Biomedical subjects
Publications and source records attributed to M Manfredi.
A low-cost microcomputer with standard peripheral is used to examine the central visual field up to 20 degrees. The test is executed in five to eight minutes, and the map is displayed on a television screen or printed out to quantitative analysis. A very simple training is required for the technician and patient.
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Tooth pulp stimulation may evoke reflex responses in the orbicularis oculi, temporal, masseter and retronuchal muscles, which may to a varying degree contaminate the cortical evoked responses. The use of repetitive stimulation reduces the amplitude of the cortical responses but avoids the onset of the majority of the muscle reflexes. The appearance of a silent period in the temporal muscle is hard to avoid and it alters the signal recorded from S1 for the first 60-70 msec. In the center-posterior leads, more protected from the EMG signal of the temporal muscle, a first negative deflection is recorded at 43 msec in 60% of subjects.
Tooth pulp evoked potentials (TPEPs) and subjective evaluation of painful dental stimuli have been recorded in healthy volunteers. The amplitude of TPEPs late components and the subjective rating have been studied in different psychological states, by the expectancy of pain with a placebo and by providing foreknowledge of stimulus timing with self-stimulation. The placebo induced a significant depression of TPEPs and pain sensation. The amplitude of TPEPs evoked by self-delivered stimuli was reduced but the subjective report remained unchanged. These results demonstrate that TPEPs are not a stable correlate of the pain perceived or of the painful input.
The corneal and blink reflexes were evaluated in 20 normal subjects and in 30 patients with motor deficits secondary to unilateral hemispheral lesions of vascular origin. In the normal population there were no differences between subjects below and subjects above 50 years of age. In the patients the reflex evoked by electrical stimulation of the cornea of the clinically affected side was depressed in 24 out of 30 cases. The depression mainly affected the afferent branch of the circuit, which triggers both homolateral and contralateral orbicularis oculi discharge (afferent abnormality). In three cases the depression was exerted concomitantly on the efferent branch (afferent and efferent abnormality) and only in one case was it limited to the efferent branch (efferent abnormality). The late R2 component of the blink reflex was depressed in 15 out of 30 patients. The early R1 component was slightly facilitated on the affected side. The changes of the corneal reflex and of the R2 component of blink reflex were similar, but the blink reflex had a greater safety factor. The patients with an abnormal corneal reflex had more extensive damage than had the patients with normal corneal response, as shown by computer tomography, but the site of the lesion was comparable in the two groups. Conduction through the brain stem circuits mediating the orbicularis oculi response is normally under pyramidal facilitatory influences while facial motoneurons are subjected to pyramidal inhibition. After pyramidal damage the transmission of impulses in the brain stem was slowed down, ultimately to a degree that abolished the reflex. Removal of pyramidal inhibition on facial motoneurons is probably the basis of the slight facilitation of the R1 component of the blink reflex.
A study was conducted in 113 children with recurrent attacks of rhinopharyngitis, a frequent affection treated in ENT practice, to determine a classification and establish the etiopathogenicity of the disorder. Children were divided into two groups according to age, and clinical, radiologic, bacteriologic, biologic, and histologic data analyzed. An allergic or immunity deficiency origin could be confirmed in some cases, but etiopathogenicity was impossible to determine in many individual cases.
1. The effects of an orally administered single dose of placebo, acetylsalicyclic acid (ASA) and (d,1)-6-chloro-a-methyl carbazole-2-acetic acid (carprofen) have been evaluated on an experimental pain model by electrical stimulation of dental pulp in man. 2. ASA and carprofen showed a significant analgesic action, while placebo was ineffective. 3. Analgesic activity of ASA and carprofen was similar. The two drugs were ineffective in modifying the pain threshold; on the contrary, the tolerance to the strongest painful sensation was significantly increased.
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The "Prune-Belly" syndrome is rare and sporadic. The authors describe three siblings of both sexes with the syndrome. Good results in two of the patients arouse new interest in surgery for this syndrome. The possibility of prenatal diagnosis is discussed.
A 16-year-old boy had congenital absence of pain sensitivity and no impairment of other sensory modalities. Routine electrophysiologic investigation showed no abnormalities. The threshold and latency of electrically elicited corneal reflex and cortical potentials evoked by tooth pulp stimulation were normal, but suprathreshold electric stimulation of corneal mucosa and dental pulp, as well as electric stimulation of dorsal roots, did not elicit pain. The total CSF opioid activity was raised. However, naloxone hydrochloride administration failed to reverse the analgesia. The axon reflex to intradermal injection of histamine dihydrochloride was absent. Cutaneous nerve branches showed unspecific changes affecting part of unmyelinated axons. most of the unmyelinated as well as the myelinated axons were normal. We consider the case an example of congenital indifference to pain.
A simple method for bipolar electrical stimulation of the tooth pulp for evaluating pain modulating procedures is described. Stimulation selectivity has been studied by means of cortical evoked potentials before and after gum anaesthesia. Results obtained by constant current and constant voltage stimulation have been compared. Constant voltage stimulation has proved to be more stable in time. This technique is able to differentiate the analgesic effect of a single dose of i.v. lysine acetylsalicylate from saline. Threshold sensation was judged as painful by about half of the subjects.
The corneal reflex can be elicited in humans by electrical stimulation of the cornea. This method is harmless and allows precise quantification of the reflex response. In 18 patients with trigeminal lesions, the reflex was abolished or significantly altered on the diseased side in all cases. Measurement of the threshold is the most significant characteristic.
A Multielectrodic EMG analysis program is developing. The purpose is to get as short as possible the main EMG parameters (amplitude, duration, frequency) of most motor units, and to reach an estimation of the anatomical extent of single units. According to the muscle extent a variable number of electrodes are inserted crosswise the fibers. EMG signals are simultaneously recorded on a multichannel AMPEX FR1300 and then off-line processed by a 21MX HP minicomputer connected with a 5Mbytes disc drive. Some technical problems had to be solved:channel amplification adjustment to avoid any difference among preamplifiers calibration and filtering, severe hum filtering of main power that is specially strong in nultielectrodic recording systems, the need of sampling at the same Nyquist time the signals of different channels. The computer is instructed to identify the "sinchronous" units i.e. the motor units recorded from more than one channel. These motor units are detected, counted and deleted from all the channels, except the one where they show the maximum amplitude. The percentage of these sinchronous units depends upon the interelectrodic distance and their anatomical area, thus it can support an evaluation of motor unit anatomical spread.
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Explore the source record for details and available documents.