur in the inferior colliculus, the present study attempted to determine if inferior colliculus levels of tyrosine kinase B receptor and fibroblast growth factor receptor 2 expression are altered with age. Immunocytochemistry was performed in the inferior colliculus, hippocampus and cerebellum of 3-month-old F344 rats to study distributions of the full-length and truncated isoforms of tyrosine kinase B receptor, and fibroblast growth factor receptor 2. The latter two brain regions served as positive controls. For all three antigens, immunolabeling was localized primarily in somata and proximal dendrites in all subdivisions of the inferior colliculus, and in the dentate gyrus and Ammon's horn of the hippocampus. In the cerebellum, the somata and dendrites of the Purkinje cells were also immunolabeled.A significant reduction in levels of the full-length form of tyrosine kinase B receptor in 18- and 25-month-old rats (respectively, approximately 20% and 30% relative to 3-month-olds) was revealed using western blot analyses. Inferior colliculus and hippocampal levels of the truncated form were modestly decreased ( approximately 7%) as well in the two older age groups. In contrast, levels of fibroblast growth factor receptor 2 in the inferior colliculus and hippocampus were elevated by approximately 35% in the two older age groups when compared to 3-month-olds. Changes in cerebellar levels of tyrosine kinase B receptor and fibroblast growth factor receptor 2, while similar to those in the inferior colliculus and hippocampus among the age groups, did not achieve statistical significance in this study. These findings give rise to the possibility that age-related reductions in tyrosine kinase B receptor levels could be a causal factor in the degenerative changes observed in the inferior colliculus of aged animals, including mitochondrial damage and dendritic regression. The observed increases in fibroblast growth factor receptor 2 levels may be compensatory to the increased oxidative stress. The effectiveness of the fibroblast growth factor receptor 2 response is questionable given the damage that occurs in the inferior colliculus and hippocampus of aged animals. However, the deficits could worsen in the absence of an increase in fibroblast growth factor receptor 2.

Hyperbaric oxygen therapy for necrotizing fasciitis reduces mortality and the need for debridements.

Twenty-nine patients with necrotizing fasciitis were treated from 1980 to 1988. This study evaluates how the addition of hyperbaric oxygen (HBO) therapy to surgical treatment has affected mortality and the number of debridements required to achieve wound control in these patients. Two groups of patients were viewed: group 1 (n = 12) received surgical debridement and antibiotics only; group 2 (n = 17) received HBO (90 minutes at 2.5 atm, average 7.4 treatments) in addition to surgery and antibiotics. Both groups were similar in age, race, sex, wound bacteriology, and antimicrobial therapy. Body surface area affected was similar, however, perineal involvement was more common in group 2 (53%) than in group 1 (12%). The admitting conditions of patients in group 1 (non-HBO) were diabetic, 33%; white blood cell count more than 12,000, 50%; and shock, 8%. The admitting conditions of patients in group 2 (HBO) were diabetic, 47%; white blood cell count more than 12,000, 59%; and shock, 29%. Although group 2 patients receiving HBO were more seriously ill on admission, mortality was significantly lower (23%) compared to group 1 (66%) (p less than 0.02). In addition, only 1.2 debridements per group 2 patient were required to achieve wound control versus 3.3 debridements per group 1 patient (p less than 0.03). The addition of HBO therapy to the surgical and antimicrobial treatment of necrotizing fasciitis significantly reduced mortality and wound morbidity (number of debridements) in this study, especially among nonclostridial infections. We conclude that HBO should be used routinely in the treatment of necrotizing fasciitis.

Age-related changes in [3H]strychnine binding in the vestibular nuclei of rats.

Glycine plays an important role as a neurotransmitter in the four vestibular nuclei (VN). The objective of this study was to determine if the levels of glycine-receptor binding in the VN change as a function of age. Quantitative receptor autoradiography was performed on brainstem sections from three age groups (3, 18 and 26 months) of Fischer 344 rats to assess binding in the VN. Glycine receptors were localized using [3H]strychnine binding. Strychnine binding declined monotonically with increasing age, such that the level of strychnine binding in each of the VN in the 28-month-old animals was approximately one-half that in the 3-month-olds. The age-related decrease in levels of strychnine binding suggest altered glycinergic function in the VN, which may in turn contribute to disturbances in equilibrium observed in the elderly.

Clinical application of saccade-reflex testing in man.

