Biomedical subjects
Publications and source records attributed to P A Neff.
This study was designed to examine clinically the accuracy and reproducibility of occlusal contacts made by a computerized device (the T-scan) in ten asymptomatic subjects. The results showed 100% accuracy and reproducibility for all contacts in all subjects. A great advantage of this instrument over silk marking ribbon is that it not only records contacts but can also analyze the timing and force of each contact.
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Computed tomography represents an effective and highly automated method to display biomedical data from many sources. It has a number of advantages over previous reconstruction methods, particularly the ability to automatically locate object-boundary outlines and produce shaded three-dimensional images of reconstructed data. A three-dimensional reconstruction of the temporomandibular joint was performed successfully on five cadaver heads using the Phillips Tomoscan and IP5000 image processor. The program used in this study of the temporomandibular joint is divided into five distinct steps: data gathering, rotation and projection, filtering, smoothing, and shading. Comparison of this type of data is important in the study of the normal and abnormal anatomy of the temporomandibular joint. Similarly, quantitative data obtained from reconstructed computed tomograms can be used to study normal anatomy in vivo and to examine the effects of various treatment modalities on the size and morphologic characteristics of tumors and other pathologic entities.
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The etiology of TMJ syndrome is usually multifactorial. The anatomic structures which may be involved are the dentition, the masticatory muscles, and the TMJ itself. The etiologic region is usually the dentition and its occlusal relationships. The symptoms are usually minimized during treatment, and a high percentage are eliminated. Among the diagnostic symptoms, the deviation of the mandible to the opposite side from the occlusal interference is the most frequent objective symptoms. The lateral pterygoid muscle is usually involved if the patient has (1) occlusal interference and (2) lateral deviation of the mandible. The clinical response in this study to the occlusal splint and occlusal adjustment indicate that 88% of muscle involvement improved and that 84% of the TMJ syndrome responded favorably to the occlusal splint.
Audiometric and tympanometric tests were used to identify patients with myasthenia gravis, a disease characterized by skeletal muscle weakness. Middle ear muscle reflexes in untreated myasthenics were found to be typically depressed or absent. Hearing was abnormally sensitive for some frequencies and middle ear pressures were often negative. Following drug administration, patients who were responding well to medication had more sensitive reflex thresholds, less sensitive hearing, and were able to equalize middle ear pressures. Tympanometric measurements have proved to be of value in the diagnosis of myasthenia and in monitoring the effects of therapy.
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Tympanometric measurements are versatile and accurate when more than one type of ear disease is present. Three cases are presented where information from tympanometry beyond that derived from otological and routine audiological testing yielded accurate diagnoses. A patient with a history of middle-ear disease presented with a sensori-neural loss. Measures of static conductance correctly identified the problem as stiffness of the ossicular chain. An infant with unilateral congenital atresia and questionable hearing in her normal-appearing ear was determined to have serous otitis media by tympanometry and reflex testing. The course of the disease was monitored and reversed. A 17-year-old female suffered a basal skull fracture with a sudden conductive hearing loss. Low conductance and high impedance correctly identified loss of mobility of the ossicular chain which was confirmed surgically. These three cases illustrate the advantages of tympanometry in making rapid, accurate, objective measurements involving complex diagnoses of middle-ear function.
Myasthenia gravis can be a difficult diagnostic and therapeutic problem. Our study on six patients consisted of pure-tone audiograms, tympanometry, and acoustic reflex tests. Positive findings in the myasthenia gravis patients prior to medication included hyperacusis and increase in the intensity of sound required to elicit an acoustic reflex. Following medication, the hyperacusis lessened and the intensity of sound required to elicit the acoustic reflex decreased. During follow-up of two of the patients we encountered cholinergic (overdosage) crisis in one patient and myasthenic (underdosage) crisis in the other patient. Muscle weakness can be a common factor in both conditions. The acoustic reflex test can differentiate between the two types of crises. We believe audiotympanometric tests can aid in diagnosis and treatment of myasthenia gravis patients.
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