Biomedical subjects
A Benini
Publications and source records attributed to A Benini.
[Consciousness and self-consciousness as biological phenomena].
Can there be a generally accepted account of consciousness? Consciousness is the main aspect of the mind-body problem and has intrigued man since he achieved the awareness of his own existence and identity, i.e. since he became self-conscious. The topic of consciousness spans the efforts of the humanist and naturalist, psychological, theological and physiological thinking and research. During the last years an upsurge of both neurophysiological and philosophical interest has tried to outline the place of consciousness and self-consciousness in the order of nature. 'Without consciousness, the mind-body problem would be much less interesting. With consciousness it seems hopeless', Nagel (16) wrote. Our thesis, supported by a significant part of today's epistemology (which takes up the believes of several main physiologists from the last century up to now), is that the question of consciousness and the mind-body problem are systematically and scientifically insoluble because the mind is fated to remain intrinsically mysterious to us. Thus, even though consciousness and self-consciousness belong to the intrinsic characteristics of our everyday life and experience, they seem to remain indefinable and mysterious and, therefore, to fall outside the scope of rational inquiry, defying both scientific and philosophical investigation. This assumption does not mean that neurophysiological sciences are unfeasible, but it is just an inquiry into their methodologic and cognitive limits.
Behavior of antibiotics during human necrotizing pancreatitis.
The aim of the study was to verify whether antibiotics excreted by the normal pancreas are also excreted in human necrotizing pancreatitis, reaching the tissue sites of the infection. Twelve patients suffering from acute necrotizing pancreatitis were treated with imipenem-cilastatin (0.5 g), mezlocillin (2 g), gentamicin (0.08 g), amikacin (0.5 g), pefloxacin (0.4 g), and metronidazole (0.5 g). Serum and necrotic samples were collected simultaneously at different time intervals after parenteral drug administration by computed tomography-guided needle aspiration, intraoperatively, and from surgical drainages placed during surgery. Drug concentrations were determined by microbiological and high-performance liquid chromatography assays. All antibiotics reached the necrotic tissues, but with varying degrees of penetration, this being low for aminoglycosides (13%) and high in the case of pefloxacin (89%) and metronidazole (99%). The concentrations of pefloxacin (13.0 to 23 micrograms/g) and metronidazole (8.4 micrograms/g) in the necrotic samples were distinctly higher than the MICs for the organisms most commonly isolated in this disease; the concentrations in tissue of imipenem (3.35 micrograms/g) and mezlocillin (8.0 and 15.0 micrograms/g) did not always exceed the MICs for 90% of strains tested, whereas the aminoglycoside concentrations in necrotic tissue (0.5 microgram/g) were inadequate. Repeated administration of drugs (for 3, 7, 17, and 20 days) seems to enhance penetration of pefloxacin, imipenem, and metronidazole into necrotic pancreatic tissue. The choice of antibiotics in preventing infected necrosis during necrotizing pancreatitis should be based on their antimicrobial activity, penetration rate, persistence, and therapeutic concentrations in the necrotic pancreatic area. These requisites are provided by pefloxacin and metronidazole and to a variable extent by imipenem and mezlocillin.
[Long-term results of diskectomy and primary spondylodesis in treatment of lumbar disk hernia].
The indication for spine fusion in combination with diskectomy it neither clearly defined nor widely accepted. It largely depends on the specialist to whom the patient is referred. While orthopedists often perform primary fusions, neurosurgeons hardly ever do so, no matter what the nature of the complaint is. Therefore, the selection of the procedure seems to be a rather random choice. The question is not whether the combined operation or the simple disc excision is superior in itself, but which of the two should be chosen in a given case. For patients with disc displacement and radicular pain as the predominant symptom, undercutting hemilaminectomy and disc excision will generally yield satisfying results. The main indication for a combined operation is a history of instability complaints long before radicular pain caused by the disc displacement appears. Since the number of patients (of all age groups) that require a disc operation is ever increasing, the selection of patients suited for a combined operation is becoming more and more important, so as to bring down the number of secondary fusions for the treatment of invalidating low back pain after disc excision. The aim of our clinical research is to test the criteria for the selection of patients for the combined operation by taking into account both patients who underwent a combined operation and others whose postoperative condition was such as to require a secondary fusion within one year after diskectomy. In the majority of these cases, one can presume that the fusion should have been carried out on the occasion of the first operation. 26 (90%) out of 29 patients showed a good result three months after the combined operation; 25 (86%) were still satisfied four years later. This confirms that patients with a long history of low back pain as a symptom of instability--in addition to the recent symptoms of the herniation--and those with a significant dislocation of one vertebral body (retrolisthesis, spondylolisthesis and pseudospondylolisthesis), too, should be examined in view of a possible combined operation. However, the combined operation is needed in no more than about three to four per cent of all diskectomies.