Computer-aided measurements of saccade-reflex reaction times, velocities, and accuracies have become important tools in the detection of central nervous system pathology. Because of improved knowledge of the reflex pathways in man, saccade testing can assist in differentiating between brain stem, cerebellar, or cerebral disorders and point toward unilateral lesions. Saccade-reflex testing is also useful in determining disability and measuring over time the course of central nervous system disorders. Further work, correlating lesions observed by high-resolution imaging techniques with abnormalities in reflexes, continues to improve the understanding of saccade mechanisms in man. Specific cases are used to show the effects of anatomic lesions on changes in saccade reflexes. The results from 100 consecutive patients evaluated for dizziness are provided in order to illustrate the prevalence of saccade abnormalities and the relationship between abnormalities in vestibular and slow and fast eye-movement reflexes. Patients complaining of disequilibrium and visual disturbances frequently have abnormalities in the saccade system, abnormalities which are often overlooked in present clinical testing of the dizzy patient.

Transpalatal approach to deeper cranial structures.

The approach to deep midline cranial structures is technically difficult. The transpalatal approach has a relatively wide exposure as compared to the transnasal, transantral and transethmoidal approches. The added advantage of a medial approach which follows medial landmarks and the flexibility of being able to extend exposure to the maxillary sinuses and pterygomaxillary space makes this an attractive approach for large lesions in the nasal passages, nasopharynx and sphenoid sinuses. Large mucoperiosteal flaps, care to avoid the palatine vessels, and application of palatal splint postoperatively, minimize complications and patient discomfort. The authors have used this approach to repair nasopharyngeal atresia, remove nasopharyngeal angiofibromas, approach the pituitary, craniopharyngioma and isolated sphenoid sinus opacification as well as sphenoid sinusitis with cavernous sinus thrombosis.

Balance and aging.

OBJECTIVES/HYPOTHESIS: To provide a basic science and clinical review of normal balance changes with age, and to provide a current review for the evaluation and treatment of elderly patients with balance disorders. As we age, we lose balance function through loss of sensory elements, the ability to integrate information and issue motor commands, and because we lose musculoskeletal function. Diseases common in aging populations lead to further deterioration in balance function in some patients. Treatment of balance dysfunction in aging populations is based on the knowledge of normal aging processes and on an evaluation of the individual's balance loss and remaining balance elements. Prevention and rehabilitation play a major role in treatment; medical and surgical therapy also have a place. STUDY DESIGN AND METHODS: Review of literature, personal research and observations. RESULTS AND CONCLUSIONS: Although older patients may be subject to most of the common balance disorders of younger patients, they have more problems with chronic disequilibrium and falls. Prevention and rehabilitation play an important role in treating these patients.

Simultaneous auditory stimuli shorten saccade latencies.

Eye movement responses induced by vestibular, smooth pursuit, and optokinetic stimulation are largely dependent on the velocity of the stimulus. Saccade latencies, on the other hand, are a function of the anatomic and physiologic components of the reflex. By producing an audible click simultaneously with the movement of a visual target used to stimulate a saccadic eye movement, the saccade latency is significantly shortened. This does not appear to be due to alerting. It is probably due to an auditory input to the superior colliculus which decreased threshold for initiating a saccadic eye movement. Twenty normal participants were tested with or without the click stimulus. Latencies were significantly shorter when the click stimulus was presented simultaneously with the eye movement. The anatomic pathways in this reflex are reviewed in the presentation. This study provides further information on sensory interaction in saccade reflexes and emphasizes the need to control stimulus conditions during saccade testing.

Predicting fall risks in an elderly population: computer dynamic posturography versus electronystagmography test results.

OBJECTIVES/HYPOTHESIS: Falls are the leading cause of morbidity and mortality for persons aged 65 years and older, with more than 2 million people falling and sustaining serious injury annually. This study compared computer dynamic posturography (CDP) and electronystagmography (ENG) results as predictors of falls. STUDY DESIGN: Retrospective. METHODS: Thirty-three patients over the age of 65 years who presented to a balance disorders and falls prevention clinic were used for this study (22 women and 11 men, with an average age of 78.0 y and a mean fall rate of 3.5 times). All had experienced at least one fall in the year before visiting the clinic and were tested with both CDP and ENG. The CDP results were divided into subcategories (sensory organization testing and limits of stability); ENG results were divided into four categories (ocular motor, rotational chair, positional, and caloric studies). RESULTS: Test findings were classified as normal or abnormal based on age-matched normative data. Of the patients in the study, 27.3% were normal for one type of testing and abnormal for the other. Twenty-six patients (78.8%) had abnormal results on CDP, and 20 individuals (60.6%) showed ENG abnormalities (42.4% for ocular motor, 28.6% for positional, 13.6% for caloric, and 11.2% for rotational chair studies). The limits of stability category was significant in predicting multiple falls. CONCLUSION: For this population, CDP was determined to be a more sensitive test for identifying patients who have fallen, with limits of stability testing the most significant part of the CDP battery; for ENG studies, the best falls indicator was the ocular motor battery.

