Biomedical subjects
Publications and source records attributed to M Koris.
Resurfacing total elbow arthroplasty is occasionally unstable. Instability may be related to insufficiency of the ligaments or improper tensioning and implant positioning at the time of surgery. Ligament reconstruction has produced mixed results; however, attempts to reconstruct the ligaments are probably worthwhile because conversion of a freshly cemented resurfacing implant to a semiconstrained hinge is very challenging.
CLINICAL RELEVANCE: Low back pain from lumbar spinal stenosis is a significant source of morbidity, especially among the elderly population. Accurate diagnosis is imperative for effective treatment to be initiated. This paper presents a quantitative method for the evaluation of spinal stenosis that, when used in conjunction with CT and MRI, may greatly aid the clinician in the diagnosis of this debilitating condition. OBJECTIVE: Precise clinical tools for the diagnosis of spinal stenosis are severely lacking. Low back pain and dysfunction derived from lumbar spinal stenosis is a significant source of morbidity, especially among the elderly. Despite its importance, there has been little progress made towards establishing valid, quantitative criteria for the diagnosis of spinal stenosis. We present a new quantitative tool for the diagnosis of lumbar stenosis, the Stenosis Ratio (SR). METHODS: CT scans and MRI scans of 43 patients presenting with clinico-radiographic evidence of lumbar stenosis were used. The patient group consisted of 13 males and 30 females between the ages 49 and 82 with average age of 67. CT and MRI/scans of 43 patients were digitized and computer analyzed. Measurements of SR, defined as the ratio of the cross-sectional dural area of the motion segment to that of the stable segment, were established for L3-L4, L4-L5 and L5-S1 stenotic levels and compared to SR values for a non-stenotic (internal control) level, L2-L3. RESULTS: The L4-L5 level had the lowest SR value of 0.71, followed by 0.74 at L3-L4, and 0.87 at L5-S1. Ninety-five percent confidence intervals of (0.66, 0.81), (0.62, 0.81), and (0.73, 1.00) were found for SR values at levels L3-L4, L4-L5 and L5-S1 respectively. The SR at L2-L3 had a mean value of 1.37 with a 95% confidence interval of (0.970, 1.78). At all levels, SRs were significantly lower for the spinal stenotic L3-S1 levels than for the L2-L3 control as confirmed by a student's t-test (p < 0.05). CONCLUSION: In a select population of patients with spinal stenosis confirmed by neuroradiological assessment, values of SRs were consistently and significantly lower than controls. We believe that measurements of SRs may provide reproducible quantitative measures for the diagnosis of spinal stenosis. SR values below the 95% confidence limit may be indicative of lumbar stenosis. Through the use of ratios, inherent differences in patient size are controlled for, thus allowing comparison of values between patients and treatment groups and effective clinical diagnosis of spinal stenosis.
K.O. Johnson reviews the architecture and low level neural mechanisms by which the external environment is transduced and encoded into the neural system, summarizing work that correlates neurophysiological and psychophysical testing with isolation of sensory components. The slowly adapting Type I afferent system is responsible for form and texture perception; the rapidly adapting afferent system is responsible for motion perception; and the Pacinian corpuscle system is responsible for vibratory sensation. R.R. Riso reviews the current level of understanding of the major factors to be considered in the design of a functional neuromuscular stimulation (FNS) grasp controller that uses cutaneous sensory feedback to detect slip. The elegant natural control scheme that matches the ratio of grip and lift forces to frictional conditions provides a model for implementing a slip-based control algorithm. D. Popović discusses the possible use of recordings from more proximal peripheral nerves to determine needed information for synthesis of locomotion. The discussion is illustrated with an animal model where rule-based closed-loop control is used for the ankle joint during treadmill locomotion. Neural signals from the tibial and superficial peroneal nerves were employed to substitute for missing afferent input from cutaneous and proprioceptive sensors. The feasibility of more invasive intraneural electrodes for distinguishing sensory from motor information in mixed nerves is considered. M. Koris raises surgical and functional issues relevant to developing clinical FNS systems. C. Van Doren suggests alternative neurophysiological and engineering approaches.
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A diagnostic test combining the sensitivity of the Semmes-Weinstein monofilament measurement and the specificity of the wrist flexion provocational test has been evaluated in a group of 21 patients (33 hands) with electrodiagnostically verified carpal tunnel syndrome and 30 asymptomatic hands (controls). Semmes-Weinstein monofilament testing consisted of several sensory threshold measurements obtained by the application of force-calibrated Semmes-Weinstein monofilaments to each digit in the hand with the wrist in neutral position. The quantitative provocational diagnostic test employed Semmes-Weinstein measurements obtained with the wrist both in the neutral and flexed positions. The sensitivity (82%) and specificity (86%) of the combined test were calculated. It was more sensitive and specific than the wrist flexion test alone and more specific than the Semmes-Weinstein sensibility test. The combined test is recommended as the most accurate and sensitive quantitative clinical test for median nerve compression evaluated by the authors to date.