[Postoperative results of intra- and extraforaminal lumbar disk hernia: microsurgical lateral approach with and without diskectomy].
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Selective decompression and translaminar articular facet screw fixation for lumbar canal stenosis and disc protrusion.
A technique is described for lumbar canal stenosis and disc protrusion combining safe and selective decompression and translaminar screw fixation. After experience with 166 cases from 1987 to 1991 we consider this technique particularly suitable for the treatment of lumbar spinal stenosis and also for the few cases of lumbar disc displacement which need a primary fusion.
[Lumbar spinal stenosis. An overview 50 years following initial description].
About 50 years after the first descriptions of lumbar stenosis and its most frequent symptom, neurogenic intermittent claudication, this update gives an overview of present-day concepts of the disease and of new experience in this area. Stenosis of the central and lateral lumbar spine is chiefly held to be one of the results of segmental degenerative instability throughout the several stages of spondylosis. The degenerative process of the spine has its starting point in regressive changes of the disc. This leads to instability of the motion segment, which explains the pathophysiological dynamics of the stenosis and its symptoms, including intermittent neurogenic claudication. Segmental instability is the crucial lesion causing all the changes in the degenerative process, which are not to be considered as separate entities but as part of the dynamics of the same disease. The spine's congenital anatomic individual patterns, which confirm the population thinking of the evolutionary biology (since they are different from one motion segment to the other) help to determine the outline of single cases. The disparity between radiological and clinical patterns is pointed out: severe stenosis may be asymptomatic or cause just modest monoradicular trouble as well as serious multiradicular deficit. The reason for the discrepancy is unknown. One must be careful to avoid surgery on a silent, purely radiological stenosis. Experience of more than 15 years confirms the uselessness of performing a complete laminectomy to achieve sufficient decompression. The author's method of selective decompression is described briefly. The English term "undercutting decompression" runs the risk of being misunderstood, since it is also used for rather destroying procedures. Finally, we point out that surgery for spinal stenosis must resolve both root compression and degenerative instability in the majority of cases. In most cases of lumbar stenosis, if decompression alone is performed, only the consequence, and not the cause of the disease, segmental degenerative instability, is treated. Osteophyte formation is an attempt by nature to stabilize the motion segments by stiffening its components. Spinal fusion tries to achieve the same effect. For most cases of spinal stenosis, we suggest our own technique, which combines safe and preserving ("selective") decompression according to Benini [1,7] with the translaminar screw fixation of Magerl [7]. In cases of degenerative spondylolisthesis, however, transpeduncular fusion is mandatory.
[Ilio-inguinal and genito-femoral neuralgia. Causes, clinical aspects, therapy].
Entrapment neuropathy of the ilioinguinal and of the genito-femoral nerves is a rare but sometimes very painful complication of abdominal surgery (herniorrhaphy, appendectomy, nephrectomy, gynecological surgery, removal of bone from the inner table of the iliac crest, etc.). Sometimes symptoms develop during a normal pregnancy or delivery. Spontaneous entrapment of the ilioinguinal nerve as it passes through the Mm. obliquus internus and transversus abdominis has also been observed. We have operated such a case. The causes, features and the associated findings of entrapment neuropathy of the two nerves are pointed out. In the frequent cases attributable to previous surgery the retroperitoneal resection of the nerves is advocated instead of a local revision, which is usually unsuccessful due to the impossibility of finding and restoring the fine nerves in a dense scar.
[Clinical aspects, pathophysiology and surgical treatment of lumbar spinal stenosis].
All the forms of spinal stenosis and spondylosis and some cases of lumbar disc displacement are considered as part of a degenerative process with a starting point in regressive changes of the disc. This leads to instability of the motion segment, which explains the dynamics of the pathophysiology and of the troubles of lumbar spinal stenosis, including the intermittent neurogenic claudication. Signs, symptoms and radiological findings of the unstable lumbar spine relating to spinal stenosis are discussed. Finally, we point out that the right surgical procedure has to solve the disturbances of root-compression and unstable spine as well. We describe a procedure which we prefer as the safest and most efficient, using selected decompression and translaminar joint screws.
[Meralgia paresthetica. Pathogenesis, clinical aspects and therapy of compression of the lateral cutaneous nerve of the thigh].
The lateral femoral cutaneus nerve is vulnerable to entrapment neuropathy where the nerve passes through the lateral end of the inguinal ligament. At the end of last century the clinical manifestation of this condition has been termed Meralgia paresthetica. It is a syndrome of pain, numbness, itching or other dysesthesias in the anterolateral aspect of the thigh, where perception of pinprick and touch often is diminished or lost. 36 patients were operated upon over a period of 17 years. After a short historical review, pathogenesis, clinical aspects and therapy of the syndrome are discussed. The correct surgical therapy is not the resection of the nerve, but its decompression, similar to the therapy of the entrapment of the median nerve at the wrist.