Trigeminal neurinomas.

Trigeminal neurinomas may produce atypical facial pain, loss of facial sensation, facial palsy, hearing loss, nystagmus, or vertigo, and thus may be confused with nasopharyngeal carcinomas or acoustic neurinomas. The diagnosis can be made by the clinical presentation together with radiographic features showing widening of the foramen ovale and/or smooth destruction of the anteromedial portion of the peterous apex. Tomography, pneumoencephalography, angiography, and other diagnostic procedures are sometimes helpful. Treatment is removal by transtemporal craniotomy and offers an excellent prognosis.

Eye tracking abnormalities in patients with cerebrovascular disease.

Ten patients with disequilibrium, ataxia, and cerebrovascular abnormalities were studied using computer aided eye tracking and vestibular function tests. The patients had severe abnormalities in smooth pursuit (decreased gain) and saccade tests (increased delay, decreased accuracy). Optokinetic responses were less affected. The gain of the vestibulo-oculomotor reflex was sometimes affected. Patients with eye tracking abnormalities frequently had symptoms of difficulty reading and watching television. When the lesion was asymmetrical, abnormal eye tracking tests usually pointed to the side of the lesion. Computer aided eye tracking tests are a useful adjunct to the evaluation of the patient with suspected vascular disease. They help to locate areas of central nervous system dysfunction, and produce an objective measurement of the severity of impairment. Conversely, when impairment of the smooth pursuit or saccade system is detected in patients being evaluated for disequilibrium, an assessment of the patients' cerebrovascular system should be considered.

Intractable vertigo--when not to operate.

Patients with episodic vertigo--or one severe episode of vertigo--may respond to vestibulosuppressive medications or operations on the labyrinth. In patients with constant incapacitating vertigo or disequilibrium, the clinician should suspect nonlabyrinthine disease. A careful history and physical and neurologic examinations will provide clues to underlying disease and direct the selection of further objective tests.

Vestibular evoked potentials in response to direct unilateral mechanical stimulation.

Evoked potentials produced by direct unilateral mechanical stimulation of the cannulated horizontal semicircular canal were investigated parametrically in anesthetized adult cats (40 mg/kg pentobarbital). Stimuli were fluid pressure pulses in a closed hydraulic system (no net flow), which was coupled to the lateral semicircular canal near the ampulla. Hydraulic waveform output and fluid pressure was monitored in situ via a parallel hydraulic circuit during experiments. Maximum fluid displacement at the level of the horizontal canal was 0.025 microliters. The intensity, duration, and presentation rate of the stimulus were varied during experiments. Field potentials were recorded differentially using subdermal electrodes, with the active lead in the region of the mastoid referenced to a distant nasal site. A total of 256 trials was accumulated for each run using an averaging computer. Evoked responses were physiologically vulnerable and reproducible, with little variance among animals. Response amplitude increased monotonically until saturation was noted and responses followed the temporal structure of the pressure wave. Polarity reversal with differing electrode placement suggests that the generator site lies within the mastoid. Further, intense broad-band acoustic stimuli and eighth nerve sectioning did not affect the vestibular evoked potentials, but could be shown to abolish the auditory evoked potentials. Results of these experiments support the notion that vestibular evoked potentials are related to the first derivative of the pressure pulse waveforms. Future experiments will be directed toward the assessment of vestibular physiology and pharmacology with this evoked response method.

Vestibular deficits in deaf children.