[Multiple intracranial and spinal meningiomas].
Meningeomas are regarded as benign tumors that as a rule can be totally removed. The great prevalence of the benign types of meningeomas does not exclude their recurrence. In some cases (6-8% in the recent literature) a solitary globular tumor represents only the most visible actual growth in context of a systemic tumoral disease spreading over a wide area of arachnoid with simultaneous or delayed growth. In a series of 188 patients operated in St. Gall because of meningeomas, 13 (8%) have multiple simultaneous or delayed tumors, in one case in the spine, without neurofibromatosis. Several operations had to be performed on each patient. The prognosis quoad valetudinem is eventually worse than a solitary tumor. We present a detailed description of our cases and a résume of the literature.
[Rehabilitation following surgery of the lumbar spine: herniated disk, spinal canal stenosis, spondylodesis].
The value of the physical therapy after the operation at the lumbar spine is unquestionable. But the treatment should be chosen individually, according to the kind of operation, the patient's age, the state of the spine, but also according to the social and familiar conditions. We present our criteria of choosing the adequate treatment. In times of sharp increase of the medical costs such frequently, rather costly treatment must only be prescribed when inevitably indicated.
[Lateral intra- and extraforaminal lumbar disk hernia: clinical aspects and therapy].
Lateral lumbar disc herniations in or beyond the intervertebral foramen account for nearly 10% of all lumbar herniations. They affect the nerve root exiting at the same level. Such a lateral herniation of disc L4, for example, would impinge on nerve root L4, while a common herniation inside the spinal canal would compromise root L5. Myelography most often provides false-negative results. High-resolution CT scanning is completely accurate in demonstrating these lesions and therefore is considered the diagnostic method of choice. We review the anatomo-pathological and clinical features and propose guidelines for radiological examination of these herniations. Finally, the lateral microsurgical approach to the intervertebral foramen is described. It permits exposure of the lateral disc prolapse without opening the spinal canal or performing facetectomy.
[Pathophysiology of vertebrogenic lumbar and leg pain (pain, sensory disorders, paralysis): review related to clinical aspects].
Vertebrogenic pain is attached to several types of spinal pathology: degenerative diseases of spinal structures, disc displacement with or without radicular disturbances, primary or metastatic tumors, inflammatory diseases. Present views on the pathogenetic mechanisms of the various types of vertebrogenic local radicular and pseudoradicular pain are discussed. Current opinions about pathogenesis of radicular deficit of sensibility and physical force are also presented.
[Lumbar segmental instability, spinal canal stenosis, intervertebral disk prolapse. Pathophysiological, clinical and surgical aspects].
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[Lipoma of the interventricular septum: its diagnosis and treatment].
We describe a case of left ventricular intramyocardial lipoma in a patient symptomatic for chest pain and syncope. The two-dimensional echocardiographic investigation showed a hyperechogenic mass inside the interventricular septum; presence of the mass was confirmed by CT scan and nuclear magnetic resonance imaging. In our experience only the CT scan was useful to clearly identify the histologic characteristics of tissue. The patient underwent successful surgical removal of the mass and the histologic examination revealed normal fat tissue.
[Acute lumbago. Guidelines for clinical practice].
Acute low-back pain without sciatica, with some spread of discomfort to the region of the sacroiliac joint, to the outer part of the buttock as well as to the lateral and the back part of the thigh, is a unifying symptom of a very common clinical syndrome whose exact underlying cause remains often uncertain. Most patients fall then into the category of nonspecific low-back pain. Probably the pathogenesis is not uniform, and the pain can arise from a variety of structures (muscles, ligament, spine). Pain which persists after 3 to 4 days should warn the clinician that a serious pathological condition may be present which requires a new approach to diagnosis and treatment.
[Segmental instability and lumbar spinal canal stenosis. Theoretical, clinical and surgical aspects].
Clinical, radiological, surgical and experimental observations make it possible to construct a rational theory of the segmental lumbar instability which explains the pathogenesis of spondylosis, of stenosis and of several cases of disc displacement as well. This theory helps us to choose the right surgical procedure. Spinal stenosis, degenerative spondylolisthesis and some cases of disc displacement are seen as part of a degenerative process with its starting point in regressive changes of the intervertebral disc and lateral joint. This leads to a marked instability of the affected mobile segment. Signs and symptoms of unstable lumbar spine are discussed. In such cases, if decompression of the roots by laminectomy, facetectomy or discectomy is performed without fusion, the consequences are usually treated but not the main cause of the trouble, namely the instability. Finally, we describe a procedure which we prefer as the safest and best of all, using selected decompression by means of joint screws (spondylodesis) as suggested by F. Magerl (41-44).