Considerable knowledge has been accumulated regarding acquired and congenital deafness in children. However, despite the intimate relationship between the auditory and vestibular systems, data are limited regarding the status of the balance system in these children. Using a test population of 15 children, aged 8 to 17 years, we performed electronystagmography testing. The test battery consisted of the eye-tracking (gaze nystagmus, spontaneous nystagmus, saccade, horizontal pursuit and optokinetic) tests, positional/positioning (Dix-Hallpike and supine) tests, and rotational chair tests. With age-matched controls, five children were tested in each of the following three categories: normal hearing, hereditary deafness, and acquired deafness. The children in the hereditary deafness category were congenitally deaf and had a family history of deafness. Those subjects in the acquired deafness category had hearing loss before the age of 2 years, after meningitis. Analysis of variance demonstrated significant differences between the two deaf groups and the control subjects in the gaze nystagmus test, saccade latencies, horizontal pursuit phase, and Dix-Hallpike and supine positionally provoked nystagmus. Also, significant differences were found in rotational chair gain and phase between the deaf and normal-hearing children. The children with acquired deafness exhibited the most profound results. In addition, there were significant differences in rotational chair gain between the acquired and congenitally deaf children. No differences were noted in horizontal pursuit gains, saccade accuracies, or saccade asymmetries. These preliminary data demonstrate that the etiologic factors responsible for congenital and acquired deafness in children may indeed affect the balance system as well. These findings of possible balance disorders in conjunction with the profound hearing loss in this patient population will have prognostic implications in the future evaluation, treatment, and rehabilitation of these patients.

Quantitative measurement of neurologic impairment in patients with multiple sclerosis.

Eleven patients with clinically diagnosed multiple sclerosis were simultaneously evaluated with history, physical, and neurologic evaluations and a series of objective neurophysiologic tests. Patients were then scored independently on clinical stage of their disease using a system based on symptoms in history or findings on physical or neurologic examination. Test scores on objective tests were compared with clinical scores with each evaluator. Patients with high test scores on clinical evaluation usually had high test scores on objective testing. Symptoms and physical findings were then correlated with abnormalities on objective tests. Objective abnormalities in visual evoked response and auditory evoked response on several occasions preceded the development of symptoms. All patients except for two had more than one abnormality on objective testing, suggesting a high likelihood that objective tests are helpful in the diagnosis of early-stage multiple sclerosis.

Scanning electron microscopic evaluation of age-related changes in the rat vestibular epithelium.

An ultrastructural study was performed to assess age-related changes in the vestibular end organs of Fischer 344 rats. The surfaces of the maculae and cristae from 3-, 12-, and 24-month-old Fischer 344 rats were observed by use of scanning electron microscopy. Age-related changes in the morphology of the vestibular neuroepithelium included a substantial loss of hair cells, as well as a reduction in the number of kinocilia and stereocilia on those that remained. These changes were greatest in the central upper regions of the three ampullae. In aged animals a greater area of the neuroepithelial surface was covered with microvilli, and in some instances, giant cilia were found among the microvillous surfaces. In contrast, there were few differences among the three age groups in the number and condition of hair cells in the saccules and utricles. The changes observed in the cristae may contribute to the age-associated impairment of vestibular function. If similar changes occur in human beings, these could in part account for the presbycusis observed in the elderly.

Computerized dynamic platform posturography.

Computerized dynamic platform posturography is defined in this technology assessment. The review discusses what computerized dynamic platform posturography measures, what the reliability and validity of the information are, and the uniqueness of the information provided. The clinical contribution and indications for testing are discussed. There are comments on future directions for research on computerized dynamic platform posturography and a summary and conclusion.

Opening and closing mechanisms of the larynx.

Opening and closing of the larynx are determined by the intrinsic and extrinsic muscles acting on the elastic forces in the tongue, pharynx, larynx, and trachea. The pharynx is opened or closed by two mechanisms: (1) Contractions of the cricothyroid and of the intrinsic muscles of the larynx open and close the vocal cords. (2) The false cords, ventricle, and true cords accordion open or close in a bellows mechanism. We conclude that the posterior cricoarytenoid opens the laryngeal airway. The cricothyroid together with the posterior cricoarytenoid accentuates this opening. The larynx is also opened by the geniohyoid, mylohyoid, sternothyroid, and middle constrictor. The thyrohyoid, cricothyroid, sternohyoid, and inferior constrictor close the laryngeal airway. Abnormalities in the soft tissues of the neck or of the innervation of the larynx, pharynx, and neck muscles may severely interfere with patency of the laryngeal airway. This occurs in such conditions as vocal cord paralysis, sleep apnea, multiple sclerosis, amyotrophic lateral sclerosis, spastic dysphonia, mandibular fractures or hypodevelopment, and cerebrovascular disease.